Effect of Functional Polycarboxylic Acid Superplasticizers on Mechanical and Rheological Properties of Cement Paste and Mortar

Abstract

Modern engineering practices require that polycarboxylic acid high-performance superplasticizers have good adaptability to various environments and materials, which indicates the importance of producing functional polycarboxylic acid superplasticizers with a variety of functions. Therefore, in this work, a functional polycarboxylic acid high-performance water-reducing agent, named superplasticizer J, a sustained-release functional polycarboxylic acid high-performance water-reducing agent, named superplasticizer H, and an early-strength functional polycarboxylic acid high-performance water-reducing agent, named superplasticizer Z, are synthesized. The produced superplasticizers were characterized by employing X-ray diffraction (XRD), thermogravimetry, mercury intrusion porosimetry, and rheometry and by measuring heat of cement hydration. The impacts of the functional polycarboxylic acid superplasticizers on the mechanical properties, rheological properties, and cement hydration of the cement pastes and mortars were investigated. The results show that the prepared functional polycarboxylic acid superplasticizers fulfill water-reducing and cement dispersion functions, can improve the fluidity and plasticity of the mortar, and have a greater effect on reducing shear yield stress and increasing plastic viscosity compared to the naphthalene-based superplasticizers. The sustained-release functional polycarboxylic acid high-performance superplasticizer H performs an excellent slump retention function, and the early-strength functional polycarboxylic acid high-performance superplasticizer Z has a significant effect on improving the early and late strength of the mortar.

Keywords

• functional superplasticizer
• polycarboxylic acid high-performance water-reducing agent
• rheological property
• heat of cement hydration
• XRD
• thermogravimetric