水泥加水后与水反应,水泥浆逐渐变稠厚,并失去流动性及可塑性而变硬为凝结。能延缓混凝土的凝结时间,并对混凝土后期强度发展无不利影响的外加剂称为缓凝剂,兼有缓凝和减水作用的外加剂称为缓凝减水剂。用作缓凝剂的材料有:糖类;未经脱糖的木质素磺酸盐及其衍生物,即含有葡萄糖、乳糖、果糖 After the cement is added with water, it reacts with water, and the cement slurry gradually thickens, loses fluidity and plasticity, and hardens into condensation. The additive that retards the setting time of the concrete and has no adverse effect on the later strength development of the concrete is called retarder, and the admixture that has both retardation and water reducing effect is called retarder water reducer. The materials used as retarders are: sugars; unsweetened lignosulphonates and their derivatives, ie glucose, lactose, fructose