One of the most efficient and environmentally friendly methods for preventing a landslide on a slope is to vegetate it. Vegetation-pervious concretes have a promising potential for soil protection. In this study, the vegetation-pervious concrete with low alkalinity was developed and studied. Combined with a grid beam structure system, the stability and strength between the vegetation-pervious concrete and base soil are believed to be enhanced effectively. For improving plant adaptability, the alkalinity of concrete can be decreased innovatively by adding a self-designed admixture into the cement paste. The effects of the admixture content on alkalinity and compressive strength of the hardened pervious concrete were investigated using X-ray diffraction (XRD) and compression test, respectively. Meanwhile, the permeability of the vegetation-pervious concrete was studied as well. Through comparing with ordinary pervious concrete, the effect of low alkaline pervious concrete on vegetation growth was investigated in a small-scale field for ten weeks. The test results indicated that the alkalinity of the cement samples decreased with the increase of admixture content, and the vegetation grew successfully on previous concrete. By increasing the admixture content to approximately 3.6%, the compressive strength of pervious concrete was more than 25 MPa. Cement based materials, such as concrete and cement mortar, are one of the most widely used building materials in world. With development of science and technology, concretes with special functions were prepared and developed ,2. More Slopes are the most common landforms on Earth. Excluding natural slopes, large-scale infrastructure and urbanization constructions have created a large number of man-made slopes in China ,4,5. UnpContinuous grid beam structures made of concrete have been used for many years in China to stabilize the natural and man-made slopes. Generally, this slope stabilization structure is called “Grid Beam”. However, the soils within the frame of grid beams are vulnerable to be washed away during heavy rain. One of the fastest and most environmentally friendly methods for preventing or remedying a runoff on a slope is to vegetate it . Many reIn practice, surface drainage can successfully reduce the runoff of a slope . Soil-ceThe ideal vegetation-pervious concrete consists of a large number of connected pores, which are filled with suitable materials that contain moisture and nutrients needed by plants. The plant roots are able to grow and extend through the pores to form an integrated system of concrete and plant matter. For application to the construction industry, several important characteristics should be considered: (1) vegetation-pervious concrete must feature high strength and relatively good durability ,16, and 2 that accounts for 20%–25% of hardened cement samples. Thus, the concrete is found to be strongly alkaline, with pH value up to 12–13 [−) and molecular sieve effects based on their studies on the formation and manifestation of alkaline solution in concrete pores through a series of means such as physical, geotechnical and biochemical methods. They also proposed more than ten methods e.g., using a modifier to not only adjust the pH value in Portland cement concrete pores to 7–7.5, but also to increase their buffer capacity, which can be defined as the maximum amount of either strong acid or strong base that can be added before the occurrence of a significant change in pH. Consequently, the concrete was found more favourable to plant growth, and its durability was also improved.However, vegetation-pervious concrete, which is suitable for vegetation growth while maintaining water drainage and mechanical properties, is challenging to be obtained. The greatest challenge is the vegetal properties of this type of concrete. The hydration reaction of cement generates Ca(OH)to 12–13 ,20. Due to 12–13  and highto 12–13  for greeto 12–13  proposedAlthough conventional methods can reduce the alkalinity of pervious concrete, the main problem identified in current research of vegetation-pervious concrete is that the conventional methods of reducing alkalinity tend to weaken the physical and mechanical properties of vegetation-pervious concrete when compared to the control concrete. Therefore, the primary goal of this study was to propose a method to reduce the alkalinity of pervious concrete for vegetation at the same time maintaining the mechanical properties of the concrete. Chemical and mineral admixtures have been extensively used to adjust or modify the properties of fresh and hardened concrete . In thisIn this research, the method of adding a self-designed admixture, which is named Reducing Cement Alkaline (RCA), was employed to reduce the alkalinity of concrete. Portland cement (PC) Type 42.5R, which conforms to British Standard BS EN 197-1 CEM I , was use3 (about USD 43/m3). Other researchers who are interested in similar area can do a cost benefit analysis based on the cost information and their project characteristics.In China, at present, the costs of the vegetation-pervious concretes produced by manufacturers are less than RMB 300/mIn this study, the procedures for sample preparation are described as follows. First, part of the mixing water was added into the coarse aggregate and stirred until the gravel surface was wet. Second, the cement was added and the mixture was stirred for approximately 30 s to allow the gravel surface being coated with a layer of cement paste. Third, the remaining mixing water and the admixture RCA were added. The mixture was then stirred continuously for about 3 min, until the cement paste coating on gravel thickened. Finally, the mixture was cast into a 100 mm × 100 mm × 100 mm mould in three steps. Moulds were filled with the mixed concrete up to one-third of the height of the mould and subjected to 25 times hand tamping. The same procedure was applied for the two-third and complete fill-ups. The vegetation-pervious concrete was removed from the mould after 24 h and cured for 28 days in a controlled environment , which is similar to the process for conventional concrete.A control mix and four hardened cement paste mixes with different proportions of the admixture RCA  were analysed. The water/cement ratio was 0.35. Cubes with a size of 100 mm were used for studying the compressive strength at 4, 7, and 15 days after standard curing in a controlled environment . The compressive test was performed according to the China national standard GB/T 50081-2002 . Three sIn this study, different properties of vegetation-pervious concretes were investigated. D) × 100 mm (H). The test procedure for the porosity of vegetation-pervious concrete was as follows:(1)M1) was measured.The sample was dried in an oven at 60 °C until the mass did not change, and the mass ((2)Vcylinder) was calculated.The diameter and height of the sample were measured, and the volume of the sample ((3)M2) was measured by a hydrostatic balance method as shown in The samples will be soaked in water for 2 h for getting a saturated station. The mass of saturated sample ((4)P) of the sample was calculated using the following equation:P is the porosity of the sample, %; M1 is the sample mass in air, gram; M2 is the mass of the sample in water, gram, ϱwater is the water density, g/mm3; and Vcylinder is the volume of the sample, mm3.The porosity (Sample used in this test is cylinder with the dimensions 100 mm ((1)D) and thickness (L) of the cylindrical samples were measured twice using callipers, and the data were averaged to 0.1 cm. Then, the sample surface area (A) was calculated.The diameter ((2)The sidewall of the cylinder was sealed by a watertight material (epoxy). The epoxy was brushed on the sidewall of the samples evenly and the thickness of epoxy was more than 1 mm. The water was allowed to penetrate the sample from the upper and lower surfaces. After the watertight material was cured, the sample was placed in water to a water-saturated state before the test.(3)t (seconds) and quantity of water outflow (Q) were measured three times, and the data were averaged.The sample was not removed from the water until the permeability test was performed. The sample was connected with the permeable tube shown in (4)H), which was accurate to 0.1 cm, between the water level in the water tank and the water level of the permeable tube was measured by a rule.The distance ((5)K) of the sample can be calculated as the following equation:K is the permeability coefficient of the tested sample, mm/s; Q is the quantity of water outflow within time t, mL; L is the thickness of the sample, mm; A is the upper surface of the sample, mm2; H is the distance between the levels, mm; and t is the testing time, s.Permeability coefficient  were used to measure strains for calculating elastic modulus. Before sticking the strain gages, the two sides of the cylinders needed to be flattened using cement paste, and the sizes of flat areas were about 60 mm length and 20 mm width, and the position of the areas was the centre of the cylinder height. After the cement paste hardened, the strain gages were adhered at the flat areas. After the compression test, the hardened cement pastes coated on the aggregate surfaces of the failure samples were collected and ground into powder to measure the amount of chemical elements in the hardened cement paste samples by using X-ray Diffraction (XRD). A Mercury AutoPore IV 9500 injection apparatus  was used for the pore analysis of the plain cement paste, and the XRD analysis was conducted using a DX—2500 X-ray diffractometer . These tests involved a Cu target, 3 kW of power, 0.03° per step and a scanning range from 5° to 70°. To avoid carbonation during grinding the cement pastes, the samples were ground in 100% alcohol and dried in a vacuum oven at 60 °C for 48 h.L) × 400 (W) × 150 mm (H). The pores of concrete specimens were grouted with mulching material (nutrient soil), which was able to retain water and fertilizer, as shown in In this study, the vegetation-pervious concrete with 3.6% admixture RCA was chosen to conduct the vegetation test, and a pervious concrete without admixture RCA was used as a control sample. All concrete specimens were employed as vegetation beds and exposed to a natural environment. In the experiment, the vegetation-pervious concrete cubes were placed in a wooden box with the dimension of 400 . The higher strength and larger strength range of vegetation-pervious concrete yield an extensive range of applications for slope protection. Specifically, when the admixture content was 3.6%, the strength substantially increased to 25.2 MPa, which is much greater than the strength range of 5–15 MPa, as reported in the previous studies ,37,38,39Elastic modulus and compressive strength are the two important properties used for the design of pervious concrete for slope protection. Although the effect of aggregates on compressive strength has been analysed, few studies have revealed the effect of admixture on the static modulus of elasticity of vegetation-pervious concrete. Static modulus can influence the deformation of vegetation-pervious concrete directly. As shown in 2) in the hardened cement samples. The intensity of the Ca(OH)2 crystal peaks in the XRD spectra was employed as an index to characterize the alkalinity of the sample. 2 in the mixes for various curing times. The peaks in the XRD curves correspond to the mineral Ca(OH)2, and the intensity of the main peaks reflect the Ca(OH)2 contents in the cement samples.In this study, the alkalinities of hardened cement pastes from concretes with different admixture dosages were measured by XRD analysis. The levels of alkalinity were compared based on the amount of calcium hydroxide (Ca(OH)The alkalinity of all cement paste mixes with admixture was initially lower than that of the cement paste mixes without admixture. The cement paste with admixture contents between 1.2% and 3.6% showed a decreasing trend in alkalinity with days of curing, and their alkalinity were even much lower than that of control samples after curing for 14 days see . HoweverBased on the above results and observation, it can be known that when the admixture content between 2.4% to 3.6% is added, the strength of vegetation-pervious concrete can be improved, whereas its alkalinity can be reduced.The growing status of Bahia grass planted on the surface of ordinary vegetation-pervious concrete (without admixture) over ten weeks of exposure to the natural environment is shown in As shown in these photos, Bahia grass started germinating typically one week after sowing; however, the grass began to wither after three weeks and died after five weeks. It is interesting to note that some Bahia grass and weeds were found to grow well in the surrounding soils or within the gap of concrete blocks in five weeks. After the ten-week observation, the plants eventually failed to grow on the concrete surface. Neither the soil in the pores of the concrete nor the soil above the concrete surface was suitable for plants because the alkalinity of this soil was higher than the alkalinity of the surrounding soil. This conclusion can be supported by XRD test results in 2) among RCA additive chemically reacted with an alkaline substance (Ca(OH)2) to generate calcium silicate hydrates (C–H–S), which resulted in the decrease of alkalinity of the vegetation-pervious concrete and formation of a dense layer that effectively prevented the alkaline substance dissolving out from the concrete to the soil.As shown in (1)The compressive strength and elastic modulus of the vegetation-pervious concretes increased with the increase of admixture, but the effect of admixture on elastic modulus was less significant compared to the compressive strength. The result showed that vegetation-pervious concretes with admixture showed lower alkalinity and higher strength. Therefore, the admixture used in this study was not only able to decrease the alkalinity of cement effectively but also improve the strength to as high as 25.2 MPa at an admixture content of 3.6%.(2)In comparison, the alkalinity of the cement cube samples with admixture was lower than that of the cement paste mixes without admixture. When the admixture content between 2.4% to 3.6% was added, the strength of vegetation-pervious concrete was found improved, whereas its alkalinity was reduced.(3)Compared with a traditional method, the developed vegetation-pervious concrete slope protection method can be adapted for different vegetation requirements and slope gradients by adjusting alkalinity and porosity of the concrete.(4)Based on the test results of alkalinity, permeability coefficient and mechanical properties of the studied concretes, the vegetation-pervious concretes have demonstrated their potential suitability when using in continuous grid beam structure for slope protection.This paper demonstrated the use of an admixture method to reduce the alkalinity of vegetation-pervious concrete to create favourable conditions for vegetation growth. A vegetation-pervious concrete for soil slope protection was developed. Based on the results presented here, the following conclusions were drawn:


