Study on the Property and Mechanism of Low Content Cement-Industrial Waste Residue Silt Solidification

Abstract

In this paper, industrial waste residue was used as the main cementing material instead of Portland cement to solidify the silt, which was in contrast with the single cement solidified silt. Firstly, the mechanical properties and influence laws of single cement and different mix ratio cement-industrial waste solidified silt were carried out. Secondly, the optimal mix ratio of solidified silt was obtained as: Portland cement: blast furnace slag: phosphogypsum = 3:6:1. Compared with the solidified silt with single cement, the compressive strength of the solidified silt with composite curing agent reached 517.19 kPa after curing for 28 days, which was 80.09% higher than that of the solidified silt with single cement. Finally, X-ray diffractometer (XRD), scanning electron microscope (SEM), thermogravimetric analyzer (TG) and nitrogen adsorption pore analyzer were used to study the composition, quantity, microstructure and pore characteristics of the minerals generated during the solidification process of the composite curing agent, so as to reveal the mechanism of the effective solidification of the silt by the composite curing agent. The test results showed that the secondary hydration reaction of blast furnace slag can be co-stimulated by the cement hydration products Calcium hydroxide and phosphogypsum, and the hydration products formed Hydrated calcium silicate colloid and Ettringite crystal. The hydration products with colloid properties were added to the solidified silt system, which will significantly improve the solidified silt performance of the composite curing agent. Hydrated calcium silicate colloid and Ettringite crystal played an important role in the skeleton and filling, and the structure of the silt solidified by the compound curing agent was more compact.