Characteristic Compressive Strength of Cement-Stabilized Rammed Earth

The standard codes of practice on the rammed-earth construction are limited. It is essential to ascertain the characteristic compressive strength of the cement-stabilized rammed earth (CSRE) for the structural design of CSRE walls. The test procedures for determining the characteristic compressive strength of CSRE are not available in the standard codes of practices. The specimen size and its slenderness can affect the compressive strength of CSRE elements. This paper deals with the relationships between the specimen's aspect ratio and compressive strength for CSRE using two cement contents (7 and 10%) and two densities. Both cylindrical and wallette specimens having an aspect ratio varying between 2 and 5.81 were tested for compressive strength. The results show that there is hardly any reduction in compressive strength as the aspect ratio was increased from 2 to 5.81 (a reduction in compressive strength of 1 and 3-5% for specimens with density of 1,800 and 1,700kg/m3, respectively). The study clearly demonstrates that the characteristic compressive strength of CSRE can be obtained by testing cylindrical (150mm diameter and 300mm height) or prism specimens (150mm square cross section and 300mm height) without applying any correction factor. Furthermore, since the moisture content in the specimen has a significant influence on the compressive strength of CSRE, it is recommended to adopt the wet compressive strength for structural design.