After adding the surfactant to the water solution it can reduce water’s surface tension(water-gas phase) and interfacial tension(water-solid phase).

Surfactant has  hydrophilic group and hydrophobic group. Hydrophobic group is various alkyl and alkaryl. Hydrophilic group is the salts which ion can be dissociated from. According to the difference of ionic dissociation by the hydrophilic group. The surfactants can be divided into cationic surfactant,anionic surfactant, zwitterionic surfactant and non-ionic surfactant.

After adding the sodium lignosulfonate into concrete,the hydrophobic group of the water reducer is absorbed on the surface of cement particle. Hydrophilic group points to water solution. And make up monomolecular or multimolecular adsorption film. Make the cenment particle (grains) are dispersed because of like charges repel each other, and release the water from cement grains in order to get the water reducing function.