纳米SiO2和纳米CaCO3增强混凝土强度的试验研究

为了研究纳米SiO2、纳米CaCO3对混凝土力学性能的影响,进行了混凝土抗压强度和抗劈裂强度试验.纳米SiO2以0.5%,1.0%,2.0%,3.0%,纳米CaCO3以1.0%,3.0%等量取代水泥,标准养护7,28,78,128 d后进行混凝土强度测试.结果表明:纳米SiO2以3%等量取代时可以加速混凝土中C-S-H凝胶在水化早期和二次水化反应中的形成,从而提高混凝土的抗压和劈裂强度,从经济的角度考虑纳米SiO2的最优掺量为2%;纳米CaCO3可以吸收Ca(OH)2,促进水化碳铝酸钙的生成而提高混凝土的强度,其最优掺量为3%.

Mechanical properties of concrete mixed with SiO2 and CaCO3 nanoparticles

In order to investigate the impact of SiO2 and CaCO3 nanoparticles to the mechanical performance of concrete,the split tensile strength and compressive strength of concrete have been experimentally studied.SiO2 nanoparticles as a partial cement replaced by 0.5%,1.0%,2.0% and 3.0% and CaCO3 nanoparticles by 1.0% and 3.0% were added partially to concrete.Curing of the specimens has been carried out for 7,28,78 and 128 days after casting.SiO2 nanoparticle as a partial replacement of cement up to 3.0% could accelerate formation of CSH gel at the early stages and hence increase the split tensile strength and compressive strength.The optimal replacement level of cement by SiO2 nanoparticles for producing concrete with improved strength was set at 2.0%.CaCO3 nanoparticles as a partial replacement of cement up to 3.0% could consume crystalline Ca（OH）2 and accelerate formation of calcium carboaluminate hydrate at the early stages and increase the split tensile strength and compressive strength.The optimal replacement level of cement by CaCO3 nanoparticles for producing concrete with improved strength was set at 3.0%.