Interaction of 2-, 3-and 4-nitrobenzoic acid with the structure of calcium-silicate-hydrate

Interaction of nitrobenzoic acid (NBA) with the structure of calcium-silicate-hydrate (C-S-H) was investigated. Phase pure C-S-H and C-S-H with 2-, 3- or 4NBA (0.01 and 0.02 mol/mol of Ca) were synthesized, and characterized by the X-ray diffraction, thermal analysis, Fourier transform infrared spectroscopy and scanning electron microscope techniques. Nitrogen adsorption measurements were also performed to estimate the surface area of the samples. It is suggested that all NBA isomers with the concentration of 0.01 mol/mol of Ca were able to fill the defects on the surface of the C-S-H layers, block access to the space between the stacked C-S-H layers, and possibly partially intercalate the layered structure. The C-S-H-based samples prepared with different types of NBA compounds, however, had different characteristics. The interaction of organic and inorganic phases was limited in the samples incorporating higher concentration of NBA. Traces of unreacted NBA were detected in a few samples with 0.02 mol of NBA/mol of Ca.