Characteristics of waste mud treated by construction waste-slag based flocculation-solidification combined method

Abstract

Nowadays, the flocculation-solidification combined method (FSCM) is considered suitable for mud treatment and recycling. However, the traditional FSCM uses ordinary Portland cement (OPC) as the main solidifying material, which pollutes the ecological environment. Currently, the evaluation mechanism of solidification efficiency is not accurate, the treatment of mud with different water content is not detailed enough, and the assessment of carbon emission is unclear. Accordingly, this paper introduces solid waste such as construction waste powder (concrete and brick mix recycled fine aggregate) and slag powder for solidification based on the traditional FSCM. Within the study context, the alkali activation effects of quicklime, NaOH, and NaSiO3 are compared to develop a new solidification agent. Besides, the flocculation time and peak settling rate are measured experimentally, and anionic polyacrylamide(APAM) is added separately to compare low-water-content mud (LW-MS) (ω < 70 %) and high-water-content mud (HW-MS) (70 %≤ω ≤ 300 %). The intrinsic flocculation-solidification mechanism is analyzed and demonstrated through microscopic testing.Finally, the feasibility of construction waste-slag based flocculation-solidification combined method (CWS-FSCM) is verified through field test. In terms of solidification effectiveness, carbon emissions and economy, CWS-FSCM performs better than the traditional FSCM.