Wain LV, Shrine N, Miller S, et al. Novel insights into the genetics of smoking behaviour, lung function, and chronic obstructive pulmonary disease (UK BiLEVE): a genetic association study in UK Biobank. Lancet Respir Med 3: 769–812015; —In this Article, in the upper section of Table 2 (Extremes of FEV1), the p values and 95% CIs for signals of association are genomic control corrected for the result in the smoking status stratum for which the signal was most highly significant, and uncorrected for the alternate smoking status stratum. This has been clarified in the column header and added to the footnote of table 2, and clarified in the header of Supplementary Table 18 of the appendix. These corrections have been made to the online version as of Dec 30, 2015.


In the assessment of reproducibility, almost 80% of individuals were correctly classified and less than 3% were misclassified (weighted κ of 0.73), while a correlation coefficient higher than 0.85 was obtained. Both in the assessment of validity and of reproducibility, a Bland–Altman index of 6.7% was recorded . Validation of the IRONIC-FFQ revealed a satisfactory level of validity and positively validated reproducibility.The aim of the study was to analyse a designed brief iron dietary intake questionnaire based on a food frequency assessment , including the assessment of validity and reproducibility in a group of 75 Polish women aged 20–30 years. Participants conducted 3-day dietary records and filled in the IRONIC-FFQ twice (FFQ1—directly after the dietary record and FFQ2—6 weeks later). The analysis included an assessment of validity (comparison with the results of the 3-day dietary record) and of reproducibility (comparison of the results obtained twice—FFQ1 and FFQ2). In the analysis of validity, the share of individuals correctly classified into tertiles was over 50% (weighted  Anemia has been indicated by the World Health Organization (WHO) as one of the main diet-related health risks, while iron deficiency was stated to be among the most important contributors to the global burden of the disease . It is iA 50% reduction of anemia in women of reproductive age is formulated as the WHO’s global target for the year 2025 . MoreoveCurrently, inadequate iron intake is observed in the case of 16%–19% of young Polish women and it is a group of the highest frequency of inadequate intake , as in sTo reduce anemia prevalence, it is necessary to conduct screening in at-risk groups and to find deficient individuals, as was recommended by the National Screening Committee of the United Kingdom . SimultaThe aim of the presented study was to assess the validity and reproducibility of the designed iron dietary intake questionnaire based on a food frequency assessment  in a group of Polish women aged 20–30 years. The aim of the validation was to obtain the iron-specific tool that would enable quick assessment of iron intake in the group of young women.The study was conducted according to the guidelines laid down in the Declaration of Helsinki. The Ethics Committee of the Regional Medical Chamber in Warsaw, Poland, approved the study protocol  and all participants provided written informed consent.The designed IRONIC-FFQ was based on a food frequency assessment. Only food products that were sources of iron were taken into account. Due to the fact that the questionnaire was designed for a group of young women (as characterised by the highest frequency of anemia), the fortified food products dedicated for other groups  were not included. During the design of the IRONIC-FFQ, information about main sources of iron in the Polish diet was taken into account—it is indicated that the main sources of iron in the analysed group are cereal products, meat/fish and meat/fish products, vegetables, potatoes and fruits . MoreoveAll food products meeting the assumed criteria were grouped into 12 food product groups and 32 related sub-groups characterised by a similar range of iron content, as presented in The most popular serving sizes were determined on the basis of the Polish food model booklet  and veriFor each group of food products, the average iron content in a serving was specified, as is presented in Individuals were asked about the exact number of servings of products from the groups specified in the IRONIC-FFQ which had been consumed during a typical week throughout the previous year (open-ended question). They were asked to indicate the servings of products consumed and added to consumed dishes. In the questionnaire, the participants declared the typical number of servings of each product .During the analysis, the number of servings was divided into 7 days a week to obtain the daily number of servings. The iron intake from the products was estimated using the following formula: iron intake (mg) = daily number of servings × typical iron content in one serving . The totFor the meat and meat products, an additional question was put in the IRONIC-FFQ—the participants were asked to indicate up to the five most frequently chosen types of meat and up to the five most frequently chosen types of meat products. If such a product/products for a group was/were specified, instead of the typical iron content in one serving, as presented in The IRONIC-FFQ was validated in a group of young women. The invitation to participate in the validation of the IRONIC-FFQ as well as information about the inclusion criteria were distributed via social media. The inclusion criteria were as follows: women, aged 20–30 years, not undergoing body mass reduction or on any special diet, not pregnant and not during lactation, without any chronic diseases, and living in Warsaw. There were 87 individuals meeting the inclusion criteria who volunteered to participate in the study. Finally, validation of the assessed IRONIC-FFQ was conducted in a group of 75 young women, as 12 of the individuals who had initially volunteered did not complete all of the required elements. It must be indicated that the main limitation of the conducted validation study was the fact that the sample was not random, so individuals who had volunteered for the study were probably motivated to properly conduct the 3-day dietary record and to fill in the IRONIC-FFQ, but such a situation is a limitation in many similar studies [EURopean micronutrient RECommendations Aligned (EURRECA) Network of Excellence Project [The sample size for the validation study was calculated on the basis of data regarding the number of women aged 20–30 years in Poland , the as Project .The study of validation was conducted in autumn, during a period of 3 months—from September to November 2014. Despite the fact that chemically assessed iron contents in Polish diets are in general similar during the four seasons of the year , it was Validation of the obtained IRONIC-FFQ questionnaire was conducted according to methodology published previously . It inclFor the 3-day dietary record, the basis of the analysis was the record conducted in three typical random and not successive days (2 weekdays and 1 day of the weekend). The dietary record was conducted on the basis of widely accepted and applied rules—using a structured format, with additional questions about name of the meal, time and location of consumption, meal ingredients and weight of serving  or size of serving (while estimated using standard household measures) . To prov(1)Calculation of root mean square errors of prediction (RMSEP) and the median absolute percentage errors (MdAPE) of iron intake in the assessment of validity (FFQ1 vs. 3-day record) and of reproducibility (FFQ1 vs. FFQ2).(2)Assessment of the share of individuals classified into the same tertile and misclassified (classified into opposite tertiles) in the assessment of validity (FFQ1 vs. 3-day record) and of reproducibility (FFQ1 vs. FFQ2).(3)Calculation of the weighted κ statistic with linear weighting to indicate the level of agreement between the classifications into tertiles in the assessment of validity (FFQ1 vs. 3-day record) and of reproducibility (FFQ1 vs. FFQ2)—according to the criteria of Landis and Koch , values (4)Analysis of the correlations between results obtained in the assessment of validity (FFQ1 vs. 3-day record) and of reproducibility (FFQ1 vs. FFQ2)—the normality of distribution of the results was analysed using the Shapiro–Wilk test and then Spearman’s rank correlation was applied for nonparametric distribution.(5)Analysis of the Bland–Altman plots in the assessment of validity (FFQ1 vs. 3-day record) and of reproducibility (FFQ1 vs. FFQ2)—the results were interpreted using the Bland–Altman index, whereas the limits of agreement value (LOA) was calculated as the sum of the mean absolute differences of iron intake measured by the two methods, and the ± standard deviation of the absolute difference of iron intake recorded for the two methods magnified by 1.96. In the analysis conducted with the Bland–Altman method to assess agreement between the measurements, a Bland–Altman index of a maximum of 5%  was interpreted, as commonly assumed , as posiThe statistical analysis of validation included five elements:Moreover, for each participant, the calculated iron intake obtained using the IRONIC-FFQ, conducted twice , and the 3-day dietary record were compared with the recommended intake (8 mg) according to Polish recommendations on the Estimated Average Requirement (EAR) level . For eacp ≤ 0.05. Statistical analysis was carried out using Statistica software version 8.0  and Bland–Altman Statistica software macro by Matt Coates, version 2009 .The level of significance was accepted as Iron intake observed in the analysed group, calculated using the 3-day dietary record and IRONIC-FFQ conducted twice , is presented in The calculated contribution of product groups into the daily iron intake obtained from the IRONIC-FFQ conducted twice is presented in The calculated RMSEP of iron estimation in the assessment of validity in comparison with the results of the 3-day dietary record for the analysed IRONIC-FFQ was 5.3 mg. Simultaneously, the MdAPE of iron intake for a comparison with the 3-day dietary record was 27.6%. The histogram displaying the distribution of iron intake estimated on the basis of the 3-day dietary record and the analysed IRONIC-FFQ1 is presented in In the assessment of reproducibility, the RMSEP of iron estimation—while the food frequency assessment was conducted twice during a period of 6 weeks—was 2.3 mg. The MdAPE of iron intake for the comparison between the FFQ1 and FFQ2 was 7.7%. The histogram displaying the distribution of iron intake estimated on the basis of the IRONIC-FFQ1 and IRONIC-FFQ2 is presented in κ statistic indicated substantial agreement, while in the assessment of validity it indicated fair agreement.The share of individuals classified into the same tertile in the validation of the IRONIC-FFQ as well as the weighted κ statistic are presented in R = 0.48) between daily iron intake obtained using the verified method of the IRONIC-FFQ (FFQ1) and the 3-day dietary record, while 23.04% of the variation was explained by the regression line.The correlation was analysed between the FFQ1 and the 3-day dietary record daily iron intake. The Spearman rank correlation coefficient revealed a statistically significant association (R = 0.87) between daily iron intake obtained using the IRONIC-FFQ for FFQ1 and FFQ2, while 75.69% of the variation was explained by the regression line.The correlation between the FFQ1 and FFQ2 daily iron intake was also analysed. In the assessment of reproducibility, similarly as for the assessment of validity, the Spearman rank correlation coefficient revealed a statistically significant association . As the aim of the study was to obtain the valid and reproducible questionnaire to assess dietary iron intake, the validation in comparison with dietary records was essential. However, in the future, the further validation in comparison with iron status indicators may be planned, in order to assess the association between dietary iron intake assessed using the IRONIC-FFQ and iron status.Taking into account the global target of the WHO for anemia prevention , obtaini(1)Assessment of the IRONIC-FFQ revealed a satisfactory level of validity and positively validated reproducibility.(2)The IRONIC-FFQ may be indicated as a practical tool for the assessment of iron intake and for analysis of the results of dietary intervention in the anemia risk group of young women.


