Molecular-scale insight into improved waterproofing of cement paste by protective epoxy resins nano-coating

XD Zhu and A Zaoui and W Sekkal, POWDER TECHNOLOGY, 426, 118679 (2023).

DOI: 10.1016/j.powtec.2023.118679

The durability of cement binding paste is an important challenge in building sector that can be improved by increasing the resistance to water infiltration in the cement paste. The aim of the present work is mainly devoted to analyze at nanoscale level the interfacial interaction of epoxy resins coated on (001) surface of the nano -granular Calcium- Silicate-Hydrate (CSH) paste. By means of molecular dynamics simulations, a full nano-coated CSH surfaces show that m-phenylenediamine (MPD) would highly improve the coating efficiency. Results reveal that the coated (001) CSH surface models are more stable and the calculated surface free energy is roughly 95% loss compared with the non-coated surface, reducing therefore the hydrophilicity of the CSH surface. The related values are found in the range of 33.7 mJ/m2- 45.5 mJ/m2, in agreement with experimental findings. The ob-tained averaged contact angle between the equilibrated water-nanodroplet and the best coated CSH is in the range of 84.29 degrees- 91.97 degrees, which corresponds to the observed experimental measurements. Finally, the calculated work of adhesion is estimated to102.81 mJ/m2, which is close to the experimental findings of 102.79 and 90.17 mJ/m2, corresponding to 2 and 28 days hydration of cement. Consequently, our findings reveal that 16.46 wt% of epoxy coating including 2.61% of MDP reduces by 3.14-3.57 times the hydrophilicity of CSH (001) surface, leading to a promising future of sustainable cementitious materials.

Return to Publications page