Post Date:30,Dec,2024
Effect of high-efficiency water-reducing agent on fresh concrete:
①Workability: Adding high-efficiency water-reducing agent can increase the fluidity of concrete; the slump of concrete increases with the increase of high-efficiency water-reducing agent dosage. When the dosage reaches 0.75%, the slump increase reaches the maximum. When the dosage increases further, the slump increases, but the increase tends to be gentle. The slump of concrete added with high-efficiency water-reducing agent loses quickly, generally losing most of the slump within 1 hour, and it is greater when the temperature is high. Generally, the suitable dosage of high-efficiency water-reducing agent is 0.5%~0.75%. When the amount of cement is large, the suitable dosage is 0.9%~1.2%. From an economic point of view, the commonly used dosage is about 0.5%.
②Setting time: High-efficiency water-reducing agent has little effect on the setting time of concrete. The type and dosage of high-efficiency water-reducing agent are different, and the degree of influence is different; the effect of high-efficiency water-reducing agent on its setting is different for different cement types. As shown in Table 1, the setting time of cement added with high-efficiency water-reducing agent.
③Bleeding: Adding high-efficiency water-reducing agent to concrete can reduce its bleeding rate. Using water-reducing agent with causative properties (such as AF and Jian-1) can reduce the bleeding rate even more. For the concrete mixed with standard cement, the bleeding rate of concrete mixed with FDN, UNF, CRS and reduced water is about 50% of the standard concrete.
④Air content: Increase the air content of concrete. The air content of CRS, FDN, and UNF increases by about 1%, the addition of AF and Jian-1 is 0.75%, and the air content of concrete is about 5%. Also note that the air content of flowing concrete will decrease when adding high-efficiency water-reducing agent.
⑤Heat of hydration: The heat of hydration and peak temperature of cement mixed with high-efficiency water-reducing agent are close to those of cement without admixtures, but the peak time of heat is delayed by several hours. High-efficiency water-reducing agent reduces the heat of hydration of slag cement. See Table 2 for the heat of hydration of cement mixed with high-efficiency water-reducing agent.
Post time: Dec-30-2024
