Synthesis and characterization of vinyltriethoxysilane-modified polycarboxylate superplasticiser for enhanced sulfate resistance

Abstract

The strategic integration of functional monomers within the molecular structure of polycarboxylate superplasticizers offers a viable route to augment their inherent performance capabilities or introduce novel functionalities. In this investigation, a novel silane-modified polycarboxylate superplasticizer (Si-PCE) was synthesized via a free radical polymerization process at room temperature. This synthesis leveraged the high reactivity of ethylene glycol monoethylene glycol ether (EPEG), acrylic acid (AA), and vinyltriethoxysilane (VTEO) as the core monomers. The chemical structure of Si-PCE was characterized by Fourier transform infrared spectroscopy (FT-IR), 1H Nuclear magnetic resonance (1H NMR), and Energy dispersion spectroscopy (EDS). To evaluate the performance of Si-PCE, its influence on the early hydration products of cement was analyzed using X-ray Diffraction (XRD). Furthermore, the dispersibility of Si-PCE was assessed through cement paste fluidity and mortar fluidity tests, while its impact on mechanical property was investigated via mortar strength measurement. The findings revealed that Si-PCE surpassed silane-free PCEs in terms of dispersibility and dispersion retention, leading to enhanced mechanical property. In addition, the adaptability of Si-PCE in sulfate-rich environments was examined by conducting cement paste fluidity, mortar fluidity, and mortar compressive strength tests. Notably, Si-PCE demonstrated superior performance compared to its silane-free counterpart, particularly in high-sulfate environments, where it effectively dispersed cement particles and significantly bolstered the mechanical property of cement mortar. In conclusion, Si-PCE exhibited not only superior performance under conventional conditions but also remarkable adaptability and stability in sulfate-rich environments, thereby portending its extensive potential for application and profound implications.