Desulfurized gypsum is a by-product of the flue gas desulfurization process at coal-fired power plants or other plants that use sulfur-containing fuels. Due to its high fire resistance, heat resistance and moisture resistance, it has been widely used in the construction industry as a building material. However, one of the major challenges in using desulfurized gypsum is its high heat of hydration, which can lead to problems such as cracking and deformation during the setting and hardening process. Therefore, there is a need to find effective methods to reduce the heat of hydration of desulfurized gypsum while maintaining its mechanical properties and properties.
Cellulose ethers are commonly used additives in the construction industry to improve the workability, strength and durability of cement-based materials. It is a non-toxic, biodegradable, renewable polymer derived from cellulose, the most abundant organic compound in the world. Cellulose ether can form a stable gel-like structure in water, which can improve the water retention, sag resistance and consistency of cement-based materials. In addition, cellulose ethers can also affect the hydration and setting processes of gypsum-based materials, further affecting their mechanical properties and properties.
Effect of cellulose ether on gypsum hydration and solidification process
Gypsum is a calcium sulfate dihydrate compound that reacts with water to form dense and hard calcium sulfate hemihydrate blocks. The hydration and solidification process of gypsum is complex and involves several stages, including nucleation, growth, crystallization, and solidification. The initial reaction of gypsum and water generates a large amount of heat, called the heat of hydration. This heat can cause thermal stresses and shrinkage in the gypsum-based material, which can lead to cracks and other defects.
Cellulose ethers can affect the hydration and setting processes of gypsum through several mechanisms. First, cellulose ethers can improve the workability and consistency of gypsum-based materials by forming stable and uniform dispersions in water. This reduces water requirements and increases the flowability of the material, thereby facilitating the hydration and setting process. Secondly, cellulose ethers can capture and retain moisture inside the material by forming a gel-like network, thereby enhancing the material’s water retention capacity. This prolongs hydration time and reduces the potential for thermal stress and shrinkage. Third, cellulose ethers can delay the early stages of the hydration process by adsorbing on the surface of gypsum crystals and inhibiting their growth and crystallization. This reduces the initial rate of heat of hydration and delays setting time. Fourth, cellulose ethers can enhance the mechanical properties and performance of gypsum-based materials by increasing their strength, durability and resistance to deformation.
Factors affecting the heat of hydration of desulfurized gypsum
The heat of hydration of desulfurized gypsum is affected by a variety of factors, including chemical composition, particle size, moisture content, temperature and additives used in the material. The chemical composition of desulfurized gypsum may vary depending on the type of fuel and desulfurization process used. Generally speaking, compared with natural gypsum, desulfurized gypsum has higher contents of impurities such as calcium sulfate hemihydrate, calcium carbonate, and silica. This affects the degree of hydration and the amount of heat generated during the reaction. The particle size and specific surface area of desulfurized gypsum will also affect the rate and intensity of the heat of hydration. Smaller particles and larger specific surface area can increase the contact area and facilitate the reaction, resulting in higher heat of hydration. The water content and temperature of the material can also affect the heat of hydration by controlling the rate and extent of the reaction. Higher water content and lower temperature can reduce the rate and intensity of the heat of hydration, while lower water content and higher temperature can increase the rate and intensity of the heat of hydration. Additives such as cellulose ethers can affect the heat of hydration by interacting with gypsum crystals and changing their properties and behavior.
Potential benefits of using cellulose ethers to reduce the heat of hydration of desulfurized gypsum
Our use of cellulose ethers as additives to reduce the heat of hydration of desulfurized gypsum offers a variety of potential benefits, including:
1. Improve the workability and consistency of materials, which is beneficial to the mixing, placement and arrangement of materials.
2. Reduce water demand and increase the fluidity of materials, which can improve the mechanical properties and usability of materials.
3. Enhance the material’s water retention capacity and extend the material’s hydration time, thereby reducing potential thermal stress and shrinkage.
4. Delay the initial stage of hydration, delay the solidification time of materials, reduce the peak value of hydration heat, and improve the safety and quality of materials.
5. Enhance the mechanical properties and performance of materials, which can improve the durability, strength and deformation resistance of materials.
6. Cellulose ether is non-toxic, biodegradable and renewable, which can reduce the impact on the environment and promote the sustainable development of the construction industry.
in conclusion
Cellulose ethers are promising additives that can influence the hydration and setting processes of desiccated gypsum by improving the workability, consistency, water retention and mechanical properties of the material. The interaction between cellulose ethers and gypsum crystals can reduce the peak heat of hydration and delay the setting time, which can improve the safety and quality of the material. However, the effectiveness of cellulose ethers may depend on factors such as the chemical composition, particle size, moisture content, temperature and additives used in the material. Future research should focus on optimizing the dosage and formulation of cellulose ethers to achieve the desired reduction in the heat of hydration of desulfurized gypsum without affecting its mechanical properties and properties. Additionally, the potential economic, environmental, and social benefits of using cellulose ethers should be further explored and evaluated.
Post time: Oct-11-2023