Title:
Experimental Study on Interface Shear Resistance through Slant Shear Tests (Prepublished)
Author(s):
Brandon Li, Andrea Campos Sanchez, Hwa-Ching Wang, Yongjae Yu, Anca C. Ferche, and Oguzhan Bayrak
Publication:
Materials Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
cold joint; concrete-to-concrete interface; interface roughness; interface shear resistance; slant shear
DOI:
10.14359/51749248
Date:
10/8/2025
Abstract:
This paper summarizes the results of an experimental study investigating interface shear resistance through slant shear tests. A total of 54 tests were conducted on 6×12 in. (150×300 mm) cylinders with inclined cold joints. Five key test parameters were investigated: cold joint inclination, interface roughness, variation in concrete compressive strength between layers, casting age difference, and aggregate size. The test results demonstrated that the most influential parameters affecting interface shear resistance were interface roughness, casting age difference between layers, and aggregate size. Conversely, cold joint inclination and variations in compressive strength between layers were identified as comparatively less influential factors. A comprehensive analytical study was conducted, including the comparison of five current design codes. A modified approach is proposed for calculating the interface shear resistance, compatible with current design codes’ expressions. The proposed approach was validated using the experimental results generated from this study and a database of 124 slant shear test results from different research programs. Overall, the proposed approach resulted in more accurate estimations for the interface shear resistance, particularly for specimens with intermediary levels of amplitude at the interface.