Initially, admixtures were used only to save cement. With the development of construction technology, adding admixtures has become a major measure to improve the performance of concrete.
Concrete admixtures refer to substances added to improve and regulate the performance of concrete. The application of concrete admixtures in engineering is receiving increasing attention. The addition of admixtures plays a certain role in improving the performance of concrete, but the selection,addition methods, and adaptability of admixtures will seriously affect their development.
Due to the availability of high efficiency water reducing agents, high fluidity concrete, self compacting concrete, and high-strength concrete have been applied; Due to the
presence of thickeners, the performance of underwater concrete has been improved. Due to the presence of retarders, the setting time of cement has been extended, making it possible to reduce slump loss and extend construction operation time. Due to the presence of antifreeze, the freezing point of the solution has been reduced, or the deformation of the ice crystal structure does not cause frost damage.
Defects in concrete itself:
The performance of concrete is determined by the ratio of cement, sand, gravel, and water. In order to improve a certain performance of concrete, the proportion of raw materials can be adjusted. But this often leads to losses on the other hand. For example, in order to increase the fluidity of concrete, the amount of water used can be increased, but this will reduce the strength of the concrete. In order to improve the early strength of concrete, the amount of cement can be increased, but in addition to increasing costs, it may also increase the shrinkage and creep of concrete.
The role of concrete admixtures:
The use of concrete admixtures can avoid the above-mentioned defects. In cases where there is little impact on other properties of concrete, the use of concrete admixtures can greatly improve a certain type of performance of concrete.
For example, as long as 0.2% to 0.3% calcium lignosulfonate water reducing agent is added to the concrete, the slump of the concrete can be increased by more than twice without increasing the amount of water; As long as 2% to 4% sodium sulfate calcium sugar (NC) composite agent is added to the concrete, it can improve the early strength of the concrete by 60% to 70% without increasing the amount of cement, and can also improve the late strength of the concrete. Adding anti crack compactor can significantly improve the crack resistance, impermeability, and durability of concrete, fully improving long-term strength.
Post time: May-29-2023