The fly ash water requirement ratio is the ratio of the maximum water addition required to configure a certain amount of concrete to the minimum water addition required for the benchmark concrete. There are many factors that affect the ratio of fly ash to water, mainly including the following aspects:
Fineness: The fineness of fly ash is an important factor affecting its water demand ratio. The finer fly ash can better fill the voids between the cement particles, reduce the water consumption of the concrete, and thus improve the strength and durability of the concrete. Therefore, the finer the fineness, the lower the water requirement ratio of fly ash.
Loss on ignition: Loss on ignition refers to the amount of water, crystal water and volatile substances lost by fly ash during high-temperature combustion. The greater the loss on ignition of fly ash, the higher its water demand ratio. Because fly ash with a large loss on ignition contains more unburned carbon, the presence of these carbons will significantly increase the water demand ratio of fly ash.
Activity index: The activity index of fly ash refers to the ratio of the hydration reaction capacity of fly ash in concrete to the hydration reaction capacity of benchmark cement. The higher the activity index of fly ash, the lower its water demand ratio. Because fly ash with a high activity index can react better with cement hydration products to form more gels and crystals, thus reducing the water consumption of concrete.
Carbon content: The carbon content in fly ash is also one of the factors affecting its water demand ratio. Fly ash with high carbon content has a high water demand ratio because unburned carbon increases the water consumption of concrete, reducing the strength and durability of concrete.
Particle gradation: The particle gradation of fly ash is another important factor affecting its water demand ratio. Better particle gradation can make fly ash play a better role in concrete, and improve the working performance and durability of concrete. Generally speaking, finer fly ash particles have better particle gradation, which can reduce the water consumption of concrete and improve the strength and durability of concrete.
In summary, the factors affecting the water demand ratio of fly ash mainly include fineness, loss on ignition, activity index, carbon content and particle gradation. These factors interact with each other to affect the water requirement ratio of fly ash. In practical applications, it is necessary to choose the appropriate fly ash and its treatment process according to the specific situation to obtain better concrete performance. At the same time, it is also necessary to pay attention to solving the possible secondary pollution problems, such as the increase of suspended solids in wastewater and the treatment of remaining fly ash.