补偿收缩高延性纤维混凝土性能研究

发布时间：2018-03-23 23:32

本文选题：补偿收缩　切入点：高延性纤维混凝土　出处：《西安建筑科技大学》2017年硕士论文

【摘要】：高延性纤维混凝土(Engineered Cementitious Composite,ECC)是一种经过系统的微观力学设计的新型先进水泥基复合材料,具有超高的延性和极大的韧性。一方面,高延性纤维混凝土中不含粗骨料,并且水胶比低、胶凝材料用量比例大,在早期容易产生收缩,引起混凝土开裂;另一方面,纤维的加入,对于混凝土早期的收缩开裂具有预防作用。但是,目前关于这两方面因素共同作用下的高延性纤维混凝土的早期收缩开裂规律的研究较少,并且加入膨胀组分会对高延性纤维混凝土的收缩规律和其他性能产生何种影响尚不明确。因此,研究加入膨胀组分的高延性纤维混凝土(补偿收缩高延性纤维混凝土)的各项性能,对于预防其早期收缩开裂、推广其在实际工程中的应用具有重要意义。本文的研究内容及结果如下:首先,将铝酸盐水泥和石膏复合作为膨胀组分加入到混凝土基体中得到补偿收缩基体,并对比补偿收缩基体与原基体的收缩规律、抗折强度和抗压强度,结果表明,补偿收缩基体中由于钙矾石生成量的增加,其收缩规律表现为早期膨胀后期收缩,而原基体从测试开始就一直收缩;补偿收缩基体的抗折和抗压强度比原基体有所提高,且在铝酸盐水泥含量不变时,补偿收缩基体的抗折和抗压强度随着石膏掺量的增加分别呈现先增大后减小和逐渐减小的规律。其次,将聚乙烯醇(Polyvinyl Alcohol,PVA)纤维掺入补偿收缩基体中得到补偿收缩PVA-ECC,利用非接触式激光位移传感器测试其28d收缩规律,结果表明,补偿收缩PVA-ECC收缩规律为早期膨胀后期收缩,并且在收缩阶段时,与普通PVA-ECC的收缩规律相反,即补偿收缩PVA-ECC的后期收缩随着纤维掺量的增大而增大;此外,在水中养护的补偿收缩PVA-ECC早期膨胀量和膨胀状态持续时间均大于在空气中的补偿收缩PVA-ECC。再次,对比了补偿收缩PVA-ECC和普通PVA-ECC的抗压强度和抗弯强度,结果表明,补偿收缩PVA-ECC的抗压强度与普通PVA-ECC相比,龄期3d时有所提高,龄期28d时,提高幅度减小,甚至有些组出现少许降低;补偿收缩PVA-ECC的抗折强度与普通PVA-ECC相比,龄期3d和28d时都有少许降低;补偿收缩PVA-ECC的四点抗弯强度与普通PVA-ECC相比,龄期3d时有所提高,龄期28d,纤维掺量为0和5%时有所降低,而纤维掺量1.0%、1.5%和2.0%时,则有所提高;此外,在无限制条件下水中养护3d的补偿收缩PVA-ECC的抗压强度、抗折强度和四点抗弯强度均低于标准养护的补偿收缩PVA-ECC。第四,利用四点弯曲测试法对比研究了补偿收缩PVA-ECC和普通PVA-ECC的弯曲韧性,结果表明,补偿收缩PVA-ECC早期的弯曲韧性大于普通PVA-ECC,而后期小则于普通PVA-ECC;此外,对比标准养护和水中养护下补偿收缩PVA-ECC早期的弯曲韧性发现,在无限制条件下水中养护3d的补偿收缩PVA-ECC的弯曲韧性小于标准养护的补偿收缩PVA-ECC。最后,对补偿收缩PVA-ECC与普通PVA-ECC各项性能的对比作了总结:膨胀组分的加入能够使PVA-ECC早期产生膨胀,有效预防收缩开裂;膨胀组分的加入并没有对PVA-ECC的其他性能带来负面影响;无限制条件下水中养护能够提高早期膨胀效果,但是不利于力学性能和韧性的提升。此外,对补偿收缩PVA-ECC未来研究方向和重点提出了一些建议。
[Abstract]:ECC (Engineered Cementitious Composite, ECC) is a novel by advanced cement based composite micro mechanical system design, with ultra high ductility and toughness greatly. On the one hand, coarse aggregate with high ductility fiber reinforced concrete, and low water binder ratio, cementitious material consumption occupies a large proportion. In the early prone to shrinkage, cause concrete cracking; on the other hand, the addition of fibre has preventive effects on shrinkage cracking of concrete at early age. However, the current research on early cracking of high ductile fiber on the interaction of these two factors of concrete under the less, and joined the group of high expansion and contraction of ductile fiber concrete and other performance impact is not clear. Therefore, the research into expansion high ductility fiber component (concrete shrinkage compensation of high ductility fiber reinforced concrete) The performance, for the prevention of early shrinkage cracking, is of great significance to promote its application in practical engineering. The research contents and results are as follows: firstly, the calcium aluminate cement and gypsum composite as expansion component added to the concrete matrix to get the shrinkage compensation matrix, and compare the shrinkage compensation matrix and the original matrix contraction rule, the flexural strength and compressive strength, the results show that the increase of ettringite formed due to shrinkage compensating matrix, the shrinkage of early shrinkage and expansion stage, from the beginning has been testing the original matrix shrinkage; shrinkage compensation matrix