Currently, the commonly used water reducing agents in our concrete industry are naphthalene series, aliphatic series, and naphthalene series composite type. The main principle of water reducing agent is to use water reducing agent to modify the surface of concrete. Various admixtures have their advantages and disadvantages. With the improvement of water reducing agent technology and the decrease of manufacturing cost, its application scope is rapidly expanding. . Commonly used water reducing agents are anionic surfactants. When cement is mixed with water and set to harden, a flocculated structure will be formed due to the different charges of cement minerals during the hydration process, causing electrostatic attraction, or due to the collision and adsorption of certain edges and corners of cement particles, and van der Waals forces. . Compared with other materials, the performance of admixtures is relatively stable.
Water-reducing agent (Polycarboxylate Superplasticizer) is a high-performance water-reducing agent and a cement dispersant used in cement concrete applications. Widely used in highways, bridges, dams, tunnels, high-rise buildings and other projects. This product is green and environmentally friendly, non-flammable and non-explosive, and can be safely transported by train and car.
According to the different main chain structures, high-efficiency superplasticizer products can be divided into two categories: one is based on acrylic acid or methacrylic acid as the main chain and grafted with polyethers of different side chain lengths. The other type is polyethers with maleic anhydride as the main chain grafted with different side chain lengths. Based on this, a series of high-performance water reducing agent products with different characteristics have been derived.
Before the appearance of admixtures, there were lignin sulfonate admixtures, naphthalene sulfonate formaldehyde condensates, melamine formaldehyde condensates, acetone sulfonate formaldehyde condensates, and sulfamate formaldehyde. Condensates, etc. In the early 1980s, Japan took the lead in successfully developing a water-reducing agent. The new generation of high-efficiency water-reducing agents has overcome some of the shortcomings of traditional water-reducing agents. It has the characteristics of low dosage, good slump retention performance, low concrete shrinkage, strong adjustability in molecular structure, great potential for high performance, and no problem during the production process. The use of formaldehyde and other outstanding advantages.
Generally speaking, in mixing stations, before purchasing admixtures for commercial mixing stations, sampling inspections or comparative experiments of cement slurry and concrete slump and time loss must be carried out before storage. After passing or meeting the requirements, it is put into the storage tank; but with the current shortage of natural sand and gravel materials, the sand and gravel raw materials used in commercial mixing stations are getting worse and worse, which is also a strict test for admixtures, especially the loss of concrete. One piece. With the development of slump-preserving agents in the past two years, concrete has basically been controlled. However, in some commercial mixing stations with special materials or frequent changes, it is difficult to control the loss of concrete using ordinary slump-preventing agent pumping agents, so It is very important to choose a water-reducing agent or slump-preserving agent that has good adaptability, is not sensitive to raw materials, and has a wide working window.
Currently, the better slump-preserving products on the market, such as energy retaining agents, ultra-sustained release components, Le-su912 and other products, have superior performance, but the average price is more than 15,000, so use these products The product is recommended to be used together with domestic products to reduce overall costs.
Facing the increasingly poor raw materials in the future, we must strictly control the quality of raw materials and use superior water-reducing agents to ensure the quality of our concrete, thereby ensuring the quality of our projects. Abandon the traditional method of relying on retarders to extend the cement setting time, and use slump-preserving agents with superior performance and diversification to meet summer construction requirements without affecting the concrete setting time.
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