1、 Influence of fly ash quality on frost resistance of concrete
If inferior fly ash is mixed into Hangzhou concrete, the freeze-thaw durability of concrete will be greatly reduced. However, when mixed with high-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 ignition loss, the frost resistance of fly ash concrete decreases. Under the condition of equal replacement, when the output of fly ash is 15%, the frost resistance of concrete can be improved, but when the content of fly ash exceeds a certain range, it will affect the frost resistance of concrete. Through long-term research and engineering practice, 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、 Benefits of concrete and fly ash
Because fly ash has chemical activity effect, particle shape effect and fine aggregate effect, adding fly ash can reduce the water demand of concrete, improve the fluidity, water retention, pumpability and surface performance of concrete. It can reduce bleeding, segregation and slump loss, prolong concrete setting time, reduce concrete hydration heat, improve concrete chemical corrosion resistance and impermeability, and inhibit alkali aggregate reaction.
3、 Influence of fly ash on some main indexes of concrete
1. It is convenient to mix concrete with fly ash, the density of concrete mixed with fly ash is reduced, the concrete with the same quality is increased, and the workability of concrete mixture is improved.
2. For the influence of concrete water outflow, the concrete added with fly ash improves the water absorption performance, and the use of fly ash is conducive to prevent bleeding of fresh concrete.
3. Improve the later strength of concrete. The early strength of fly ash concrete is low, and the later strength is obviously improved. Therefore, adding fly ash concrete can improve the later strength.
4. Reduce the hydration heat of concrete. Fly ash concrete can effectively reduce the hydration heat of concrete.