compressive strength and flexural strength than the original matrix increased, at the same cement content when the shrinkage compensation matrix of the compressive strength and flexural strength increased with the amount of gypsum were increased first and then decreased and gradually decreased. Secondly, polyvinyl alcohol (Pol Yvinyl Alcohol, PVA) to get PVA-ECC shrinkage compensation fiber shrinkage compensation matrix, the shrinkage of 28d testing, using non-contact laser displacement sensor. The results show that the shrinkage of PVA-ECC shrinkage compensation for the early expansion and contraction in the late contraction stage, the shrinkage of PVA-ECC and general on the contrary, the late shrinkage compensation PVA-ECC shrinkage increases with the increase of fiber content; in addition, in the water curing shrinkage compensation PVA-ECC early expansion and expansion duration were greater than PVA-ECC. shrinkage compensation in the air again, comparing the compressive strength of PVA-ECC shrinkage compensation and ordinary PVA-ECC and bending strength, the results show that the compressive strength and shrinkage compensation PVA-ECC compared with ordinary PVA-ECC, the age of 3D is increased, the age of 28d, improve the rate of decrease, and even some groups appear a little lower; compensating shrinkage of PVA-ECC resistance The flexural strength compared with ordinary PVA-ECC, the age of 3D and 28d are a little lower; four PVA-ECC shrinkage compensation of flexural strength and ordinary compared to PVA-ECC, the age of 3D is increased, the age of 28d, the fiber content was 0 and 5% lower, while the fiber content of 1%, 1.5% and 2% that increased; in addition, in the water without restrictions in the maintenance of PVA-ECC shrinkage compensation 3D compressive strength, shrinkage compensating PVA-ECC. fourth flexural strength flexural strength and four were lower than the standard curing, toughness of PVA-ECC shrinkage compensation and ordinary PVA-ECC by comparing four point bending test results and the shrinkage compensation flexural toughness of PVA-ECC early than ordinary PVA-ECC, while the latter is small in PVA-ECC; in addition, compared to the standard curing and water curing shrinkage compensating flexural toughness of PVA-ECC found in the early, in water conservation 3D under no restriction of compensation The flexural toughness of PVA-ECC. shrinkage compensation shrinkage of PVA-ECC is smaller than the standard maintenance. Finally, comparison of PVA-ECC shrinkage compensation and properties of the PVA-ECC are summarized: expansion component added can make early PVA-ECC expansion, effectively prevent shrinkage cracking; expansion component is added and did not bring other negative effects on the performance of the PVA-ECC; no restrictions in water curing can improve the early expansion effect, but is not conducive to the mechanical properties and toughness improved. In addition, some suggestions on the future research direction of PVA-ECC shrinkage compensation and emphasis are put forward.

【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.572

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