and can they be used without them?

concrete admixtures include: 1. admixtures that improve the performance of concrete mixtures and workability, including various water reducing agents, air entraining agents and pumping agents; 2. admixtures that adjust the setting time and hardening performance of concrete, including retarder, early strength agent, accelerator, etc.; 3. admixtures that improve the durability of concrete, including air-entraining agents , waterproofing agents and rust inhibitors, etc.; 4. admixtures that improve…