It is necessary apical plug material to exhibit proper adaptation with the root canal walls. Presence of voids at the interface between the root canal wall and this material result in micro leakage, which might have a relationship with post treatment disease. The aim of the present study was to evaluate the effect of different mixing  and placement  method of Mineral Trioxide Aggregate (MTA) on the void count and dimension in the apical plug in natural teeth with simulated open apices.P<0.05. Eighty human maxillary central incisors were selected. After simulation of the open apex model, the teeth were assigned to 4 groups based on the mixing and placement techniques of MTA: group 1, manual mixing and manual placement; group 2, manual mixing and manual placement in association with indirect ultrasonic; group 3, ultrasonic mixing and and manual placement; and group 4, ultrasonic mixing and manual placement in association with indirect ultrasonic. The prepared samples were placed within gypsum sockets in which the periodontal ligament was reconstructed with polyether impression material. In group 1, after mixing, the material was condensed with a hand plugger. In group 2, after mixing, the ultrasonic tip was contacted with the hand plugger for 2 seconds. In groups 3 and 4, mixing was carried out with the ultrasonic tip for 5 seconds and in groups 3 and 4, similar to groups 1 and 2, respectively, the materials were placed as apical plugs, measuring 3 mm in length. A wet cotton pellet was placed at canal orifices and dressed with Cavit. After one week, the cone beam computed tomography (CBCT) technique was used to count the number of voids between the material and root canal walls. The void dimensions were determined using the following scoring system: score 1, absence of voids; score 2, the void size less than half of the dimensions of the evaluated cross-section; score 3, the void size larger than half of the dimensions of the evaluated cross-section. Chi-squared and Fisher’s exact tests were used for statistical analyses. Statistical significance was set at p >0.05). Evaluation of void dimensions showed no score 3 in any of the study groups and the dimensions of all the voids conformed to score 2. The maximum (13) and minimum (3) number of voids were detected in groups 2 and 3, respectively. There were no significant differences between groups 1 and 3 in the number of voids ( Under the limitations of the present study, use of ultrasonic mixing and manual placement techniques resulted in a decrease in the number of voids in the apical plug. Key words:Apical plug, MTA, ultrasonic, void. MTA has several uses in endodontics, including its use as an apical plug in the apexification procedure of immature permanent teeth . A materMTA is a technique-sensitive material and requires careful delivery to create a proper seal . PreviouPowder-to-liquid ratio and porosity might affect the mechanical properties of dental cements. Therefore, the mixing and placement variables are key factors that affect the performance of dental materials ,12. EvalIdentification of voids is important clinically and evaluation of voids between the root canal wall and the material is an acceptable technique for the evaluation of the obturation quality ,16. RadiNo studies to date have been carried out to simultaneously evaluate the effects of different mixing and placing techniques on the quality of the apical plug. The present study was designed to measure the voids in the apical plug with the use of the CBCT technique by considering the above parameters.The protocol of this study was approved by the Ethics Committee of Tabriz University of Medical Sciences (IR.TBZMED.REC.1395.31). A total of 80 human maxillary central incisors with straight and fully developed roots were selected. The teeth had no cracks and fractures. The tooth crowns were removed at the level of cement-enamel junction with the use of a diamond saw  under water coolant to leave 12 mm of the root length. Then 3 mm of the root was cut away from the apical end to leave 9 mm of the root length in all the samples.-Simulation of periodontal ligament The roots were covered with molten wax and mounted in gypsum blocks. After complete setting of the gypsum , the wax was removed by rinsing with hot water, which resulted in the creation of a gypsum socket. Polyether impression material  was poured within the socket and the roots were placed within the socket. After setting of the polyether impression material, the roots were removed from the sockets.-Root canal preparation and simulation of open apex modelTo simulate apexification, the root canals were instrumented using #5, #4, #3, #2 and #1 Gates-Glidden drills  with the crown-down technique. To this end, #5 drill was inserted into the root canal up to 3 mm, followed by 5, 7 and 9 mm of penetration into the root canal by #4, #3 and #2 drills. To simulate the open apex condition, #1 drill was used 1 mm beyond the apical foramen by moving it through the apical foramen once without any resistance. Then #40 RaCe rotary file  with 10% taper was inserted into the root canal through the apical foramen so that its entire cutting length was placed in the root canal. A total of 5 mL of 0.5% NaOCl solution was used as a root canal irrigant during instrumentation. At the end of instrumentation, 5 mL of 17% EDTA was used to remove the smear layer. A total of 5 mL of normal saline solution was used as a final irrigant.-Placement of the apical plugThe samples were randomly divided into 4 groups (n=20) based on the MTA  mixing and placement techniques as follows:Group 1: manual mixing and manual placementGroup 2: manual mixing and manual placement in association with indirect ultrasonic Group 3: ultrasonic mixing and manual placementGroup 4: ultrasonic mixing and manual placement in association with indirect ultrasonic In all the study groups, MTA was mixed according to manufacturer’s instructions at a powder-to-liquid ratio of 3:1. In group 1, after mixing the material, an MTA carrier was used to carry the material incrementally into the root canal; the material was packed with the use of a hand plugger up to the proper length, which continued until a plug length of 3 mm was achieved. In group 2, a similar approach was used except for the fact that after packing the material with a hand plugger the ultrasonic tip was placed in contact with the plugger for 2 seconds to apply an indirect vibratory motion to the material. The power of the ultrasonic unit was adjusted at its lowest settings. In groups 3 and 4, the material was mixed with the ultrasonic tip for 5 seconds and then the placement was done in group 3, similar to group 1, and in group 4, similar to group 2. A wet cotton pellet was placed at the orifice of all the root canals and the samples were dressed with Cavit . Then the samples were incubated at 37°C and 100% relative humidity for 1 week.-Evaluation of the samples with the CBCT techniqueEach root underwent a CBCT imaging procedure with the use of a Newtom VGI unit  at axial and cross-sectional views by a radiologist. This x-ray unit delivers a conical x-ray beam and has a flat-panel detector, with 1536×1920 and 127×127 pixel sizes, a pixel depth of 14 bits, a rotation of 360°, a scan time of 18 seconds and a KVP of 110. The initial and final reconstructions were carried out with NNT Viewer software program version 2.17. The unit’s exposure conditions were adjusted automatically. Data collected from the CBCT evaluations were entered into the NNT Viewer software program version 2.17. The resultant images were displayed on a 19-inch LCD monitor  with a resolution of 1024×1208 pixels and 32 bits in a dimlylit room. The number of voids between the material and the root canal wall was counted in all the samples and recorded as the number of voids in 20 samples in each group. The following scoring system was used to characterize the dimensions of the voids:Score 1: No voidsScore 2: The size of the void less than half of the dimensions of the cross-section evaluatedScore 3: The size of the void larger than half of the dimensions of the cross-section evaluated-Statistical analysisp<0.05.After drawing cross tabs for the data, chi-squared and Fisher’s exact tests were used for statistical analysis of data. The significant difference was set at P=0.001) and between these two groups and groups 1 and 4 were significant (P<0.05). There was no significant difference between groups 1 and 3 in the number of voids (P=0.7). Evaluation of the dimension of the voids showed no score 3 in any of the study groups and the dimensions of all the voids conformed to score 2.The present study was undertaken to evaluate the quality of MTA apical plug and the effect of different mixing and placement techniques on the number and dimensions of voids between the material and root canal wall in the apical plug with the use of the CBCT technique. The results showed that in two groups with identical mixing technique, use of manual condensation in association with indirect ultrasonic technique resulted in more voids; on the other hand in two groups with identical placement technique, mixing with an ultrasonic tip resulted in less voids.MTA is used as an apical in the treatment of permanent immature teeth due to its favorable properties; however, its difficult handling has always been reported as one of its chief disadvantages . On the The effect of ultrasonic technique on the quality of MTA obturation has been evaluated in two studies ,10. In oet al. (In another study, Yeung et al.  evaluateet al., mixing with the ultrasonic technique resulted in an improvement in some of the properties of MTA, including a decrease in setting time (The innovation in the present study, compared to the two studies mentioned above, was the use of ultrasonic mixing. In a study carried out by Shahi ing time . In addiing time , which mIt is suggested that such a study be carried out in curved canals because it is much more difficult to place MTA at the apical end of curved canals compared to that in straight canals. In addition, it appears it is necessary to design a study to evaluate the density of obturations by weighing the samples. Under the limitations of the present study, it is suggested that ultrasonic mixing and hand placement techniques be used to improve the quality of MTA apical plugs.


