["< sod > a'''cement accelerator'''is an admixture for the use in [ [ concrete ] ], [ [ mortar ( masonry ) | mortar ] ], rendering or screeds. the addition of an accelerator speeds the setting time and thus [ [ curing ( chemistry ) | cure time ] ] starts earlier. < ref name = justnes > justnes, h. ( 2000 ) : accelerator blends for portland cement. proceedings of cement and concrete technology in the 2000s, september 6 – 10, 2000, istanbul, turkey, vol. 1, pp. 433 - 442 < / ref > this allows concrete to be placed in winter with reduced risk of frost damage. < ref name = korhonen > korhonen, c. j., cortez, e. r. and durning, t. a. ( 1997 ) : antifreeze admixtures for concrete. special report 97 - 26. cold regions research & engineering laboratory, us army corps of engineers < / ref > < ref name = aci > aci 306r - 88 : cold weather concreting. http : / / www. ccagc. org / pdfs / aci _ 306r - 88 _ cold _ weather _ concreting. pdf < / ref > < eod > < sod > a'''cement accelerator'''is an admixture for the use in [ [ concrete ] ], [ [ mortar ( masonry ) | mortar ] ], rendering or screeds. the addition of an accelerator speeds the setting time and thus [ [ curing ( chemistry ) | cure time ] ] starts earlier. < ref name = justnes > justnes, h. ( 2000 ) : accelerator blends for portland cement. proceedings of cement and concrete technology in the 2000s, september 6 – 10, 2000, istanbul, turkey, vol. 1, pp. 433 - 442 < / ref > this allows concrete to be placed in winter with reduced risk of frost damage. < ref name = aci > aci 306r - 88 : cold weather concreting. http : / / www. ccagc. org / pdfs / aci _ 306r - 88 _ cold _ weather _ concreting. pdf < / ref > concrete is damaged if it does not reach a strength of { { 4 convert | 500 | psi | mpa } } before freezing. < ref name = korhonen > { { citation | last = korhonen | first = charles j. | last2 = cortez | first2 = edel r. | last3 = durning | first3 = timothy a. | institution = [ [ cold regions research and engineering laboratory ] ] | year = 1997 | title = antifreeze admixtures for concrete | work = special report 97 - 26 | isbn = 9781428913158 } } < / ref > { { rp | 19 } } < eod >"]