Geotechnical characteristics of crushability of granular soils

When components of granular soils are broken into smaller pieces due to an external force, the physical and mechanical properties of the soil undergo a significant change. Therefore, it is important to be able to identify the soil characteristics and understand their influence on particle crushing. Our research focused on both artificial and natural materials. Availability in different sizes and easy crushability were taken into account in choosing pasta and hydro granules as artificial materials. They can also represent the more crushable fractions in natural soils. Glass beads, another artificial material, were used to represent the finer, less crushable parts in natural soils. A wide range of crushability and grain size distribution in the natural materials was obtained by choosing a quartz sand, a glauconite sand and two carbonate sands. In order to calculate the necessary parameters, density and specific gravity were measured for each material. A first series of one dimensional compressibility tests with a constant strain rate of epsilon=1,2%/min and maximum load of 30 MPa, was meant to study the impact of characteristics like strain rate, particle strength, type of material and grain size. An attempt to study the influence of the time on the crushability was made in a series of long term oedometer tests. The amount of crushing in each test is represented by Bt, which is the total breakage factor. Yield point and compressibility are two other parameters that were used to compare the crushing between two different materials. Tests with the different artificial materials were analyzed with regard to particle shape, strength, angularity and size. Single particle crushing tests completed the study of these characteristics. Mixtures of glass beads with pasta were tested to simulate natural crushable soils. Finally a comparison of the different natural materials was performed to study the influence of the shape, mineralogy and grading of particle size