High-calcium fly ash (FH) is the combustion residue from electric power plants burning lignite or sub-bituminous coal. As a mineral admixture, FH can be used to produce high-strength concrete and high-performance concrete. The development of chemical and mechanical properties is a crucial factor for appropriately using FH in the concrete industry. To achieve sustainable development in the concrete industry, this paper presents a theoretical model to systematically evaluate the property developments of FH blended concrete. The proposed model analyzes the cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO. The mutual interactions among cement hydration, the reaction of free CaO in FH, and the reaction of other phases in FH are also considered through the calcium hydroxide contents and the capillary water contents. Using the hydration degree of cement, the reaction degree of free CaO in FH, and the reaction degree of other phases in FH, the proposed model evaluates the calcium hydroxide contents, the reaction degree of FH, chemically bound water, porosity, and the compressive strength of hardening concrete with different water to binder ratios and FH replacement ratios. The evaluated results are compared to experimental results, and good consistencies are found. Fly ash is produced in coal-burning electricity generation stations and has been widely used for producing high-performance concrete. Fly ashes can be divided into two categories according to their calcium content. The first type of fly ash, containing less than 10% analytical CaO, is generally a product of the combustion of anthracite and bituminous coals. The second type of fly ash, typically containing 15% to 40% analytical CaO, is generally a product of the combustion of lignite and sub-bituminous coals [Many investigations on the physical, chemical, and durability properties of concrete incorporating low-calcium fly ash  have been performed ,3,4,5,6.Compared to the abundant experimental investigations on FL blended concrete ,8,9, theTo overcome the limitations of the current models ,12,13,14kd, the reaction coefficient in the induction period; De, the effective diffusion coefficient of water through the CSH gel; and kr, a coefficient of the reaction rate of cement, as shown in Equation (1):v is the stoichiometric ratio by mass of water to cement (=0.25); wg is the physically bound water in the CSH gel (=0.15); ρw is the density of water; Cw-free is the amount of water at the exterior of the CSH gel; r0 is the radius of unhydrated cement particles (r0 = 3/(Sρc), in which the terms S and ρc stand for the Blaine surface area and the density of the cement, respectively); Sw is the effective surface area of the cement particles in contact with water and S0 is the total surface area if the surface area develops unconstrained; Bce controls the rate of the initial shell formation and Cce controls the rate of the initial shell decay; and De0 is the initial value of the effective diffusion coefficient.In this study, the cement hydration model originally developed by Tomosawa  and modiCw-free is expressed as a function of the degree of hydration in the previous step, as shown in Equation (1d):C0 and W0 are the mass fractions of cement and water in the mix proportion.The amount of water in the capillary pores et al. [The effect of temperature on the reaction coefficients is assumed to follow Arrhenius’s law ,16. Usin2O, C: CaO, S: SiO2, A: Al2O3, F: Fe2O3, 3, CH: Ca(OH)2. For FH, the majority of calcium is present in crystalline and reactive constituents, such as C3A, C4A3Cement notation chemistry is used throughout this paper, where H: Hrability . Conversrability . The frerability :C + H 2O at different curing temperatures. The reaction of free CaO in FH is a first-order reaction whose rate is directly proportional to the degree of reaction. Chen [CF can be described as follows:k is reaction rate coefficient . FH essentially consists of aluminosilicate glass modified by the presence of large amounts of calcium and magnesium. High-calcium fly ashes are pozzolans that will react with the calcium hydroxide resulting from the hydration of Portland cement to produce calcium silicate hydrate (CSH) and calcium aluminate hydrate (C–A–H). However, FH are also hydraulic in nature, as they will react directly with water to form a range of hydration products, and a mix of FH and water will set, harden, and gain a certain strength even in the absence of Portland cement (or other activators). This behavior results from the hydraulic nature of the crystalline products and the dissolution and reaction of the glass due to the presence of soluble alkalis and calcium within the FH ,11,12. TFH is the reaction degree of the active part in FH other than free CaO, mCH(t) is the mass of calcium hydroxide, Wcap is the mass of capillary water, P is the quality of the FH in the mixing proportion other than the mass of free CaO, νFH is the stoichiometry ratio by mass of CH to FH other than free CaO, r0FH is the radius of the FH particle, ρFH is the density of FH, kdFH is the reaction rate coefficient in the dormant period (BFH and CFH are coefficients), krFH is the reaction rate coefficient of the phase boundary reaction process, and De0FH is the initial diffusion coefficient. Saeki and Monteiro  proposed3S2 will not react. The non-reactive part of silica is present in quartz and in crystalline A–S phases. The inert part is assumed to be chemically inert and does not react. The reacted ratio of FH other than free CaO (including both an active part and an inert part) can be obtained based on Equation (4a) through (4c) and the mass compositions of the fly ash. Considering both the active part and the inert part, the total reaction degree of FH other than free CaO can be determined as follows:FH-total is the reactive degree of the total FH other than free CaO and γactive is the weight fraction of the active part of FH other than free CaO.Papadakis  proposedAs proposed by Papadakis , the cheFH has a composition closer to Portland cement than low-calcium fly ash (FL) or silica fume (SF). The active part of FH consists of an aluminosilicate glass phase, a calcium phase, and a sulfate phase. The majority of the active part of the silica in FH is present in aluminosilicate (A–S) and calcium aluminosilicate (C–A–S) glass. Calcium silicate hydrate (CSH) is formed from the pozzolanic action of the reactive silica of FH as follows :2S + 33A) and monocalcium aluminosulfate C3A3S2 will not react. The rest of the alumina present in A–S and C–A–S glass is expected to react as follows [The crystalline part of alumina found in corundum and A follows :(7c)A+C2 (S), Al2O3 (A), Fe2O3 (F), SO3  is the mass of the reacted free CaO at time t, and CF0 is the mass of the free CaO content in FH. The term C0RCHCEα considers the production of calcium hydroxide from cement hydration, the term 1.321CF(t) considers the production of calcium hydroxide from the reaction of free CaO in FH, and the term −νFHαHFP considers the consumption of calcium hydroxide from the reaction of phases in FH other than free CaO.The Portland cement and FH can be analyzed in terms of oxides: total CaO (C), free CaO (CF), SiOfS,cαC0 considers the production of CSH from cement hydration, and 2.85γSfS,pαFHP considers the production of CSH from the FH reaction.Similarly, the mass of calcium silicate hydrate (CSH) relates to the cement hydration and FH reaction. The mass of CSH can be determined as follows:Wcbm can be determined as follows:RCWFH is the mass of chemically bound water from 1 gram of reacted FH  denotes the production of chemically bound water from the reaction of free CaO in FH, and the term RCWFH× αFH× P denotes the production of chemically bound water from the reaction of phases in FH other than free CaO. The mass of chemically bound water relates to the cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO. The mass of chemically bound water H = 0.09 ). The teWcap can be calculated as follows:RPWFH is the mass of physically bound water from 1 gram of reacted FH . The tec, ΔɛCF, and ΔɛFH are the porosity reduction due to the Portland cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO, respectively; these terms can be determined from the amount of chemically bound water consumed in the Portland cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO, respectively [The porosity of hydrating blends is reduced due to the Portland cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO. The porosity, ɛ, can be estimated as follows:ectively .Papadakis  proposedCF, and the reaction degree of phases in FH other than free CaO αFH at each time step, the amount of calcium hydroxide, capillary water, chemically bound water, porosity, CSH, and compressive strength can be calculated. The flow chart for a numerical simulation process is shown in 2/kg Blaine’s fineness). Prior to use, high-calcium fly ash was pulverized to meet the cement mean particle size. The physical properties and chemical compositions of cement and FH are shown in W/C) was 0.5 and the aggregate-cement ratio (A/C) was 3. Two different cases were studied: FH replaces either aggregate or cement. When FH replaces aggregate, three contents of FH were selected: 10%, 20%, and 30% additions to the control cement weight for specimens FHA, 10%, FHA, 20%, and FHA, 30%, respectively. When FH replaces the cement, the same FH contents were selected: 10%, 20%, and 30% replacements of the control cement weight for specimens FHC, 10%, FHC, 20%, and FHC, 30%, respectively.Experimental results from reference  are used2 occurs between 440 °C and 520 °C. The paste properties were reduced to the corresponding mortar specimen volume by multiplying the appropriate paste volume/mortar volume fraction [The developments of strength, porosity, bound water, and calcium hydroxide were measured . The spefraction .active, which includes an aluminosilicate glass phase, a calcium phase, and a sulfate phase, can be calculated. The weight fractions of FH used for modeling are shown in In the proposed model, the reaction of free CaO and other phases in FH are simulated separately. Equation (3) is used to model the rapid reaction of free CaO in FH, and Equation (4) is used to model the reaction of phases in FH other than free CaO. Using the chemical analysis of FH shown in Bce, Cce, De0, and kr can be determined. Using the experimental results of calcium hydroxide from cement-FH paste, the FH reaction coefficients BFH, CFH, De0FH, and krFH can be determined. The values of the reaction coefficients are shown in Using the experimental results of calcium hydroxide from Portland cement and a predictor-corrector algorithm , the reaet al. [After calibrating the coefficients of the reaction model, multiple checks, such as the evolution of chemically bound water, porosity, CSH contents, and compressive strength, were performed to verify the proposed model. The procedure of the proposed model is similar to that of Tomosawa et al. ,19. In Tet al. ,19.The evaluation results of the calcium hydroxide contents are shown in In addition, FH-total is shown in active). For concrete with 30% FH, until the age of one year, part of FH is still un-reacted.The evaluation of the reaction degree of fly ash αThe evaluation results of chemically bound water and porosity contents are shown in i.e., the compressive strength = 0.29 × CSH. Papadakis ,12 propoUsing the regressed linear relationship between the compressive strength and the CSH content, we can evaluate the development of the compressive strength of FH-cement blends. In addition, the free CaO in FH also affects the compressive strength developments of hardening cement-FH blends. Tsimas and Moutsatsou-Tsima  