Mechanical activation in the production of lime-sand mixtures
This paper presents a review of the author’s research of the effect of different grinding units’ on the physical and chemical profile and geometry of quartz powders. Thus, when quartz sand is being treated in a vortex layer machine for 3–5 minutes, the mean particle size decreases from 235 to 6–7 μm, and the maximum size – from 498 to 81–77 μm. In this case, the specific surface area of the quartz powder, determined by the BET method, is 1.14–1.5 times larger than that of the powder obtained in other grinding units. It was shown that only the treatment of quartz sand in the vortex layer machine allows identifying this process as mechanical activation. The same positive results were obtained when treating building lime in the machine. There is an intensification of the building lime hydration process observed. The rational treatment time of the lime-sand compounds mixture in the vortex layer machines is 5 minutes. For compounds obtained from such mixtures at the age of 28 days, an increase in compressive strength by 209 % and bending strength by 172 % is observed. A decrease in the porosity of the compounds by 24 % was also found. Increasing the time of treatment of a lime-sand mixture in the vortex layer machine for more than 5 minutes has shown a slight effect on the physical and mechanical properties of the materials obtained.