纳米CaCO_(3)增强混凝土抗压强度分析及细观数值模拟研究

Analysis of compressive strength and meso numerical simulation of Nano-CaCO_(3) reinforced concrete

为了探究纳米CaCO_(3)对混凝土力学性能的影响规律,试验取掺量分别为0%、1.5%、2.0%、2.5%、3.0%、3.5%的纳米CaCO_(3),分析不同掺量的纳米CaCO_(3)对不同龄期混凝土抗压强度的影响,并采用扫描电子显微镜(SEM)对纳米CaCO_(3)增强混凝土的微观结构进行分析,然后基于随机骨料模型结合内聚力本构关系,在细观层次上分析纳米CaCO_(3)对混凝土力学性能的影响,将试验与模拟结果进行对比,验证模型的正确性与适用性。结果表明:纳米CaCO_(3)的掺入可以提高混凝土的抗压强度,但并非掺量越高越好,最优掺量为2.0%,3、7、14、28 d龄期抗压强度增长率分别为3.93%、5.21%、4.99%、7.84%;采用SEM分析表明,纳米CaCO_(3)的掺入可以减少混凝土内部的裂缝和孔隙,改善混凝土的微观结构。试验与数值模拟结果具有良好的一致性,各组工况相对误差均在10%以内。

In order to explore the influence of Nano-CaCO_(3) on the mechanical properties of concrete,the experiment takes Nano-CaCO_(3) content of 0%,1.5%,2.0%,2.5%,3.0% and 3.5% to analyze the influence of Nano-CaCO_(3) with different content on the compressive strength of concrete at different ages.Scanning Electron Microscope(SEM)is used to analyze the microstructure of Nano-CaCO_(3) reinforced concrete.The influence of Nano-CaCO_(3) on the mechanical properties of concrete is analyzed at meso level based on the random aggregate model and the cohesive constitutive relation.The results of the experiment are compared with the simulation to verify the correctness and applicability of the model.The results show that the admixture of Nano-CaCO_(3) can improve the compressive strength of concrete,but it does not mean a better effect with higher content of the admixture.The optimal content is 2.0% and the growth rates of compressive strength at the ages of 3 d,7 d,14 d and 28 d are 3.93%,5.21%,4.99% and 7.84%respectively;SEM shows that the admixture of Nano-CaCO_(3) can reduce the cracks and pores in concrete,which can improve its microstructure;the results of the experiment are in good agreement with numerical simulation,and the relative error of each working condition is within 10%.