Influence of normal stress and reinforcement ratio on the behavior of LWAC interfaces. (20th December 2018)

• Record Type: Journal Article
• Authors: Costa, H.; Carmo, R.N.F.; Júlio, E.
• Is Part Of: Construction & building materials. Volume 192(2018)
• Page Start: 317
• Page End: 329
• Publication Date: 2018-12-20
• Subjects: Interface -- LWAC -- Normal stress -- Roughness -- Shear stress -- Strengthening; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2018.10.116
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Experimental assessment of the LWAC-to-NDC interfaces, with different surface roughness. Influence of the normal stress and reinforcement ratio at the interface behavior. The lightweight aggregates decrease the interface strength. The rebars did not increase the maximum shear strength, contrary to codes predictions. Proposal of expressions to predict the coefficients of cohesion and friction. Abstract: This experimental study aims to characterize the behavior of LWAC-to-NWC interfaces, using a substrate of normal weight concrete (NWC) with different surface roughness and three lightweight aggregate concrete (LWAC) mixtures for the overlay, with a density ranging between 1500 and 1900 kg/m 3 and a compressive strength varying between 45 and 75 MPa. The NWC-to-NWC interfaces were also tested to be used as reference, only one NWC with a compressive strength of 50 MPa was used. Two more parameters were considered in this study, the normal stress applied at the interface and the reinforcement ratio crossing the interface. Results were analyzed and compared with predictions according to Eurocode 2, fib Model Code 2010 and ACI 318-14, showing significant differences, mainly when LWAC is added, proving that the binding matrix strength is an important parameter in this analysis and that the cohesion component is underestimated by codes. It was also concluded that the incorporation of the lightweight aggregates decreases the interface strength and the rebars did not have a clear increase in the maximum shear strength, contrary to predictions of some codes. Expressions based on the roughness parameter are presented to predict the coefficients of cohesion and friction.