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Abstract

High water content of titanium gypsum results in diffiicult dehydration and comprehensive utilization. To achieve the large-scale application of solid waste of titanium gypsum in road subgrade, this paper employed red mud and slag as the curing agents. Meanwhile, it designed a three-factor four-level test with the gypsum-slag ratio of 4:6, 5:5, 6:4, and 7:3, red mud-slag ratio of 1:4, 1:3, 1:2, and 1:1, and mixing contents 0, 2%, 4%, and 6% of sodium silicate. The unconfined compression strength of solidified titanium gypsum at 7 and 28 days was determined, and its coefficient of softness was calculated. The microstructure of the specimens was analyzed by adopting scanning electron microscopy, energy spectrometer, and X-ray diffraction. The results show that the strength of solidified titanium gypsum is high under the gypsum-slag ratio of 4:6, red mud-slag ratio of 1:4, and sodium silicate content of 6%, with the compressive strength at 7 and 28 days reaching 7.2 MPa and 25.1 MPa respectively. The gypsum-slag ratio has the greatest influence on the strength of solidified titanium gypsum, while the red mud-slag ratio and sodium silicate exert a smaller effect. As the gypsum-slag ratio and red mud-slag ratio decrease, the strength of solidified titanium gypsum increases. When the gypsum-slag ratio is no more than 6:4, the compressive strength at 7 and 28 days exceeds 4.7 MPa and 18.2 MPa respectively, with the coefficient of softness greater than 0.95. The main reaction products of solidified titanium gypsum are ettringite crystal and hydrated calcium silicate gel, which are spatially interconnected to form a grid structure and connected with the titanium gypsum matrix to ensure the strength and water stability of solidified titanium gypsum. Generally, when the gypsum-slag ratio is not less than 6:4, the solidified titanium gypsum has sound water stability and its strength can meet the requirements of cement-stabilized subgrade for highway grade II and below.

Publication Date

1-18-2024

DOI

10.14048/j.issn.1671-2579.2023.06.049

First Page

315

Last Page

321

Submission Date

March 2025

Reference

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