Poly(carboxylated ether)s as Cement Additives: The Effect of the Addition Method on Hydration Kinetics

Area of Science:

• Materials Science
• Civil Engineering
• Chemical Engineering

Background:

• Polycarboxylate ethers (PCEs) are crucial superplasticisers in cement formulations.
• Recent research explores the link between PCE molecular structure and performance.
• Understanding PCEs' impact on cement hydration is vital for material optimization.

Purpose of the Study:

• To investigate the effect of PCEs with varying side chain lengths and charge densities on ordinary Portland cement (OPC) hydration.
• To determine how different PCE addition methods influence cement hydration kinetics.
• To correlate PCE microstructure with observed hydration effects.

Main Methods:

• Synthesis of PCEs with controlled side chain lengths and charge densities via free radical copolymerisation.
• Addition of synthesized PCEs to OPC paste using direct and delayed methods (5 min post-water addition).
• Analysis of cement hydration kinetics and microstructure.

Main Results:

• The method of PCE addition significantly alters OPC hydration kinetics.
• Direct PCE addition shows a linear relationship between hydration retardation and PCE microstructure.
• Delayed PCE addition reduces hydration rate but does not cause retardation, irrespective of PCE microstructure.

Conclusions:

• PCE addition methodology is a critical factor in controlling cement hydration.
• Direct addition offers a means to tailor hydration retardation based on PCE molecular design.
• Delayed addition provides a method to moderate hydration rates without significant retardation, offering flexibility in concrete технології.