聚合物改性水泥砂浆配制及动态性能研究

发布时间：2018-06-17 01:11

本文选题：聚合物改性水泥砂浆 + 配合比　；参考：《北京建筑大学》2017年硕士论文

【摘要】：在实际应用中,许多混凝土结构设计除了承受正常的设计荷载外,有可能承受如冲击、爆炸、地震等不确定外力的作用。选择好的加固方式对现有的钢筋混凝土结构进行加固、维护变的尤为重要。高强钢丝绳网—聚合物改性水泥砂浆加固是现如今新发展的新型加固方式,较好的耐火性和耐久性,逐渐成为国内外学者广泛关注的混凝土结构加固工艺。该加固工艺中,高性能砂浆的性能对加固效果起到至关重要的作用,现如今对聚合物改性水泥砂浆(以下简称砂浆)的动态力学性能研究较少。为了拓展该加固技术在抗爆抗冲击领域内的应用范围,很有必要系统研制适用于冲击环境下的高性能砂浆。本文对高性能砂浆的研制和动态性能进行了系统研究,主要做了两方面的工作:一是配制砂浆配合比及研究材料掺量对砂浆力学性能的影响;二是研究确定砂浆应变率效应及非线性损伤本构关系。具体研究成果和结论如下:1.试配用于高强钢丝绳网片-聚合物改性水泥砂浆加固技术中的高性能砂浆,本文试验条件下研究了水胶比、胶粉掺量、粉末减水剂掺量、纤维掺量等对砂浆抗压强度、抗折强度、粘结性能和流动度等力学性能和耐久性的影响,结果如下:(1)通过试配确定力学性能和施工性能均能满足混凝土结构加固设计规范的要求的配比,即水胶比为0.24,胶砂比为2,胶粉掺量为2%,纤维掺量为0.15%。(2)聚合物掺量为2%时,砂浆的抗压强度、抗折强度和粘结强度等性能得到大幅度改善;随水胶比的增大,砂浆的抗压、抗折强度和界面粘结强度减小,流动度增大;当纤维掺量为0.15%时,砂浆的耐久性、抗裂性和韧性作用显著提高;粉末减水剂掺量在0.4%-0.6%范围内,对砂浆的抗压、抗折强度等力学性能无显著变化,主要会对砂浆的抹面施工性能和流动度的影响。2.通过霍普金森压杆(SHPB)冲击压缩试验,研究了砂浆的冲击破坏形态及应变率效应。研究结果表明:(1)聚合物改性水泥砂浆是一种应变率敏感材料。砂浆的动态强度随应变率的增大而提高,其应变率效应随砂浆强度的增大而降低。弹性模量随应变率的增大逐步降低。(2)随着加载速率的增大、砂浆试块的破坏形态变化显著,大致分为:无裂纹,少量裂纹、大量裂纹整体完整、大量裂纹且整体性差、粉碎破坏等。(3)当冲击速度及纤维掺量一定时,砂浆强度越大,试块的破坏程度越小,即裂纹越少及破碎程度越低;(4)砂浆强度分别为60MPa和50MPa时,随着纤维掺量的增加,砂浆的峰值应力、峰值韧性和极限韧性先增大后减小,其作用效果高于70MPa砂浆;钢纤维砂浆相比PVA砂浆和PF砂浆,掺入足量的纤维可以提高砂浆的韧性和抗冲击性能,且增强效果更加明显。(5)根据试验数据参数拟合的ZWT本构模型与试验所得应力-应变曲线吻合度较好,该模型可以用来描述砂浆在冲击荷载作用下不同应变率的本构关系。
[Abstract]:In practical application, many concrete structures may bear the effects of uncertain external forces, such as shock, explosion, earthquake and so on, in addition to the normal design load. It is very important to choose a good reinforcement method to reinforce the existing reinforced concrete structure. The reinforcement of high-strength steel wire rope network-polymer modified cement mortar is a new type of reinforcement method. The better fire resistance and durability gradually become the strengthening technology of concrete structure which is widely concerned by domestic and foreign scholars. In this reinforcement process, the performance of high performance mortar plays an important role in the reinforcement effect. Nowadays, the dynamic mechanical properties of polymer modified cement mortar (hereinafter referred to as mortar) are less studied. In order to expand the application scope of the reinforcement technology in the field of anti-explosion and anti-impact, it is necessary to systematically develop the high performance mortar suitable for impact environment. In this paper, the development and dynamic performance of high performance mortar have been studied systematically. Two aspects of work have been done: first, the mix ratio of mortar and the effect of material content on the mechanical properties of mortar; The second is to determine the strain rate effect and nonlinear damage constitutive relation of mortar. The specific research results and conclusions are as follows: 1. In this paper, the compressive strength of high strength steel wire rope mesh-polymer modified cement mortar was studied under the experimental conditions, such as water / binder ratio, rubber powder content, powder water reducing agent content, fiber content, etc. The effects of mechanical properties and durability, such as flexural strength, bond strength and fluidity, are as follows: (1) the ratio of mechanical properties and construction properties can meet the requirements of the design code for strengthening concrete structures. When the ratio of water to binder is 0.24, the ratio of cement to sand is 2, the amount of rubber powder is 2, and the content of fiber is 0.15.1%, the properties of mortar such as compressive strength, flexural strength and bond strength are greatly improved, and the compressive strength of mortar increases with the increase of water-binder ratio. When the fiber content is 0.15, the durability, crack resistance and toughness of mortar are improved significantly, and the compressive strength of mortar is increased in the range of 0.4% -0.6% of powder water reducing agent. The mechanical properties, such as flexural strength, have no significant change, but mainly affect the construction performance and fluidity of mortar. The impact failure mode and strain rate effect of mortar were studied by means of the impact compression test of Hopkinson compression bar (SHPB). The results show that polymer modified cement mortar is a strain rate sensitive material. The dynamic strength of mortar increases with the increase of strain rate, and the strain rate effect decreases with the increase of mortar strength. The modulus of elasticity decreases gradually with the increase of strain rate. (2) with the increase of loading rate, the failure mode of mortar specimen changes significantly, which can be roughly divided into three parts: no crack, a small amount of crack, a large number of cracks, and the integrity is poor. When the impact speed and fiber content are constant, the higher the mortar strength is, the smaller the damage degree of the test block is, that is, the less cracks and the lower the crushing degree are, the higher the mortar strength is 60 MPA and 50 MPA, respectively, with the increase of fiber content. The peak stress, peak toughness and ultimate toughness of mortar first increase and then decrease, and its effect is higher than that of 70 MPA mortar. Compared with PVA mortar and PF mortar, the fiber of steel fiber mortar can improve the toughness and impact resistance of mortar. And the enhancement effect is more obvious. (5) the ZWT constitutive model fitted according to the parameters of the test data is in good agreement with the stress-strain curve obtained from the test. The model can be used to describe the constitutive relations of mortar under different strain rates under impact load.
【学位授予单位】：北京建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ177.62

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