Interaction between cement and chemical admixture from the point of cement hydration, absorption behaviour of admixture, and paste rheology

摘要

Chemical admixtures can improve the properties ofconcrete. High performance concrete with high strength, superiorfluidity, and self-compactibility can be realized mainly because ofchemical admixtures. Rheological properties of fresh concrete canbe strongly affected by the combination of cement and chemicaladmixture, method of admixture addition, or the water-cementratio. Problems in fluidity, such as stiffening and large slump-loss,occasionally happen under a particular combination of cement andadmixture. These phenomena are generally called incompatibilitiesbetween cement and chemical admixtures. In this study, theinteraction between cement and the chemical admixture typeslignin sulfonate, naphthalene sulfonate, melamine sulfonate,amino sulfonate, and polycarboxylate, together with the workingfactors and mechanisms, are discussed from the viewpoint ofcement hydration, although the polycarboxylate, together with theworking factors and mechanisms, are discussed from the viewpointof cement hydration. Although the polycarboxylate typesuperplasticizer was considered to have better compatibility incombination with different kinds of cement, th4 authors show thatits compatibility is affected by the amount of alkaline sulfates in cement.