3D printed self-sensing alkali-activated coatings for civil infrastructure

Monitoring civil infrastructure is paramount due to the ageing of existing civil infrastructure. Apart from electronic devices, self-sensing materials are also used for these types of applications. In this paper, we present 3D printed self-sensing coatings for civil infrastructure. The coating is an alkali-activated material, which attains similar properties to ordinary Portland cement binders but is more electrically conductive due to the alkali ions in the matrix. The coatings were printed onto concrete cubes and glass fiber reinforced plastic sheets to investigate their strain response under cyclic loading in compression and tension. The electrical response under compression presented reasonable repeatability among loading cycles. In tension, the patches presented slight repeatability issues in subsequent cycles. For both compression and tension the patches present a linear electrical response in regards to the applied strain. The gauge factor of the coatings was calculated as 657 for compression and 144 for tension. 3D printed coatings have shown the potential of acting as a nondestructive evaluation method of existing infrastructure.