EXPERIMENTAL STUDY OF CORROSION POTENTIAL OF CONCRETE WITH VOLCANIC ASH OF MOUNT MARAPI AS PARTIAL REPLACEMENT OF CEMENT IN EXTREME EXPOSURE ENVIRONMENT

Abstract

Most of the damage to concrete structures is caused by corrosion of the reinforcing steel in the concrete due to chloride intrusion in the pores of the concrete, especially on structures exposed to extreme weather. The eruption of Mount Marapi in West Sumatera left a lot of volcanic ash and became waste around the affected areas. Using volcanic ash is known to make porosity tighter and inhibit the entry of chloride ions into concrete. This study aims to obtain corrosion potential in concrete with volcanic ash as a partial replacement for cement with the Half-cell potential method. A sample of 15x15x15 cm cube-shaped reinforced concrete with a thickness of 4 cm concrete blanket was made with a composition of 0%, 10%, and 20% volcanic ash. The properties of the concrete-forming material were tested to obtain the K-250 concrete mix design at 28 days. Samples were exposed to different exposure simulations, including being cured using wet cloths and other samples placed under extreme weather without treatment. The corrosion potential was tested using Ag/AgCl reference electrodes during the concrete treatment period of up to 28 days. The results showed that the use of volcanic ash gave a half-cell potential result of 0% VA substitution (extreme) on day 1 still tended to be high with a potential value of - 201.61 mVvsCSE and a curing process of -200.17 mV vs CSE, a 10% VA substitution (extreme) value of -242.94 mV vs CSE and a curing process of -198.39 mV vs CSE, a 20% VA substitution (extreme) value of -215.83 mV vs SCE and curing of -221.61 mV vs CSE. On day 28 potential outcomes dropped significantly at VA 0% (extreme) -142.06 mV vs CSE and curing -99.06 mV vs CSE, substitution 10% (extreme) -209.83 mV vs CSE and curing -112.17 mV vs CSE, substitution 20% (extreme) -141.17 mV vs CSE and curing -102.61 mVvs CSE.