Tensile strength of compacted rammed earth materials

Abstract

A rammed earth technique is a traditional architectural technique to build soil structures by compacting geo-materials in a form. In this study, tensile strength properties of rammed earth materials and effects of test conditions are evaluated by conducting direct tension tests and splitting tests on several specimens. It is inferred from the result of these test that the direct tension test should be used to evaluate tensile strength of a layer interface, while the splitting test might evaluate the strength related to the tensile strength inside a compaction layer. When rammed earth structures are constructed, the results from the experiments indicate that it is important to scarify interfaces during compaction in order to prevent reduction and variation of the tensile strength of the layer interfaces. The tensile strength of the rammed earth specimens made of compacted soils without lime increased with the decrease in their water contents. The tensile strengths of the specimens represent 5.0–12.5% of corresponding values of unconfined compression strength at the same water content range. The tensile strength of rammed earth specimens made of lime-mixed soil was in the range of 15–20% of the corresponding unconfined compression strength at 28 days curing. In the series of cyclic tensile loading test, no significant reduction of tensile strengths was observed even after undergoing the cyclic loading history.