superplasticizer

The use of rubber crumb from used tires in concrete as a partial replacement of natural aggregates is an ecologically oriented direction of their utilization. When rubber crumb was added to Portland cement, a decrease in strength was observed. Modification of rubber-containing Portland cement systems with a complex organic and mineral additive makes it possible to compensate for the loss of compressive strength and provide increased impact strength. Samples without rubber show high strength but are characterized by fragility and sudden destruction of the material.

The article presents the peculiarities of obtaining superplasticized cementitious systems "Portland cement – fly ash - superplasticizer" to find a rational provision of the given construction and technical properties of concrete. It was studied the physico-chemical peculiarities of the hydration processes of superplasticized cementitious systems. There were solved problems of directional formation of the microstructure of cement stone.

In this article concrete mixture composition with the additives of zeolitic tuff and superplasticizer was optimized by the method of mathematical planning of experiment. The research reveals that use of optimal amount of zeolitic tuff results in increasing strength of concrete at later age of hardening and does not influence significantly the water absorption, porosity and freezing temperature of the liquid phase of fresh frozen concrete mixture.