再生混凝土物理力学性能研究及数理统计分析

发布时间：2018-03-10 22:02

本文选题：再生骨料　切入点：再生混凝土　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：建筑垃圾资源化,它既满足了我国快速的工业化、城镇化进程,又兼顾到了环境问题,是建筑垃圾处理的正确出路。再生骨料是将废弃混凝土块经过破碎、清洗、筛选,形成的可以再次作为混凝土粗骨料使用的材料。再生骨料根据不同的粒径范围分为再生细骨料与再生粗骨料。而再生骨料与天然骨料的不同物理性能指标,使其配制的再生混凝土与普通混凝土性能有很大的区别。其中,再生细骨料对混凝土的性能影响极大,在工程应用中并不具有经济性,而再生粗骨料对混凝土的影响一般可以通过某些方式进行改善,具有应用的价值。本文的研究对象是再生粗骨料,通过对其物理性能、力学性能的测试,结合数理统计,针对再生粗骨料的几项物理性能指标之间的关系,以及再生混凝土的强度离散性问题进行讨论。并在细微观的层面对再生混凝土的破坏现象进行描述。首先,使用再生骨料取代部分天然骨料,取代的比例分别为0%、3 0%、5 0%、80%、100%,由此形成混合骨料,测试了骨料的吸水率、压碎指标、表观密度。结果表明:再生骨料与天然骨料形成的混合骨料是符合混合定律的。结合一些文献中不同来源的再生骨料的45个测试数据来分析三个物理性能指标的相关关系,发现:吸水率与表观密度存在一定的线性关系。利用线性拟合的办法来描述两者的关系是比较合理的。若想提高拟合的精度,可以采用二项式表达。线性表达与二项式表达的适用范围为吸水率值大于5%的骨料。不同来源再生粗骨料的吸水率与压碎指标的数值关系离散性大,无法得到具有普适性的公式。其次,配制再生粗骨料取代率为0%,30%,50%,80%,100%的再生混凝土,每组测试21个试件的28d抗压强度。结果表明:随着再生粗骨料的取代率增加,再生混凝土强度降低;再生粗骨料的加入使再生混凝土的抗压强度标准偏差随取代率呈现出“中间大两边小”的现象;通过假设检验的方法,验证了在显著水平α = 0.5时,再生混凝土的强度概率分布是符合正态分布的。最后,为了观察再生混凝土的破坏情况,采用3种不同配合比的再生混凝土,再生混凝土的破化形态与普通混凝土相同,高水灰比时是砂浆的破坏,低水灰比时是再生粗骨料的劈裂。纳米压痕观察低水灰比下再生混凝土的界面过渡区情况,发现:再生粗骨料岩石部分-新砂浆界面(新界面)的界面过渡区长度为55μm左右,而再生粗骨料岩石部分-旧砂浆界面(旧界面)的界面过渡区并不明显。新砂浆的硬度高于旧砂浆,新界面的硬度与旧界面的硬度相近,再生粗骨料成为体系的薄弱环节。
[Abstract]:The recycling of construction waste not only satisfies the rapid industrialization and urbanization of our country, but also takes into account the environmental problems, and is the correct way out for the disposal of construction waste. The recycled aggregate can be used as concrete coarse aggregate again. The recycled aggregate can be divided into recycled fine aggregate and regenerated coarse aggregate according to different particle size ranges. The properties of recycled concrete are different from that of ordinary concrete. The recycled fine aggregate has great influence on the performance of concrete, and is not economical in engineering application. However, the influence of recycled coarse aggregate on concrete can be improved in some ways, which has the value of application. The research object of this paper is recycled coarse aggregate, through the test of its physical and mechanical properties, combined with mathematical statistics, The relationship between several physical properties of recycled coarse aggregate and the strength dispersion of recycled concrete are discussed. The failure phenomenon of recycled concrete is described in detail. Some natural aggregates were replaced by recycled aggregates, with a ratio of 0 / 30 / 50 / 50 / 100, which formed a mixture of aggregates. The water absorption and crushing indexes of aggregates were tested. The results show that the mixed aggregate formed by recycled aggregate and natural aggregate obeys the law of mixing. Combining 45 test data of recycled aggregate from different sources in some literature, the correlation of three physical performance indexes is analyzed. It is found that there is a linear relationship between water absorption and apparent density. It is reasonable to use linear fitting to describe the relationship. The binomial expression can be used. The applicable range of linear expression and binomial expression is aggregate with water absorption ratio greater than 5%. The relationship between water absorption rate of regenerated coarse aggregate from different sources and crushing index is discrete. The formula with universal applicability can not be obtained. Secondly, the recycled concrete with a replacement ratio of 0% and 30% and 50% and 80% / 100% of recycled coarse aggregate is prepared. The 28d compressive strength of 21 specimens is tested in each group. The results show that the replacement rate of recycled coarse aggregate increases with the increase of the replacement rate of recycled coarse aggregate. The strength of recycled concrete is decreased, the standard deviation of compressive strength of recycled concrete is "large and small" with the substitution rate, and it is verified by hypothesis test that at the significant level 伪 = 0.5, The strength probability distribution of recycled concrete is in accordance with the normal distribution. Finally, in order to observe the failure of recycled concrete, three kinds of recycled concrete with different mix ratio are adopted, and the broken form of recycled concrete is the same as that of ordinary concrete. High water-cement ratio is the destruction of mortar, and low water-cement ratio is the splitting of recycled coarse aggregate. Nanometer indentation is used to observe the interfacial transition zone of recycled concrete under low water-cement ratio. It is found that the length of the interfacial transition zone between the rock part of recycled coarse aggregate and the new mortar interface (new interface) is about 55 渭 m. The hardness of the new mortar is higher than that of the old mortar, and the hardness of the new interface is close to that of the old interface, and the recycled coarse aggregate becomes the weak link of the system.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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