Reducing carbonation degradation and enhancing elastic properties of calcium silicate hydrates using biomimetic molecules

This study presents a novel way of reducing the carbonation-induced degradation of CSH using organic molecules. Synthetic CSH batches were prepared with the addition of l-aspartic acid and polydopamine. The effects of these molecules on the synthesized CSH before and after carbonation were monitored using various experimental techniques, including 29Si NMR, TEM, nanoindentation, and FTIR. It was observed that, without the presence of biomimetic molecules, CSH was converted to a fully polymerized silica gel after 168 h of carbonation, as evident by the presence of Q3 and Q4 species in 29Si NMR spectra. On the other hand, biomimetic molecules modified CSH retained the original chain-like arrangements even after 28 days of carbonation, as identified by the presence of Q1 and Q2 species in 29Si NMR spectra. Additionally, the biomimetic molecules modification increased the elastic modulus of CSH by 3–9 times, which were further increased upon carbonation.