抄録
Experiments have been performed to investigated vaccum effect. In vaccum pacage aggregates and cement particles can be absorbed with water ideally. Generally some of cement particles contact with air or each other. This phenomena is undesirable as for as compressive strength of concrete. Then experimentes were carried out to improve absorption between water to aggregate and cement particle. First experiment was carried out on bond strength between cement paste and aggregates. Relationship between bond strength and age was shown in Fig. 2. Bond strength in vaccum was not greater than in air. Tested surface in vaccum was observed very clear and in air it was recognized void. (See photograph) Second experiment was carried out on compresive strength of vaccumed concrete. It was vaccumed after cement and and aggregates were cast in the place and three minutes later water was poured in it. Then concrete was mixed and cast in test piece. Consequently four percentage of water was reduced from concrete and water……cement ratio was improved four percentage. Specific gravity of vaccumed concrete was greater than in the air of concrete. Compresive strength of vaccumed concrete is greater 10〜20 percentage than in the air of concrete. Relationship between compresive strength and age is shown Fig. 10. Coefficient of contribution of water……cement and cement volume occupied neary 100 percentage. Vaccumed procedure and air content are not significant.
