Bond Behaviour of Structural Lightweight Concrete

The European normative context (EN 1992-1-1) imposes additional requirements for the use of lightweight aggregate concrete (LWC) in reinforced and prestressed structural products. This results in structural terms, by a reduction of the mechanical properties (tensile strength, modulus of elasticity) and an increase of the concrete cover by 5 mm to ensure an equivalent bond strength (EN 1992-1-1 Sect. 11.4.2). The aim of this study is to investigate if this rule can be omitted for structural LWC with densities ranging from 1600 to 2000 kg/m(3). To achieve this objective, bond tests are conducted on 21 beam specimens. The primary experimental variables are aggregate types (expanded clay/expanded slate/normal weight aggregate), reinforcing bars diameters (Phi = 10 mm, Phi = 14 mm) and embedment length. The load - slip responses, failure modes and bond strengths of LWC and normal weight concrete (NWC) are compared. Results indicate that tested LWC with densities greater than 1600 kg/m(3) have a similar behavior to that of NWC. Durability properties for LWC was studied previously and shown good performance in comparison with NWC, (Bello et al. 2013). These results prove that the Eurocode rule for additional concrete cover in case of structural LWC may be withdrawn.