Interface design and mechanical performance evaluation of MKPC-based materials reinforced with fibreglass spacer fabric

The bonding force of hardened magnesium phosphate cement (MPC) based materials comes from the ionic and covalent bonds with high bond energy and strength between cementitious phosphate hydrates, resulting in high brittleness under stress. Fiber reinforced MPC matrix composites can consume energy through the various effects of fibers, thereby improving the brittleness of the MPC matrix. This study uses glass fiber three-dimensional spacing fabric with good fiber directional reinforcement ability and interlayer shear resistance as the reinforcement material, and potassium magnesium phosphate cement (MPKC) mortar was used as the matrix to prepare glass fiber reinforced MKPC based composite materials. Design and optimize the surface treatment method of three-dimensional spacing fabrics through uniaxial tensile testing of fiber reinforcement and its pull-out test in MKPC matrix. The mechanical properties of MKPC based composite material specimens reinforced with fabric were studied through compressive and four point bending tests. The results are as follows: the axial tensile force of the glass fibre reinforcement treated with water glass impregnation containing an appropriate amount of magnesium oxide powder is 2.5 times that of the untreated fibre reinforcement (the reference sample), and its tensile force in the MKPC matrix can reach 2 times that of the reference sample. The three-dimensional spacing fabric can improve the compressive strength of MKPC-based material specimens, and the larger the spacing between the fabric sandwich layers, the better the reinforcement effect. The reinforcement effect of the three-dimensional fabric impregnated with water glass containing magnesium oxide powder is better, and its compressive strength can be increased by 14.3% in comparison to the reference specimens without fabric fibers. The MKPC thin plate containing three-dimensional spacing fabric can withstand larger loads after initial cracking, and multiple cracks develop simultaneously. The initial cracking strength and initial cracking displacement slightly increase, and the ultimate strength and ultimate displacement significantly increase. The toughening effect of spacing fabrics with low-core columns on MKPC-based thin plate specimens is better than that of spacing fabrics with high-core columns. Impregnating three-dimensional spacer fabrics with water glass containing magnesium oxide powder can significantly improve the initial crack strength, deformation, ultimate strength, and displacement of MKPC-based thin plate specimens. In comparison to the reference sample without fabric fibers, the surface treated fabric reinforced MKPC matrix composite material specimen M1-1 exhibited a significant increase in cracking load and strain (26.01% and 33.96%), and its ultimate load and displacement were significantly increased (113.26% and 1125.13%). The above research content provides a theoretical basis for further research and engineering applications of this type of composite material.