This section will define high-range water reducers, commonly known as superplasticizers, and describe their chemical types, including sulfonated naphthalene formaldehydes, sulfonated melamine formaldehydes, and polycarboxylate ethers. The mechanism of action of HRWRs will be detailed, emphasizing how they interact with cement particles to reduce water content without compromising the workability of the concrete mix. The significance of this reduction in water-cement ratio on the hydration process and microstructure formation in concrete will be explained.