investigIn the concrete industry, considering the economic and environmental effects, high-calcium fly ash is generally used as a mineral admixture to replace cement. Using the hydration model, we can calculate the CSH contents. Furthermore, using the regressed linear relationship between the compressive strengths and CSH amounts, we can calculate the compressive strength development of FH concrete. SfS,pαFHP, relates to the FH content P and the reaction degree of FH αFH. With increasing FH content P, the reactivity of FH will decrease  This paper proposes a numerical procedure to simulate the hydration of cement and high-calcium fly ash (FH) blends. The hydration of cement, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO are modeled. The interactions among the hydration of cement, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO are considered through the available calcium contents and capillary water contents in the system. The reaction of free CaO in FH is described as a first-order reaction. The reaction of other phases in FH is divided into three processes, (2) Using the numerical procedure, the hydration degree of cement, the reaction degree of free CaO in FH, and the reaction degree of phases in FH other than free CaO are calculated. The amount of calcium hydroxide, bound water, porosity, and compressive strength of FH blended concrete are determined considering the contributions from the hydration of cement, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO. At different curing ages, for FH blended concrete with different FH contents, a single linear relationship exists between the compressive strengths and the calculated CSH amounts. The proposed model can reproduce the compressive strength crossover phenomenon between control Portland cement concrete and FH blended concrete. The proposed model also can be used to determine the optimum content of FH.


Transmission of infectious agents might be associated with iatrogenic actions of charitable help in health care. An example is the vaccination against yellow fever in USA that transmitted hepatitis B virus. Another example is injections of praziquantel for treatment and cure of schistosomiasis in Central and Northern Africa, with a focus in Egypt that has spread hepatitis C virus. There is no indication that human T-lymphotropic virus type 1 was spread by injection treatment for African trypanosomiasis, syphilis and treponematosis, but these treatments might have contributed to the early spread of human immunodeficiency virus type 1 (HIV-1) in Central Africa. Slave trade contributed as well to the spread of viruses from Africa to the Americas; it was stopped in 1850. Until that date HIV-1 was not transported to the Americas. By analysis of nucleic acid sequence data it can be concluded that the continental spread of HCV and HIV-1 might have started around 1920 with an exponential phase from 1940 to 1970. Further iatrogenic actions that promoted the spread of HCV and HIV-1 might be vaccinations to prevent deadly diseases. The successful vaccination was followed by diminution of the infectious agent in the population such as small pox, yellow fever and measles. Measurements to reduce the spread of plague and cholera were further benefits increasing survival of diseased subjects in a population. Thus, the reduction of exposure to deadly infectious agents might have given a chance to HIV-1 infected subjects to survive and for HIV-1 to be distributed around the world starting from Central Africa in the 1950s. Caring for ill and injured members of a community is as old as mankind. Specialization in health care started in archaic communities with certain skill and experience and finally iatrogenic action by assisting to reach an improved outcome of a disease or of pregnancy. Iatrogenic bacterial transmission to delivering women and its reduction by hand disinfection was nicely demonstrated by Ignaz Semmelweis in 1847 .Blood transfusion is a further possibility of spreading viruses. The first efforts of improving anaemia by blood transfusion started around 1901 with the identification of blood groups by Landsteiner and the use of different salts as anticoagulant in 1915 by Lewisohn . At thatIn this review a few examples of the history of iatrogenic transmission of viruses are given, discussing also the aspect of time delay until scientific results may have reached the medical community. It has to be stated as well that all the injection activities had been performed under the aspect of noble goals to treat and cure infectious disease . In a reApprox. 300,000 US American soldiers were vaccinated in 1942 against YFV before being send to East-Asia with 3 different vaccine preparations , 7: two The anti-HAV infection rate corresponds to the prevalence value of a Western population at the time during World War Two. The anti-HBc titer of 6 plus 7% in the ‘control’ population corresponds as well to the HBV prevalence and natural course of the disease in the general population at that time , while tYFV vaccine preparation started in 1928, and data of the circulation of 2 different agents causing hepatitis was reported as early as 1885, with the characteristics of a so-called epidemic catarrhal jaundice that was affecting mainly children that was published in 1914 .HCV is generally only transmitted by blood and not as HBV by sexual activity and blood, and therefore, HCV has been transmitted in historic times by scarification, tattooing, circumcision etc. . Age of A small area with a high prevalence of HCV genotype 5a that was most probably transmitted by iatrogenic action was observed on Rhodes island. While in Greece HCV-5 has a prevalence of 1.9% 19/973), in Rhodes 13% (16/122) were found; 82% (13/16) of the patients infected with HCV-5a in Rhodes were females and the average age was 62 ± 6 years [/973, in A further possible event of iatrogenic transmission of HCV-1b was reported in 2002 from the small town of Camporeale in Sicily. The general HCV prevalence was 10.4% (75/721), while in people >60 the prevalence was 34% (48/141) and in subjects 10–29 years it was 0.4% (1/225); correlation analysis showed that a previous hospitalization was highly linked with HCV infection [Several studies were performed in Central Africa to determine the HCV genotype distribution in various cohorts and countries and to calculate the time of rapid spread of HCV transmission –24. In CA study performed in the Central African Republic in 905 subjects aged >55 on the molecular epidemiology of HCV revealed a high prevalence of HCV-4 , with subtypes 4k, 4c and 4f . PhylogeCameroon is a further Central African country with a high HCV prevalence  and withLooking at further ways of HCV transmission the transport (migration) of people being chronically infected with HCV is a possibility. A study performed at Amsterdam in 189 patients revealed in 178 the presence of HCV-2, determined by nucleic acid sequencing. HCV-2 could be subdivided in 8 distinct subtypes . By analIn a further study on HCV nucleic acid sequences performed in Guinea-Bissau the origin of HCV-2 was calculated to have evolved in this region around 1470. By virus migration in slaves HCV-2a and HCV-2c were transported repeatedly to Madagascar and Martinique . Thus, iIn contrast to HBV and HCV the retrovirus HTLV is a strictly cell bound virus that is usually absent from serum and is transmitted by whole blood, as blood transfusion, and by sexual contact. HTLV is an old virus that circulates in monkeys since ca 50,000 and in man since ca 25,000 years . HTLV-1 Iatrogenic transmission of HTLV-1, together with HCV-4, in colonial Equatorial Africa by injection of pentamidine for treatment of sleeping sickness from 1936 to 1953 was reported in a cross-sectional survey in 2010 . The ageAs discussed within the HCV topic also slave trade was a way of spreading HTLV-1, which could be followed up by analyzing the different subtypes A to C. Subtype A was found in the Caribbean area, South America and in the Ainu population in Japan, subtype B in Japan and India, and subtype C in West-Africa and the Caribbean area . The WesIn conclusion HTLV-1 is a further virus causing chronic disease that was spread by iatrogenic treatment during colonial time, but to a lower extent than HBV an HCV.Pan troglodytes troglodytes) [Cercopithecus atys) that was spread according to the calculation of the molecular clock around 1933–1945 to man [HIV-1 is a retrovirus causing chronic infection that is transmitted by cells and plasma of blood and sexual contact. According to molecular clock analysis HIV-1 with its 4 groups had been present in Africa in man around 1890–1930 or earlier and in chimpanzees before 1460 dependent on the viral gene analyzed , 38. Thelodytes) , and HIV5 to man  and show5 to man . Accordi5 to man .Spread of HIV in man: the speed of spread of HIV-1 subtypes A and D from Central Africa to East Africa was low before 1950 but grew exponentially during the 1970s , 42. A pWhen slave trade is considered there is, as discussed, enough evidence of transport of HBV, HCV and HTLV-1, however, HIV-1 was not transferred to the Americas; either subjects infected with HIV-1 died during the ship transport, or HIV-1 had not entered humans up to 1850 when slavery was stopped in the West, Central and East African populations . HIV-2 eInfluence of human superspreaders on the distribution of HIV-1: the US American HIV-1 epidemic started around 1970, it was preceded by a Caribbean epidemic in 1963 and one patient (patient zero) was discussed of having triggered the AIDS epidemic , 51. TheInfluence of the availability of syringes and anticoagulant allowing the injection of blood: a further possibility of the emergence of HIV-1 is the injection of monkey (chimpanzee) blood by traditional healers that was performed in the area of the great lakes of Central Africa .Influence of the pathogenicity of HIV: the change of the pathogenicity of the chimpanzee virus, SIVcpz, after transfer to man from very aggressive, killing people in a few weeks, to low, allowing a chronic course for a decade, would be a further reason for the onset of the epidemic some 100 years ago.Trypanosoma brucei, or similarly treatment of plague, cholera, malaria, etc. Absence of those infectious agents that kill patients with severe immunodeficiency would have contributed to preserve the life of HIV-1 infected subjects with minor immunodeficiency and thus allowing the spread of HIV by the sexual route.Influence by the success of vaccination and disease treatment: a further possibility of iatrogenic contribution would be as well the diminution of deadly viruses in the Central African populations by vaccination against small pox virus between 1850 and 1950 , yellow Several possibilities have to be discussed for the worldwide burst of HBV, HCV and HIV-1 and their evident spread in the 1940–1970s. The main possibility is lack of hygiene during mass vaccination and mass injection treatment of diseases as for African trypanosomiasis and syphilis. Due to poor hygienic conditions by persons performing those actions and due to the absence of knowledge of the presence of blood borne viruses at that time HIV-1 transmission was promoted. A further possibility is that successful drug treatment of tropical diseases and vaccination supported a longer survival of HIV infected subjects allowing them to spread the virus within their community.The occurrence of HIV is a reason for health workers caring for patients to actualize knowledge on infectious agents and their transmission route, to question and check the validity of recommendations of action periodically and to balance beneficial and harmful events in sick people for years.


