Use of Organic Residues for the Mechanical Enhancement of Sustainable Rammed Earth

This research focuses on defining a sustainable rammed earth (RE) material using organic residues. Based on the wide availability and the positive effects on earthen materials, it was decided to incorporate used cooking oil as an organic stabilizer and rice husk as fiber reinforcement to enhance the mechanical properties of RE. Considering these residues, six mix-designs were evaluated with different concentrations of used cooking oil and rice husk. Two additional mix-designs based on unstabilized and cement-based stabilized RE were evaluated for comparison purposes. The optimum water content was defined based on compaction curves obtained with standard proctor tests. The compressive strength of the sustainable RE at different curing conditions was assessed by uniaxial compression tests on cubic samples extracted from the RE walls, and the results were compared with those of an unstabilized and cement-based stabilized RE. Results indicated that using rice husk residue could enhance the compressive strength of RE, obtaining similar strength values to traditional cement-based stabilized RE. On the contrary, used cooking oil samples were characterized by a substantial reduction in compressive strength at ambient curing conditions. However, this negative effect was overcome when oven-induced drying was applied.