Effect of a Lignosulfonate Plasticizer on the Hydration of a Belite-Ye’elimite-Ferrite Cement Paste

Belite-Ye’elimite-Ferrite (BYF) cements have been recently developed in order to substitute ordinary Portland cement (OPC), as they release up to 30 % less CO2 and their performances tend to be similar. This work aims to give a first insight and understanding on the influence of a lignosulfonate plasticizer (LS) on the hydration and the properties of a BYF cement paste. For this purpose, hydration of neat cement paste (w/c=0.4) was followed by isothermal calorimetry associated with in situ XRD for the first 4 hours. In addition, plasticizer adsorption was investigated using TOC measurements. Rheological and compressive strength tests were also performed. The results showed that LS changes the hydration kinetics, modifying both induction period (that becomes shorter for low dosage and longer for higher dosage) and rate of ettringite precipitation. For all dosages used, LS decreases the heat of hydration and the compressive strength in the first day. Also, its impact on particle surfaces improves their dispersion and causes a diminution of the shear stress of cement paste, allowing better workability.