Our results showed that the use of the MAMAD technique resulted in the reduction of the size and number of uric acid and l-alanine crystals up to >40% when exposed to intermittent microwave heating (up to 20 W power at 8 GHz) in the presence of 20 nm gold nanoparticles up to 120 s. This study demonstrates that the MAMAD technique can be potentially used as an alternative therapeutic method for the treatment of gout by effective decrystallization of large crystals, similar in size to those that often occur in gout.Gout is caused by the overproduction of uric acid and the inefficient metabolism of dietary purines in humans. Current treatments of gout, which include anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and systemic glucocorticoids, have harmful side-effects. Our research laboratory has recently introduced an innovative approach for the decrystallization of biological and chemical crystals using the Metal-Assisted and Microwave-Accelerated Evaporative Decrystallization (MAMAD) technique. In the MAMAD technique, microwave energy is used to heat and activate gold nanoparticles that behave as “nano-bullets” to rapidly disrupt the crystal structure of biological crystals placed on planar surfaces. In this study, crystals of various sizes and compositions were studied as models for tophaceous gout at different stages  and  Gout is a painful crystal deposition disease with increasing prevalence throughout numerous regions of the world. Gout affects approximately 8.3 million individuals in the United States of America, and it is caused primarily by elevated serum uric acid levels, also known as hyperuricemia . A diagnThe treatment for gout and its symptoms include a change in dietary habits, which can be considered a long-term preventative treatment of hyperuricemia. Additionally, nonsteroidal anti-inflammatory drugs (NSAIDs), cyclooxygenase-2 (COX-2) inhibitors, colchicine, or systemic glucocorticoids are administered for short-term treatment of chronic gout ,8. StudiThe use of microwaves has been explored for medical care purposes from the diagnosis of the various type of cancers to the ablation of affected tissues ,13. DuriThe Aslan Research Group has recently introduced a novel technique that focused on the decrystallization of crystals, called the Metal-Assisted and Microwave-Accelerated Decrystallization (MAMAD) technique with the combined use of metal colloids (silver and gold) and microwave heating as a potential treatment for gout ,15. In ol-alanine (size ~ 300 µm) and large l-alanine (size 4300 µm) crystals. Medium and large l-alanine crystals are employed as representative of the formation of tophi by either the accumulation of uric acid or calcium products in the body. Moreover, this study differs from our previous efforts where we have now used a medically approved solid-state microwave source and an applicator tip, rather than an impractical conventional microwave oven. The medical microwave is designed for the thermal ablation of tissue tumors formed in cancer with the use of heat supplied by the microwave energy, which functions by supplying localized dielectric heating to cause controlled destruction of tissue. We observed a decrease in the size and number of uric acid and the size of the l-alanine crystals by >40% when heated for intermittent periods between 60 s and 120 s with the MAMAD technique. Evaporation time, size of crystals, and concentration of crystals were found to be important factors that determine the efficiency of the MAMAD technique.In this paper, our objective is to demonstrate that the MAMAD technique can be used for the decrystallization of crystals of various sizes with a medical microwave to evaluate its potential as a noninvasive method for the treatment of crystal deposition diseases in the future. Decrystallization of crystals of varying sizes and composition was carried out with the use of a low power medical microwave . The model crystals that we used are small uric acid crystals (size ~ 10–100 µm), medium In the presence of gold nanoparticles and microwave heating at 20 W, the average count for uric acid crystals showed a decrease of ~40% after 60 s. Under identical experimental conditions, control samples without gold nanoparticles exposed to 20 W microwave power showed a decrease of 31% in the number of uric acid crystals, which implies that there is a 9% difference between the control and the MAMAD technique.According to Additional experiments were carried out under identical conditions for uric acid crystals with an initial concentration of 0.2 mg/mL , where tt = 0 s to 24 crystals at t = 60 s  and optical images of the uric acid crystals on iCrystal plates after exposure to 2–20 W of microwave heating in the presence (labeled as MAMAD) and absence of gold nanoparticles (labeled as control) are given in In the control experiments, microwave heating of uric acid crystals in the absence of gold nanoparticles did not result in a significant decrease in the number of uric acid crystals . To furtl-alanine crystals (~300 µm) in the presence and absence of gold nanoparticles (control) exposed to 2–20 W of microwave heating for 120 s. The normalized size retention rates were calculated using the same method employed for calculation of the normalized retention rates of uric acid crystals. Microwave heating time for the decrystallization of l-alanine crystals was twice the length of time as that employed for the uric acid crystals due to the difference in sizes of the l-alanine and uric acid crystals. l-alanine crystals in the presence of gold nanoparticles: after 120 s of microwave heating at 10 W, there was about a 40% decrease in the size of l-alanine crystals. When microwave power levels of 2 W and 20 W were used in the presence of gold nanoparticles, the size of the l-alanine crystals were reduced by an average of 29% and 21%, respectively. l-alanine crystals were exposed to microwave heating in the absence of gold nanoparticles: the overall decrease in the size of l-alanine crystals exposed to 2 W and 10 W microwave power levels was approximately 15%, while a 1% decrease was observed for l-alanine crystals heated at 20 W. The reduction in size observed for the l-alanine in control experiments can be attributed to the partial dissolution of the crystal due to increase in the temperature of the solvent. It is important to note the possibility of re-crystallization of l-alanine during microwave heating: as l-alanine molecules are cleaved from the crystal structure and dissolved in solution due to increase temperature of the solvent, intermittent microwave heating can result in a heating/cooling cycle, which, in turn, can result in re-crystallization of l-alanine on the existing crystal surface. In another control experiment, where both gold nanoparticles and microwave heating are omitted from the experiment, the size of medium l-alanine crystals in deionized water was reduced by 10%, which can be attributed to dissolution of the crystals at room temperature  and absence of gold nanoparticles  during intermittent microwave heating (10 W) for 120 s. l-alanine crystals was reduced by 47% and from 305 µm to 250 µm with the application of the MAMAD technique, respectively. In a control experiment, microwave heating of medium l-alanine crystals in the absence of gold nanoparticles for 120 s resulted in 20% reduction in crystal size, and the length of medium l-alanine crystal was decreased from 295 µm to 263 µm  results in significant damage to the crystal structure, where large and irregular-shaped cracks appear on the crystal surface. As compared to the use of the MAMAD technique, microwave heating of medium l-alanine crystals in the absence of gold nanoparticles results in a lesser extent of damage to the crystal structure, where the narrow cracks and minor surface ablation are observed. These observations provide direct evidence that the MAMAD technique can be used to decrystallize l-alanine crystals at the size of several hundred micrometers in 120 s.o 263 µm b. It is  heating a. Microwl-alanine crystals ~300 μm in size, we investigated whether even larger l-alanine crystals (~4300 µm) can be decrystallized with the MAMAD technique. These results are given in l-alanine crystals (~4300 µm) in the presence and absence of gold nanoparticles (control) exposed to 2–20 W of microwave heating for 120 s.After the successful demonstration of the use of the MAMAD technique for the decrystallization of l-alanine crystals exposed to microwave heating in the presence of gold nanoparticles was reduced by 18%, 7% and 1% for power levels of 20 W, 10 W, and 2 W, respectively. l-alanine crystals exposed to microwave heating without gold nanoparticles was reduced by 18%, 6% and 7% for power levels of 20 W, 10 W, and 2 W, respectively. These results indicate that microwave heating of large l-alanine crystals in the presence and absence of gold nanoparticles yield comparable results. The reduced effectiveness of the MAMAD technique for the decrystallization of large l-alanine crystals was likely due to several factors: size of the crystal, size of the gold nanoparticles, amount of gold nanoparticle solution added (10 μL) and evaporation of the solvent during microwave heating. It is important to note that the size of the gold nanoparticles used in this study (20 nm) is significantly smaller than the size of the l-alanine crystals (~4300 µm). In addition, 10 μL of gold nanoparticles cover only the top region of the l-alanine crystals. Therefore, the collisions of the gold nanoparticles are expected to only occur when the solvent is present. After 30 s of microwave heating at 20 W, the solvent quickly evaporates and the reduction in solution volume limits the movement of gold nanoparticles in solution. Subsequently, the collisions of gold nanoparticles with l-alanine crystals are significantly reduced. The dissolution of large l-alanine crystals in deionized water in the absence of gold nanoparticles at room temperature was negligible  and absence of gold nanoparticles  during intermittent microwave heating (20 W) for 120 s. l-alanine crystals was observed in 30 s of microwave heating in the presence of gold nanoparticles. l-alanine crystals are exposed to microwave heating in the absence of gold nanoparticles  analysis to determine the effect of microwave heating on the polymorphism of these crystals and/or potential conversion of the crystalline structure into an amorphous material. l-alanine were maintained after the addition of gold nanoparticles . These observations imply that both uric acid crystals and l-alanine crystals can be broken down into smaller crystals and decrystallized by the use of MAMAD technique.It is also important to characterize the uric acid crystals and It is important to note that medical microwaves are used in hyperthermia therapy, inflammation therapy, and in the diagnosis and treatment of cancer ,17,18. Tl-alanine crystals. In the MAMAD technique, microwave heating of the crystals in the presence of solution with gold nanoparticles results in the increase in the kinetic energy of the gold nanoparticles [l-alanine or uric acid crystals. In addition, a slight increase in the temperature of the solvent and crystal can be observed. Subsequently, increased collisions between the gold nanoparticles and increased solvent temperature