Role of alcohol-ethylene oxide polymers on the reduction of shrinkage of cement paste

Concrete drying shrinkage is a major practical problem, but it can be ameliorated by means of “shrinkage-reducing agents” (SRAs). Water vapor sorption isotherms and low temperature DSC measurements suggest that alcohol-ethylene oxide polymers (AEOPs) with a better hydrophilic-lipophilic (HL-) balance are present in meso-pores in which water molecules evaporate from 75% RH to 40% RH. Short-term drying shrinkage measurements show that the better HL-balanced AEOPs reduce irreversible shrinkage, which occurs mainly from 75% RH to 40% RH during the first drying. Based on the similarity between corresponding RH regions, it is concluded that the better HL balanced AEOP in relevant meso-pores hinders agglomeration of C-S-H during the first desorption to mitigate the irreversible shrinkage and reduce the first drying shrinkage.