Evaluating Pre-Corrosion and Post-Corrosion of Oil Palm Shell Concrete with Non-Destructive Testing

Abstract

Corrosion of reinforcement can decrease the quality and cause damage to reinforced concrete, so it is necessary to know the resistance of concrete, especially with oil palm shells (OPS) and mask fibers in a corrosive environment. This study aims to determine the effect of corrosion levels on OPS concrete and mask fiber using the NDT (non-destructive testing) method. Oil palm shells are a 10% replacement for coarse aggregate in the concrete mix. The mask fiber is 0.2% of the volume of the specimen, and the superplasticizer is 0.25% of the cement used as an additive in the concrete mixture. The specimen is 50 cm long, 10 cm wide, and 10 cm high. There are two types of specimens, namely pre-corrosion and post-corrosion. In pre-corrosion specimens, corrosion acceleration of the reinforcement is carried out before the concrete molding process. While the post-corrosion specimen is being prepared, corrosion acceleration is carried out after the concrete is 28 days old. Corrosion acceleration is carried out by immersing the concrete specimen in a 5% NaCl solution and using a DC power supply. After the concrete is corroded, NDT is carried out. The NDT methods used are resistivity and impact-echo as analysis and detection tools for the effect of corrosion on palm shell concrete and mask fiber. The pre-corrosion specimen got the highest resistivity value on the 0% specimen at 21.35 kΩ.cm and the lowest resistivity on the 5% specimen at 16.70 kΩ.cm. The resistivity value decreases with increasing corrosion levels. The post-corrosion concrete has the highest resistivity on the 0% specimen, with 18.56 kΩ.cm, and the lowest resistivity on the 5% specimen, with 13.88 kΩ.cm. The resistivity value decreases with increased corrosion levels. The impact-echo testing on the pre-corrosion specimen yielded a 0% specimen with a value of 14394.53 Hz and a 1% specimen of 18266.6 Hz. The frequency value decreases with increasing corrosion levels. The result of impact-echo testing on post-corrosion concrete was 14394.53 Hz for the 0% specimen and 1567.38 Hz for the 5% specimen. The frequency value decreases with increasing corrosion levels.