Why do we need to add "water reducing agent" in cement? The effect is very big

In order to improve the performance of concrete, such as rheology, durability, setting time, we usually add a variety of admixtures to it, the most commonly used concrete admixtures are: water reducing agent, air-entraining agent, pumping agent, retarding agent, early strength agent, quick-setting agent, etc., different admixtures to achieve different functions, the specific addition of which, according to the construction process, construction environment, temperature, humidity and a variety of factors to be integrated Consider.
　　Today, I focus on explaining the [water reducing agent], from a number of angles, focusing on the role of water reducing agent.
　　First, what is water reducing agent
　　Water reducing agent, as the name suggests, is to add it can reduce the amount of water admixture; and then in layman's terms, is the equivalent of adding water reducing agent after adding water. If defined from a scientific and rigorous point of view, water reducing agent is a kind of concrete admixture that can reduce the amount of mixing water under the condition of maintaining the concrete slump basically unchanged.
　　High efficiency water reducing agent
　　Second, the classification of water reducing agent
　　Most water reducing agents belong to anionic surfactants, which are classified as follows.
　　(1) according to the appearance of the form, can be divided into: ① water agent; ② powder.
　　(2) According to the water reducing and enhancing ability, it can be divided into
　　(1) Ordinary water reducing agents, also known as plasticizers, mainly including lignin sulfonates.
　　② high efficiency water reducing agent, also known as superplasticizer, mainly including naphthalene, mimosa, aminosulfonate, aliphatic system, etc.
　　③ high-performance water reducing agent, mainly including polycarboxylic acid system water reducing agent.
　　Polycarboxylic acid system water reducing agent
　　Third, the role of water reducing agent
　　(1) enhance the rheology of concrete
　　Can improve the rheology of concrete without changing the performance of concrete, especially in the construction conditions of concrete self-flow or pumping the most applications, can greatly improve the construction speed, reduce construction energy consumption, and thus achieve the effect of cost savings.
　　(2) Improving the strength of concrete
　　Adding water reducing agent can reduce the amount of water without changing the premise of concrete collapse, thus greatly improving the strength of concrete, early strength can be increased by more than 60%, later strength can be increased by more than 20%.
　　(3) Reduce the amount of cement
　　Adding water reducing agent can also reduce the amount of cement per unit volume of concrete without changing the premise of concrete strength, adding 0.2% to 0.5% of the cement mass of concrete water reducing agent, can save more than 15-30% of the amount of cement.
　　(4) Improve the life of concrete
　　Water reducing agent has a dispersing effect, which is conducive to the growth of cement stone microstructure, so that there are fewer large spaces, generating more small holes, but also grow crystallization, improve the denseness of concrete. Thus, to improve the durability of concrete, chemical erosion resistance, and significantly improve the service life of concrete.