基于再生粗骨料预处理的再生混凝土干燥收缩试验研究

发布时间：2018-03-12 23:37

本文选题：再生混凝土　切入点：粗骨料　出处：《福州大学》2013年硕士论文　论文类型：学位论文

【摘要】：随着建筑业的迅猛发展,与混凝土相关的砂石资源日益匮乏,环境问题也异常突出,为使混凝土业能够可持续发展,一种新型绿色环保建筑材料——再生混凝土也随之应运而生。再生混凝土技术的应用不仅最大限度的减少了资源的消耗,而且有效地保护了环境,产生了明显的经济和生态效益。由于再生粗骨料与天然粗骨料之间存在着显著的差异,使得再生混凝土的干燥收缩与普通混凝土有所不同,而目前在此方面的研究较少,本文主要针对再生粗骨料预处理后的再生混凝土干燥收缩进行试验研究,主要研究的工作和结论如下：1、进行再生粗骨料的基本性能及预处理方法试验研究,结果表明,相比天然粗骨料,再生粗骨料具有表观密度和堆积密度大,吸水率和压碎指标高等特点,其基本性能不如天然粗骨料。通过三种方法(预湿法、净浆裹石工艺法、掺加硅灰的净浆裹石工艺法)对再生粗骨料预处理后,其再生混凝土的立方体抗压强度有了明显的提高。其中经过掺加硅灰的净浆裹石工艺法预处理的再生混凝土立方体抗压强度提高的效果最佳。2、通过再生混凝土干燥收缩试验,分析不同的再生粗骨料取代率对再生混凝土干燥收缩的影响规律,并比较与普通混凝土干燥收缩的区别。结果表明,随着再生粗骨料取代率的增加,再生混凝土的干缩应变显著增大且再生粗骨料取代率为100%时比50%取代率的再生混凝土干缩应变发展速率更快。3、基于不同的再生粗骨料取代率的前提下,分析三种预处理方法(预湿法、净浆裹石工艺法、掺加硅灰的净浆裹石工艺法)对再生混凝土干燥收缩的影响规律,并分析比较与普通混凝土干燥收缩的区别。结果表明,通过上述三种方法对再生粗骨料强化预处理后,再生混凝土干缩应变有一定程度的降低,其中通过掺加硅灰的净浆裹石工艺法预处理的再生混凝土干缩应变降低最为明显。4、通过再生混凝土干燥收缩试验所得的试验值与目前应用较为广泛的混凝土干燥收缩模型的计算值进行对比分析,选取相对吻合较好的GL2000干燥收缩计算模型作为参考,结合本文再生混凝土干燥收缩试验结果,考虑不同的再生粗骨料取代率、不同的预处理方法对再生混凝土干燥收缩的影响,通过参数修正建立适用于再生混凝土干燥收缩预测模型,提高了模型预测的准确性。
[Abstract]:With the rapid development of the construction industry, the sand and stone resources associated with concrete are increasingly scarce, and the environmental problems are also outstanding. In order to make the concrete industry sustainable development, The application of recycled concrete technology not only minimizes the consumption of resources, but also effectively protects the environment. Due to the obvious difference between recycled coarse aggregate and natural coarse aggregate, the drying shrinkage of recycled concrete is different from that of ordinary concrete, but there is little research on this aspect. In this paper, the dry shrinkage of recycled concrete after pretreatment of recycled coarse aggregate is studied. The main work and conclusions are as follows: 1. The basic properties and pretreatment methods of recycled coarse aggregate are studied. The results show that, Compared with natural coarse aggregate, regenerated coarse aggregate is characterized by high apparent density and packing density, high water absorption and crushing index, and its basic performance is inferior to that of natural coarse aggregate. After pretreatment of regenerated coarse aggregate with silica fume, The cube compressive strength of recycled concrete has been obviously improved. Among them, the cube compressive strength of recycled concrete pretreated with silica fume is the best. The test of drying shrinkage of recycled concrete is carried out. The effect of different recycled coarse aggregate replacement rate on the drying shrinkage of recycled concrete is analyzed, and the difference between the dry shrinkage of recycled aggregate and that of ordinary concrete is compared. The results show that with the increase of recycled coarse aggregate replacement rate, The dry shrinkage strain of recycled concrete increases significantly and the replacement rate of recycled coarse aggregate is 1000.The dry shrinkage strain development rate of recycled concrete is faster than that of recycled concrete with 50% replacement rate. Based on the different replacement rates of recycled coarse aggregate, The effects of three pretreatment methods (prewetting method, paste wrapping process and silica fume method) on the drying shrinkage of recycled concrete are analyzed. The results show that the drying shrinkage of recycled concrete is different from that of ordinary concrete. Through the above three methods, the dry shrinkage strain of recycled concrete can be reduced to a certain extent after the reinforced pretreatment of recycled coarse aggregate. The dry shrinkage strain of recycled concrete pretreated by adding silica fume is the most obvious. 4. The test value obtained from the drying shrinkage test of recycled concrete is compared with the widely used concrete drying at present. Contrastive analysis of the calculated values of the shrinkage model, According to the results of drying shrinkage test of recycled concrete, the effect of different replacement ratio of recycled coarse aggregate and different pretreatment methods on drying shrinkage of recycled concrete is considered. The prediction model of drying shrinkage of recycled concrete is established by parameter modification, and the accuracy of prediction is improved.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528

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