Experiment on the bonding performance of the lightweight aggregate and normal weight concrete composite beams

Aiming at the bonding performance of the casting interface in the composite ceramsite lightweight aggregate concrete (LWAC) and normal weight concrete (NWC), the experiment on the shear bonding blocks and bending composite beams were designed for progressive study. The Z-shaped composite blocks were first made by the LWAC and NWC with different strength grades considering the variation of the casting interval time and the interface preparing method. The bending composite beams were designed considering the variation of the casting interval time, the relative position between the casting interface and the calculated sectional neutral axis in the LWAC and NWC composite beam. The result indicates that, the bonding shear performance of the casting interface decreases most obviously within 2 days of the casting interval time. The shear strength of the casting interface with 14 days casting interval time for considered different interface preparing methods is higher than that calculated according to the specification. Although there is no bonding sliding failure happening on the casting interface in the composite beam during the experimental loading, a certain influence exists on the crack developing near the casting interface, the load-deflection curve developing, the strain developing of the mid-span section and the subtle damage variation considering the variation of the casting interval time, the relative position between the casting interface and the calculated neutral axis in the composite beam.