Scientists have found that recycled glass and lime can strengthen compressed earth blocks. This could be a sustainable alternative to cement for eco-friendly, durable construction materials.
Compressed earth blocks are produced by mixing soil with water and compacting the material under high pressure. Cement is commonly added to improve the blocks’ mechanical properties, but its production has a high environmental impact.
Researchers at the University of Portsmouth have shown that powdered recycled glass can effectively stabilize compressed earth blocks. Their findings, published in Discover Civil Engineering, suggest that combining recycled glass with lime could reduce reliance on traditional cement while maintaining strength and durability.
The scientists created compressed earth blocks with recycled waste glass particles at varying ratios up to 25 %. They assessed their material performance over 28 days, analyzing changes to the microstructure with an electron microscope and assessing the blocks’ mechanical strength and water absorption.
They tested various parameters at each percentage level. They assessed the resistance of the blocks to breaking when compressed, and determined the maximum stress the block could withstand while being stretched or pulled, before breaking or becoming deformed.
The highest compressive strength of 5.77 MPa was achieved with 10 % recycled waste glass particles and 10 % lime compressed earth blocks. In comparison, the unstabilized specimens achieved 3.03 MPa after 28 days of curing, indicating a 90 % improvement.
The highest tensile strength of 0.52 MPa was achieved with 10 % recycled waste glass particles and lime CEBs, while unstabilized specimens achieved 0.40 MPa after 28 days of curing.
Microscopy revealed that the 10 % glass and lime mix produced a dense structure free of microcracks. However, microcracks began to appear at higher glass proportions of 25 %, demonstrating the optimum stability of a 10 % blend.
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