1. The preparation ratio is wrong.
2. Issues with cement and admixtures.
Problems with polycarboxylate water-reducing agents
1. Insufficient slump retention in high-temperature environments; 2. Strong temperature sensitivity, the same type of polycarboxylate water-reducing agent in different environments During seasonal construction, the slump retention of concrete varies greatly; 3. There are few functional products and it is difficult to meet the requirements for ultra-high and ultra-long distance concrete pumping, negative temperature construction, preparation of ultra-early strength concrete, and high durability of concrete; 4 .High viscosity. In the preparation of concrete with high admixture and low water-to-cement ratio, the viscosity of concrete is high, which is not conducive to construction; 5. It is highly sensitive to the mud content of sand and gravel aggregates. 6. It has poor adaptability to machine-made sand and is sensitive to the dosage, which affects construction.
From your general description, the general situation is that there is a problem with the adaptability of the admixture and certain cementitious materials (mainly cement). But don’t be swayed by the opinions of some salesmen. There is nothing too mysterious about concrete and admixtures.
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. 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 replaced 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 admixture. 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.
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