Experimental investigation of durability and mechanical properties of EICP treated raw earth Available to Purchase

Recent research in geomechanics has increasingly focused on developing carbon-efficient construction materials, with raw earth emerging as a promising candidate due to its favourable hygroscopic properties and natural abundance. Despite these advantages, raw earth’s major drawback is its inadequate durability against water erosion and its relatively weak strength compared to concrete or cement/lime-treated raw earth. This paper investigates the durability, mechanical and microstructure properties of a fine silty-clayey raw earth through enzymatically induced carbonate precipitation (EICP) stabilisation, employing soybeans as a cost-effective source of urease enzyme in its crude extract form. With an anticipated calcium carbonate content of 8%, durability tests reveal a significant improvement in the EICP-treated samples compared to untreated ones. Nevertheless, both untreated and treated samples are deemed suitable only for dry applications due to observed cracking in contact tests. Results from triaxial tests indicate a substantial increase in cohesion for the treated samples relative to the untreated samples. Mercury intrusion porosimetry tests illustrate a decrease in large sized pores and an emergence of a single pore family in EICP-stabilised samples. It is concluded that the properties of EICP-treated samples could be further enhanced with a greater calcium carbonate content as well as by using water-repellent coatings.