Application of triisopropanolamine in cement grinding aid_Industrial additives

Foreword

Isopropanolamine is divided into monoisopropanolamine [1-amino-2-propanol, MIPA for short] and diisopropanolamine [1, 1’imino-2-propanol, Three homologous products: DIPA for short] and triisopropanolamine [1,1,1″ amino-2-propanol, TIPA for short]. It is an alkanolamine substance and has an amine group and an alcoholic hydroxyl group. Alcoholamine compounds, because their molecules contain both amino groups and hydroxyl groups, have the comprehensive properties of amines and alcohols, have a wide range of industrial uses, and are an important basic chemical raw material.

Application

In the field of cement grinding aids, the early alcoholamine compounds used as cement grinding aids were mainly triethanolamine. Since triisopropanolamine has better dispersion and later strength than triethanolamine, with the development of the cement industry With the intensification of development and competition, the application of triisopropanolamine in cement grinding aids has developed rapidly.
The application of triisopropanolamine in cement grinding aid is characterized in that the cement grinding aid contains triisopropanolamine, triethanolamine, additives and water. The auxiliary agent is one or more of carboxylic acid, lignosulfonate, and alkyl sulfonate. According to the formula requirements, add a certain proportion of water to triisopropanolamine, then add other raw materials and stir in the kettle at normal temperature and pressure until the product meets all indicators and is discharged. The amount of triisopropanolamine added is about 20% to 60% of the total raw materials according to the formula requirements. There are two addition methods: one is that triisopropanolamine is added directly during the cement grinding process: when the temperature is low (< 10°C), triisopropanolamine with a content of 85% has high viscosity and is difficult to transport. Before adding, dilute triisopropanolamine with water to about 65% to 70% and transport it with a pump. The optimal addition amount is about one ten thousandth of the total raw materials. Second, triisopropanolamine is added directly in concrete production: triisopropanolamine is mixed with a water-reducing agent. The dosage range of triisopropanolamine is about 0.1% of cement, and the water-reducing agent is 0.8% of cement. (primary excitation intensity). As the amount of triisopropanolamine increases, the strength will gradually increase. However, due to its increased dispersion, the amount of air entrainment increases, which hinders the strength. When the air entrainment amount exceeds 3%, the strength begins to decrease as the air content increases. At this time, a certain amount of block polymer, preferably an epoxy compound (about one-tenth of triisopropanolamine) can be added. one).

Advantages

In cement and cement concrete applications, triisopropanolamine has the following advantages over triethanolamine in terms of dispersibility, age enhancement, and application conditions:

01 Better dispersion:
When used in cement grinding aids, the fundamental principle of grinding aids is the dispersibility of the two as surfactants. Due to the isomeric three-dimensional structure of the alkyl chain and hydroxyl group of triisopropanolamine, This makes the dispersion of triisopropanolamine better than that of triethanolamine; and dispersion is an important indicator of cement. In practical applications, the effect of triisopropanolamine on increasing the production of cement is better than that of triethanolamine, and it has a better effect on the flow of cement. Sexual improvement is also better than triethanolamine.
02 Early performance enhancements:
Both are early strength agents, but triethanolamine reverses the early setting characteristics of cement to achieve early strength effects, while triisopropanolamine achieves early strength effects by promoting early setting characteristics. Specifically, triethanolamine promotes the early hydration of aluminates, delays the hydration of silicates, increases early strength, but shortens the setting time; triisopropanolamine promotes the hydration of ferrites that are difficult to hydrate. The hydration and dispersion of cement minerals can improve the hydration degree of cement minerals, thereby improving the early strength.
03 Post-performance enhancement:
Triethanolamine mainly promotes early strength, while triisopropanolamine greatly improves the later strength of cement by promoting the hydration of refractory minerals and improving the dispersion of cement. Foreign tests show that the later strength can be increased by 3 trillion. Above Pa, even 5-12 MPa.
04 Application performance is stable:
The application of triethanolamine has obvious restrictions on its dosage. When the dosage exceeds 0.1%, flash condensation will sometimes occur, affecting the setting characteristics of cement; the dosage range of triisopropanolamine is 0.001% to 0.2%, and as the dosage increases, the enhancement effect will gradually increase.
Under the dual effects of rising oil prices and increased demand for ethylene series products, the price of ethanolamine continues to rise. The gap between the price of isopropanolamine and ethanolamine has greatly narrowed. Ethanolamine has gradually lost its price advantage. As countries around the world increasingly pay attention to environmental issues, Attention is paid to the fact that the application of ethanolamine is gradually being restricted. For example, the Pollutant Emission and Transfer Registration System of developed countries lists ethanolamine as a hazardous substance and restricts its use, thus accelerating the replacement of ethanolamine.