Evaluation of engineering characteristics of stabilized rammed-earth material sourced from natural fines-rich soil

Abstract

Rammed earth construction is an ancient technique using local soils that are compacted to form structural elements. This method has attracted renewed interest throughout the world due to its social, economic, and environmental benefits. This paper furthers the understanding of rammed earth as an engineering material. A local soil is selected as representative of readily available matrix material and its suitability is studied by conducting compression, tension, bending, and durability tests on the end product. The viability of using a natural soil with high fines content is adopted as one of the key target elements of this research. The effect of using varied percentages of two stabilizers, cement and natural lime, on the mechanical properties of rammed earth is also assessed. Additionally, the efficacy of reinforcement using hemp fibers to improve tensile properties is investigated. Experimental results show that natural soils with high fines content are a viable construction material when stabilized by a combination of lime and cement. For this optimal combination, the compressive strength improves roughly threefold and the durability performance is enhanced to acceptable levels. Furthermore, the combination of 6% chemical stabilization and 0.75% fiber reinforcement is found to provide optimal benefits in imparting tensile strength and toughness to rammed earth. The obtained improvements are on the order of 500% and 30,000% in the tensile strength and toughness, respectively. © 2018 American Society of Civil Engineers.