results in the rapid decrystallization of the crystals, when the MAMAD technique is employed. Several factors, which include solvent evaporation, microwave heating power and time, and the size and amount of both gold and organic crystals, were found to influence the rate of decrystallization using the MAMAD technique.The combined use of microwave and metal nanoparticles in solution  was proven and tested to be an effective method for the reduction of the crystallinity of uric acid and articles . The incl-alanine crystals. In the MAMAD technique, evaporation of the solvent plays an important role in the decrystallization process. After the commencement of microwave heating, the volume of solvent starts to decrease, and the movement of gold nanoparticles in solution is hindered. The largest extent of evaporation was observed for microwave heating at 20 W. The use of the MAMAD technique resulted in the decrease in the size and number of the uric acid and l-alanine crystals and the evaporation of the solvent promoted the precipitation of crystals from solution, which account for the appearance of smaller uric acid crystals on the iCrystal plates. Microwave heating at 10 W in the presence of gold nanoparticles was found to be the most efficient power level for the decrystallization of uric acid crystals and medium l-alanine crystals as compared to smaller uric acid crystals. The MAMAD technique proved more efficient for the decrystallization of uric acid crystals and the medium sized l-alanine crystals, though it was less efficient for the large l-alanine crystals under identical experimental conditions. At a particular crystal size , the use of 20 nm gold nanoparticles is no longer effective in the decrystallization of large l-alanine crystals due to the small size of gold nanoparticles and the evaporation of the solvent. The limitation of the use of the MAMAD technique for the large crystals may be alleviated by increasing the size of gold nanoparticles and increasing the amount of solvent available for the gold nanoparticles to move around in solution. These studies are underway and will be reported in due course.The amount of time necessary for effective decrystallization of crystals was found to be dependent on the initial size of the crystals. Longer microwave heating periods were needed for the medium and large Furthermore, the initial number of uric acid crystals was found to affect the optimal power level and the efficiency of the MAMAD technique. When the number of uric acid crystals were increased from within the range of 52–76 to 150–180 crystals, effective microwave power levels also varied: the use of microwave heating at 2 W and 10 W were most effective for the reduction of uric acid crystal count and size at a concentration of 0.1 mg/mL. The use of microwave heating at 10 W and 20 W were efficient for uric acid crystals at concentrations of 0.2 mg/mL. Our observations suggested that as the number of crystals in solution increases, the 2 W power level becomes less efficient in the decrystallization of uric acid crystals, which may be attributed to the inability of microwave heating at 2 W to provide adequate kinetic energy to the gold nanoparticles to disrupt the structure of the uric acid crystals. It is interesting to note the observation shown in l-alanine crystals. Although an increase in the temperature in the solvent contributes to the dissolution of crystals, increased collisions between the gold “nano-bullets” and “target” crystals due to focused microwave heating is found to be the major factor in decrystallization of uric acid and l-alanine crystals. Further studies will cover the use of larger gold nanoparticles and larger uric acid crystal masses to investigate the efficiency of the use of the MAMAD technique for the decrystallization of crystals in similar size and number observed in chronic gout patients. These studies are also underway and will be reported in due course.It is also necessary to comment on the effect of temperature on decrystallization. Real-time temperature measurements of the solvent during microwave heating reveal a slight increase (up to 2 °C) at the end of microwave heating 60 s for uric acid crystals and 120 s for l-Alanine, uric acid, gold nanoparticle solution , glass coverslips, 20 mL glass vials, stir bars and thermometers were purchased from Sigma-Aldrich . Deionized water was obtained from Millipore Direct Q3 UV apparatus . Adhesive silicone isolators with 21-well capacity  were designed by the Aslan Research Group and manufactured by Grace BioLabs . Poly(methyl)methacrylate (PMMA) discs (5 cm diameter) were purchased from McMaster-Carr . The iCrystal plates were created by combining the PMMA discs and the adhesive silicone isolators. Adhesive silicon isolator was carefully attached to the PMMA platform and gently pressed to ensure water-tight attachment. The 8 GHz medical microwave (maximum wattage 20 W) was obtained from Emblation Microwave .Uric acid solutions were prepared at room temperature and at concentrations of 0.1 mg/mL and 0.2 mg/mL, similar to that found in humans with gout. Uric acid solutions of 20 mL were freshly prepared by dissolving 2 mg and 4 mg of powdered uric acid in 20 mL of deionized water before each experiment.l-alanine crystals were crystallized at room temperature and the medium l-alanine crystals were crystallized using microwave heating [l-alanine solutions were prepared by dissolving 0.3 g of powdered l-alanine into 1.25 mL of distilled water in a 20 mL glass vial and stirred with a magnetic stir bar and heated to 60 °C. A 20 µL portion of the l-alanine solution was placed in the wells of the iCrystal plates. For medium sized l-alanine crystals, the solutions were heated at microwave power level 1  until all the liquid had been evaporated. For the large l-alanine crystals, the solutions in the iCrystal plates were left to crystallize at room temperature overnight.Large  heating . In thisl-alanine crystals were conducted under various conditions as shown in Decrystallization of uric acid and l-alanine crystals were selected based on the area of the well the crystal occupied: medium l-alanine crystals  occupied less than half of the surface area of the well while the large l-alanine crystals (~4300 μm in length) occupied most of the surface area of the well. Large l-alanine crystals occupied one crystal per well due to the comparable size of the well and l-alanine crystals. In addition, 10 µL of gold nanoparticle solution was added to each well and then covered with a glass coverslip used to encase the well . As shown in l-alanine crystals. The crystals were then exposed to microwave power levels  for 120 s. Optical images were taken every 10 s for 120 s. An additional control experiment was conducted whereby 10 µL deionized water was added to the l-alanine crystals in the well and left at room temperature. Optical images were taken every 10 s for 120 s. The control experiments were repeated at least three times and average data reported.Medium and large l-alanine crystals were calculated using the ImageJ software. The area was obtained by closely outlining the selected crystals for each interval. An infrared thermometer was used to measure the temperature of the top layer of the solution that was exposed directly to the microwave heating. Each temperature measurement was completed within 3 s after the microwave heating stopped.Powder XRD data was collected with Rigaku MiniFlex . The total surface area and crystal count for each optical image of uric acid crystals were quantified and measured with the use of the ImageJ software . The crystal length and total surface area for all optical images of both medium and large l-alanine crystals. Our observations showed that microwave heating at 10 W in the presence of 20 nm gold nanoparticles were the most efficient experimental conditions for the decrystallization of uric acid and l-alanine crystals. Although small uric acid crystals and medium l-alanine crystals were decrystallized efficiently with the use of gold nanoparticles, decrystallization of large l-alanine crystals were found to be less efficient with the use of 20 nm gold nanoparticles, which can be attributed to the relative size of the large l-alanine crystals. The results in this study show that the MAMAD technique has the potential to be employed as a therapeutic aid for the decrystallization of crystals related to crystal deposition diseases.In this study, the MAMAD technique was demonstrated to be an effective method to significantly reduce the size and number of uric acid and


This paper intends to evaluate the feasibility of reintroducing recycled concrete aggregates in the precast industry. The mechanical properties of self-compacting concrete (SCC) with incorporation of recycled aggregates (RA) (coarse recycled aggregates (CRA) and fine recycled aggregates (FRA)) from crushed precast elements were evaluated. The goal was to evaluate the ability of producing SCC with a minimum pre-established performance in terms of mechanical strength, incorporating variable ratios of RA  produced from precast source concretes with similar target performances. This replication in SCC was made for two strength classes (45 MPa and 65 MPa), with the intention of obtaining as final result concrete with recycled aggregates whose characteristics are compatible with those of a SCC with natural aggregates in terms of workability and mechanical strength. The results enabled conclusions to be established regarding the SCC’s produced with fine and coarse recycled aggregates from the precast industry, based on its mechanical properties. The properties studied are strongly affected by the type and content of recycled aggregates. The potential demonstrated, mainly in the hardened state, by the joint use of fine and coarse recycled aggregate is emphasized. The consumption of natural resources in the construction industry has been growing in the last decades, as well as the production of demolition, construction and rehabilitation works waste. This process of “construction-demolition” has exerted great pressure on natural resources, especially the natural aggregates (NA), and generated high levels of the so-called construction and demolition waste (CDW), often ending up in landfills. Both these aspects have a negative impact on the environment. Because of the present economic and environmental crisis, the demands for a more sustainable development in the construction sector require a different approach to the concrete technology.The use of recycled aggregates (RA) to produce new concrete seems to be a potential solution. It could solve the problems related with storage, transportation and dumping of CDW and contribute to the sustainability of the environment by adding value to this waste and consequently limiting the consumption of NA.On the other hand, since the capacity to satisfy the clients’ needs and the relationship performance-quality-cost are the main distinctive factors of a healthy competition in the construction sector, the study of self-compacting concrete (SCC) with RA must contribute to an approach between the technological development activities and the needs of both the construction industry and its final clients.The presence of adhered mortar in RA is one of the main reasons for their loss of