Smart Cementitious Composites for Road Traffic Monitoring and Weighing in Motion

Abstract

The addition of electrically conductive materials at micro scale, such as carbon fibres (CF) or steel fibres (SF), to conventional cementitious materials makes piezo-resistive behaviours possible in terms of changes in electrical resistivity due to applied stresses. Smart cementitious composites (SCCs) may thus be able to detect traffic density and sense weight in motion thanks to such piezo-resistive property. Three types of cement-based sensors, with CF, SF, or a hybrid of CF and SF, were experimentally evaluated by applying quasi-static and dynamic load cycles after seven days of curing in different load directions reflecting the electrodes and different circuit type connections of the specimens. The performance of each type of sensor was assessed based on measuring the changes in electrical resistivity (ER) under compressive and flexure stresses, with test results revealing that the use of CF in these composites was the best choice because this generated more sensitivity to applied loads in terms of the change in ER compared with other types. These results were achieved when the applied load was parallel to the electrode direction. The findings also indicated arrangement of specimens as an electric series circuit type was the best setup configuration for traffic monitoring and weight in motion measurement.