Optimum lime content identification for lime-stabilised rammed earth

• We have studied the strength and stiffness of lime-stabilised rammed earth (LSRE).
• Oven-drying curing conditions significantly altered the strength of LSRE.
• The existence of an Optimum Lime Content (OLC) was found that maximises the compressive strength.
• Plasticity limit and pH testings might help to identify OLC in LSRE.

The rising price of energy and a recognition of the human impact on climate change has resulted in growing interest in environmentally–friendly construction techniques such as rammed earth. Modern rammed earth is generally stabilised with small quantities of Portland cement in order to improve its strength and durability, however an alternative is to use lime to stabilise the raw soil. This is common practice in road construction, for example, but is less common in RE. This paper presents experimental results illustrating the existence of an optimum lime content that maximises the unconfined compressive strength and stiffness of an engineered lime-stabilised rammed earth and the experimental procedures employed to determine it. The effect of curing regime (oven as opposed to natural drying) on the final unconfined compressive strength of the material was also investigated. An optimum lime content for the tested soil has been identified and several methods to determine its rough value presented which have the potential to reduce testing times and so associated costs.