Study on Modification of the Magnesium Phosphate Cement-Based Material by Fly Ash

Abstract

Fly ash can improve the physical and mechanical properties of the magnesium phosphate cement (MPC) paste. The influence of fly ash on the strength, the mortar fluidity, the durability and the setting time of MPC paste were studied in this paper. The results show that: The function of fly ash to the MPC is as followed: physical fill, superplastic and chemical reactions; the optimal content of fly ash is about 30% by weight, and MPC with 30% fly ash has excellent mechanical property and high fluidity; the fineness of magnesia affected the mechanical properties of MPC.

Early properties of magnesium phosphate cement repairing material used in slab track

“…Simultaneously, it contributes to densifying the microstructure of the MPC paste, consequently increasing its mechanical strength. Moreover, the incorporation of fly ash can lead to cost savings, thereby reducing the overall price of MPC [ [42] , [43] , [44] ]. Therefore, 10 wt% fly ash was added to the MPC in this study.…”

Mechanical Properties and Hardening Mechanism of Magnesium Ammonium Phosphate Cements Modified by Fly Ash

“…The above results are mainly caused by the following two aspects: on the one hand, the addition of fly ash improves the microaggregate effect, reduces porosity, refines the pore structure, efficiently fills the micropores, and increases water stability [9]. On the other hand, as an amorphous silicon-aluminum material, the secondary hydration reaction of fly ash occurs at the later stage of hydration and increases with the increasing of the alkalinity of the cementitious materials system so as to refine the pore structure and improve the stability of MAPC [26]. When the content of fly ash is higher than 40 wt%, the amount of struvite in the hydration products of MAPC decreases, and so, the strength retention rate decreases.…”

Non-conventional mineral binder-bonded lignocellulosic composite materials: A review

“…FA can significantly improve the technical properties of the MPC system, even at higher mass contents (up to 40 wt%) (Ding and Li 2005a). Additionally, FA inclusion at certain mass content can reduce the total heat evolution during hydration, increase setting time and flowability of fresh MPC paste as well as improve the mechanical strength and moisture-related properties of MPC mortar (Donahue and Aro 2010;Li and Feng 2010;Li and Chen 2013). The addition of FA improves the microstructural compactness of MPC paste, and thus its mechanical performance, through the dual mechanisms of physically filling the pores of MPC paste and the participation of its alumina (Al2O3) and amorphous silica (SiO2) components in the hydration reaction to form a new cementitious gel.…”

“…The addition of FA improves the microstructural compactness of MPC paste, and thus its mechanical performance, through the dual mechanisms of physically filling the pores of MPC paste and the participation of its alumina (Al2O3) and amorphous silica (SiO2) components in the hydration reaction to form a new cementitious gel. This new product (gel) makes the MPC structure denser while generating more binder in the mixture (Laufenberg and Aro 2004;Ding and Li 2005a,b;Donahue and Aro 2010;Li and Feng 2010).…”