Effects of compaction on desiccation cracking of clayey soils

Cracking in desiccating soils is an important topic in soil compacted works. This paper presents an experimental study on the effect of compaction on the cracking of a silty clay soil, which was subjected to drying conditions. The specimens were compacted at different initial moisture contents with the purpose of studying the effect that the amount of water has in the crack formation and propagation. As initial condition, different points were considered from the Standard Proctor curve. Three specimens were dried in an environmental chamber at a constant temperature and relative humidity while the main soil variables (suction, temperature and relative humidity) were recorded. On the other hand, a couple of specimens were subjected to drying in laboratory atmosphere conditions, measuring the weight loss along time. In both cases the drying process was monitored taking images at regular intervals that later were processed using image analysis techniques. From these analyses, the Crack Intensity Factor (CIF) was obtained. In both type of tests, the specimens compacted on the wet side of the Proctor curve tended to lose more water and had a higher CIF than the ones compacted on the dry side. The difference in behaviour can be explained by the microstructure generated by compaction on the dry or on wet side.