Properties of using excavated soil waste as fine and coarse aggregates in unfired clay bricks after dry-wet cycles

Buildings and Constructions in civil engineering have led to quite a large production of excavated soil wastes. In order to use excavated soil waste, this paper investigated the physical and mechanical properties of excavated soil-based unfired clay bricks (ESUCB) with different mix proportions before and after dry-wet cycles. A total of 108 specimens are separated into nine groups according to the criterial of orthogonal experimental design of four factors (i.e., water-to-cement ratio, cement-to-excavated soil ratio, fine recycled concrete aggregate-to-excavated soil ratio and compound additives content) and three levels. Dry-wet cyclic experiments characterized with 5, 10 and 20 cycles respectively on ESUCB were carried out before conducting the compressive loading test. The test results indicate that increasing the dry-wet cycle number leads to larger mass loss, higher strength reduction rate and reduce the compressive strength of ESUCB. Four strength categories including Grade Ⅰ (higher than 20 MPa), Grade Ⅱ (15–20 MPa), Grade Ⅲ (10–15 MPa) and Grade Ⅳ (5–10 MPa) were divided to provide the specific mix proportion for a certain compressive strength requirement of ESUCB. Variance and range analysis shows that the water-to-cement ratio has the most significant effect on the compressive strength and the smallest one is the additive content. Using the experimental data-driven approach, nonlinear regression equations for compressive strength of ESUCB without and with dry-wet cycles were proposed, respectively.