1、 Influence of fly ash quality on frost resistance of concrete
If the fly ash with poor quality is added into the concrete, the freeze-thaw durability of concrete will be greatly reduced. However, when mixed with better quality fly ash, the freeze-thaw resistance can be effectively improved. At the same time, the water cement ratio can be reduced to improve the freeze-thaw resistance. With the increase of Fly Ash Fineness and combustion loss, the frost resistance of fly ash concrete decreases. Under the condition of equal replacement, when the yield of fly ash is 15%, the frost resistance of concrete can be improved, but when the content of fly ash exceeds a certain range, the frost resistance of concrete will be affected. Through long-term research and engineering practice, in order to prevent carbonation of fly ash concrete, the primary factor is to ensure the compactness of fly ash concrete. Only when the compactness is ensured can the carbonation resistance be improved.
2、 The benefits of concrete mixed with fly ash
Because of its chemical activity, particle shape and fine aggregate, the addition of fly ash can reduce the water demand of concrete and improve the fluidity, water retention, pumpability and surface performance of concrete mixture. It can reduce the leakage, segregation and slump loss, prolong the setting time of concrete, reduce the hydration heat of concrete, improve the chemical resistance and impermeability of concrete, and inhibit the alkali aggregate reaction.
3、 Influence of fly ash on some main indexes of concrete
1. Affect the usability of fly ash concrete, reduce the density of fly ash concrete, expand the concrete of the same quality, and improve the workability of concrete mixture.
2. Due to the influence of concrete seepage, the water absorption performance of concrete mixed with fly ash is improved, and the use of fly ash is beneficial to prevent the water seepage of fresh concrete.
3. Improve the later strength of concrete. The early strength of fly ash concrete is lower, and the later strength is obviously improved. Therefore, the concrete added with fly ash can improve the later strength.
4. Reduce the hydration heat of concrete. The concrete with fly ash can effectively reduce the hydration heat of concrete.
