Bond strength and interface characteristics between magnesium phosphate cement mortar and ordinary Portland cement concrete in a frigid environment

ABSTRACT

The rapid repair of airport runways and concrete pavements using magnesium phosphate cement mortar (MPCM) in frigid environments requires the MPCM to have high bond strength with ordinary Portland cement (OPC). In this study, the effects of the pouring temperature of MPCM, surface roughness, water content, and strength grade of concrete on the interfacial bond strength and characteristics between MPCM and OPC were investigated in a frigid environment (−20°C ± 2°C). The results indicated that the 3-h compressive strength of MPCM reached 30 MPa, whereas the 3-h flexural bond strength between MPCM and OPC (BS_MPCM-OPC) exceeded 2.5 MPa when the pouring temperature for the MPCM mixture is 0-5°C in a frigid environment. The moisture content of concrete before freezing had a more significant impact on BS_MPCM-OPC than the influence of concrete roughness in a frigid environment; however, the influence of the concrete strength grade can be disregarded. The hydration heat of MPCM can quickly release with an increase in the pouring temperature, which accelerates phosphate dissolution and promotes the generation of struvite and the development of the BS_MPCM-OPC. Furthermore, the interface bonding between MPCM and OPC involves physical bonding, mechanical anchoring, and weak chemical bonding in a frigid environment.

KEYWORDS:

• Magnesium phosphate cement mortar (MPCM)
• ordinary Portland cement concrete (OPC)
• bond strength between MPCM and OPC (BS_MPCM-OPC)
• interfacial characteristics
• frigid environment

Acknowledgment

This work was supported by the National Natural Science Foundation of China (No. 52072049) and the Key R&D and Transformation Plan of Xining Science and Technology Bureau (2023-Y-19), which were highly acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Key R&D and Transformation Plan of Xining Science and Technology Bureau [grant number: 2023-Y-19]; the National Natural Science Foundation of China [grant number: 52072049].