Mixture design for eco-friendly hybrid clay treated with two stabilizers based on water absorption and retention of stabilizers

Abstract

Major challenges are encountered when using high-water-content clays as construction materials owing to their low shear strength and high compressibility. Processes, such as sun drying and stabilization using chemical agents, can address the problems met with these clays during their conveyance and reuse. However, natural dehydration is a time-consuming process, and chemical stabilization can lead to an increase in the hydrogen ion index (pH) of the surrounding environment. Thus, the aim of this study is to improve the performance of high-water-content clay using a combination of green and byproduct materials, specifically bamboo chips and fly ash, which are cost-effective and eco-friendly. No previous study has attempted to design a mixture for the purpose of improving the performance of clay based on the water absorption and retention performance of stabilizers. In this study, the water absorption and retention rate (W_ab), which is the mass of the water absorbed and retained by 1 g of each stabilizer, was measured by removing the unabsorbed and unretained water through filtration under vacuum suction. A series of Cone Index tests were conducted on clay, separately treated with bamboo chips and fly ash, and the tests demonstrated a correlation among the Cone Index (q_c), W_ab, and amount of stabilizer added (A_st). A novel mixture design was proposed for hybrid-treated clay, using the two types of stabilizers in the composite, based on parameter β, which is defined as the sum of the product (W_ab/100)×(A_st/100) of each stabilizer used in the hybrid-treated clay. The results of the Cone Index tests performed on the hybrid-treated clay showed that the proposed mixture design can predict the combinations of certain amounts of each stabilizer needed to attain the target q_c with minimal errors. The results of pH measurement tests indicated that the hybrid-treated clays produced by the proposed mixture design were more eco-friendly than fly ash-treated clays. Furthermore, the theoretical maximum CO₂ fixation capacities of the hybrid-treated clays were evaluated to assess their feasibility as CO₂-fixing materials.