Dissolution characteristics of chloride ion in alkali residue and its effect on the properties of light-weighted soil

Abstract

Environmental pollution and steel-bar corrosion are worsening owing to the high content of chloride ions (Cl-) in alkali residue (AR), and its application is limited. In this study, a washing program is proposed to remove Cl- and manufacture AR-based light-weighted soil (A-LS). Several tests were conducted to analyze the influence of the number of washing cycles on AR and the performance of A-SL. The results show that Cl- can be effectively removed by the washing program. After washing, the particle size of the AR decreases, and the water absorption is enhanced. The pore structure of A-LS changes, and its compressive strength decreases with washing. According to the requirements of the specification for Cl-, the AR must be washed twice. Finally, when A-LS is mixed with ordinary Portland cement (OPC), ground granulated blast slag (GGBS), and AR washed two times in the ratio of 30:40:30 (wt%), the compressive strength is 1.03 MPa based on the water–solid ratio of 0.9 and wet density of 600 kg/m3 at 28 d; this meets the application requirements of most filling projects. The findings of this study can help reduce the usage of OPC and avoid environmental pollution, portraying great social and economic benefits..