高性能再生混凝土物理及力学性能试验研究

发布时间：2018-01-20 16:01

本文关键词： 高性能再生混凝土强化再生骨料物理性能力学性能界面过渡区疲劳性能　出处：《内蒙古工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：由于再生骨料混凝土自身存在诸多缺陷,近年来高强高性能再生混凝土的研究日益受到专家学者的关注。在研究再生混凝土基本物理力学性能的基础上,本文着重研究了再生骨料高性能强化途径、强化效果、高性能再生混凝土的界面特征以及高性能双层再生混凝土梁的疲劳性能,主要内容如下:首先,对再生骨料混凝土基本物理力学性能进行了研究,试验结果表明:再生粗骨料与天然骨料相比表面更为粗糙,棱角较多且吸水率较大,压碎值高,缺陷较为明显。再生混凝土立方体抗压强度、抗折强度、劈裂抗拉强度均低于同配比普通混凝土。通过正交试验得出:粉煤灰掺量和再生骨料取代率是影响再生混凝土28d抗压强度和抗折强度的两个主要因素。第二,采用物理强化结合化学强化的再生粗骨料强化方法对再生粗骨料进行处理,结合二次搅拌法,较好的改善了再生骨料混凝土的工作性和力学性能。其中最优处理方法为:先水洗去除粉尘,用5%HCL溶液处理,再用机械强化法去除松动的水泥砂浆壳,最后用1%EVA乳液处理得到强化再生粗骨料。与处理前相比,强化再生骨料24h吸水率降低22.7%,压碎值降低26.5%,表观密度提高12.5%。使用ESEM场发射电子扫描显微镜,观察再生混凝土、普通混凝土以及高性能再生混凝土的界面结构及水化产物,结果表明:再生混凝土中骨料与水泥石界面存在较明显的微裂纹和较薄弱的过渡区,强化处理方法使得再生混凝土界面过渡区得到了改善。第三,通过改变水胶比、砂率、强化再生粗骨料取代率,研究其对高性能再生混凝土工作性、28d立方体抗压强度和抗折强度的影响。设计正交试验研究了矿粉、水灰比、减水剂对高性能再生混凝土早龄期干缩性能的影响。得到满足工作性、力学性能以及干缩性的高性能再生混凝土最优配合比。最后,对双层高性能再生混凝土梁疲劳试验进行了研究。试验表明:双层高性能再生混凝土梁弯曲疲劳寿命能够较好的服从两对数威布尔分布。应力水平为0.8时,使用取代率为30%强化再生骨料制成的高性能再生混凝土梁的抗疲劳性能优于非强化再生混凝土梁;应力比为0.7时,两者接近。
[Abstract]:Due to the defects of recycled aggregate concrete, the research of high strength and high performance recycled concrete has been paid more and more attention by experts and scholars in recent years, based on the study of the basic physical and mechanical properties of recycled concrete. This paper focuses on the high performance of recycled aggregate strengthening way, strengthening effect, interface characteristics of high performance recycled concrete and fatigue performance of high performance double-layer recycled concrete beam. The main contents are as follows: first. The basic physical and mechanical properties of recycled aggregate concrete are studied. The experimental results show that the recycled coarse aggregate has more rough surface, more angles, higher water absorption and higher crushing value than natural aggregate. The defect is obvious. Recycled concrete cube compressive strength, flexural strength. The splitting tensile strength of concrete is lower than that of common concrete with the same ratio. The content of fly ash and the replacement ratio of recycled aggregate are two main factors affecting the compressive strength and flexural strength of recycled concrete for 28 days. The regenerated coarse aggregate was treated by physical strengthening combined with chemical strengthening and combined with secondary agitation. The workability and mechanical properties of recycled aggregate concrete were improved, and the optimal treatment methods were as follows: wash dust first, treat it with 5 HCL solution, and then remove loose cement mortar shell by mechanical strengthening method. At last, the recycled coarse aggregate was treated with 1 / EVA emulsion. Compared with the pre-treatment, the 24h water absorption of the reinforced recycled aggregate was reduced by 22.7and the crushing value was reduced by 26.5%. The apparent density was increased by 12.5. The interface structure and hydration products of recycled concrete, ordinary concrete and high performance recycled concrete were observed by ESEM field emission electron scanning microscope. The results show that there are obvious microcracks and weak transition zone in the interface between aggregate and cement stone in recycled concrete. By changing the water-binder ratio, sand ratio, and strengthening the replacement rate of recycled coarse aggregate, the effects of high performance recycled concrete on the compressive strength and flexural strength of high performance recycled concrete for 28 days were studied. The orthogonal test was designed to study the ore powder. The effect of water-cement ratio and water-reducing agent on the dry shrinkage performance of high performance recycled concrete at early age. The optimum mix ratio of high performance recycled concrete satisfying workability, mechanical property and dry shrinkage is obtained. Finally. The fatigue test of double-layer high performance recycled concrete beams is carried out. The results show that the fatigue life of double-layer high performance recycled concrete beams can be well distributed from two logarithmic Weibull distributions, and the stress level is 0.8. The fatigue resistance of high performance recycled concrete beams made of reinforced recycled aggregate with substitution ratio of 30% is better than that of non-reinforced recycled concrete beams. When the stress ratio is 0.7, the two are close.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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