The Influence of Retarding Admixtures on the Drying Shrinkage of Concrete.

摘要

Concretes were made containing six bags of cement per cubic yard,five retarding admixtures plus control,and at slumps of two or six inches. The admixtures were a lignosulfonate, a hydroxyacid,and a carbohydrate proprietary materials and glycolic acid and sucrose. The hardened concretes were dried at 73F and 50percent relative humidity. Shrinkage was determined at times from 7days to 6months. There were no systematic differences in the maximum shrinkage values except that those for concrete containing the hydroxyacid retarder were slightly lower than the others. The shrinkage-log time date seem,in most cases,to be reasonably well represented by two straight lines breaking at the 28-day value.