Assessing the effects of self-consolidating concrete components on workability to compensate the negative impacts resulted by temperature and time
الموضوعات :
1 - Associate Professor, Department of Civil Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran
الکلمات المفتاحية: temperature, Cement, Limestone powder, Viscosity-modifying agent, Retarding admixture,
ملخص المقالة :
Compared to other concrete types, the self-compacting concrete (SCC) offers a higher workability. Accordingly, the SCC performance is highly affected by the ambient temperature and extended transportation time. In previous studies, the effect of constituents on SCC at various time and temperature was only studied after the concrete temperature reached the normal range. Nonetheless, in the present research, it is tried to reduce the negative impacts of changing temperature and time by using cement, limestone powder, and chemical admixtures without considering temperature constraints for concrete. In this research, SCC samples temperature were selected for different seasonal conditions. Therefore, once the concrete temperature reached the ambient temperature, slump flow, T50, VSI, J-ring, and rheology tests were conducted on a total of 21 different concrete mixtures with water to cement ratio of 0.4. According to the results, application of retarding admixture and increased cement dosage contributed to improved workability and rheological behavior. On the other hand, an increase in the limestone powder dosage, rather than cement, was seen to impose a larger contribution to increased passing ability of SCC through rebars, but since the concrete containing limestone powder exhibited larger slump losses, one should increase the dosage of cement or retarding admixture to retain the concrete workability. Generally, it was found that the temperature and concrete mixture composition effectively control performance characteristics of the SCC. Therefore, it is recommended to keep the concrete from being overheated as it can otherwise lead to the acceleration of cement hydration and hence decreased workability.
