Comparison and Review of Concrete-to-Concrete Interface Shear Resistance According to Major Design Codes

Abstract

The paper focuses on interface shear behavior, more precisely on shear resistance of the interface between lightweight and regular concrete layers cast at different times without shear reinforcement crossing the interface. Different approaches according to most of major design codes (Eurocode, ACI and Model Code 2010 among other) are briefly reviewed, with emphasis on difference between variables resp. material and cross-section characteristics, on which interface resistance depends. Furthermore, two sets of experiments were carried out: direct shear test on Z-type specimens and slant shear test slightly modified to enforce adhesive failure. Obtained results are compared with theoretical values.

Suitability of different tests for characterization of the dimpled concrete‐to‐concrete interface

“…This procedure, nonetheless, cannot be used for this type of surface since it would lead to partial filling of the dimples, and the results might thus be unrepresentative. For that reason, the MTD was estimated using Equation (1), which is based on previous studies, 30 and is in agreement with Randl's suggestion. 25 MTD…”

“…In order to minimize work-intensity in comparison with the LTP, a simplified small-scale test setup was proposed and referred to as the Z-type test (Figure 5b, see Ref. [30]). One hundred and fifty mm-sided cubes were proposed as specimens so that standard cube formwork can be used.…”

“…Efficiency was defined as the ratio between specimen volume and interfacial area, and characterized as low for values lower than 30%, medium in the range from 30 to 60%, and high if higher than 60%. The presented coefficients of variation (CoV) are based on the experimental program carried out within this (and previous 30,33 ) research, and data available in the literature. 7,8,35,36 Some authors have obtained both adhesive and cohesive failures (interface and monolithic concrete failure modes).…”