Preparation and mechanical properties of magnesium phosphate cement for rapid construction repair in ice and snow

Abstract

In an icy and snowy environment, the rapid construction repair of infrastructure faces many challenges of cold weather and complex technical problems, such as the challenge of mixing water and rapidly preparing repair materials with a high early strength. Some experiments have been carried out to prepare magnesium phosphate cement (MPC) in icy and snowy environments. A small amount of light burnt magnesia (LBM) partially replaced dead burnt magnesia and ice particles completely replaced mixing water to prepare MPC at a negative temperature. The effects of LBM and ice particle content on the fluidity, setting time, early strength and volume stability of the MPC at a negative temperature were studied. Ice particles can be melted by reaction and friction heat that are released during the mixing of MPC, and an appropriate amount of LBM can accelerate ice particle melting and increase the reaction rate of MPC paste. Therefore, the MPC paste condenses and hardens normally at a negative temperature. When the LBM/M ratio is 2%–4%, 4%–6% and 8%–12% at −2 ± 2 °C, −10 ± 2 °C and −20 ± 2 °C, respectively, the 2-h compressive strength of the MPC reached 20–40 MPa. When the ambient temperature returned to a normal temperature, the 28-day compressive strength of the MPC that was prepared at −20 °C reached ∼70% of that of the MPC that was prepared at a normal temperature because of the secondary reaction of MPC and the growth of struvite.