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The high flowability of self-consolidating concrete (SCC) is often achieved by reducing the amount of coarse aggregate and using more water. This can lower concrete strength. This study investigates the behavior of SCC columns under concentric compression by testing two series of column specimens. The first series contained 16 columns made with normal concrete (NC), and the second 16 columns were made with SCC. In the study, the amount of coarse aggregate in SCC was kept approximately the same as in NC and the amount of water was kept as low as possible. The test variables included the concrete strength, amount of longitudinal reinforcement, volumetric ratio of transverse reinforcement, strength of transverse reinforcement, and arrangement of transverse reinforcement. Comparisons were made between the SCC and NC specimens. Behavior of the SCC used in this study was also compared with that of high-flowability concretes in other studies. The results show that SCC can have better structural performance than NC, as long as the concrete is properly proportioned. The ductility and crack control ability of SCC columns are better than NC columns, and the stiffness of SCC is also higher than that of NC. The larger amount of coarse aggregate improves the mechanical behavior of the SCC in this study compared with other SCC. These findings indicate that the SCC in this study showed satisfactory structural performance.

This paper will discuss that copper slag, a by-product of copper production, contains large amounts of iron oxide and silicate. It is chemically stable and its physical properties are similar to that of natural sand. The physical and chemical properties of copper slag were investigated. Copper slag, in amounts of 20, 40, 60, 80, and 100 percent, was substituted for fine aggregate in cement mortar and concrete. The fineness modulus of the combination of copper slag and fine aggregate was roughly 2.6, the optimum fineness modulus for concrete mix design. At this value, workability was found to be satisfactory with minimal bleeding. Addition of copper slag also improved the strength of the concrete. When the substitutional amounts exceeded 80 percent, lower strengths were obtained, possibly due to the formation of ettringite. It was also found that the effect of copper slag on long term strength development was also dependent on the amount used and its fineness. It was concluded that copper slag could be used as a fine sand substitute for ordinary reinforced concrete.

This paper describes how rice husk ash (RHA) was obtained under different burning conditions from 400 to 1200°C. The changes in the properties of the RHA were investigated using microanalytical techniques. When RHA obtained at different burning conditions was added to cement paste or mortar, several properties such as hydration, setting time, porosity, and strength revealed changes and these changes are described.