Effect of Admixture and Water-to-Binder Ratio on Hydration Heat of Mass Concrete

• Main Authors: Lin,Siao-Shan, 林筱珊
• Other Authors: Liu,Yu-Wen
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/bs6vea

碩士 === 國立嘉義大學 === 土木與水資源工程學系研究所 === 106 === In this study, three groups of water-to-binder ratio (0.3, 0.4, 0.45), five groups of slag and fly ash substitution rate (0%, 40%, 50%, 60%, 65%) and two chemical agents, strong plasticizers and retarders, a total of nine groups of ratios, to explore the effect of the admixture and water-to-binder ratio on the hydration heat in the initial stage of concrete condensation. In addition, two sets of ratios were used to carry out large-scale trials on the spot to simulate the actual construction of the mass concrete. The laboratory results showed that the initial setting time of each group of fresh concrete was between 5.5 and 8.8 hours, and the final setting time was between 7.9 and 11.2 hours. The initial setting time of retarded concrete was extended to 22 hours and the final setting time was extended to 71 hours. The compressive strength of each group of concrete is more than 27.5MPa in 28 days. In terms of concrete hydration heat, when the water-to-binder ratio is 0.45, the substitution of slag and fly ash is increased, and the maximum heart temperature and hydration heat temperature rise rate and temperature drop rate are lower; the heart surface temperature difference is between 0.76 and 1.18 °C, of which pure The cement concrete core surface has the largest temperature difference, followed by the slag replacement amount of 65%, and the slag and fly ash substitution amount of 40%, 60%, 65% and 50%. When the substitution amount of slag and fly ash is 65% (35% of slag and 30% of fly ash), the maximum temperature of retarded concrete is only 79% of pure concrete. The hydration heat temperature rise rate of the retarded concrete did not change significantly within 72 hours, and began to rise slowly after 72 hours, reaching the maximum temperature at 110 hours. On the other hand, the local test (2m × 2m × 2m) uses slag and fly ash concrete and retarded concrete. Block A is completely placed on the slag and fly ash concrete, and the bottom of the block B is first poured with a retarding concrete thickness of about 40 cm, and then the slag and fly ash concrete is poured. From the measurement results of hydration heat, the maximum heart temperature of block A occurred at 58.6 °C at 43 hours, and the maximum heart temperature difference was 18.3 °C; the maximum heart temperature at block B occurred at 50.7 °C for 48 hours, the maximum cardiac temperature difference It is 15.8 ° C. Both methods are in compliance with the specifications.