The effect of steam curing on chloride penetration in geopolymer concrete

¹ Department of Civil Engineering, Institut Teknologi Sepuluh Nopember, Surabaya, East Java 60111, Indonesia
² Indonesian Consortium for Geopolymer Research, Institut Teknologi Sepuluh Nopember, Surabaya, East Java 60111, Indonesia
³ Logistic Engineering Department, Indonesian International University for Cement Studies, Gresik, East Java 61122, Indonesia
⁴ Faculty of Civil Engineering, Ho Chi Minh City University of Technology, Ho Chi Minh City, Ho Chi Minh 70000, Vietnam
⁵ Department of Civil Engineering, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033, Japan
⁶ Department of Applied Chemistry and Biochemistry, National Institute of Technology, Wakayama College, Gobo City, Wakayama 644-0023, Japan

^* Corresponding author: januartije@gmail.com
^* Corresponding author: davin@wakayama-nct.ac.jp

Abstract

In this paper, we present the result of our study on the effect of steam curing to chloride ion penetration in geopolymer concrete. Class F fly ash was activated using sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃). The concrete specimens were then steam-cured at 40°C, 60°C, 80°C and room temperature at 24 hours. The treatment was followed by wet curing for 28 days, and then followed by immersion of all specimens in salt water for the durations of 30, 60, and 90 days. Cylindrical specimens were then prepared for compressive strength, chloride ion penetration, pH, and porosity tests. A 16 mm-steel bar was fixed at the center of the specimen concrete blocks (specimen size: 10cm × 10cm × 15cm). Corrosion probability was determined by conducting Half Cell Potential test. Our result showed that increasing the curing temperature to 80°C induced chloride ion penetration into the concrete’s effective pores, despite improvements in compressive strength. We also found that chloride ingress on the geopolymer concrete increases commensurately with the increase of the curing temperature. The corrosion potential measurement of geopolymer concrete was higher than OPC concrete even if corrosion was not observed in reinforcing. Based on our result, we suggest that the corrosion categorization for geopolymer concretes needs to be adjusted.