Effects of superplasticizer type on packing density, water film thickness and flowability of cementitious paste

Superplasticizer (SP) is nowadays an indispensable ingredient for the production of concrete, With SP added, the cementitious materials would be dispersed to reduce agglomeration, and thus the packing density, water film thickness (WFT) and flowability of the cementitious paste could be improved. However, there have been few studies on the effects of SP type on the packing density and WET. This study aims to evaluate the roles of SP type in the packing density, WET and flowability of cementitious paste. In the study, cementitious paste samples with three cementitious material compositions, two SP types (namely, a naphthalene-based SP and a polycarboxylate-based SP) and increasing SP dosages were tested. The test results showed that the addition of either type of SP would significantly increase the packing density and WET, but the polycarboxylate-based SP is more effective than the naphthalene-based SP. Besides, the combined effects of SP and WET on the flowability of cementitious paste were analyzed. (C) 2015 Elsevier Ltd. All rights reserved.