Research progress on interfacial bonding between magnesium phosphate cement and steel: A review

Wang, Xin; Xiang, Huimin; Yang, Jianming; Chong, Linlin; Shi, Caijun

doi:10.1016/j.conbuildmat.2022.127925

Cited by 29 publications

(1 citation statement)

References 95 publications

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“…Magnesium potassium phosphate cement has many excellent characteristics, such as rapid setting, high early strength, high fluidity, good volume stability, strong bonding strength to concrete substrates, and superior durability. Therefore, it has been applied in various fields such as the rehabilitation and repair of civil structures, the treatment of wastewater, and the stabilization of hazardous waste [ 12 ]. However, current studies on magnesium potassium phosphate cement mainly focus on the reaction and retardation mechanisms, the influencing factors on the properties of the magnesium potassium phosphate cement, and similar subjects.…”

Section: Introductionmentioning

confidence: 99%

Inorganic Flame-Retardant Coatings Based on Magnesium Potassium Phosphate Hydrate

et al. 2022

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A magnesium potassium phosphate hydrate-based flame-retardant coating (MKPC) is formulated by dead-burnt magnesium oxide (magnesia) and potassium dihydrogen phosphate (KH2PO4), behaving as a matrix. Constituents of the MKPC include wollastonite, vermiculite, aluminum fluoride, aluminum trihydroxide, and calcium carbonate. Some of the ingredients inter-react to produce mullite whiskers at high temperatures, despite an acid-base hydration induced reaction between magnesia and KH2PO4. The MKPC’s thermal, corrosion-resistant, mechanical, and flame-resistant properties were analyzed using scanning electron microscopy, electrochemical corrosion testing, compression testing, thermogravimetric analysis, and freeze/thaw tests. The results show that with the molar ratio = 4 of magnesia to KH2PO4, MKPC demonstrates lower thermal conductivity (0.19 W/m K), along with better corrosion resistance, stronger compressive strength (10.5 MPa), and higher bonding strength (6.62 kgf/cm2) to the steel substrate. Furthermore, acceptable additives to the formulation could enhance its flame-retardancy and increase its mechanical strength as well. Mullite whisker formed from the interaction of wollastonite, aluminum trihydroxide, and aluminum fluoride acts as an outer ceramic shield that enhances mechanical strength and compactness. In addition, Mg-containing minerals with calcium carbonate treated at high temperatures, transform into magnesium calcium carbonate after releasing CO2. At the optimum composition of MKPC (magnesia/KH2PO4 molar ratio = 4; wollastonite:vermiculite = 20:10 wt.%; aluminum trihydroxide = 10 wt.%; and calcium carbonate = 5 wt.%), coated on a steel substrate, the flame-resistance limit results exhibit below 200 °C on the back surface of the steel substrate after one hour of flaming (ca. 1000 °C) on the other surface, and the flame-resistance rating results demonstrate only 420 °C on the back surface of the steel substrate after three hours of flaming (>1000 °C) on the other surface. Both requirements for the flame-resistance limit and three-hour flame-resistance rating are met with the optimum compositions, indicating that MKPC plays an effective role in establishing flame-retardancy.

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Section: Introductionmentioning

confidence: 99%