Properties of a magnesium phosphate cement-based fire-retardant coating containing glass fiber or glass fiber powder

Abstract

Magnesium phosphate cement (MPC) is a type of chemically-bonded ceramic and has excellent resistance to high temperatures. In this study, the properties of the MPC as a fire-retardant coating were evaluated to expand the application of the MPC. The MPC coating was prepared by blending with glass fiber (GF) or glass fiber powder (GFP) as a mineral admixture (the content was 0%, 2%, 4%, and 6%). The physical and mechanical performances of the MPC pastes were tested and their fire retardancy was investigated in detail. The results showed that the spread fluidity values of the GFP-blended MPC pastes were higher than 200 mm and the initial setting time exceeded 60 min. The bonding strength values of all MPC specimens were greater than 0.6 MPa. The tests results showed that the MPC coating had excellent fire retardancy. During a fire, the free water in the MPC paste and the chemically-bonded water in the hydrate product (struvite of potassium) of the MPC dissipated a large amount of heat, which effectively retarded the spread of the fire. At the same time, the glass fiber and glass fiber powder played an important role in preventing cracks in the MPC coating during the fire retardancy test. With the aid of micro-analyses, such as thermo-gravimetric and differential thermal analysis (TG-DTA), X-ray diffractometer analysis (XRD), and optical micrograph observations, the causes for the excellent fire retardancy of the MPC coating were determined.