How to solve the problem of late-stage bleeding when early-strength water-reducing admixture is mixed into concrete? According to professionals, the general situation is that there is a problem with the adaptability of the admixture and certain cementitious materials (mainly cement). As a chemical industry practitioner, how should we deal with such problems?
To solve the problem, start from several aspects:
1. Adjust the mix ratio, adapt to local conditions, and combine the quality of raw materials in your area, especially sea sand, etc., to have a better effect on bleeding. It also has an impact. Sometimes fly ash is too coarse and can cause bleeding.
2. Of course, the most important thing is the bleeding caused by cement. However, in many mixing stations, cement is rarely replaced even if the admixture is changed due to bleeding. Therefore, you should contact the cement factory (if you are not from the mixing station, you can ask the chief engineer of the mixing station to contact the cement factory) to check the chemical composition of the cement you are using, and then adjust the admixtures in a targeted manner. I have encountered the phenomenon you mentioned caused by cement.
3. Adjust the admixtures. The synthesis process and raw materials of the admixture mother liquor will have a great impact on the water reduction rate, etc., so it is possible that a certain mother liquor is suitable for this cement, but it can also be adjusted, Add small materials to reduce the amount of bleeding to meet construction requirements.
Characteristics of early-strength water-reducing agent
1. Water reduction is high, so a high water reduction rate can be achieved at low dosage, up to about 45%. water reduction rate.
2. Improve the working performance of concrete, making it have good workability and better slump retention performance, which is more suitable for concrete pumping.
3. Improve the early strength of concrete and enhance strength development, which plays a role in improving the later strength of concrete.
4. Good plasticizing and dispersing cement particles, suitable for concrete with lower water-cement ratio. Therefore, it is suitable to incorporate a large amount of mineral active admixtures to reduce production costs, improve the durability and self-compacting properties of concrete, reduce the hydration heat of large-volume concrete, and reduce shrinkage and creep.
5. There is no obvious bleeding and segregation phenomenon when producing concrete. It produces fewer bubbles, higher density and small color difference. It is suitable for the production of fair-faced concrete.
6. The alkali content is extremely low and does not contain chloride ions and formaldehyde. It has no pollution to the environment and no corrosion to steel bars.
Precautions for using early-strength water-reducing admixture when the mud content is high
1. Since early-strength water-reducing admixture has a higher water reduction effect on concrete, the slump of concrete has an impact on the concrete slump. The amount of water added is highly sensitive, so sufficient trial mixing tests should be carried out before use to find the optimal dosage and water consumption for different batches of raw materials and different grades of concrete.
2. When the early-strength water-reducing agent is used alternately with other admixtures, attention should be paid to cleaning the relevant equipment to avoid mixing the early-strength water-reducing agent with other admixtures to reduce the risk of early-strength water-reducing agents. performance.
3. Early-strength superplasticizers are more sensitive to the mud content of aggregates. Excessive mud content will reduce the performance of early-strength superplasticizers. Therefore, the quality of aggregates should be strictly controlled during use. </p
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