Measurements on the moisture state in a heavily trafficked concrete flat slab repaired with a bonded concrete overlay

The paper describes a part of a larger project where the authors are studying an RC structure and ambient air with respect to temperature and moisture state during several years. This paper focuses on the moisture state in a concrete bridge deck repaired with a bonded Steel Fibre Reinforced Concrete (SFRC) overlay without any isolation. The concrete overlay is therefore directly exposed to the environment. Seven so called Sahlen sensors (temperature and moisture gauges) have been installed in the overlay and in the old concrete slab. The temperature and the relative humidity (resistance) are measured every hour and collected in data loggers. The measurements during the winter 1996-97 indicate that the moisture state at the level of 35 mm from the wear surface and further down is not affected by diurnal changes of the relative humidity in the ambient air.