An Inspection Method for Construction Joints in Concrete Structures

1992 Fiscal Year Final Research Report Summary

• Project/Area Number: 03650460
• Research Category: Grant-in-Aid for General Scientific Research (C)
• Allocation Type: Single-year Grants
• Research Field: Building structures/materials
• Research Institution: Shibaura Institute of Technology
• Principal Investigator: SOSHIRODA Tomozo Shibaura Institute of Technology Dept, Architecture and Building Eng, Professor, 工学部・建築工学科, 教授 (90052745)
• Project Period (FY): 1991 – 1992
• Keywords: Construction joint / Inspection method / Concrete structure / Ultrasonic method / Surface method / Early age / Nondestructive testing / Tensile bond strength

Research Abstract

A series of experiment on 15x15x45cm concrete column type specimens which have a model construction joint at the center of them respectively was undertaken to establish a new testing method by ultrasonic apparatus for nondestructive inspection of construction joints in concrete structures.
Three kinds of joints were prepared : (1)treated with wire-brushing (2)non-treated (3)scattered with sawdust. Two sensers were applied at a interval of 10cm across the joint and ultrasonic pulse velocity was measured by "surface" method with them, the data were compared with the pulse velocity through the parent concrete without joint. The indicators of quality of jointing were tensile bond strength and permeability by a simple test.
From the results it is concluded on an inspection method by ultrasonic for construction joint in concrete structures as follows.
(1)Earlier inspection is possible(for example, at the age of one day).
(2)It is possible to detect the crevice by impurities like as sawdust.
(3)It is difficult to detect the difference between good bond and less bond with out opening.