Improvement of Cemented Gangue Backfill Material with Barium Hydroxide in Acid Mine Water

As a kind of green concrete, the mechanical properties and durability of cemented gangue backfill material (CGBM) will be affected if they are in acid mine water with sulfate ions in the long term. To improve the performance of CGBM in acid mine water with sulfate ions, CGBM specimens with different doses of barium hydroxide were immersed in sulfuric acid solutions of different concentrations for 270 days. The changes of mass, ultrasonic pulse velocity (UPV) and compressive strength of the specimens at different ages were analyzed. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the microstructure and composition of the specimens. The results show that incorporation of barium hydroxide into CGBM specimen can promote the formation of barium sulfate precipitation and inhibit the generation of corrosion products such as ettringite. Meanwhile, barium sulfate precipitation blocks the pore channel invaded by sulfuric acid solution, delaying the progress of corrosion reaction and making the interior of CGBM specimen more complete. And the specimen with 2.0 kg/m(3) barium hydroxide was more effective in improving performance. This study provides a basis for the ratio design of CGBM in acid mine water with sulfate ions.

Automated summary

This study investigates the effect of barium hydroxide on the performance of cemented gangue backfill material (CGBM) in acid mine water with sulfate ions. The results show that adding barium hydroxide promotes the formation of barium sulfate precipitation and inhibits corrosion products, delaying the progress of corrosion reactions and improving the performance of the CGBM specimens.