Experimental Study on the Mechanical Properties of Nano-Silicon-Modified Polyurethane Crack Repair Materials

Abstract

This study aims to solve the problem of dynamic crack repair in concrete. Although conventional polyurethane has good strength, its tensile and shear properties are poor. It was found that nano-silicon had an overall enhancing effect on the mechanical properties of polyurethane; therefore, five sets of tests with different dosages (0%, 2%, 5%, 7.5%, and 10%) were designed. The compressive, tensile, and shear mechanical properties of nano-silicon-modified polyurethanes were tested by compression, tensile, and straight shear tests, and the microscopic appearance of the materials was observed by scanning electron microscopy. The results showed that nano-silicon could enhance the mechanical properties of polyurethane. The best filling effect on polyurethane was achieved at a dosage of 5%, which increased the compressive, tensile, and shear strengths by 29.4%, 257.6%, and 202.1%, respectively, compared with the substrate. The compressive and tensile moduli in the small strain range were enhanced by 268.5% and 511.8%, respectively. After exceeding 5%, the mechanical properties of the materials decreased due to the enhanced nanoparticle agglomeration effect, which led to the appearance of voids inside the materials. The comprehensive analysis shows that nano-silicon can better enhance the mechanical properties of polyurethane with an optimal dosage of 5%, which is stronger relative to other repair materials and does not require time maintenance.