What is a high-efficiency water reducing agent?

Admixtures that can significantly reduce the amount of mixing water under the condition that the concrete slump is basically the same are called high-efficiency water-reducing admixtures.
An admixture that can reduce mixing water consumption by more than 15% when the slump of concrete is basically the same.
--Quoted from DL/T5100-2014 "Technical Specifications for Hydraulic Concrete Admixtures"
Development History
The first generation of high-efficiency water-reducing agents-naphthyl-based high-efficiency water-reducing agents and melamine resin-based high-efficiency water-reducing agents were developed in the early 1960s. Due to their performance compared with ordinary water-reducing agents-the naphthyl-based superplasticizers developed in the late 1930s Represented by lignin sulfonate - it has been significantly improved, so it is also called a superplasticizer. The second generation of high-efficiency water-reducing agents is sulfamate, although chronologically it is after the third-generation high-efficiency water-reducing agent-polycarboxylic acid system. The graft copolymer with both sulfonic acid group and carboxylic acid group is the most important of the third generation high-efficiency water-reducing agent, and it is also the most excellent high-performance water-reducing agent.