Concrete pumping agent came into being with the birth of ready-mixed concrete, laying a good technical foundation for the development of ready-mixed concrete and providing good quality assurance. However, in actual projects, the variability of raw materials often causes problems such as poor adaptability of pumping agents. The technical staff of the concrete mixing station should strengthen their scientific knowledge in cement chemistry, admixture application, etc., and accumulate richer experience to ensure the safe and efficient application of pumping agents in ready-mixed concrete. To prevent concrete from segregating or bleeding, it is not enough to adjust the concrete proportion alone. You must rely on concrete admixtures, especially concrete pumping agents. Concrete pumping agents are suitable for low-grade concrete and short-distance transportation. , On-site pumping concrete pumping construction projects. After being incorporated, the concrete has little slump loss and good workability, and can greatly improve the physical properties and durability of concrete. The main technical parameters of concrete pumping agent are:
1. Dosage: 1-2%;
2. Water reduction rate: ≥12%;
3. Increased value of slump: compared with the base concrete with the same mix, it can increase by 100mm-120 mm;
4. Retention value of slump: compared with the base concrete with the same mix, 60min≥120mm;
5. Compressive strength ratio: With the same mix ratio and slump, compared with the benchmark concrete, the strength can be increased by about 20% in 7 days and by about 10% in 28 days;
6. Condensation Time: Compared with the benchmark concrete, it can retard setting for more than 90 minutes, and the setting time can be adjusted according to construction requirements
Composition and classification of concrete pumping agents
In order to meet the performance requirements, concrete pumping agents mainly It is composed of water reducing agent, water retaining agent, air entraining agent and retardant.
(1) Water-reducing agent, adjust workability and strength to meet project needs;
(2) Air-entraining agent, appropriate air content can reduce the impact of concrete pumping The pumping resistance can prevent concrete from bleeding and segregation, and can also improve the ability of concrete to resist freeze-thaw cycle damage;
(3) Retarder, commercial concrete needs to be delayed due to the need for long-distance transportation. Setting time, reducing slump loss, especially for large-volume concrete and high-temperature construction projects in summer;
(4) Water-retaining agent, its function is to increase the viscosity of the concrete mixture, so that the concrete can be maintained at low viscosity There will be no bleeding or segregation under the conditions of large slump and the amount of condensing material.
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