Impact of different types of plasticizing admixtures on the rheological properties and hydration of blended cements

Abstract

Portland cement manufacturing significantly contributes to CO 2 emissions into the atmosphere. In order to reduce CO 2 emissions, limestone and slag mineral admixtures are most prospective both technologically and economically in cement production. For such cements, it is important to select a certain type and amount of plasticizer and evaluate what plasticizers influence the heat released during hydration. In order to achieve the objectives of research, viscosity, conductivity, and DSC analyses of cement pastes with A and B plasticizers were performed. This study analyzes the effect of polycarboxylate ester (A) and modified lignosulfonate (B) plasticizers amount on rheological properties and hydration processes of the limestone and slag cement pastes. The use of A additive in contrast to B additive has a long-term effect on viscosity of both cement pastes and is less sensitive to mineral composition. Optimal A additive amount in case of limestone cement is 1.25 % and in case of slag cement is 0.3 %. In limestone cement additive A reduces total heat value by 6 % and additive B by 15 % after 48 h of hydration. In slag cement additive A increases total heat value by 4 % and additive B by 2 % after 48 h of hydration. Exothermal profiles show that in limestone cement additive A extends the EXO maximum time by 25 % and additive B by 40 % in samples after 24 h of hydration. In slag cement additive A extends the EXO maximum time by 37 % and additive B by 25 % in samples after the same time of hydration.

The Effect of the Electrical Conductivity of Superplasticizers on the Fluidity and Early Hydration Parameters of Cement Paste

“…We can see that SP (A) had a very high EC, which was 3.9 times higher than the EC of SP (C) and 2.5 times higher than that of the EC of SP (B). Similar EC results of the SP have also been reported in another study [42]. The water solutions of the SP (Figures 1, 2) reveal very similar trends: the highest EC values were recorded in the SP (A) water solution and the lowest values in the SP (C) water solution.…”

Effect of Calcium Nitrate on the Properties of Portland–Limestone Cement-Based Concrete Cured at Low Temperature

“…This difference is partly due to the higher w/c in the CEM IIR paste. Another reason is that CEM IIN contains significantly more minerals C 3 A and C 3 S, which are immediately involved in the hydration process and increase the viscosity of the paste [ 42 ]. A similar difference persists after 30 min of measurements.…”