Damage in cement-based materials, studied by electrical resistance measurement

Real-time monitoring of a structural component gives information on the time and condition at which damage occurs, thereby facilitating the evaluation of the cause of the damage. Moreover, it provides information once damage occurs, thus enabling timely repair and hazard mitigation. Real-time monitoring also allows study of the damage evolution. This paper reviews the use of electrical resistance measurement to monitor damage in cement-based materials. This method is advantageous in its sensitivity to even minor, microscopic and reversible effects. Damage can occur within a cement-based material, at the interface between concrete and steel rebar, and at the interface between old concrete and new concrete (as encountered in the use of new concrete for repair of an old concrete structure). This paper addresses all three aspects of damage, whether the damage is due to static stress, dynamic stress, freeze-thaw cycling, creep or drying shrinkage. Moreover, monitoring during straining at various rates allows study of the effect of strain rate on the damage evolution.