The Research on Self-Curing Admixtures with Mineral Admixtures-Mortar and Concrete

• Main Authors: Lin, Li-Chen, 林立晨
• Other Authors: Jau, Wen-Chen
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/brbkd4

碩士 === 國立交通大學 === 土木工程系所 === 102 === The purpose of curing is to prevent excessive evaporation of water from the concrete to achieve full hydration to improve quality of the concrete. With today’s environmental consciousness of human being, the progress of material technology and economic needs, the use of mineral admixtures (slag, fly ash) often replace part of cement, but pozzolanic reaction of mineral admixture is later than the hydration reaction of cement. This makes curing more important to guarantee the effectiveness of pozzolans. This study use different pozzolan replacements with the addition of SCA to test the fresh and hardened concrete’s properties and to achieve more energy-efficient concrete. The experiment was divided into two phases. The first used w/b 0.38 of mineral admixtures-cement mortar in different proportions with SCA, and after curing, the weight loss, compressive strength and shrinkage were tested to investigate the best combinations of replacement ratio and SCA. The second phase was to select the mix proportion which show better performances and then use them in producing concrete and test the workabilty, mechanical properties, volume stability and durability. Several curing regimes were employed for comparison. And multi-variable regression analysis was executed. The results show that the optimum replacement ratio for slag is 30-50% and fly ash is 0-10% of total cementitious material in mineral admixtures-cement mortar. The 3 day wet curing specimens with SCA (C5S5 and C7S3) are very close or even better than standard cured specimens without SCA in mechanical properties and durability. The 3 day strength with SCA has exceeded the design strength and reaches 280 kgf/cm2, and the specimens with SCA at 90 days, the resistance to chloride ion penetration (RCPT) and resistivity are better than the specimen without SCA. Proportions use 3 day wet curing with SCA can reach the performances of standard cured specimens without SCA.