There are many types of retarder, which can be divided into two categories: organic substances and inorganic substances. The main characteristic of organic substance retarder is that the usage amount is very small, usually a few ten thousandths to a hundred thousandths of cement cementitious materials; another characteristic is that improper use will cause the final strength of concrete or cement mortar to decrease. The characteristic of inorganic salt retarder is that the dosage is larger than that of general cement cementitious materials. Some traditional varieties are not very stable, and their effects on various types of admixtures are different. According to the commonly used retarder types, they can be classified into the following 8 subcategories:
1. Organic substances containing hydroxyl groups (-OH): monohydric alcohols and polyols, polyvinyl alcohol, polyol derivatives - sugars
2. Organic compounds containing carboxylic acid groups (-COOH): citric acid, lactic acid, tartaric acid, salicylic acid
3. Hydroxycarboxylate and amino carboxylate: gluconic acid Sodium, sodium citrate, sodium sulfamate
4. Organic amines and derivatives
5. Phosphate and phosphonate retarder
6. Boric acid and borate
7. Zinc salt
8. Others, such as sodium fluorosilicate, ferrous sulfate</p
