Nano-reinforced Ternary Lime-Based Composites for Structural Health Monitoring of Cultural Heritage Monuments

Τhe development of ternary lime-based cementitious nanocomposites for applications related to the restoration/conservation of Cultural Heritage Monuments is investigated. The research aim is to transform the material into a sensor by dispersing carbon nanostructures in the restoration material matrix in order to form electrically conductive paths. Measurement of the electrical resistance of the material can be exploited as an non-destructive method to prognose on the structural health of the restored members (working pronciple). Commercially available graphene nanoplatelets (GnPs), within the range of 0.15 to 1.0 wt.% of the binder, were incorporated in ternary pastes consisting of lime, pozzolan (metakaolin) and cement. The effect of superplasticizer on the dispersion capability of the GnPs was also examined and different ratios of superplasticizer per nanomaterial were investigated. The mechanical properties of the newly developed nanocomposite pastes were examined and compared against the respective properties of the reference paste. It was concluded that the incorporation of graphene nanoplatelets significantly increases the compressive strength, while at the same time decreases the flexural strength of the nanocomposites. Regarding the correlation between the SP/GnPs ratio and the mechanical properties, the addition of double quantity of superplasticizer in low concentrations (0.15 wt.%) slightly increases the compressive and flexural strength while the opposite is noticed at higher concentrations (i.e., 1.0 wt.%). The experimental results strongly indicate the potential use of the nanocomposite binder for structural health monitoring purposes of Cultural Heritage Monuments.