Abstract
We produced the concrete which was mixed the low-class treatment recycled aggregate and the blast furnace slag sand（maximum dimension of 5mm or 1.2mm）at the same time, also it was evaluated about the bleeding properties, the construction placement performance, the compressive strength, and the freezing-thawing resistance. The low-class treatment recycled aggregate, whose density corresponds to the recycled aggregate of class M（JIS A 5022）and whose water absorption rate corresponds to class L（JIS A 5023）. In this research, the mix proportion of concrete had been designed with the water cement ratio of 47％, was used for the experiment. As a result, the bleeding capacities were kept to 0.1cm3/cm2 or less when the mixing ratio of the blast furnace slag was 50％ or less. During the filling ability test for the fresh concrete, the clearance passing ability was superior when the blast furnace slag fine aggregate was mixed to the concrete. Also, the compressive strength was lower than that of the normal aggregate concrete, however, it was verified that it possesses enough freeze-thaw resistance. Therefore, it was verified that within the concrete of which mix proportion was designed as range of normal strength（W/C＝47）, the low-class treatment recycled aggregate concrete that had been mixed the blast furnace slag sand（replace to crushed sand at 50％ or less）had sufficient performance about the bleeding property, construction placement performance, and the freezing and thawing resistance.
