Mechanism elucidation and constitutive laws of expansive concrete for durable and high performance concrete structures

耐久性高性能混凝土结构膨胀混凝土的机理阐明和本构规律

基本信息

批准号：
13450179
负责人：
KISHI Toshiharu
金额：
$ 9.66万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Crack resistant mechanism of chemical prestressed reinforced concrete (CPRC) with expansive agent was studied in microscopic point of view as followings,(1) In cyclic loading of uni-axial test for CPRC unloading stiffness is gradually decreased and residual strain is remarkably increased up to cracking. Further, CPRC has higher deformability and tension stiffening effect after peak range is higher than normal RC.(2) A series of flexural test of CPRC with various specimen sizes were conducted. The deformability and cracking load of CPRC is higher in smaller cross section in which curvature becomes large. Not only ultimate load but also shear stiffness are enhanced by providing lateral reinforcement The effect of lateral shear reinforcement is more significant in larger cross section since plain concrete zone becomes larger in that situation.(3) Flexural test for CPRC was conducted where reinforcement ratio was varied under constant content of expansive agent It is shown that crack resistance is enhanced in accordance with not only chemical prestress but also chemical prestrain. Then, crack resistance of CPRC under long-term drying was also tested It was found that crack resistance of CPRC subjected to 1 month drying is decreased like normal RC, however it is recovered in 3 months drying.(4) A series of pull-out test of deformed bar embedded in massive concrete was conducted to check bond characteristic. Bond between expansive concrete and deformed bar is almost same as normal RC irrelevant of degree of lateral confinement Further, it was found in case where bar diameter is larger than maximum size of coarse aggregate, that very strange strain distribution appears in deeper zone of re-bar at very small stress level.Due to the above mentioned complicated governing mechanism of CPRC behaviors, formulations for crack width and constitutive laws for CPRC could not be yet established

在显微镜的角度研究了具有膨胀剂的化学预应力钢筋混凝土（CPRC）的裂纹机制，如以下内容，（1）（1）在单轴测试中以CPRC卸载刚度的循环载荷逐渐降低，残留应力显着增加至破裂。此外，CPRC在峰值范围后具有更高的变形和张力僵硬效果高于正常RC。（2）进行了一系列具有各种样品尺寸的CPRC的弯曲测试。在曲率变大的较小的横截面中，CPRC的变形性和开裂载荷较高。不仅最终负载和剪切刚度通过提供侧向增强来增强，在较大的横截面中，横向剪切加固的效果更为重要，因为在这种情况下，普通混凝土区域变得更大。（3）进行CPRC的弯曲测试，在膨胀剂的恒定含量下，不仅可以使裂纹抗性在不断变化的情况下，因此不仅可以使裂纹抗性在化学上，而且还具有化学性化学作用。然后，还测试了CPRC在长期干燥下的裂纹抗性，发现接受1个月干燥的CPRC的裂纹抗性像普通RC一样降低，但是在3个月的干燥中恢复了。（4）在大量混凝土中嵌入了嵌入在大量混凝土中的变形杆的拉出测试，以检查键键的特征。膨胀混凝土和变形杆之间的键几乎与正常的RC不相同的侧向限制程度无关紧要，如果条形直径大于最大的粗骨料大小，则发现，这种非常奇怪的应变分布出现在非常小的应力水平上的更深层次的重复区域。