掺膨胀剂HCSA的超高性能混凝土性能的研究

发布时间：2018-03-28 08:42

本文选题：超高性能混凝土　切入点：HCSA　出处：《湖南大学》2014年硕士论文

【摘要】：超高性能混凝土（Ultra-High Performance Concrete，UHPC）是一种高强度、高韧性、低孔隙率的水泥基材料，作为一种新型的具备优良性能的复合材料，必将成为未来一种极具应用价值的材料。混凝土的收缩是指由于混凝土中所含水分的变化、化学反应及温度变化等因素引起的体积缩小。收缩主要分为五大类，分别是塑性收缩、自收缩、干燥收缩温度下降引起的温度收缩以及碳化收缩。混凝土在收缩变形会产生拉应力，当拉应变超过混凝土的极限抗拉强度时会导致混凝土开裂，从而影响其使用性能和耐久性。普通混凝土的收缩应力主要指干燥收缩引起的干缩应力；但超高性能混凝土，由于其低水胶比和矿物掺合料的大量掺入使其自收缩在总收缩中所占的比重较大。因此，对于超高性能混凝土的应用，找到控制混凝土出现收缩裂缝的方法就显得十分重要。掺加膨胀剂的补偿收缩混凝土被广泛应用于工程中，研究新型膨胀剂及其补偿收缩混凝土的作用原理，工程需求量巨大。本文选用高性能混凝土膨胀剂（High Performance Calcium Sulpho Aluminate，，HCSA）作为超高性能混凝土的外加剂，利用补偿收缩原理，以达到减少超高性能混凝土收缩，减少开裂，提高超高性能混凝土的工作性能的目的。为了更好的了解HCSA膨胀剂对超高性能混凝土性能的影响，本文主要研究了如下内容： (1)对加入膨胀剂HCSA的超高性能混凝土，通过测量不同膨胀种类、同种膨胀剂不同掺量和不同水胶比下的流动度和初凝时间，得到膨胀剂对超高性能混凝土工作性能的影响规律； (2)通过波纹管试验测量不同膨胀剂种类、不同水胶比、不同膨胀剂掺量的超高性能混凝土基体的体积变化，得到膨胀剂对超高性能混凝土自收缩性能的影响情况； (3)通过混凝土收缩应变测试仪测量超高性能混凝土的体积变化，得到高性能膨胀剂HCSA对未添加钢纤维及添加钢纤维的超高性能混凝土有约束干燥收缩性能的影响情况； (4)通过测量不同掺量、不同水胶比、不同龄期的超高性能混凝土的抗折强度及抗压强度，得到了膨胀剂HCSA对超高性能混凝土力学性能的影响情况；并通过电镜试验和差热试验，通过分析微观结构分析，得到膨胀剂HCSA对超高性能混凝土力学性能的影响规律。最后，通过测量掺钢纤维超高性能混凝土的抗压强度，得出膨胀剂HCSA对掺钢纤维超高性能混凝土强度的影响规律。
[Abstract]:Ultra-High Performance concrete (UHPC) is a kind of cement-based material with high strength, high toughness and low porosity. As a new type of composite material with excellent properties, it will become a kind of material with great application value in the future. The shrinkage of concrete refers to the volume reduction caused by the change of moisture content, chemical reaction and temperature change in concrete. The shrinkage is divided into five categories: plastic shrinkage, autogenous shrinkage, etc. When the tensile strain exceeds the ultimate tensile strength of concrete, it will lead to concrete cracking, which will affect the performance and durability of concrete. The shrinkage stress of ordinary concrete mainly refers to the dry shrinkage stress caused by dry shrinkage, but the proportion of autogenous shrinkage of super-high performance concrete in total shrinkage is larger because of its low water-binder ratio and large amount of mineral admixture. For the application of ultra-high performance concrete, it is very important to find the method to control the shrinkage crack of concrete. Contractive concrete with expansive agent is widely used in engineering. The function principle of new expansive agent and its compensating shrinkage concrete is studied, and the engineering demand is huge. In this paper, the high Performance Calcium Sulpho aluminum chloride (HPC) is used as the additive of UHPC, and the principle of compensating shrinkage is used to reduce the shrinkage and crack of UHPC. The purpose of improving the working performance of super high performance concrete. In order to better understand the effect of HCSA expansion agent on the performance of UHPC, the main contents of this paper are as follows:. 1) by measuring the fluidity and initial setting time of UHPC with different kinds of expansive agent, different amount of the same expansive agent and different water / binder ratio, the influence of expansive agent on the working performance of UHPC is obtained. (2) the volume change of the matrix of UHPC with different kinds of expansive agents, different water / binder ratio and different amount of expansive agent was measured by corrugated tube test, and the effect of expansion agent on the autosynthetic property of UHPC was obtained. 3) the volume change of UHPC was measured by concrete shrinkage strain tester, and the effect of high performance expansive agent (HCSA) on confined drying shrinkage of UHPC without steel fiber and steel fiber was obtained. 4) by measuring the flexural strength and compressive strength of UHPC with different dosage, water / binder ratio and age, the influence of expansive agent HCSA on the mechanical properties of UHPC was obtained, and the mechanical properties of UHPC were tested by electron microscope and differential thermal test. The influence of expansive agent HCSA on the mechanical properties of UHPC was obtained by analyzing the microstructure. Finally, the compressive strength of UHPC with steel fiber was measured. The influence of expansion agent HCSA on the strength of superhigh performance concrete with steel fiber was obtained.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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