| dc.description.abstract | This study is about the effect of temperature on the use of ready-mixed ultra-early-strength concrete for rigid pavement, and a strategy to stabilize the strength improvement in a low-temperature environment is drawn up. The experiment will formulate a process based on on-site work. The preliminary tests will use mortar to explore the relationship between the amount of cement and the water-cement ratio and temperature. The main experiment will use concrete to test the effectiveness of thermal curing strategies in providing strength development in low-temperature environments, and to find the correlation between maturity and early strength, and verify the performance of thermal curing by field work. According to the experimental results, the performance of on-site work was verified. The performance of on-site work was tested by rebound hammer and maturity. The target strength for on-site acceptance was set at 210 kgf/cm2.
In preliminary tests, it is found that the compressive strength decreases as the water-cement ratio increases, and the compressive strength increases as the curing temperature rises, but the curing temperature has less influence on the low water-cement ratio.Conversely, when the water-cement ratio is higher, the increase in curing temperature will increase the strength more significantly. Compressive strength and maturity have a positive relationship with age, but cement content and water-cement ratio will affect the growth rate of strength. It can be inferred that the composition of cement paste is different, which reduces the correlation between different groups.
In the main test, the mixing design is tested with a cement content of 500kg/m3 and a water-cement ratio of 0.31. It can be found that there is no significant difference in the slump and slump fluidity of concrete between 26°C and 32°C. In the compressive strength, it can be found that temperature is the main factor affecting the early strength. When the ambient temperature is 32℃, the compressive strength of 4 hours can have the target strength of 210 kgf/cm2; When the ambient temperature is 26℃, the compressive strength for 6 hours of age has the target strength of 210 kgf/cm2. When the ambient temperature is less than 26°C, thermal curing is an effective strategy to provide early strength development. Hot water curing can provide a stable heat source while preventing heat loss. And in the case of using thermal curing, the maturity can evaluate the compressive strength well, and verify the correctness of the compressive strength of the rebound hammer test. | en_US |