Evaluation of long-term reinforcement of soils using waste brick powder: Insights from strength and characterization

This study presents an investigation into the reuse potential of waste brick powder (WBP), a cost-effective, environmentally friendly, and easy-to-use waste-based geopolymer for soil improvement as a grouting material. The WBP was obtained by crushing and sieving waste brick to produce the recycled aluminosilicate starting material. Various factors, including liquid-to-solid ratios (1.5, 2.0, and 2.5), NaOH molarities (4, 8, 12, and 16), types of soils, and aging (7, 28, and 365 days), were comprehensively investigated to gain insight into the usability of WBP in soil injection. The effect of alkali-activated waste brick powder (AAWBP) on the mechanical strength and injectability of the soils was assessed, as well as the influence of these factors on the microstructure of samples. The primary structure of AAWBP was determined to be the C-S-H gel, which significantly enhanced the strength development of soil samples. The compressive strength of geopolymer-treated S1, S2, and S3 soil samples reached 4.72, 3.79, and 2.5 MPa after 365 days, respectively, significantly higher than the samples at 28 days (3.32, 1.00, and 0.61 MPa, respectively). Moreover, the strength of samples increased with a decrease in the liquid-solid ratio in all samples, whereas it increased with a rise in the concentration of the activator up to 8 molar for S2 and S3 soil and up to 12 molar for S1 soil. Also, reducing soil particle size positively influenced the development of strength characteristics.