quality. Consequently, RA have lower density, greater water absorption and lower mechanical strength than the NA. These properties are the ones that most influence the performance of the SCC in which they are incorporated .It is very important to evaluate the SCC fresh-state properties, since it must have specific characteristics to be considered self-compacting, i.e., it must have the capacity to flow and compact under its own weight only, fill the moulds with all the reinforcement bars, piping, negatives, etc., maintaining its homogeneity, and without the need of any on site vibration means .The fluidity of SCC was evaluated through the slumpflow diameter. In the studies analyzed, this parameter decreases for high coarse recycled aggregates (CRA) incorporation ratios, since they absorb more water than the coarse natural aggregates (CNA) ,4. SafiuThe viscosity of SCC is evaluated through the V-funnel flow time. It was found that it increases for high CRA incorporation ratios because of their rougher surface and more angular shape relative to CNA. Safiuddin et al.  and Modap) content [In terms of the SCC’s passing ability through confined spaces evaluated through the L-box passing ability index (PL), it was found that the PL values increase with the RA incorporation ratio. This was justified by the lower water absorption of the FRA in the beginning of the mixing , a highe content .In terms of the SCC’s segregation resistance evaluated through the segregation ratio (SR), three different trends occur. Kou and Poon  found thIn terms of the SCC’s passing ability through confined spaces evaluated through the J-ring slump flow diameter, it was found that the slump-flow diameter increases for small CRA incorporation ratios (30% and 40%). For higher ratios (70% and 100%), the J-ring slump flow diameter decreases, because of the fracture into smaller particles of the CRA during the mixing process, leading to greater water absorption of the RA.In the hardened state, it was found that the SCC’s bulk density at 28 days decreased around 3% for 100% CRA incorporation  and the Based on the works analysed, As seen in The incorporation of CRA reduces the modulus of elasticity . The decShrinkage increases with the FRA incorporation ratio . This waModani and Mohitkar  found thOn the other hand, Pereira-de-Oliveira et al.  found thThe chloride migration decreases as the FRA content grows, which was explained by the greater pores filling effect caused by the FRA, since they have a higher content of small particles than river sand . On the 3, whose chemical composition is provided in One type of cement complying with NP EN 197-1 [3, and limestone filler (LF) complying with specification LNEC-E466 [3, whose chemical composition is given in In order to reduce the amount of cement in the mix, two mineral additions were used: fly ash (FA) complying with NP EN 450-1  and NP ENEC-E466  with a d3, Dmax of 11 mm and water absorption of 1.60%, and gravel 2 with a density of 2690 kg/m3, Dmax of 20 mm and water absorption of 0.80%  with a density of 2670 kg/m3 and water absorption of 0.40% ;A third-generation high-range/strong water-reducing admixture (Sp) complying with NP EN 934-1  and NP ETap water complying with NP EN 1008 .The following materials were used:The RA were separated according to their size by mechanical sieving, and all fractions were used so the particle size distribution of the NA and RA was the same. Despite this, the grading curves of the NA and RA were different, and therefore, it was necessary to adjust the latter to match the former to achieve a similar fineness modulus. To accomplish this, it was necessary to separate the RA according to their different particle sizes. Although this type of procedure is difficult for practical application, it enables comparisons between mix compositions with the same particle size distribution, even though the replacement ratios differ.To cover all the content alternatives used in the mixes and the corresponding analysis of the RA influence, 10 SCC mixes were produced according to NP EN 206-9 . The mixA preliminary stage of mortar study was carried out, which allowed determining the composition of the various mixes by adjusting the W/C ratio and the superplasticizer content, before adding the coarse aggregate  in order to evaluate, at this stage, the workability parameters.p/Vs) was set. According to the results obtained by Silva et al. [p/Vs = 0.80 was considered.A value for the ratio, in absolute volume, between the total amounts of fine material (cement and additions) and fine aggregates in the mixes  was determined taking the target strength into account. For 65 MPa mortars, the value of fad is necessarily lower than the one assumed for 45 MPa mortars, since mixes with higher strengths require higher percentage of cement in their formulation.The percentage of cement replacement by additions  and Sp/p%  values vary according to the need of water and Sp of each mix. Since the objective was to maintain the workability constant while maintaining the volume of fine material in each family of self-compacting mortar (45 MPa and 65 MPa) constant, a starting pair of hypothetical values for Vw/Vp and Sp/p% was considered (Vw/Vp = 0.80 and Sp/p% = 0.65 for 65 MPa mortars and Vw/Vp = 0.85 and Sp/p% = 0.50 for 45 MPa mortars) and gradually adapted to the target workability parameters in an iterative process. These parameters were chosen while taking into account several works on SCC using the Nepomuceno et al. [The Vo et al.  method, o et al. ,20,21,22p/Vs, fad, Vw/Vp and Sp/p%) remained constant, and only natural aggregate replacements were made . This substitution was made in mass and for each particle size fraction, reproducing the reference curve obtained by Nepomuceno et al. [The adjustments were only made for the reference mortar (100% NA). Once the proper self-compacting mortar workability was reached, all the method parameters  was considered constant and equal to 0.03 m3, according to the Nepomuceno et al. [p/Vs  and Vm/Vg , and depends on the desired degree of self-compactability. This parameter was set at 1.82, according to the satisfactory results obtained by Silva and de Brito [m/Vg was calculated, which is required to calculate the amounts of coarse aggregates  in the mix and, along with the fixed parameters determined in the mortar phase, it was possible to calculate all mix contents.For the SCC formulation, it was necessary to set some additional parameters. The value of the void volume  is described in LNEC E 397 [The test procedure used to determine the secant elastic modulus of elasticity  present the highest compressive strength, reaching 78 MPa and 43 MPa at 28 days, for the families PC 65 and PC 45, respectively. The SCCs with 100% FRA are those with lower resistance: 69 MPa and 29 MPa, respectively, in the PC 65 and PC 45 family (with 12% and 32% reductions relative to the reference SCC). Therefore, it is concluded that the objective of replicating the strength of the source concrete was only achieved (and exceeded) in the PC 65 family.2 = 0.85 and R2 = 0.94 (PC 65) and R2 = 0.96 and R2 = 0.92 (PC 45). This conversion factors are near the values presented in Table 7 from NP EN 206-1 [EN 206-1  that varck) were obtained using Equation (1), from Table 3.1 of EC2 [cm is the average compressive strength of concrete.1 of EC2 , where fComparing the characteristic strength values obtained in cubes and cylinders at 28 days with those specified in NP EN 206-1 , it was 2 = 0.93 and R2 = 0.96 (PC 65) and R2 = 0.88 and R2 = 0.92 (PC 45), thus allowing concluding that there is a string link between the two properties.ctm) based on the average values of the compressive strength obtained experimentally in cylinders :Table 3.1 from EC2  presentsComparing the results of the tensile strength obtained experimentally with those taken from this equation , it is fA decrease in the ultrasonic pulse velocity was observed with the increase of the RA in-corporation ratio , and theAccording to the classification suggested by Malhotra , all conAnalysing the results , there wcm) based on the average values of the compressive strength obtained experimentally in cylinders :Table 3.1 from EC2  presentsComparing the results of the modulus of elasticity obtained experimentally from the PC 65 family with those taken from this equation , it is f2 = 0.93 and R2 = 0.90 (at 28 and 91 days) for strength in cubes and R2 = 0.96 and R2 = 0.89 for strength in cylinders, allowing for the conclusion that there is a strong link between the two properties. In order to limit the volume of data, only the results from the PC 45 family were presented.The tests in the fresh state were performed in order to check the compliance of the SCC mixes with the fresh properties required by NP EN 206-9 . As suchAll mixes complied with the requirements demanded from a SCC: fluidity; flow speed, both in the absence and the presence of obstructions; filling capacity; flow capacity; passing ability; and segregation resistance. The concrete density did not significantly change with the incorporation of RA and its variation is closely related with the density of the RA used in each composition.In terms of the SCC’s mechanical strength, in compression and tension, it is concluded that the replacement of NA with RA causes a performance loss, explained by the lower quality of RA compared to NA, due to the adhered mortar. The strength loss was greater in the PC 65 family, due to the worst quality of the RA, resulting from a lower strength source concrete. The objective of reproducing the strength of the RA’s source concrete was reached only in the PC 65 family. However, for the PC 45 family, all the mixes, except for the one with 100% FRA, belong to the C20/25 strength class or higher, and can thus be used as structural concrete. Besides the RA’s lower strength, the higher W/C ratio may have contributed to the poorer performance of the PC 45 family mixes.The modulus of elasticity suffered a reduction as the FRA incorporation increased, explained by the latter’s lower stiffness and the greater deformability of the adhered mortar. It was found that the mix with 100% CRA had a better performance than the one with 50% RA, meaning that this property was most influenced by the FRA content. The ultrasonic pulse velocity decreased with the RA incorporation ratio, even though this reduction is small, being caused by the increase in porosity of the RA, again linked with adhered mortar. The abrasion wear increased with the FRA replacement ratio, because of the latter’s greater porosity and consequent lower density, leading to a stiffness loss.The aggregates used, coming from discarded elements from the concrete precasting industry, are of excellent quality, with a better performance in terms of all their properties than that reported in most of the research consulted;For the majority of the mechanical properties, incorporation ratios of 25% RA, 50% RA and 100% CRA are viable;Therefore, it is considered that an increase of the maximum incorporation ratios of this type of aggregates in existing codes could be contemplated, provided that their quality is demonstrated (as in the case of aggregates from precast concrete elements).Finally the following general conclusions are presented, based on the results of the experimental work performed: