Abstract
Greater emphasis is given to the reduced period of construction and the performance of concrete following recent trend of high-rise and large-sized buildings. Especially, the focus is on the management of concrete quality in the early stages regarding reduced construction period. Domestic and foreign studies have already examined the technique of accelerating the hardness to check the quality of the concrete in a short period of time such as hot water curing and microwave irradiation as a method to check the concrete quality in the early stage. However, there are not many studies that considered such techniques on ultra-high strength concrete. To examine ultra-high strength concrete, tests were conducted on following settings: W/B 20.7%, 80MPa strength for unit quantity $155kg/m^2$, and curing in hot water heated to 20, 40, 60, and $80^{\circ}C$ using curing water tank. Three specimens were produced for each age and the mean value was taken for compression strength to reduce error, and mock-up specimens (column, wall) were produced, the core was extracted using KS F 2422 (Method of Obtaining and Testing Drilled Cores and Sawed Beams of Concrete) for the comparison with heated specimen for each age, and the compression strength was measured three times for each age to review field applicability. Also, it appeared that the distribution of pores and hydration products which appears to have impact on the concrete strength was not fully considered, and therefore, the generation and distribution of micropores were observed using mercury intrusion porosimeter and the distribution of microtissue was observed using scanning electron microscope (SEM) to increase the accuracy of the test.
