Bond Performance Of Reinforcement In Self-compacting Lightweight Concrete

Self-compacting lightweight concrete (SCLC) is a new type of concrete combined with the favorable properties of self-compacting concrete (SCC) and lightweight concrete (LWC), which has the characteristics of high flowing capacity, light weight and high strength. As a new construction material, the researches on the workability and bond behaviors of SCLC are not comprehensive, yet. In order to ensure the application of SCLC in engineering practice, this thesis studies the relationship between the flowability and the segregation resistance of SCLC, the bond behavior of plain round bars in SCLC subjected to lateral tension. The main contents and conclusions are as follows:(1) Three mix proportions for SCLC were designed by the overall calculation method with fixed fine and coarse aggregate contents. The strength grades of the three designed SCLCs are C20, C35 and C50, respectively. The workability of the three types of SCLCs is quantitatively evaluated by the slump flow, T500, V-funnel, L-box, U-box, and sieve segregation tests. It is found that the workability of SCLC (C20, C35 and C50) satisfies standard of EFNARC.(2) By comparing the workability of three mix proportions, the relationship between the flowability and the segregation resistance of SCLC was analyzed. The results of this comparison show that the increase in flowability increases the segregation resistance of SCLC.(3) The bond behaviour of SCLC with plain round bars under lateral tension was studied. A total of 39 pull-out specimens were tested. Through the measurements of bond strength, slip at the peak bond stress and residual bond strength, the bond behavior between plain round bars and self-compacting lightweight concrete under lateral tension with different ratios was analyzed. The experimental results show that the ultimate and residual bond strengths decrease, but the slip at the peak bond stress first increases and then keeps constant with the increase of the lateral tension. The numerical regressions of bond strength, slip at the ultimate bond stress, and the ratio between residual and ultimate bond stress were obtained and validated through the experimental results.(4) The mathematical model of bond-slip relationship of plain round bars in SCLC is proposed. The bond-slip curves of plain round bars in SCLC subjected to 1 lateral tension are reasonably predicted and agree well with experimental results.