Effect of several cement grinding aids on properties of fly ash cement

The use of grinding aids can improve the grinding efficiency, improve the performance of cement, and achieve energy saving and emission reduction. At present, with the continuous improvement of the requirements for cement and building materials and the increase in cement production, more and more cement plants have begun to use grinding aids and achieved satisfactory results. The most commonly used grinding aids in domestic cement plants are roughly divided into two types: solid grinding aids and liquid grinding aids. Liquid grinding aids are favored for their superiority in terms of safety, stability and convenience. The main components of the grinding aid are: surfactants such as polyols, polyamines, and lignosulfonates. Fly ash refers to the substance that is collected from the flue and collected by the dust collector after the fine coal powder in the coal-fired power plant is burned in the boiler. Fly ash occupies a large amount of land and seriously pollutes the environment, which has become an obstacle to the sustainable development of the national economy. Therefore, the recycling of fly ash has become an important part of China's sustainable development strategy. The main chemical components of fly ash are silica and alumina, containing a small amount of calcium oxide, which has volcanic ash properties and is a kind of volcanic ash mixed material. The vitreous content is relatively high, and this part of the amorphous material has a large amount of chemical potential stored therein, and can be used as an active mixture of cement. Triethanolamine, triisopropanolamine and laboratory-made grinding aids all have a certain reinforcing effect on fly ash cement. But the enhancements are not the same. The early enhancement effect of triisopropanolamine was the most obvious. The later enhancement effect of triethanolamine is better. The laboratory self-made grinding aid can combine the advantages of both, and can achieve good reinforcement effect in the early and late stages; triisopropanolamine can promote the hydration reaction of tricalcium silicate and dicalcium silicate in the early stage to form hydration Calcium silicate gel achieves early strength; Triethanolamine can promote the reaction of gypsum in cement with hydrated calcium aluminate to form insoluble hydrated calcium sulphoaluminate needle crystals, also known as ettringite crystals. It can promote the disintegration of fly ash glass body in the later stage, so that the active silica and alumina in fly ash participate in the reaction to achieve the later enhancement effect; the self-made grinding aid can promote the tricalcium silicate and silicate in the early stage. Calcium hydration can then promote the participation of fly ash particles in the reaction, achieving better results in both early and late reinforcement;

Grinding aid can improve the grinding efficiency. The grinding aid with reinforcing effect can reduce the amount of clinker under the premise of ensuring the strength of cement, and accordingly increase the blending amount of the mixture, thereby effectively reducing the energy consumption of cement production and reducing carbon emissions. . The enhanced grinding aids can be broadly classified into early strength type, late strength type, and early strength and rear strength type. The early strength type grinding aid is mainly used to improve the early strength of cement (3d), and is suitable for cements with less early strength and more strength in the later stage. The market demand for such grinding aids is relatively large, and related research is also relatively large, mainly based on triethanolamine series. The post-strong grinding aid is mainly used to improve the late cement strength (28d), and is suitable for cements with more early strength and less strength in the later stage.