Evaluation of phosphated superplasticizers in high-performance α-calcium sulfate hemihydrate-based floor screeds

In the present study, the applicability of phosphated comb polymers as high range water reducing agents in a fully formulated α-calcium sulfate hemihydrate-based self-leveling floor screed was evaluated. A phosphated and two mixed phosphated-carboxylated superplasticizers were synthesized and compared to a strictly carboxylated sample (PCE) and a commercial melamine formaldehyde sulfite polycondensate (PMS). Self-leveling screeds of variable water content (w/b = 0.41 – 0.25) containing the different polymers were prepared and their key properties such as spread flow, fluidity retention, flow speed, shrinkage as well as setting behavior and strength development were examined. The results obtained encourage the utilization of phosphate group modified comb polymers in screeds based on CaSO4-hemihydrate, particularly in high-performance screeds formulated at low w/b ratio. [Display omitted] •Use of phosphate modified comb polymers in α-CaSO4 ∙ 0.5H2O self-leveling screed.•Water reducing capacity of phosphated polymers much higher than that of PCE or PMS.•Much higher strength of screeds achievable with phosphated polymers than with PMS.•Phosphated polymers are a new generation of high-performance α-hemihydrate screeds.