Role of Granulometry of Mixed Binders in Formation of Their Microstructure and Strength

Abstract

A complex system is formed when grinding Portland cement and various mineral fillers. It consists of grains of various sizes with a predominance of a highly dispersed phase. The work investigates the effect of mixed binders prepared on the basis of Portland cement and volcanic ash at various dosages. The analysis of volcanic ash particles is carried out. It is found that the presence of the smallest fractions in the range from 0.3 to 0.07 microns predicts active interaction in the system and the filling of the pore space with hydration products. It has been established that mixed binders obtained by mechanical mixing (without grinding) with a content of 10% volcanic ash have a strength 13% higher than no addition cement. Mixed binders activated by milling in a vibration mill with a volcanic ash content of 10% are characterized by an increase in compressive strength by 22%, which saves Portland cement by up to 10%. Mixed binders with a volcanic ash content of 20% correspond to the strength of cement free. The results obtained indicate the effectiveness and feasibility of using volcanic ash as a mineral component of mixed binders. The microstructure of a cement stone sample from an activated mixed binder is highly homogeneous, dense intergrown plates of a secondary hydrosilicate structure are clearly visible in the sample cleavage, and crystalline products of pozzolanic reactions between ash particles and cement hydration products are formed on the surfaces of secondary hydrosilicate structures. The purpose of this article is to study the role of granulometry of mixed binders in the formation of their microstructure and strength.