The work is treating about the results of the survey of the fly ash to clay and his influence selected on physical and mechanical qualities of get composite. The survey were done on samples where contents of the fly ash in the attitude to the clay hesitated from 10–30%. Samples were subjected to examinations of determining the contraction of the drying, determining the density and mass, the compressive strength and the resistance to cutting. Final results of the survey obtained that the rise in the content of the fly ash is having a positive effect to physical qualities, negatively on mechanical qualities. Examined physical and mechanical qualities should take into account at design and structural buildings works associated with raising of buildings from clay.

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