Heat-resistant ash and slag concrete with activating admixtures

The paper shows the use of activators for the hardening of cement-ash concrete, incl. passing when heating concrete. Such an activator is a composition of sodium fluorosilicate and naphthalene-formaldehyde superplasticizer. The addition of sodium fluorosilicate makes it possible to increase the early strength of the cement-ash binder, enhance the kinetics of pozzolanic reaction and reduce the drop in the strength of the cement-ash stone when it is heated to 800°C. Experimental dependences of concrete mixture water demand and concrete strength on the cement and aggregates consumption for different workability mixtures have been obtained. These dependences take into account the influence of complex admixtures of superplasticizer and sodium fluorosilicate that enabled to propose a method for design of ash and slag concrete compositions. The positive role of the proposed complex activating admixture on the change in strength and shrinkage of ash and slag concrete after drying and subsequent heating has been experimentally confirmed. A complex of experimental-statistical models of ash and slag concrete properties has been obtained, taking into account the influence of activation admixture, superplasticizer and sodium silicon fluoride consumption, cement-water ratio, temperature and the number of heating and cooling cycles.