Performance and Curing Mechanism of Sodium Silicate Modified Phosphogypsum Road Stabilizing Material

Abstract

Abstract: With the purpose of resource utilization of phosphogypsum, this paper explored the optimal ratio design of silica fume and cement curing high-concentration original phosphogypsum to prepare road stabilizing materials, on this basis studied the performance of sodium silicate enhanced road stabilizing materials, and analysed the curing mechanism. The results show that when the mass ratio of cement, silica fume and slaked lime is 5 ∶3 ∶2, and 1.5% (mass fraction) of sodium silicate is added, the mechanical properties and water resistance of phosphogypsum road stabilizing materials are significantly improved, and the unconfined compressive strength of 28 d reaches 9.77 MPa, the softening coefficient reaches 0.81, and the water stability coefficient reaches 1.0. At the same time, the concentration of fluorine ions and soluble phosphorus in the leaching solution meets the first-level limit of the "Comprehensive sewage discharge standard" (GB 8978—1996). Microscopic tests show that a large amount of hydrated calcium silicate gel produced by the hydration reaction could wrap calcium sulfate dihydrate. At the same time, the filling effect of silica fume and sodium sulfate makes the overall structure more dense, forming a phosphogypsum road stabilizing material with good performance.

Key words: phosphogypsum, sodium silicate, mix design, unconfined compressive strength, water stability coefficient, softening coefficient, leaching toxicity

CLC Number:

TU526

HUANG Xuquan, CAI Jiawei, ZHAO Xiaorong, XUE Fei, WANG Haojie, WANG Jun, WANG Ming. Performance and Curing Mechanism of Sodium Silicate Modified Phosphogypsum Road Stabilizing Material[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2024, 43(12): 4471-4479.

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