High performance polycarboxylate water reducer with high dispersibility, good retention performance, low concrete shrinkage and strong molecular structure.In addition, the polycarboxylate water reducing agent does not use formaldehyde and other outstanding advantages in the production process, which meets the needs of modern society to promote green environmental protection. Since entering the 21st century, it has gradually replaced other types of water reducing agents, and has been widely used in concrete engineering.
In particular, the technical limitations of traditional high-efficiency water reducers such as naphthalene and aliphatic are difficult to meet the requirements of engineering concrete such as bridges, dams, tunnels, and high-rise buildings.
Therefore, polycarboxylate water reducing agent has gradually become the preferred water reducing agent for formulating high performance concrete.
But the influence of the composition of concrete on the water reducing agent.
1、Influence of fine aggregate
In the preparation of concrete, there are two main types of fine aggregates, namely mechanical sand and natural sand.Natural sand also covers river sand, earth sand and desalinated sea sand.Fine aggregates have an impact on concrete slump and, in addition, affect concrete strength under special conditions.Other properties in the fine aggregate also have an effect on the adaptability of the concrete. For example, the specific fineness modulus of the sand, that is, when the sand fineness modulus is relatively small, the concrete will be in a dry state, thereby reducing the concrete fluidity.
The cement itself contains relatively large amounts of water, so the performance relationship between the cement component and the polycarboxylate superplasticizer is very close.Compared with ordinary water reducing agents, polycarboxylate water reducing agents can quickly combine various components in concrete.That is, the connection with water molecules is very close, so that a large amount of water molecules are absorbed.However, the water reducing effect of the polycarboxylate superplasticizer is also affected by temperature factors.In the concrete mixing process, it is necessary to control the appropriate temperature to prevent the temperature from restricting the fluidity in the concrete raw materials, thereby failing to achieve the effect of water reduction, and also affecting the condensation effect and speed in the concrete material.
3、The effect of coarse aggregate
Under the condition that the mud content is higher than 3%, the performance of the water reducing agent can be significantly reduced. At this time, good fluidity cannot be obtained by appropriately increasing the dosage.In the process of preparing concrete materials in the future, it is necessary to take good measures to adjust the grade of cement materials to ensure the quality of concrete materials.
4、The influence of other substances
The effects of other substances are also important. For example, blast furnace slag and fly ash are more common, which makes the adaptability of polycarboxylate superplasticizers affected. The amount of fly ash and blast furnace slag needs to be controlled within a certain range, namely 30% and 20% respectively, which can well guarantee the fluidity of concrete materials.