Bond Strength of Normal Weight Concrete - to - Lightweight Aggregate Concrete Interface: Influencing Factors, Testing Methods, Research Review and Assessment

Abstract

This paper investigates the interface between normal weight concrete (NWC) and lightweight aggregate concrete (LWAC) of different ages, focusing on shear resistance. The main parameters affecting bond strength and commonly used testing methods are analyzed. Design shear resistance is also reviewed according to different guidelines, including Eurocode 2 (EC 2), the second-generation (draft) of Eurocode 2 (prEC 2), ACI 318-19 and the fib Model Code 2010. Methods for determining friction coefficients and surface roughness parameters are presented, along with a description of several methods for measuring surface roughness. Experimental results from the literature are considered to assess the influence of key parameters. The paper also highlights limitations in current surface roughness characterization methods and the lack of standardized approaches for determining friction and cohesion parameters.