Characterization and Steel Corrosion of Cement Produced from Incinerator Ashes

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Ecocement is a new type of hydraulic cement produced from incinerator ash. However. the incinerator ash contains large amounts of chloride, which, if not removed during the production process, is expected to accelerate the corrosion of steel bars when ecocement is used in reinforced concrete structures. The chlorides can be removed in the production process but at a high cost. Two types of ecocement have been produced, a high chloride type (type I) and a low chloride (type II). This paper investigates the corrosive behavior of steel bars embedded in the mortars containing both types of ecocement, cured under and exposed to wetting and drying cycles. Corrosion of the mild steel bars was monitored by halfcell potential, polarization resistance, and AC impedance measurements. The relative performance of the two types of ecocements with respect to the corrosive behavior of the embedded steel bars was discussed.From the results, the following conclusions could be drawn.(1) Steel bars embedded in mortars of high-chloride type ecocement is more susceptible to corrosion than that of low-chloride type one.(2) Carbonation accelerates corrosion of steel bars embedded in the mortars of both ecocements, although the effect is higher in high-chloride type than in low-chloride type.(3) Electrical measurement yields a good result in the monitoring of corrosion of steel bars embedded in cement mortars.(4) In both types of ecocement, the extent and severity of the corrsion of the embedded steel bars depend on the water to cement ratio, the higher the water to cement ratio, the greater the severity of corrosion.