【作者】 高淑玲；

【导师】 徐世烺；

【作者基本信息】 大连理工大学 ， 结构工程， 2006， 博士

【摘要】 日本一家公司开发的高强高模聚乙烯醇(polyvinyl alcohol，简称PVA)纤维K-Ⅱ可乐纶(REC15)应用在很多方面都对基体的韧性有很大的提高，PVA纤维增强水泥基复合材料(PVA fiber reinforced cementitious composites，简称PVA-FRCCs)，是以水泥或以水泥加填料为基本粘结料，或者再加上小粒径细骨料作为基体，再加入体积掺量不大于2％～4％的PVA纤维做增强材料复合制成的建筑用材料。此种材料的特点是具有较高韧性，其拉应变值将近是混凝土的100倍，这种材料本身所具有的应变-硬化特性是实现稳态开裂的结果，也是这种材料独特韧性的来源，由于此种材料饱和多条裂缝宽度较小，低于100μm，以期将此种材料用在水工混凝土结构中，有效地防止结构开裂，极大地提高水工结构的耐久性。本文基于此完成了以下工作： 1．对PVA-FRCCs使用的原材料性能、投料顺序的影响以及搅拌工艺进行了大量的试验，得到既节省时间、又有利于纤维分散、流动性好的配制方法。 2．对PVA-FRCCs圆柱体试件进行单轴抗压试验，得到其抗压应力-应变曲线，其抗压强度不是很高，在16MPa～33MPa，但峰值荷载对应的拉应变比混凝土高3～6倍，极限压应变是混凝土的将近100倍。 3．分别利用外夹式和粘贴式两种方法在1000kN微机控制液压伺服试验机、250kNMTS-NEW上进行无切口和两边切口单轴直接拉伸试验，得到硬化的应力-应变全曲线，极限拉应变最大可达到0.7％甚至更高，并伴随着密集的多条裂缝的出现，裂缝宽度小于100μm，对假硬化的应力-应变全曲线进行了分析与模拟，建立拉应力的计算公式。 4．进行了与无切口直接拉伸试件同尺寸的单边切口薄板直接拉伸试验，得到硬化的荷载P-裂缝口张开位移(crack mouth opening displacement，简称CMOD)曲线(以下简称P-CMOD曲线)，不仅在预制切口端部出现多条裂缝，在远离切口处还有多条微小裂缝出现，且裂缝开裂形式受切口长度的影响，将硬化的P-CMOD曲线分为5部分进行分析，并利用断裂力学的方法计算分析了此种材料不同部分的断裂韧度。 5．利用两种缝高(65mm，50mm)楔入劈拉试验对比分析对比研究了高强混凝土、高强钢纤维混凝土、玻璃纤维增强水泥基复合材料、钢纤维增强水泥基复合材料、PVA-FRCCs的韧性，分析对比它们的P-CMOD曲线的特性，得出PVA纤维增韧效果最好的结论。PVA-FRCCs的起裂荷载可以利用P-CMOD曲线得到，高强混凝土和高强钢纤维混凝土的起裂荷载利用全桥电测法得到，并计算得到临界裂缝扩展长度。 6．与单边切口直接拉伸类似，PVA-FRCCs得到硬化的P-CMOD曲线，在预制缝端乃至远处同样有多条裂缝的出现；PVA-FRCCs开裂后，在硬化段产生了多条微小裂更多还原

【Abstract】 High strength and high modulus polyvinyl alcohol (PVA, in short) fiber (KURALON K-II, REC15) exploited by Japanese company can enhance the ductility to matrix in many ways. PVA fiber reinforced cementitious composites(PVA-FRCCs, in short) is a kind of composites reinforced by PVA fiber less than 2%～4% volume ratio.Furthermore, the matrix is just cement, cement adding some admixture, or extra adding some small particle diameter fine aggregate.Above all, the characteristic of the composites is ultra-high ductility whose ultimate tensile strain is about 100 times to concrete. Moreover, inherent pseudo strain-hardening character of the composites is the result of stable cracking and the reason of its unique ductility. In addition, the saturated multiple crack width of the composites is less than 100μm. Accordingly, a series of tests and analytical work about the composites have been completed in order to put the composites into hydraulic structure preventing cracking and improving durability:1. Material component performance, feeding sequence and mixing technology are described in detail. Based on a large number of tests, the optimal compounding method which can reduce the mixing time, make fiber dispersed uniformly and get better flowability can be acquired.2. Complete stress-strain curves of uniaxial compressive cylinder test of PVA-FRCCs are drawed. Although compressive strength is much low between 16MPa and 33MPa, tensile strain at peak load is 3 to 6 times to concrete and ultimate strain is almost 100 times to concrete.3. Uniaxial direct tensile test of nonotched and double-edged notched thin sheets which individually employ grip jaw and bended steel plate method are carried on 1000kN microcomputer control hydraulic servo machine and 250kN MTS-NEW. As a result, pseudo hardening stress-strain complete curves can be got and ultimate tensile strain is 0.7% at the most. Accompanyingly, densely multiple crack occurred whose width is only less than 100 μm. Furthermore, the analysis and simulation of stress-strain curves are carried out. In addition, the formula of calculating tensile stress is established.4. Uniaxial direct tensile test of single-notched thin sheet whose geometric dimension is the same to that used in foregoing direct tensile test is also done on 1000kN microcomputer control hydraulic servo machine. Pseudo hardening Load P-crack mouth opening displacement (P-CMOD, in short) is gained. Besides, not only multiple dispersive cracks更多还原