The invention relates to the design and synthesis of a poly
carboxylic acid water
reducing agent, the coagulating time of which can be controlled. The poly
carboxylic acid water
reducing agent is prepared by co-polymerize the following three monomers in water: the
monomer a occupying 30 to 70 percent and indicated by a general expression 1, the
monomer b occupying 10 to 50 percent and indicated by the general expression 2, and the
monomer c occupying 10 to 40 percent and indicated by the general expression 3. The coagulating time is controlled by the monomer a which is made by condensing
maleic anhydride and polyoxyethylene monoalkyl
ether. The length of a polyoxyethylene monoalkyl
ether chain controls the change of the coagulating time: the longer the chain, the shorter the coagulating time is; and the shorter the chain is, the longer the coagulating time is. The monomer a does not contain inhibitive substances in the process of synthesis, therefore, the water
reducing agent is easy to be controlled in the coagulating process. The poly
carboxylic acid water reducing agent is suitable for the construction of concrete under different temperature conditions: under higher temperature, the water reducing agent with longer coagulating time can be adopted, and under lower temperature, the water reducing agent with shorter coagulating time can be adopted. The poly carboxylic
acid water reducing agent has good adaptability to
cement and admixtures and has the advantages of low mixing quantity, good
slump constant hold facility and water segregation resistance, and the like.