Post Date:8,Jan,2024
The characteristics of water-reducing agent directly affect the shrinkage performance of concrete. Under the same concrete slump, the shrinkage rate of concrete with water-reducing agent is about 35% higher than that of concrete without water-reducing agent. Therefore, concrete cracks are more likely to occur. Here’s why:
1. The water reduction effect is highly dependent on concrete raw materials and mix proportions.
The water reduction rate of concrete is a very strict definition, but it often causes misunderstandings. On many different occasions, people always use the water reduction rate to express the water reducing effect of the product.
At a lower dosage, taking polycarboxylate water-reducing agent as an example, it has been proven that its water-reducing rate is much greater than that of other types of water-reducing agents, and it has a better water-reducing effect. However, it must be noted that compared with other water-reducing agents, the water-reducing effect of polycarboxylate water-reducing agents is more affected by test conditions.
Among the factors that influence the plasticizing effect of polycarboxylate superplasticizer, the sand rate and particle gradation of aggregates in concrete also have a greater impact. Compared with other high-efficiency water-reducing agents such as naphthalene series, the plasticizing effect of polycarboxylate water-reducing agents is greatly affected by the mud content of fine aggregates.
2. The water-reducing effect is highly dependent on the dosage of water-reducing agent.
In general, as the dosage of water-reducing agent increases, the water-reducing rate of concrete also increases, especially for polycarboxylic acid-based water-reducing agents, the dosage directly affects the water-reducing effect.
However, there are exceptions in practical applications. That is, after a certain dosage is reached, the water-reducing effect "decreases" as the dosage increases. This is because at this time the concrete mixture becomes hardened, the concrete suffers from serious bleeding, and the slump Law can no longer express its liquidity.
3. The performance of the prepared concrete mixture is very sensitive to water consumption.
The performance indicators of concrete mixtures are usually reflected in aspects such as water retention, cohesion, and fluidity. Concrete prepared using polycarboxylic acid-based superplasticizers does not always fully meet the usage requirements. The performance of the prepared concrete mixture is very sensitive to water consumption, and some problems often occur.
Post time: Jan-08-2024