Enhancement of magnesium phosphate cement with sintered sludge ash

• Published in: Developments in the built environment 2024-03, Vol.17, p.100313, Article 100313
• Main Authors: Zhang, Jinrui, Qi, Yingnan, Yang, Youzhi, Long, Wujian, Dong, Biqin
• Format: Article
• Language: English
• Subjects: Magnesium phosphate cement; Mechanical strength; Setting time; Sintered sludge ash; Volume deformation; Water resistance
• ISSN: 2666-1659; 2666-1659
• DOI: 10.1016/j.dibe.2023.100313

Magnesium phosphate cement (MPC) is a promising material known for its rapid hardening and high early-strength properties. However, its potential in engineering applications is hindered by its harden at an uncontrolled rate, considerable volumetric distortion and poor water resistance. To address the limitations, this study investigates the influence of sintered sludge ash (SSA) modification on the setting time, volume deformation, mechanical strength and water resistance of MPC composites. Experimental reveals that the setting time of MPC composites increase with higher SSA content, and the inclusion of SSA significantly mitigate volumetric deformation. Moreover, the mechanical strength exhibits improvement at all ages, and combine with water resistance analysis, 15% SSA content is the optimal level. Based on the XRD, TG, MIP and SEM, the enhanced properties of the MPC composites may be attributed to the reaction of SSA in the MPC system, leading to the resulting aluminum-containing gel phase acting as a binder along with guano to densify the microstructure. •Modification of magnesium phosphate cement using sintered sludge ash is a proven method.•The incorporation of a suitable quantity of sintered sludge ash not only mitigates volume deformation and improves water resistance but also augments mechanical strength across the full age range.•Sludge ash sintered was utilized as a cost-saving reactant, and the resulting aluminum-containing gel phase acted as a cementing agent along with guano stone to densify the pores.