まさ土を細骨材として用いたコンクリートの物性

抄録

Three kinds of decomposed granites are selected based on the content of materials finer than 75μm sieve and ignition loss among decomposed granites produced in Tottori prefecture. The selected decomposed granites are sifted with 10mm sieve and used as fine aggregate for concrete. In this paper, the properties of fresh and hardened concrete with decomposed granite and the application of decomposed granite to fine aggregate for concrete are investigated.
The test results show that the dosage of a retarder type of air-entraining high-range water reducing agent (HWRA) required to attain the same slump value increases as the material finer than 0.15mm sieve included in the decomposed granite increases and its water retaining factor becomes larger. An increase in dosage of HWRA leads to an extension in setting time. Consequently, the setting time of the concrete with decomposed granite becomes long compared to that of concrete with normal sand. However, the fundamental properties of concrete with decomposed granite such as slump and air loss with time, bleeding, compressive strength, drying shrinkage and freeze-thaw resistance are almost the same as those of concrete with normal sand.