Cement-polymer and clay-polymer nano- and meso-composites: spotting the difference

Abstract

Calcium silicate hydrate (C-S-H), the most important reaction product of Portland cement with water, is a layered lattice silicate which has much in common with smectite clays. Both materials may be synthesised (C-S-H) or found in nature (smectites) in the form of particles which are stacks of negatively charged nanometre-thick platelets separated by water molecules and charge-compensating cations. Smectite clays are well known for their ability to intercalate molecular species including polymers, to ''swell'' in a remarkable variety of solvents and to form nano-composites with polymers in which total delamination may eventually be obtained. In this work, we explore the possibility of intercalating cationic, anionic and neutral water-soluble polymers in C-S-H. Contrary to recent reports, no clear signs for intercalation of the macromolecules were observed. Nevertheless, the significant amount of polymer retained by the silicate suggests that the composite materials formed may be considered as meso-composites in which the individual solid units are not the individual C-S-H sheets but crystallites thereof. The localisation of electric charges and the strong Coulombic forces acting in cement hydrates are thought to be responsible for this difference.

Hysteresis from Multiscale Porosity: Modeling Water Sorption and Shrinkage in Cement Paste

“…Such analysis can be used, for example, to assess the gel-pore ratio and initial water-to-cement ratio of an existing sample of cement. The structure of gel pores can change due to drying, load, or even deliberate alteration such as by filling these (10-100)-nm-scale spaces with polymer [76]. Since such a change in structure will greatly influence properties, our proposed technique for assessing the gel pore structure can be a valuable research tool.…”

Adsorption and heterocoagulation of nonionic surfactants and latex particles on cement hydrates

“…The plateau of the isotherm is on the order of 1 ± 0.5 µmol g −1 , which is really at the detection limit in our experimental conditions and which, considering the surface area of C-S-H, is very small. Indeed, the surface area of C-S-H readily accessible to water molecules, as measured by NMR relaxation for instance, is on order of 100 m 2 /g [28,29] (this does not take into account the interlayer surface area, which is not accessible to neutral p(EO) chains [30]). Thus, the maximum surface concentration of TX100 adsorbed is on the order of 0.01 µmol/m 2 .…”

Effect of poly(diallyldimethylammonium chloride) on nanostructure and mechanical properties of calcium silicate hydrate

“…doi:10.1016/j.msea.2010.07.057 one of the most viable for producing C-S-H/polymer nanocomposites [6]. However, Merlin et al [11] observed no evidence of PDC intercalation and suggest that this polymer is adsorbed on the surface or in the void space left by the crystallites stacks, forming a mesocomposite.…”