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Study of the Treatment of Construction Joints in Concrete Using Water Jet Method

水射流法处理混凝土施工缝的研究

基本信息

批准号：
07650554
负责人：
ADACHI Ichiro
金额：
$ 1.22万
依托单位：
Chiba Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650554/
关键词：
Water Jet Rotary Jet Surface Treatment Vertical Joint Bleeding Ratio of the Flexural Strength Depth of the Treatment Strength of Construction Joint 打継強度打継ぎ水平打継ぎ

项目摘要

The aim of this study is to investigate the effectiveness of water jet cutting for the surface treatment of hardened concrete and to find out the bond strength of construction joints. The flexural strength ratio was used to evaluate the strength of construction joints. The ratio of the flexural strength of the speciments with construction joints to the strength of the specimens without construction joints was regarded as the flexural strength ratio.The flexural strength ratios for vertical construction joints are generally lower than the horizontal construction joints because of being caused by the loss of adherence properties of concrete due to the formation of a thin water layr by bleeding. This study showed that the flexural strength ratio of the vertical construction joints were obtained ranging 80% and 90% when a rotary jet cutting methed was used and the depth of the indentations of surface treatment maintained a specified value. It can be seen from the experimental results that the suitable value of specified depth is more than 7mm.The depth of surface treatment is mostly affected by the water pressure of the compressor.The flexural strength ratios were not affected by the type of coarse aggregate and the water-cement ratio of old concrete.AE signals were monitored during the tests of solid beams and jointed beams. AE events counts, amplitude distributions and wave form were obtained and the following tendencies were showed. AE event counts and long wave lengths were concentrated around vicinity of center of the beam as the load is close to the falure load. But large amplitude distributions and frequency were not affected by the construction joints.

本研究的目的是探讨水射流切割硬化混凝土表面处理的有效性，并找出施工缝的粘结强度。采用抗弯强度比来评价施工缝的强度。将有施工缝试件的抗弯强度与无施工缝试件的抗弯强度之比作为抗弯强度比，竖向施工缝的抗弯强度比一般低于水平施工缝，这是由于泌水形成薄水层，使混凝土失去粘结性能所致。研究表明，采用旋喷切割方法，表面处理压痕深度保持在规定值时，竖向施工缝的抗弯强度比可达80%~ 90%。试验结果表明：混凝土表面处理深度以大于7 mm为宜;混凝土表面处理深度主要受压水器水压的影响;粗骨料种类和老混凝土水灰比对混凝土抗折强度比影响不大;实梁和节点梁试验过程中均监测到声发射信号。获得了声发射事件数、幅值分布和波形，并显示出以下趋势。当载荷接近失效载荷时，声发射事件数和长波长都集中在梁的中心附近。但大振幅分布和频率不受施工缝的影响。