Effect of Superplasticizer on Dry Shrinkage of Hardened Concrete

Any concrete structure is mainly used to bear loads or resist various forces. Therefore, strength is the most important mechanical property of concrete. Under certain conditions, the performance of concrete required by engineering is always closely related to the strength of concrete. The water-cement ratio determines the strength of concrete.

Effect of Superplasticizer on Concrete Strength

When water reducing agent is added into concrete, the water-cement ratio of concrete can be reduced and the compressive strength of concrete can be improved. Generally speaking, the greater the water reduction rate of the superplasticizer, the higher the compressive strength of concrete.

Superplasticizer dosage in concrete is the main reason to improve the compressive strength of concrete. In addition to reducing the water-cement ratio, the dispersion of the water reducer can also improve the effective utilization rate of cement. Commonly used water reducing agents are sodium gluconate, lignosulfonate acid sodium salt, naphthalene sulfonate formaldehyde, and polycarboxylate superplasticizer.

Dry shrinkage is a kind of bulk deformation of hardened concrete under non-load.Due to the different properties and use conditions of water reducing agents, different water reducing agents are used under different conditions, which have different effects on the dry shrinkage of concrete. The influence of water-reducing agent on the dry shrinkage of concrete basically has the following three conditions:

1. With the same water consumption and strength of concrete, a water reducer is added to improve the workability and fluidity of concrete. At this time, the dry shrinkage value of concrete with ordinary water-reducing agents increases somewhat, but the increased range is within the normal range; In the case of high-efficiency water-cement ratio, it has little effect on the dry shrinkage of concrete.
2. Under the condition of maintaining the slump of concrete mixture and the same amount of cement, add water reducing agent in concrete to reduce water consumption and increase strength. At this time, the dry shrinkage value of concrete mixed with water-reducing agents may increase slightly.

3. Under the condition that the slump of a concrete mixture is the same as the strength of hardened concrete, the water reducing agent is added to reduce the water consumption per unit of concrete and the amount of cement. At this point, the dry shrinkage value of concrete with a water-reducing agent will be less than that of concrete without a water-reducing agent. There are some related articles about concrete admixtures on Kingsun’s website, welcome to visit.

Influence of Water Reducer on the Durability of Hardened Concrete

The ability of concrete to resist the action of environmental media and maintain good performance for a long time is called the durability of concrete. Concrete in various environmental media for a long time will be damaged or even destroyed to different degrees.

In the design of the concrete structure, we should not only pay attention to the influence of strength on the structure but ignore the effect of the environment on the structure. Otherwise, when the concrete structure does not reach the predetermined service life, there will be corrosion of reinforcement, deterioration of concrete peeling, and other damage phenomena, which need a lot of investment to repair, reinforce or even dismantle and rebuild. To improve the durability of concrete, prolong the life of the structure and reduce the repair works is of great significance to improve the economic benefits.

When water reducing agent is added to the concrete mixture, the water consumption for mixing can be greatly reduced under the condition of the same workability, thus reducing the evaporation of the remaining hydration water and the pores left by bleeding water, improving the compactness of concrete and reducing the porosity. Water reducing agents can also refine the hole diameter of concrete, improve the whole structure of concrete. Therefore, adding water reducing agent in concrete can significantly improve its impermeability and frost resistance.

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