Crushability on granular materials by strain controlled oedometer testing at high stress levels

Abstract

The crushability of artificial and natural granular materials has been analyzed using one-dimensional strain-controlled compression tests and standard oedometer tests at high stress levels to study the effect on the breakage of a number of parameters such as: grain mineralogy, grain size, uniformity coefficient, strain rate and loading time. Measuring the breakage factor at different stages of compression, it was demonstrated that the crushing started before reaching the point of maximum curvature (yield point) in the compressibility curve. Beyond yielding the crushing increased abruptly. Among the natural materials analyzed, the lowest yield stress value occurs in the carbonate sand, and the highest in the silica sand. We found that the breakage increases with increasing size of the grains. Coarse uniform samples showed higher breakage than uniform fine samples and well-graded samples. The breakage increased with decreasing strain rate or increasing load application time. For natural soils it is difficult to study separately the influence of isolated parameters on the breakage. The study of homogeneous artificial materials facilitated this analysis.