M.R. Sadri - Chief of Laboratory of Chamshir Dam; SABIR Construction Company

The use of chemical admixtures in hydraulic-cement concrete mixtures has been common in recent decades for different purposes. The diversion tunnel of Chamshir dam in Gachsaran has about 45,000 m3 reinforced and mass conventional concrete. Due to the hot climate of Chamshir district, suitable admixtures should be used to prolong workability and reduce the cement content and help prevent thermal problems for mass concrete. On the other hand the stripping time interval may be an important criterion to speed up lining. Some different kinds (brands & types) of plasticizers andsuper-plasticizers were tested in the dam local laboratory. The test program included Marsh cone flow test of cement slush plus admixtures to investigate the water reducing effect and flow retention. Some admixtures in some dosages showed incompatibility that is described in the paper. Eventually the top-3 admixtures were selected to be tested in concrete trial mixtures. In this paper the commercial name of admixtures and their manufacturers will not be mentioned and just be named A, B, C and etc.

Chemical Admixture, Compatibility, Flow Time, Water Reducing Effect, Flow Retention, Chamshir Dam