Specifics of studying crushability of construction rocks

Abstract

Objectives: The existing techniques of studying crushability of rocks are based on the determination of power consumption and aggregate size of the resulting products. Given that during disintegration of the construction rocks it is required to retain rock strength in the crushed stone grains, to improve methodology for crushability assessing is an urgent task. Method: When choosing a method to study crushability of rocks it should be considered that the processes of disintegration in various crushing machines have different mechanisms of action, the most accurate forecast figures are provided by the technique using the destruction mechanism similar to an industrial crusher. A deformation field is created in the entire volume of the body under the load, which leads to a change in the structure and strength of the products formed. In this regard, the strength of crushed stone grains being a final product of disintegration is introduced as an additional indicator that characterizes crushability of rocks. Findings: The article presents the results of studying crushability of construction rocks by different methods. It was found that porosity, particle size, grain shape and loading effort application rate are the factors affecting the strength of crushed stone grains. Mechanical stresses undergone by the rocks during blasting and disintegration result in increased porosity and, consequently, reduce strength. Theoretical dependence of increased strength while reducing the fraction size appears for gabbro-diabases being homogeneous in texture. For granites that are non-uniform in composition and texture there is no unique relationship between the strength and the fraction size. Increased grain cubicity of crushed stone enhances its strength. The study of the crushing kinetics revealed that with decreased loading rate the strength of granite crushed stone having high porosity is reduced, while the strength of the low-porous crushed stone made of gabbro-diabase remains practically unchanged. When choosing a crushing method, either shock or static one, it is necessary to take into account, first, the size of the crushed objects and, second, mineral composition and texture-structural features of the rocks. Improvements: The results obtained are of practical value in selecting rational processing technology and relevant equipment, as well as in the crushing process management to reduce energy costs and improve product quality.