Influence of lignosulfonate on the early age rheology and hydration characteristics of cement pastes

Four different cements made from gypsum mixed with clinkers possessing varying amounts of clinker phases were employed to investigate the influence of lignosulfonate on the early age rheological and hydration properties of cement pastes. Two test methods were employed; the parallel plate rheometry and isothermal calorimetry. Here, lignosulfonate was quantitatively shown to impact the early age hydration of cement pastes depending on the C3A and C3S compositions, in the respective order. A threshold amount of ~4.6% C3A is needed to sufficiently impair the performance of lignosulfonate at normal working dosages (0.4% bwoc). When high amounts of C3A was present (~10%), flash set of the cement paste occurred even at the low dosage of 0.2% bwoc of lignosulfonate. When cement possessed low amount of C3A, lignosulfonate mainly retarded the hydration of C3S, but this effect decreased when the C3S was doped with Al.