Compatibility between superplasticizer admixtures and cements with mineral additions

The incorporation of mineral additions to Portland cement reduces the amount of clinker required in cement manufacture improving the eco-efficiency of this process. They also impact rheology and it may affect the interaction between superplasticizers and cements. The presented study explores the effect of limestone, fly ash and silica fume on Portland cement and the interaction of these additions with naphthalene (PNS)-, melamine (PMS)-, lignosulfonate (LS)- and polycarboxylate (PCE)-based admixtures. The adsorption isotherms, zeta potentials and rheological behaviour of the blended cements were found and compared to the same parameters in non-blended cement. The results showed that cement–superplasticizers compatibility was altered by the physical (specific surface) and chemical (surface charge) characteristics of the mineral additions studied.