Study on formula and mechanism of chemical admixtures for slurry-like mud treated by physicochemical combined method

Abstract

To achieve value-added recycling of slurry-like mud (MS) and resolve the shortage issue of construction fill materials, physicochemical combined methods (PCCMs), which integrate flocculation, solidification, and vacuum preloading (optional), have been proposed to enhance the engineering properties of MS. The optimization of chemical admixtures, which consist of solidification and flocculation components, is crucial in ensuring the effectiveness and cost-efficiency of PCCM in practical application. In this study, a number of solidification model tests are performed to optimize the solidification components for PCCM via determining the optimal mixing ratio in each of the two GGBS-based binders. Subsequently, surcharge preloading deposition tests and vacuum preloading model tests, with different types/dosages of flocculant, are conducted to determine the appropriate flocculation components. The results indicate that OPC-GGBS exhibits remarkable effectiveness in strength improvement, and the use of a combination of organic and inorganic flocculant, particularly CaO-PAM, can significantly enhance the efficiency of PCCM. Moreover, increasing the dosage of the composite flocculants enhances the dewatering process, but the benefit becomes less significant when the dosage exceeds a threshold value of 0.16%. Additionally, this study provides a preliminary understanding of the key mechanism involved in synergizing flocculation, solidification and preloading to enhance the performance of MS. These findings contribute to the optimal design and application of PCCM for the treatment of MS.