Influence of MgO-Based Basic Salt Cement on the Mechanical Properties of Sewage Sludge

Abstract:

Magnesium oxychloride cement (MOC) was used in the sludge stabilization experiments as a new type stability agent in this paper. When the mass ratios of MOC/Sludge are 5/100-20/100, molar ratios of MgO/MgCl2 are 3/1-5/1, the highest compressive strength of stabilized sample can be achieved at 85.14 kg/cm2, the coefficient of permeability up to 2.17×10-3 cm/s, the plasticity index is as low as 7.9, and the grain size increases in linear. When the range of the sludge grain size gets to 45-72 μm, sludge specific resistance decreases sharply. XRD and SEM were used to characterize the macroscopic and microscopic effects of sludge caused by MOC. The results reveal that gelling and hydration reaction would be happened in the MOC-sludge system. Mg-Si-Al gel system is formed with Si2+, Al3+, Cu2+ in the sludge under alkaline condition. The hydrate can be seen and it plays an important role in the sludge stabilization.