Influence of Temperature and Retarder on Superplasticizer Performance
Karen Luke and Adrian Torres
Appears on pages(s):
Calorimeter; polycarboxylate; polynaphthalene; sulfonated acetone formaldehyde; rheology; retarder; temperature; zeta-potential
Superplasticizers are often used in conjunction with other additives and this can produce either an adverse or synergistic effect on rheology and setting properties of cementitious systems. These effects can be enhanced when temperatures are increased due to environmental changes or induced temperature as in hydrothermal curing. This research focuses on the compatibilities of different types of superplasticizer either sulfonated naphthalene or polycarboxylate based in combination with a lignosulphonate or hydroxycarboxylic acid type retarder.
Rheological measurements were made using a rotational viscometer at temperatures from 25°C (77°F) to 120°C (248°F) under pressure, and plastic viscosity and yield point determined based on the Bingham Plastic model though in almost all cases it was noted that the Power Law or more so the Herschel-Buckley model gives a better fit. Zeta potential was used to characterize particle surface interactions to understand synergy of additive combinations. Setting properties, investigated using conduction calorimetry, were observed to be dominated by retarder response.