Assimilating nanographene into the pervious concrete - surface treatment for enhanced paving performance

This research aims to assess the impact of surface treatment with a nanographene solution on the properties of pervious concrete paving flags (PC paving flags). Four different methods of applying the nanographene solution were examined: spraying, submerging, double submerging, and brushing. The properties of the PC paving flags, as specified by EN 1339, were tested, including bending strength/breaking load, water absorption, abrasion resistance, unpolished slip resistance value (USRV) as well as porosity and permeability. To aid in the interpretation of the results, SEM analysis and optical microscopy were conducted. It is concluded that the surface treatment of PC paving flags with the nanographene solution resulted in a moderate increase in bending strength/breaking load and had a negligible impact on USRV and abrasion resistance values while reducing water absorption, total porosity, and permeability. Optical microscope images revealed that the nanographene treatment smoothed the surface of the PC paving flags sealing it and reducing open porosity. The sealed surface explained the observed reduction in water absorption while reduced open porosity clarified the reduction in total porosity and consequently, water absorption and permeability. The micrographics showed further evidence of the changes in mechanical strength and porosity introduced with nanographene and the presence of carbon on the surface. The elongated pores were present in all the samples, being largest in the sprayed sample.