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A novel type of ultra-high-performance concrete–normal concrete (UHPC-NC) superimposed sandwich slab is introduced, which eliminates the need for conventional longitudinal reinforcement. This sandwich slab consists of a prefabricated thin UHPC layer at the bottom, a cast-in-place NC layer at the top, and an extruded polystyrene foam core that provides both acoustic and thermal insulation. The resulting lightweight composite sandwich structure is integrated with web walls reinforced by a three-dimensional truss reinforcement system. The flexural performance is examined through four-point bending tests and compared with that of a fully UHPC sandwich slab of identical structural configuration and casting progress. Relative to the fully UHPC slab, the UHPC-NC slab demonstrates superior flexural structural integrity, significantly reduces costs and improves construction efficiency. The ductility coefficient of the UHPC-NC slab reaches 3.23, which is superior to the UHPC slab. This indicates that it has a stronger collaborative working ability with the rebars and the compressed concrete. Comprehensive analytical, numerical, and experimental investigations into the flexural behavior of the proposed UHPC-NC sandwich slab yield accurate evaluation of cracking and ultimate load capacities, thereby offering valuable guidance for the engineering application of this innovative superimposed sandwich slab system. Full article

In this study, a full-scale test on the bending performance of concrete sandwich laminated floor slabs with integrated thermal and sound insulation was carried out, and the effects of different reinforcement ratios on the bending performance of concrete sandwich laminated floor slabs were investigated as well as the variation law of the failure modes, characteristic loads, load-mid span deflection, load-rebar strain curves, and anti-slip performance. The results indicate that the concrete sandwich laminated floor slabs present typical bending failure characteristics. According to bending failure characteristics, the damage process can be divided into three stages, i.e., elasticity, cracking, and failure. The bearing capacity significantly increases with the increase in reinforcement ratio. The normal service, yield, and ultimate loads of bearing capacity of the floor slabs with a larger reinforcement ratio increase by 54.55%, 52.94%, and 46.46%, respectively. Moreover, the mid-span deflection decreases significantly with the increase in reinforcement ratio, and the cracking expansion is also delayed. Before cracking, the prefabricated layer and laminated layer can realize load bearing together, and the floor slab is in a state of complete interaction. When the floor slabs reach the ultimate state, the superimposed surface produces a sliding effect, and the floor slab is in a state of partial interaction. The finite element analysis software ABAQUS (with the version number of ABAQUS 2020, the chief creator of David Hibbitt, and the sourced location of the United States) was used to perform nonlinear numerical simulation. The test results accord well with the simulation results, which verifies the correctness of the finite element model. Based on finite element simulation, the influence of post-cast concrete strength on the ultimate load can be ignored. Full article