FLY ASH AS A CEMENT SUBSTITUTE: EVALUATING EARLY-STAGE CORROSION POTENTIAL IN REINFORCED FOAMED CONCRETE
Corrosion attack on the steel of reinforced foam concrete is initiated by chloride ions which increased its potentiality levels of corrosion. The fine particle size of fly ash was considered as good as the filler to reduce the capillary of the concrete. This study investigated the effect of cement replacement with fly ash on the potential corrosion of reinforced foamed concrete in the initial stage by using the half-cell potential technique. The beam of 15cm × 20cm × 80cm was investigated by reinforced foamed concrete and 10% fly ash reinforced foamed concrete. Conventional reinforced concrete was used as a control in this study. All types of samples were designed for compressive concrete strength of fc' 25MPa. Furthermore, this study was prepared by the water-cement ratio of 0.4, the longitudinal bar used of 4Ø – 10mm, and the shear reinforcement of Ø6 – 10mm. The specimen was immersed in 3.5% sodium chloride solution. The result showed that the potential corrosion was -600mV for reinforced normal concrete, -300mV for reinforced foamed concrete and -500mV for fly ash reinforced foamed concrete. It means that the risk of corrosion in reinforced foamed concrete is less than in reinforced normal concrete. Moreover, the addition of fly ash in the reinforced foamed concrete increased the corrosion risk of reinforcement in the initial stage. This is caused by the slow hydration time of the fly ash material, thus requiring a longer concrete curing time. The utilization of fly ash also reduces the pore in the concrete, thereby increasing its density, and an higher concrete density reduces the infiltration of water. Judging from the corrosion behavior of the reinforcement, foam concrete and foam concrete with fly ash are suitable to be employed as a structural element of the building constructed near the coast.
Foam Concrete, Fly Ash, Corrosion, Lightweight Concrete, Half Cell Potential.