Lifetime prediction of reinforced concrete structures in carbonation environments carbonation modelling vs air permeability modelling

Abstract

This article compares two models for the prediction of lifetimes of reinforced concrete structures in carbonation environments based on different tests: carbonation test-based modelling and air permeability test-based modelling. The study also includes experimental testing of five concrete mixes with different types of cement in order to validate the models using safety factors. The tests included compressive strength, accelerated carbonation and air permeability. Both models are defined in a European standard as being alternative to each other, meaning that their results for the same concrete composition and the same environment should converge. The results show that both current models can scarcely constitute alternative to each other. Design lifetime results are far from similar for each concrete mix and each exposure class. The different nature of each test – accelerated carbonation and air permeability – and their different characteristic such as the scattering of results and the unrelated parameters of the modelling equations are some of the features discussed, including the possibility of using different safety factors as function of the model and definition of possible correlation between tests.

Keywords:

• air permeability
• carbonation
• corrosion
• design lifetime
• partial safety factor method
• performance-based approach
• semi-probabilistic method

Additional information

Notes on contributors

Pedro Faustino

Pedro FAUSTINO. MSc, Structural Engineer at LEB, Ltd. in Portugal. He received his degree in Civil Engineering at NOVA Lisbon University in 2002 and his MSc degree at IST – Technical University of Lisbon in 2007. He has carried out projects for the durability retrofitting and repair and strengthening of reinforced concrete structures. He has also conducted research studies as regards durability and strengthening of reinforced concrete structures. He has authored and co-authored approximately 20 publications concerning his developed research studies.

Fábio Gonçalves

Fábio GONÇALVES. MSc in Civil Engineering received at the ESTB-Polytechnic Institute of Setúbal (IPS) in Portugal in 2013. He has co-authored research projects in the field of durability of reinforced concrete structures and the thermal performance of buildings using systems with cork and industry waste.

Ana Brás

Ana BRÁS. PhD, Civil Eng, Adjunct Professor at the ESTB-Polytechnic Institute of Setúbal (IPS) in Portugal. She received her PhD degree at the NOVA Lisbon University in 2009. She authored and co-authored approximately 20 research publications and has reviewed articles for ISI journals. Her research interest includes buildings life cycle analysis, buildings thermal performance, fresh and hardened state performance of concrete with blended cements, concrete and mortars blended with industry waste.

Ângela Nunes

Ângela NUNES. MSc in Materials Engineering. Executive Director at SECIL S.A. in CDAC – Cement Application Development Centre. She received her degree in Civil Engineering at IST – Technical University of Lisbon in 1984 and her MSc degree by joint universities of NOVA/IST/FEUP in 1996. She has given technical support for cement applications for designers and architects in special projects with white, coloured and textures concrete. Conducts cement/concrete performance control and quality specification, market oriented for Secil cement plants in 3 continents. Manages the Secil concrete Laboratory for concrete, aggregates and precast tests. Representative of Secil corporate member at RILEM. Manages Secil’s product development plan for cement, concrete mortars and precast products for the delivery of new market oriented new cementitious-based products.