The effect of steam curing on chloride penetration in geopolymer concrete

Januarti Jaya Ekaputri,Koichi Maekawa,Inne Syabrina Mutiara,Davin H E Setiamarga,Davin H E Setiamarga,Siti Nurminarsih,Nguyen Van Chanh,J.-W Park,P Thayaalan,H Hardjasaputra,H Ay Lie

doi:10.1051/matecconf/201713801019

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 (Na 2 SiO 3 ). 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.

Highlights

Seawater greatly affects the strength of concrete for construction, especially on offshore buildings
We report the result of our detailed investigation into the effect of moist curing using steam on the strength and durability of geopolymer concrete and its rebar, in order to elucidate if such method is effective to prevent the negative effect of chloride ion penetration
We reported mechanical properties and elastic modulus changes of geopolymer concrete, due to steam curing, it was found that the mechanical properties change and the elastic modulus on geopolymer concrete due to steam curing

Summary

Introduction

Seawater greatly affects the strength of concrete for construction, especially on offshore buildings. High salt content gradually decreases the strength of concrete, causing a decrease on the durability of concrete significantly. Such breaches on concrete strength and durability greatly affect the building’s service life, and bring safety concerns at the same time. Previous studies have shown that the compromise of concrete strength caused by seawater is due to aggressive penetration of the chloride ions (Cl-) from the saltwater into the concrete [1]. In order to reduce the level of chloride ion penetration, concrete mixed with high volume of fly ash is commonly used to build concrete structures in aggressive environments [2, 3]

Methods

Results

Conclusion