Study on the microstructure of metakaolin-based geopolymer enhanced by polyacrylate

Abstract

In order to explore the microscopic mechanism of the remarkable improvement of the organic polymer on the mechanical properties of the geopolymer, fourier transform infrared spectroscopy, 29 Si nuclear magnetic resonance, scanning electron microscope and molecular imprinted polymer were used to investigate the effects of polyacrylate (PAAS) on the microstructure of the metakaolin-based geopolymer (MKG). The load-deflection curves were also tested to confirm the toughing effect. The results show that the organic polymer can modify the structure of the geopolymer at the molecular scale and submicroscopic scale. At the molecular scale, SiOC bonds formed in MKG after the incorporation of PAAS and the polymerization degree of [SiO 4 ] tetrahedra reduced resulting in the mean chain length of [SiO 4 ]/[AlO 4 ] tetrahedra change. At the submicroscopic scale, the MKG became denser after adding PAAS because PAAS could fill the cracks and capillary pores of MKG. Also, PAAS formed a film with an interconnected network structure, which interpenetrated to geopolymer. The loaddeflection curves confirmed increase by 50% in the flexural toughness coefficient of the MKG with the incorporation of 0.8 wt % PAAS.

Alkali-Activated Mortars Modified by Epoxy-Carbon Fiber Composites Wastes

“…These functional groups can interact with the hydroxyl groups in the alkali-activated network, creating a stronger link between the two phases through hydrogen bonds. This last reaction may provide the greatest contribution to the enhanced adhesion; however, it should be noted that, in similar systems [26], the creation of Si-O-C strong covalent bonds was detected. A last possible contribution may result from the different smoothness of the pristine and treated epoxy surface.…”

Geopolymers and Functionalization Strategies for the Development of Sustainable Materials in Construction Industry and Cultural Heritage Applications: A Review

“…In the last decades, in addition to studying the effects of organosilanes and organic polymers, such as polyethylene glycol and polyacrylamide, researchers also showed interest in polyacrylates to reshape the structure of geopolymers and improve their qualities. In this regard, Chen et al described how polyacrylate affects the microstructure of geopolymers synthesized starting from metakaolin [ 60 ]. According to this study, the organic polymer incorporated in the inorganic matrix caused a reduction in the SiO 4 4− polymerization degree, making more compact the geopolymeric paste and filling the pores, avoiding cracks.…”