Influence Mechanism of Lime on Strength and Water-Resistance Properties of Phosphogypsum Autoclaved Brick

Influence mechanisum of lime on the strength and water-resistance properties of phosphogypsum autoclaved brick is exploited for the manufacture of preparing phosphogypsum autoclaved brick. Results of XRD and SEM analysis of phosphogypsum and phosphorous slag powder, influence of lime on the properties of phosphogypsum autoclaved bricks, phase composition, microstructure and thermal analysis of phosphogypsum autoclaved bricks with different lime content, and influence mechanisum of lime on the strength and water-resistance properties development have been discussed. The test results reveal that (a) when the dosage of lime is zero, the major mineral compositions of the autoclaved bricks are CaSO4 and SiO2, thus the strength and water-resistance properties of the bricks are poor, (b) optimum lime to phosphorous slag powder and phosphogypsum ratio yielding maximum strength and Softness coefficient is about 0.03, (c) excess lime beyond the optimum limit (in this case 5%) can remain unreacted and act as weak filler in the phosphogypsum autoclaved bricks leading to reduction in strength and water-resistance properties.