The current shortage of sand and gravel aggregates and the irregular production of commercial concrete make it easier than ever to introduce mud into concrete. Because the mineral interlayer structure presented by the clay in the mud powder adsorbs the early-strength water-reducing agent, resulting in a reduction in the working performance of the concrete, thereby adversely affecting the strength and durability of the concrete structure, it is necessary to investigate the sources of mud in the concrete. Analysis, and then study its impact on the performance of early-strength water-reducing agents
Because in the construction of large-scale projects such as high-speed railways, high-performance concrete is now commonly used, and high-performance concrete has a certain impact on the performance of water-reducing agents. required. According to that requirement, only early-strength water-reducing admixtures can achieve it. Therefore, only early-strength water-reducing agents can be used.
The early-strength water-reducing agent can reduce the unit water consumption without affecting the workability of concrete; after the cement is mixed with water, a hydration reaction occurs, and some flocculation-like structures appear, which wrap A lot of mixing water, thus reducing the workability of fresh concrete (also known as workability, which mainly refers to the ability of fresh concrete to remain uniform and dense without delamination during construction, that is, during mixing, transportation, pouring, etc. phenomenon performance). In order to maintain the required workability during construction, the amount of mixing water must be increased accordingly. Because the increase in water amount will form excessive pores in the cement stone structure, which will seriously affect the physical and mechanical properties of hardened concrete, if these wrapped When the moisture is released, the water consumption of concrete can be greatly reduced. In the process of preparing concrete, adding an appropriate amount of water reducing agent can play such a role well.
Early-strength water-reducing agent is a high-performance water-reducing agent. The water-reducing rate can be around 25%, while other types of water-reducing agents can reach 20%. You can search for its description. Be careful not to add too much when producing concrete! If it is too much, the concrete will bleed, segregate, catch the bottom, and have many bubbles. The requirements for sand and gravel are strict, especially sand. The mud content cannot be high, otherwise there will be no effect if the amount is large.
After water-reducing agent is mixed into concrete, the hydrophobic groups of the water-reducing agent are directionally adsorbed on the surface of the cement particles, while the hydrophilic groups are directed toward the aqueous solution, forming a single-molecule or multi-layer adsorption film. Due to the directional adsorption of the surfactant, the surface of the cement particles has charges of the same sign. Therefore, under the action of same-sex repulsion, not only can the cement-water system be in a relatively stable suspended state, but also the cement can be added with water. The flocculated structure formed in the initial stage is dispersed and disintegrated, thereby releasing the water in the flocculated structure to achieve the purpose of water reduction. After the water-reducing agent is added, not only can the workability of fresh concrete be improved, but also because the water-cement ratio in the concrete has dropped significantly, the internal pore volume of the cement stone has been significantly reduced, the cement stone has become denser, and the resistance of the concrete has increased. The compressive strength is significantly improved. The addition of early-strength superplasticizer also affects the hydration rate and setting time of cement. These properties are very important in practical applications. </p
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