Views: 14 Author: Mary Publish Time: 2019-04-06 Origin: Horizon Chemical
How does the strength of cement come into being?
Answer: after mixing cement and water, the clinker minerals are rapidly hydrated, forming a large amount of hydration products, hydrated calcium silicate (C - S - H) gel, and forming calcium hydroxide Ca (OH) 2 solution; hydration product hydrated calcium aluminate (C-A-H) react with calcium sulfate (CaSO4) in gypsum to produce ettringite (AFt) crystal of three sulfur type. After a certain period of time, C-S-H also grows from clinker particles with long fibre crystals, and Ettringite crystals grow up gradually. They interweave and connect with each other in cement paste to form a network structure. With the further hydration, the quantity of hydration products increases continuously, and the crystal size grows continuously, thus making the structure of hardened paste more compact, forming cement stone and strength. It's getting higher and higher.
Why do cement grinding aid also enhance cement products?
Answer: The main raw materials of grinding aid are triethanolamine and triisopropanolamine, and diethanolisopropanolamine, which do not disappear after grinding, but remain in cement products. They are also good complexing agents, which can accelerate the hydration heat release in the process of cement hydration, accelerate the action of tricalcium aluminate and gypsum, and form ettringite as soon as possible to enhance the effect. In the alkaline solution of cement hydration, it can form relatively stable complex ions with Fe3+ and Al3+ plasma. This complex ion reacts with cement hydration to form complex salts with very low solubility. Therefore, triethanolamine and triisopropanolamine do not change the hydration products of cement, but only promote the reaction between components of cement, and eventually form ettringite after reacting with other substances. With the hydration of cement system, triethanolamine, triisopropanolamine and diethanolisopropanolamine do not change the hydration products of cement. The strength of cement paste increases with the increase of solid precipitation.