Influence of aggregate size and water content on compactability of soil using short-time static loads

Abstract

A laboratory test using a “Proctor” mould and applied unidirectional pressures was carried out using a sandy clay loam soil, but with samples of varying water content and aggregate sizes (0 to 2, 2 to 5, 5 to 10 and 0 to 10 mm). The applied pressures were in a limited range 35 to 93 kPa and were applied as static loads for periods of less than 5 s. The resulting compaction was measured as bulk density and H/H i where H i is the initial height of the sample and H is the height after compaction. Tensile strength of the soil aggregates at the same water contents used above was determined. The ratio of the applied pressures to aggregate tensile strength was established. This ratio was then used to explain the differences in level of compaction obtained with the different sized aggregates and water contents. This information was used to explain why the resulting bulk densities obtained in this soil in a field situation did not vary when using tractors of different weights giving different applied pressures.