Bond of Reinforcement in High-Strength Concrete

This paper describes an examination of the development of tension lap splices in high-strength concrete and the applicability of the restriction in the ACI 318 code where the values of √fc′ used to calculate development length shall not exceed 100 psi. The focus is on the development of splices with Grade 60 epoxy-coated and uncoated bars in normalweight concrete. A summary of the behavior of bond is presented to provide context for the study. It is followed by a literature review to analyze the relevant previous experimental work in this area. Based on the analysis of those data, a modification to the current code limitation is proposed. The main conclusion of this paper is that the limit of 100 psi (0.689 MPa) on the square root of the specified compressive strength in Section 12.1.2 of ACI 318-11 (Section 25.4.1.4 of 318-14) may be extended to 120 psi (0.827 MPa) based on the analysis of available data without significant modifications to the current provisions for concrete strengths up to 16,000 psi (110 MPa).