How water cement ratio and workability is related to compaction factor?

Answer 1

If you are talking about shrinkage, then quite a bit. To make concrete, cement and water react together. There is a specific amount of water required to hydrate the concrete. Any water extra must leave the concrete and while it makes the concrete more workable, hurts the concrete is several ways. The volume of the concrete will change by whatever excess water you have added. To get workability, it's always best to use a water reducing admixture.

Answer 2

To answer this question, we must first clarify what is water-cement ratio and what is slump.

The water-cement ratio refers to the ratio between the weight of water in concrete and the weight of cement.

For the calculation of water-cement ratio, there is an empirical formula: water-cement ratio=0.46÷(concrete strength÷cement strength+0.2392).

According to this formula, when the cement used in the preparation of concrete is determined, the greater the water-cement ratio, the lower the strength of the concrete, and the smaller the water-cement ratio, the greater the strength of the concrete. In other words, the concrete strength is related to the water-cement ratio.

Slump is one of the fluidity indicators of concrete, and fluidity belongs to the workability of concrete, which means that the concrete mixture can flow under the action of its own weight or mechanical vibration, and fill it evenly and densely. The performance of the template.

The slump can be measured by the slump bucket. Fill the slump bucket with concrete, and then pull up the bucket to measure the slump.

From the above description, the water-cement ratio is related to the strength of concrete, and the slump is related to the fluidity of the concrete. There is no direct relationship between the two, but if we dig deeper, we will find that the water-cement ratio and slump are It is not unrelated to each other. The key is that the water-cement ratio and slump are closely related to the same component, that is, WATER.

The effect of the amount of water on the water-cement ratio and the strength of concrete has just been mentioned. The following describes the effect of the amount of water on the slump.

The main factors affecting the workability of concrete mixtures are water consumption per unit volume, sand ratio, properties of the constituent materials, time, temperature, and so on. The most important factor affecting the workability of the concrete mixture is the water consumption per unit volume. Slump is one of the indexes reflecting the fluidity of concrete mixture, and fluidity is part of the workability of concrete mixture, so the influence of water consumption per unit volume on slump is self-evident. The greater the water consumption per unit volume, the better the fluidity and the greater the natural slump.

But the relationship between the two ends here. It would be unkind if you have to pull the water-cement ratio and slump together by force.

We can take pumping concrete as an example. Pumped concrete has relatively high requirements for the fluidity of concrete, so its slump is relatively large, and the water consumption per unit volume is relatively large. However, the water-cement ratio has not increased accordingly, especially for high-strength concrete with a strength higher than C50, which has a lower water-cement ratio. This is because in order to ensure the strength of concrete, the amount of cement must be increased while increasing the water consumption, so as to ensure that the water-cement ratio meets the strength requirements of concrete.

In the actual construction process, in order to facilitate vibrating and reduce the difficulty of pouring, it is absolutely prohibited to add water to the concrete without authorization. Because this may improve the fluidity of the concrete mixture, but it will have a fatal impact on the strength of the concrete. Therefore, the slump and water-cement ratio of the concrete mixture are determined at the beginning of the trial mix, which means that the mix ratio of the concrete must not be changed without authorization. During the construction process, we have always emphasized "to ensure the water-cement ratio and control the slumping degree", which needs to be kept in mind at all times. This is the key to the success or failure of concrete pouring.