Static Compaction of Soils with Varying Clay Content

Abstract

The use of compressed earth blocks (CEBs) is widespread in the field of earth construction. They present better mechanical performance than adobe and the equipment for their production is simple. Laboratory testing of compressed earth blocks requires large amounts of material. There are variations of unconfined strength testing procedures such as testing halves of the blocks with layers of mortar between them or testing whole blocks in diverse directions. This complicates the interpretation of test results as the shape factor and mortar characteristics influence the results significantly. Static compaction test can be used to produce cylindrical samples representative of CEBs. The water content of soil used for the production of CEBs is often determined in standard Proctor test while experimental data indicate that the optimum moisture content for static and dynamic compaction is different. The present article addresses the behavior of four soil mixes with varying clay content compacted statically with a constant rate of strain. Static compaction curves were compared with those obtained in standard Proctor test. For all the soil mixes the static optimum moisture content was found to correspond to the start of consolidation. The compaction curve presented no wet side of optimum in contrast to Proctor test. The energy needed to achieve a desired density by static compaction was analyzed for soils with varying clay contents. Static compaction was found to be more efficient than dynamic for clayey soils. An increase in water content was observed to help achieving higher densities at low pressures, which can improve the performance of manual CEB presses.