Suitability of Vetiver straw fibers in improving the engineering characteristics of compressed earth blocks

Abstract

Although conventional earth construction has been replaced by modern materials in industrialized nations over the last century, interest in earthen materials has surged in industrialized countries due to their economic, social, and environmental sustainability benefits. Compressed earth blocks (CEBs) have gained popularity for their energy efficiency and lower greenhouse gas (GHG) emissions compared to fired clay bricks or cement concrete (CC) blocks. This research explores the potential of Chrysopogon zizanioides, commonly known as Vetiver, a perennial grass found in tropical and subtropical regions, to enhance the engineering properties of CEBs. While the use of Vetiver roots for soil erosion prevention and slope stabilization is well documented, the impact of Vetiver straw fibers on CEBs has not been sufficiently researched. Here, CEBs were manufactured with varying Vetiver straw fiber contents (0%, 0.5%, 1%, 1.5%, 2%, 2.5%, and 3% by dry soil mass). The physical properties of the Vetiver straw fiber-reinforced CEBs revealed a reduction in bulk density and volumetric shrinkage. As for the strength-ductility behavior, the Vetiver straw fibers noticeably increased the ductility of the CEBs. However, the rise in strength was not significant, and it showed little change over time. Durability characteristics were assessed through capillary water absorption and wear resistance tests, indicating reduced water absorption and enhanced wear resistance in CEBs with Vetiver straw fibers. Microstructural analysis through scanning electron microscopy reveals a more uniform and isotropic soil matrix with fewer voids, indicating stronger bonding between the fibers and the soil. Overall, Vetiver straw fiber has demonstrated its potential as a valuable reinforcement material for CEBs, making them more sustainable and resilient.