Flexural behavior of eco-efficient and ultra-high durability concrete beams

The present paper describes an experimental study conducted to characterize the behavior of structural members produced with a new concept, consisting of using an ultra-high durability concrete (UHDC) in the cover of structural members, being the core produced with a low-binder concrete. This solution allows to build structures more durable and simultaneously eco-friendly because the UDHC that requires high dosages of Portland cement is applied only in the outer layer, where is most needed to protect the structure against the environmental actions. To reduce even more the cement consumption and the corresponding drawback regarding sustainability, the bulk of the members was produced with a concrete with a lower mechanical performance but also with lower cement dosage, only 125 kg/m(3). Many of the previous studies were focused on the mixtures design, as well as on the shear strength of the interface between the cover and the bulk, considering different types of surface conditions. This work explores this concept in terms of structural behavior, particularly, on beams. With this aim eight beams with different longitudinal tensile reinforcement ratios were tested and the following parameters were analyzed: load-displacement relation; curvature in critical sections; flexural stiffness; ductility, cracking pattern, and failure mode. The tested eco-efficient high durability beams exhibited an excellent structural behavior, presenting both stiffness and flexural strength increase. (C) 2019 Elsevier Ltd. All rights reserved.