Based on two kinds of isothiazole antiseptic,we explore the effect of antiseptic on the inhibition of bacteria and fungi in polycarboxylate water reducers (PCs),and discusses the influences of antiseptic on the appearance,pH value and performance of PCs.The results show that the antiseptic can effectively inhibit the growth and reproduction of bacteria and mold,especially for the mold.Accordingly,it can prevent the PCs from becoming mouldy on the surface and decreasing of pH value.For the PCs stored in a short time,the adding of antiseptic leads to a decreasing dispersibility while an increasing dispersion stability.The effect of antiseptic content on the decreasing dispersibility of PCs is gradually diminished with the prolonged storage time.Overall,the appropriate dosage of antiseptic in PCs is 0.05%.