To ensure the solidity of the reinforced concrete structures being erected and their maximum strength and durability, concreting must be carried out continuously. Without the use of additives for concrete, this is possible only for small volumes and for the construction of simple structures.
Previously, when carrying out complex and voluminous work in industrial volumes, they could not avoid interruptions in the concreting of structures, and therefore on construction sites they had to resort to the device of “working seams”.
The main technological solution is the introduction of retarders for the setting and hardening of concrete into the concrete mixture.
This solution provides delivery of concrete mix from the concrete plant without loss of mix quality, workability and smooth strength gain of massive concrete structures without the device of “cold” joints in the areas of technological breaks in concreting.
How concrete hardening inhibitor works
The mechanism of action of additives-retarders of the setting and hardening of concrete is to slow down the processes of cement hydration and hardening processes. This does not affect the final strength of the concrete.
There are two main types of concrete retarders:
- Create a difficult-to-permeate film on the surface of cement grains, slowing down the hardening of concrete.
Plus: increased adhesion and moisture protection.
- Based on the deceleration of the growth of the crystal lattice in the concrete mixture.
Pros: When the natural growth of the concrete crystal lattice slows down, it turns out to be more complex and uniform, which leads to a significant increase in the final strength of the concrete structure. The preservation of the finished solution increases up to five hours, which is a definite plus for concrete and plastering works.
Features of hardening retarders
For additives that slow down the hardening of concrete, an important indicator is a decrease in the strength of concrete by 30% or more at the age of up to 7 days. At the same time, at the design age, after 28 days, the concrete strength increases, and the permeability decreases.
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Preparation of hardening retarder additives consists in their dissolution in the batch water to the required concentration. For more articles like this one, click here.