This paper studied the compatibility of shrinkage reducing agent and water reducing agent in cement-based composite material and analyzed the change of dispersity, stability and mechanical characteristics of cement- based composite material at different ratios of shrinkage reducing agent and water reducing agent, which revealed the mechanism of action of these two chemical agents on cement-based composite material. The results showed that when cement admixture with water reducing agent was

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... with a small amount of shrinkage reducing agent, the initial fluidity of cement had little variation, but the thickening time of cement paste extended significantly. The effect of shrinkage reducing agent on ester water reducing agent was relatively larger compared with ether water reducing agent and the fluidity loss was about 10mm. Ether water reducing agent could significantly reduce the degree of shrinkage of the cement mortar test block. After the maintenance for 70d, the shrinkage value of cement mortar test block with shrinkage reducing agent and water reducing agent reduced by 21.4% compared with cement mortar test block with only shrinkage reducing agent. There is no reduce shrinkage effect when adding ester water reducing agent. However, the shrinkage value of cement mortar with ester shrinkage reducing agent and water reducing agent reduced by 17.4% compared with cement mortar with only shrinkage reducing agent. Water reducing agent could effectively inhibit the defoaming effect of shrinkage reducing agent on the cement-based composite material and the strength of cement-based composite material adding water-reducing agent and shrinkage reducing agent was greater than that with shrinkage reducing agent alone.