Concrete setting retarders

Abstract

1. When placing a concrete mix in massive structures it is necessary to prolong the time of setting for a number of reasons (long hauling, time of covering the layers, etc.). To attain this goal it is necessary to introduce retarding admixtures to the concrete mix. 2. The proposed admixture — syrup — is a sufficiently reliable agent for retarding the time of setting, which permits increasing the time of loss of mobility of the concrete mix to 7–8 h when added in an optimum amount. 3. The addition of syrup reduces the consumption of cement by 12–15% in comparison with a concrete mix without the admixture, provided their equal mobility and equal strength of the concretes at the design age. 4. Syrup, in comparison with a well-known admixture, sulfite waste liquor and sulfite-yeast waste liquor, increases the compressive and tensile strengths of concrete and improves its impermeability and frost resistance. 5. The addition of syrup markedly increases the rate of heat liberation of concrete, which can simplify considerably the technology of concreting and sealing the joints of massive structures. 6. The addition of syrup to concretes with an accelerated hardening regime (steam curing, heating, etc.) is contraindicated.