High dropping non vibration concrete is widely used in high-rise steel tube concrete construction. In this paper, a high dropping non vibration self-compacting concrete with high mobility, low slump loss, and good anti-segregation ability is developed by mixing addition of PCA superplasticizer and SCC composite expansive admixture. The test results showed that the admixture and cement used in the test possess sound compatibility. The slump flow of self-compacting concrete prepared are more than 660mm, T500 of 2.8~7.5s, 1h slump flow loss of less than 10%, and the segregation rate of less than 7.5%. Through strictly control production and dropping construction, supplemented by field ultrasonic detection measures, the high dropping self-compacting concrete in steel tube achieved successful application for a high-rise building.

An investigation of early anti-cracking performance and permeability of hybrid cellulose fiber and PVA fiber reinforced concrete is presented in this article. The test results show that, both cellulose fiber and PVA fiber effectively improve the splitting tensile strength. The early anti-cracking performance of concrete is obviously improved by PVA and cellulose hybrid fibers, and there exists the synergistic effect for restrain matrix cracking with hybrid fibers. Based on the practical application of a subway station project during two years, result shows the underground concrete wallboard containing hybrid fibers does not produce obvious cracks and leakage problem.

Thin composite laminate attachments were designed and added onto the conventional double-strap joints so that additional load transfer paths were created and localized interfacial stress concentrations near the joint edge were reduced. Experiments were performed and the result revealed that the new double-strap joint with attachments had significantly greater strengths than the conventional double-strap joint. Joints with attachments having different angular configurations and lay-ups were tested and different failure modes were observed. Interfacial stresses along the bondlines were analyzed in order to understand the increase in joint strength and the change of failure modes in joints with attachments.