Effect of PCE-type superplasticizer on early-age behaviour of ultra-high performance concrete (UHPC)

• Published in: Construction & building materials Vol. 153; pp. 740 - 750
• Main Authors: Li, P.P., Yu, Q.L., Brouwers, H.J.H.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30-10-2017; Elsevier B.V
• Subjects: Concretes; Dispersing ability; Early-age behaviour; Fluid-retaining ability; Influence; PCE superplasticizers; Properties; Retardation effect; Shrinkage; Shrinkage (Materials); Superplasticizers; Ultra-high performance concrete; China; Early-age behaviour; Retardation effect; Fluid-retaining ability; Ultra-high performance concrete; Dispersing ability; Shrinkage; PCE superplasticizers
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2017.07.145

•Early-age behaviours of UHPC incorporated different dosages of four PCE-type SPs are measured.•Dispersing and fluid-retaining mechanisms of SP on UHPC are identified by zeta potential, flow and water demand.•The retardation effect is analysed by setting time, hydration kinetics and early-age strength.•Different influence of SP on setting time, hydration and shrinkage are explained by physical and chemical process.•The effects of clay, w/p, nano-silica on SP’s dispersing ability are discussed.
The effect of PCE-type SP on zeta potential of particles, spread flow, hydration kinetics, setting time, autogenous shrinkage and chemical shrinkage of UHPC pastes is investigated, as well as the spread flow, slump life and early-age strength development of UHPC. Furthermore, the dispersing and fluid-retaining ability of SP, retardation effect of SP, physical and chemical process effects are analysed. The results show that the dispersing ability of PCE-type SP is determined by its chemical structure, which shows an exponential relationship between the flowability of pastes and SP dosages. The fluid-retaining abilities of UHPCs are sensitive to the water-to-powder ratio, while the further addition of SP will not enhance the slump life after excessing the saturation dosage. Both the adsorbed PCE and the PCE remaining in the aqueous phase contribute to retardation effect. A linear correlation between the final setting time (tfinal) and the time of maximum heat flow rate (tQ¨=max) is derived. The types and dosages of SP primarily influence the absolute chemical shrinkage of pastes within 1day, but have a great effect on the autogenous shrinkage due to different physical coagulation and chemical process.