不同粒径纳米二氧化硅混凝土宏微观性能研究

Research on the macro and micro performance of concrete under the action of different nano SiO_(2) particle size

为研究不同粒径及掺量纳米二氧化硅对混凝土力学性能的影响,将粒径为15、30、80 nm的纳米SiO_(2)分别取代1%、3%、5%体积率的水泥配制出9组纳米SiO_(2)混凝土进行抗压、劈裂抗拉及抗剪强度试验,基于试验结果利用Matlab数值计算软件提出了不同粒径及掺量下纳米SiO_(2)混凝土力学性能预测模型,同时借助SEM电镜试验,对纳米SiO_(2)增强混凝土力学性能机理进行分析。结果表明:纳米SiO_(2)粒径与掺量对混凝土抗压、劈裂抗拉及抗剪强度的影响是相互的,混凝土力学性能随掺量的增加增幅逐渐降低,粒径越大混凝土力学性能增幅越低,纳米SiO_(2)掺量为5%时,混凝土各项力学性能指标开始下降。适量粒径与其掺量的纳米SiO_(2)掺入可促进水泥水化反应,但由于过高掺量纳米SiO_(2)材料的掺入,一定程度上影响水泥水化过程。数值软件建立预测模型各项指标拟合度较高,可为工程上确定其配合比时提供借鉴。

In order to study the effect of different particle size and amount of nano-SiO_(2)on the mechanical properties of concrete,9 groups of nano-SiO2 concrete were prepared by replacing 1%,3% and 5% volume fraction of cement with particle size of 15,30 and80 nm,respectively,Based on the test results,the prediction model of mechanical properties of nano-SiO_(2)concrete with different particle size and content is proposed by using Matlab numerical calculation software.At the same time,the mechanism of nano-SiO_(2)reinforced concrete mechanical properties is analyzed by means of SEM test.The results show that the influence of nano-SiO_(2)particle size and content on the compressive strength,splitting tensile strength and shear strength of concrete is mutual.The mechanical properties of concrete gradually decrease with the increase of nano-SiO_(2)content.The larger the particle size is,the lower the increase of mechanical properties of concrete is.When the nano-SiO_(2)content is 5%,the mechanical properties of concrete begin to decline.The addition of nano-SiO2 with proper particle size and content can promote the hydration reaction of cement,but the addition of nano-SiO2 with excessive content can affect the hydration process of cement to a certain extent.The results show that the fitting degree of each index of the prediction model established by the numerical software is high,which can provide reference for engineering to determine its ratio.