Dual Nanoparticles Synergistically Reinforce Polyurethane/Epoxy Grouting Material with High Mechanical Properties and Low Volume Shrinkage

Abstract

Single-resin grouting materials are inadequate for complex construction environments. To enhance these materials, nano-SiO2 and nano-Al2O3 were incorporated into a polyurethane/epoxy (PU/EP) blend emulsion to create novel grouting materials: nano-SiO2/PU/EP, nano-Al2O3/PU/EP, and nano-SiO2/nano-Al2O3/PU/EP. To prevent particle agglomeration, lower quantities of nanoparticles were introduced when the loadings exceeded 1.5% for nano-SiO2 or nano-Al2O3, or 2% for their combination. The introduction of nanoparticles increased the viscosity of the slurry materials, thereby reducing their initial setting time, without negatively affecting the porous structure. Different nanoparticles exerted distinct influences on mechanical properties. Nano-SiO2 enhanced the toughness of the grout materials, increasing impact and tensile strength, and slightly improving wet adhesive strength, but reducing compressive strength. Conversely, nano-Al2O3 increased the strength and rigidity of the grout materials, enhancing compressive and wet adhesive strengths, but at the expense of impact and tensile strength, making the materials more brittle. The simultaneous addition of nano-SiO2 and nano-Al2O3 significantly improved the overall performance of the grouting material. Compared to nano-SiO2/PU/EP, the tensile, compressive, and adhesive strengths of nano-SiO2/nano-Al2O3/PU/EP increased by 22%, 48%, and 29%, respectively. Compared to nano-Al2O3/PU/EP, these strengths increased by 193%, 12%, and 27%, respectively, with a particularly notable 207% increase in impact strength. Additionally, the volume shrinkage rate was reduced to below 0.39%.

Keywords: Grouting, Polyurethane, Epoxy, Nanoparticle, mechanical properties