Fabrication and mechanism of cement-based waterproof material using silicate tailings from reverse flotation

- Waterproof material as a novel approach to utilize RFT was investigated.
- Characteristic of hydrophobic surface of RFT were used.
- Both the internal and surface of the RFT mortars were hydrophobic.
- Origin of the hydrophobicity of RFT was chemical adsorption of surfactant.

In this work, based on the surface hydrophobic characteristic of the reverse flotation tailings (RFT), the feasibility of fabricating cement-based waterproof material from RFT was investigated. The waterproof and mechanical properties of RFT mortars were evaluated by water absorption coefficient, contact angles and compressive strength. The results showed that RFT mortars presented lower water absorption coefficient of 21.1 g/m2 s0.5 compared with 148.6 g/m2 s0.5 for ordinary mortars. Moreover, both the internal and surface of the RFT mortars were hydrophobic, indicating the characteristic of the integral waterproof. Meanwhile, the compressive strength was hardly affected by the RFT as the raw materials. The waterproof mechanism of the cement mortars with RFT was performed by UV, SEM, XPS, FTIR and AFM. It was found that the origin of the hydrophobicity of RFT was the chemical adsorption between silicate particles and surfactant. Moreover, it was observed that RFT was in favor of early strength of the mortars through the investigation on hydration thermodynamical properties and kinetics behaviors of RFT.

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