MECHANOACTIVATION OF MIXED BINDING AGENT AND ITS INFLUENCE ON THE STRENGTH OF CONSTRUCTION MORTAR

Abstract

The issues considered in the article are related to determining the effect of mechanical activation of a mixed binder on the properties of a building mortar. The study involved partial replacement of cement with ground crystalline quartz sand and amorphous microsilica (hereinafter MS) in combination with the use of the superplasticizer Relaxol-Super PC (hereinafter SP). The amount of ground sand was adjusted in the range from 0 to 40%, MS from 0 to 10% and SP from 0 to 1% of the binder mass. The activation period of the binder was 180 sec. The use of this formulation allows increasing the strength and reducing the consumption of Portland cement in the technology of manufacturing a building mortar. The obtained experimental data confirmed the influence of formulation and technological factors on the water-solid ratio of the cement-containing composition. It was found that the main contribution to the reduction of the water-solid ratio (provided that equiviscous compositions are obtained) is made by mechanical activation in combination with the replacement of 40% of cement with ground quartz sand and the addition of 1% SP. The water-solid ratio decreases by more than 50%, which has a positive effect on the strength of the solution. The increase in the strength of the mortar with the addition of SP reached 93% (at the early stages of hardening) and 56% (at the grade age) compared to the control. The use of MS in the composition of the mortar provides a relatively small increase in strength (12%) at the early stages of hardening and 8% at the grade age compared to the control. The use of mechanical activation alone provides an increase in the strength of the mortar by 18% (at the early stages of hardening) and 13% (at the grade age) compared to the control. The combined effect of mechanical activation, SP and MS in the composition of the building solution compensates for the negative impact of ground quartz sand and has a positive effect on the growth of strength (up to 38%), ensuring a reduction in cement consumption by 40%.