包浆再生骨料混凝土的性能研究

发布时间：2018-04-03 11:07

本文选题：包浆再生骨料　切入点：球度系数　出处：《宁夏大学》2017年硕士论文

【摘要】：为应对砂石骨料资源日趋短缺和废弃混凝土垃圾日渐剧增的双重压力,再生混凝土是混凝土材料实现可持续发展的必然选择。然而,再生骨料低强脆裂的品质却严重制约着再生混凝土的发展。如何从根本上显著提升再生骨料的骨架刚性,是当前混凝土研究中一个重要而艰难的课题。本文通过对再生骨料施以预包浆的方法试图克服再生骨料的性能缺陷,寻求制备出粒型球体化、力学性能良好、表面具有潜在火山灰性的包浆再生骨料的技术途径;并在优化包浆材料组成和包浆方法、比较和优选包浆龄期的基础上试验研究了包浆再生骨料粒型优化的球度效应、物理力学性能及其对包浆再生骨料混凝土力学性能和耐久性的影响,通过微观结构研究明确包浆再生骨料与水泥石界面过渡区的火山灰效应与二次水化机理,以期为再生骨料的精品化发展开辟新方向和新途径。(1)通过对再生骨料包浆处理,可以改善再生骨料粒形级配,消除再生骨料表面微裂纹,优化再生骨料的粒径分布,降低骨料针片状含量,显著提高再生骨料压碎指标,但对吸水率的影响较弱。总的来说,通过对再生骨料进行包浆可以提高骨料的整体性能。(2)对再生骨料包浆,并不能绝对提高混凝土强度,但可以提高混凝土韧性。包浆3d时掺入混凝土可获得最佳强度,符合预期试验目标。由于包浆对骨料自身强度影响较大,所以对混凝土的韧性影响并不是很显著。(3)包浆再生骨料混凝土的收缩趋势与普通混凝土相似,但包浆混凝土早期收缩变化更缓慢。混凝土的收缩率随包浆龄期增大而增大,而且趋势均为先急后缓,在60d内收缩变化比较大,尤其是7d内收缩变化最快,混凝土收缩呈指数型增长趋势。包浆可以提高再生混凝土的抗冻性,其中骨料包浆28d时配制的混凝土抗冻性最好。(4)通过综合分析,优选出的包浆再生骨料较优组为Y3组,并且经实验确证,使用水胶比0.35、胶粉含量2%的水泥浆对再生骨料包浆,养护3天后配制混凝土,制备的包浆再生骨料混凝土综合性能最优。
[Abstract]:In order to cope with the double pressure of the shortage of aggregate resources and the increasing waste concrete garbage, recycled concrete is the inevitable choice for the sustainable development of concrete materials.However, the quality of recycled aggregate with low strength embrittlement seriously restricts the development of recycled concrete.How to improve the skeleton rigidity of recycled aggregate is an important and difficult subject in the present concrete research.In this paper, we try to overcome the performance defects of recycled aggregates by precoating the recycled aggregates, and seek a technical way of preparing pellet pellets with good mechanical properties and potential pozzolanic properties on the surface.On the basis of optimizing the material composition and sizing method, comparing and selecting the age of the slurry, the sphericity effect of the optimization of the size of the regenerated aggregate was studied.The physical and mechanical properties and their effects on the mechanical properties and durability of recycled aggregate concrete are studied. The pozzolanic effect and the secondary hydration mechanism of the transition zone between recycled aggregate and cement stone are clarified through the microstructure study.In order to open up a new direction and new way for the fine quality development of recycled aggregate, it can improve the gradation of recycled aggregate, eliminate the micro-cracks on the surface of recycled aggregate, and optimize the particle size distribution of recycled aggregate through the treatment of recycled aggregate slurry, which can improve the gradation of recycled aggregate, eliminate the microcracks on the surface of recycled aggregate, and optimize the particle size distribution of recycled aggregate.The pellet content of aggregate was reduced and the crushing index of regenerated aggregate was significantly increased, but the effect on water absorption was weak.In a word, the whole performance of recycled aggregate can be improved by grouting the recycled aggregate, but the strength of concrete can not be improved absolutely, but the toughness of concrete can be improved.The best strength can be obtained by adding concrete into the slurry for 3 days, which is in line with the expected test objective.However, the shrinkage trend of recycled aggregate concrete is similar to that of ordinary concrete, but the early shrinkage change of concrete is slower than that of ordinary concrete because of the great influence of slurry on the strength of aggregate itself, so the effect on toughness of concrete is not very significant (3) the shrinkage trend of recycled aggregate concrete is similar to that of ordinary concrete.The shrinkage rate of concrete increases with the increase of grouting age, and the trend is first rapid and then slow, and the shrinkage change is relatively large in 60 days, especially in 7 days, the shrinkage of concrete changes fastest, and the shrinkage of concrete increases exponentially.The frost resistance of recycled concrete can be improved by grouting. The concrete prepared with aggregate paste for 28 days is the best. Through comprehensive analysis, the best group of recycled aggregate is Y3, which is confirmed by experiments.Using cement slurry with water / binder ratio of 0.35 and rubber powder content of 2% for recycled aggregate slurry, concrete was prepared after 3 days of curing, and the comprehensive properties of recycled aggregate concrete were optimized.
【学位授予单位】：宁夏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

【参考文献】