Abstract
Based on ACI 306R-10, the minimum temperature necessary for maintaining concrete hydration and strength gaining is 5 degrees C. If the weather becomes lower than 5 degrees C, some special measures should be taken in order to prevent decrease in the rate of hydration and to prevent fresh concrete from freezing. Most of the cold weather living countries spend annually plenty of money in order to facilitate concrete placing in the cold weather and to extend the construction season. It has been investigated that the behavior of fresh and hardened concrete contained calcium nitrate at different curing temperatures below freezing temperature of water and compare the results with the both control samples. For this reason, calcium nitrate is used at level of 6% by weight of cement dosage in mixes. After casting, one group of samples was cured in the different deepfreezes at -5 degrees C, -10 degrees C, -15 degrees C, and -20 degrees C for 7, 14 and 28 days, and then the same samples were cured in water at (23 +/- 1.7)degrees C for 7, 14, and 28 days. Calcium nitrate increased the compressive strength of concrete between 48-964, 50-721, 29-393 and 24-183%, for -5 degrees C, -10 degrees C, -15 degrees C and -20 degrees C, respectively, when compared to mixes without antifreeze admixtures. The results showed that it is possible to use calcium nitrate as an antifreeze admixture in concrete technology in cold weather concreting without additional precautions. (c) 2013 Elsevier B.V. All rights reserved.