Intrinsic graphene/cement-based sensors with piezoresistivity and superhydrophobicity capacities for smart concrete infrastructure

Different surface coatings were applied for graphene/cement-based sensors with self-sensing capacity to achieve an effective way for superhydrophobicity to mitigate piezoresistive instability due to various humidity in this paper. The results show that the cement-based sensors treated by the twice coating can reduce the water absorption by half and exhibit the highest water contact angle of 163.4 degrees. The hydrophobic silane can penetrate into the cement-based sensors after the once/twice coating if 4% silane is used with isopropanol. However, it was still difficult to observe the hydrophobic groups inside the cement matrix subjected to the silane without isopropanol. On the other hand, the effect of surface coatings on the piezoresistive sensitivity was also investigated after the surface coating treatments. The sensitivity of cement-based sensor was dozens of times higher than the commercially available strain gauges. The related results will promote the practical application of superhydrophobic cement-based sensors for structural health monitoring of the smart concrete infrastructure.