Clay-Slag Autoclaved Composite Materials with the Usage of Activated Aluminosilicate Raw Materials

In order to expand the raw materials base of building materials industry, not only industrial waste, but the off-grade natural aluminosilicate raw materials—clay minerals of incomplete mineral-forming stages,—have been more and more involved into the industrial usage. As initial materials the steelmaking slag with basicity factor 1.15 and characterized as neutral and the clay-containing component—sandy loam—were used in this study. The paper presents the results of dry milling and MW (microwave) treatment of sandy loam influence on strength properties of clay-slag autoclaved silicate concretes. It has been demonstrated that dry milling of sandy loam provides the highest gain of specific surface—26.15%, while using the MW-field (power 800 W, 2 min.) increases the specific surface by only 8.83% in comparison with the original sample. Then the reactive properties of mechanically activated sandy loam are considered. The reactive properties of sandy loam, modified with microwave radiation, are composed of the increased sorption capacity to Ca(OH)₂ of the dispersed clay minerals and reactive polymorphic modifications of quartz. At the optimal ratio, wt%, clay component: slag = 40:60 the highest strength properties were obtained at using the sandy loam, activated in the microwave field at the following radiation parameters—power 800 W, treatment time 2 min. The gain of strength properties made up 60% as compared to the non-activated sandy loam.