MECHANOCHEMICAL ACTIVATION OF MIXED BINDER AND ITS EFFECT ON CONCRETE PROPERTIES

Abstract

The issues considered in the article are related to the determination of the combined effect of mechanochemical activation of Portland cement and its consumption, ground quartz sand, superplasticizer (hereinafter SP) and amorphous microsilica (hereinafter MS) on the strength and abrasion resistance of concrete. The effect of partial replacement of Portland cement with ground quartz sand was studied, the consumption of which in the mixed binder varied in the range from 0 to 40%. The consumption of MS in the mixed binder varied in the range from 0 to 10%, and the consumption of SP ‒ from 0 to 1% of the Portland cement mass. The consumption of Portland cement in the concrete mix varied in the range from 350 to 450 kg/m3 . The activation period of the binder was 180 sec. The obtained experimental results indicate the possibility of varying the recipe and technological factors to increase the strength of concrete and reduce the consumption of Portland cement in the concrete mix. The obtained experimental data indicate a significant effect of mechanochemical activation of the mixed binder on the strength of concrete. Of the listed factors, the greatest effect on the compressive strength of concrete is exerted by the consumption of ground sand and SP in the mixed binder. The addition of ground quartz sand (40%) to the mixed binder causes a decrease in the strength of concrete from 35.1 MPa to 22.5 MPa (by 35.9%) at the grade age. An increase in the consumption of SP (up to 1%) in the mixed binder causes an increase in the strength of concrete from 17 MPa to 28 MPa (by 64.7%) at the early stages of hardening and from 35.1 MPa to 49.7 MPa (by 41.6%) at the grade age. The use of MS (10%) in the composition of the mixed binder provides a relatively insignificant increase in strength (6.5%) at the early stages of curing and (4.6%) at the grade age compared to the control. The use of mechanical activation provides an increase in concrete strength by 62.4% (at the early stages of hardening) and 25.1% (at the grade age) compared to the control. The combined effect of mechanical activation (180 sec), addition of ground quartz sand (40%), MS addition (10%) and an increase in the consumption of SP (1%) in the composition of the mixed binder (Portland cement consumption 350 kg/m3) causes an increase in the compressive strength of concrete (8, ), a decrease in concrete abrasion from 0.33 (40% ground sand) to 0.21 g/cm2 and a decrease in Portland cement consumption from 350 kg/m3 (control) to 189 kg/m3 (by 46%).