Location
University of Leeds
Keywords
Durability, Supplementary Cementitious Materials, Glass Powder, Chloride Ions Penetration, Bulk Resistivity, Pore Solution Conductivity
Abstract
The capacity of concrete to prevent chloride ions penetration represents a key durability factor for steelreinforced structures exposed to de-icing salts and/or marine environments. Although blended-cement systems are commonly characterized with accelerated chloride penetration tests developed for Portlandcement concrete (e.g. the ASTM C1202 method), their microstructures and pore solutions are very different. This study aims to illustrate how the full potential of blended-cement systems to resist chloride ingress (and thus, chloride-induced corrosion) may not be justly disclosed by these accelerated tests using electrical current, even when tested after three months of curing. A Portland-cement-only mortar and five binary blended-cement mortars containing typical dosages of fly ash, slag, metakaolin, glass powder or rice husk ash were characterized using the ASTM C1202 chloride penetration test, bulk resistivity measurements and pore solution resistivity measurements. The results showed similar very low chloride penetration potential after three months for the investigated systems (except for the slag system which showed a low potential). The microstructure was densified with time particularly for systems with fly ash or glass powder, as shown by comparing bulk resistivity measurements after three months and one year of curing. However, measurements of the pore solution resistivity suggested a reinterpretation of the observed trends and the glass powder showed unique features for long-term resistance to chloride-induced corrosion. Finally, this work illustrates the importance of understanding the effects of supplementary cementitious materials on both the microstructure and the pore solution, while motivating further work on complementary aspects such as chloride migration coefficients, chloride binding, porosity distribution, or interfacial transition zone.
Included in
Will Blended-Cement Systems with Similar Chloride Penetration Potentials Resist Similarly to Corrosion?
University of Leeds
The capacity of concrete to prevent chloride ions penetration represents a key durability factor for steelreinforced structures exposed to de-icing salts and/or marine environments. Although blended-cement systems are commonly characterized with accelerated chloride penetration tests developed for Portlandcement concrete (e.g. the ASTM C1202 method), their microstructures and pore solutions are very different. This study aims to illustrate how the full potential of blended-cement systems to resist chloride ingress (and thus, chloride-induced corrosion) may not be justly disclosed by these accelerated tests using electrical current, even when tested after three months of curing. A Portland-cement-only mortar and five binary blended-cement mortars containing typical dosages of fly ash, slag, metakaolin, glass powder or rice husk ash were characterized using the ASTM C1202 chloride penetration test, bulk resistivity measurements and pore solution resistivity measurements. The results showed similar very low chloride penetration potential after three months for the investigated systems (except for the slag system which showed a low potential). The microstructure was densified with time particularly for systems with fly ash or glass powder, as shown by comparing bulk resistivity measurements after three months and one year of curing. However, measurements of the pore solution resistivity suggested a reinterpretation of the observed trends and the glass powder showed unique features for long-term resistance to chloride-induced corrosion. Finally, this work illustrates the importance of understanding the effects of supplementary cementitious materials on both the microstructure and the pore solution, while motivating further work on complementary aspects such as chloride migration coefficients, chloride binding, porosity distribution, or interfacial transition zone.
