Interface role in composite RC beams with a light-weight concrete core and an ultra high-durability concrete skin

Reinforcement detailing of connections between perpendicular hollow precast walls

“…Probably the reason for different strength capacities is the incorporation of the lightweight aggregates and, especially, the increase of the matrix strength of this concrete, required to compensate the loss of strength that happens when the Table 4. Mechanical properties of concretes (Martins et al 2021a;Antunes et al 2020).…”

“…The core of the walls is casted with a low cement concrete (LCC), combining normal density and lightweight aggregates. More details about the MC-Pool project can be found in (Martins et al 2021a; Antunes et al 2020). This hybrid solution has the advantage of increasing the durability and simultaneously reducing the environmental impact of the final product, because the UHDC is used only in the outer layer, where is most needed to protect the steel rebars (Martins et al, 2020a; b).…”

“…The pre-wall system is made by two different concretes cast at different ages, UHDC in the outer layers and LCC in the core, therefore the shear strength between the two concretes is an important issue that must be taken into consideration, because it is necessary to ensure that the composite wall has a monolithic behavior (Saldanha et al 2013; Costa et al 2018; Santos et al 2007). Based on previous studies by the authors (Martins et al 2021a; Robalo et al 2021), it has been concluded that the interface must be treated to increase its roughness and consequently to ensure the wanted bond between both concrete layers. A proper shear strength at interface can be obtained using a superficial hardening inhibitor followed by light washing, providing a strength that is approximately the double of the case with smooth surface (Martins et al 2021b; Robalo et al 2021).…”

“…There are some studies that show how important and weak the connections between precast walls can be (Brunesi et al, 2019a; 2019b). Martins et al (2021a) already carried out several tests to evaluate the structural behavior of the pre-wall system, including the connections, namely, the lateral or horizontal connection between two pre-walls and the connection between the foundation and the pre-walls. In order to have this pre-wall system comprehensively characterized, also the corner connections between the pre-walls need to be addressed.…”

“…Estimated service life and minimum cover, c min,dur , for current structures(Martins et al 2021a; Antunes et al 2020).ConcreteMinimum concrete cover, c min,dur (mm) Estimated service life (years) XS1 a XS2 b (1.4-25 m) XS3 c XC2 XC3 XC4 (dry reg.) XC4 (wet reg.)…”