Understanding the effect of MPEG-PCE's microstructure on the adsorption and hydration of OPC

Polycarboxylic ethers or polycarboxylate (PCEs) are one of the most employed superplasticizers in construction. However, the understanding of their microstructure–property relationship is still incomplete. Recently, a theoretical model was proposed that relates the microstructure–conformation of the PCE to its effect on the adsorption onto cement particles and cement hydration time. In this work, the effects of a wide range of PCEs with different side chain lengths (P = 5, Group 1; P = 20, Group 2; and P = 45 and 113, Group 3) having flexible backbone worm conformation except one which has stretch backbone worm conformation (P = 113) were experimentally investigated for their effect on adsorption and cement hydration. It is found that PCEs from Group 1 show electrostatic repulsion as dispersing mechanism, unlike PCEs from Groups 2 and 3. Furthermore, the prediction of the theoretical model is also assessed for all the studied PCEs. Only Group 1 PCEs (shortest side chains) showed deviation from the theoretical predictions, and it was attributed to their different behaviors from the standard PCEs for which the theoretical model was developed.