International RILEM Conference on Materials, Systems and Structures in Civil Engineering Conference segment on Frost action in concrete 22-24 August 2016, Technical University of Denmark, Lyngby, Denmark 91 THE INFLUENCE OF CARBONATION AND AGE ON SALT FROST SCALING OF CONCRETE WITH MINERAL ADDITIONS Ingemar Löfgren (1 & 2) , Oskar Esping (1) & Anders Lindvall (1) (1) Thomas Concrete Group, Gothenburg, Sweden (2) Chalmers University of Technology, Gothenburg, Sweden Abstract Resistance to salt frost scaling is tested by accelerated methods such as CEN/TS 12390-9 which originally were developed for Portland cement concrete. However, it has been shown that ageing and coupled deterioration mechanisms, like carbonation or leaching, alter the frost resistance. An example is concrete with high amount of slag where the frost resistance is reduced when the concrete is carbonated. Hence, modifications to the test methods have been proposed to take these effects into account and often an accelerated carbonation at an early age have been used. Though, it has been found that the accelerated tests show a much more negative effect than what is experienced in field conditions. This paper presents results from a laboratory study of concrete with mineral additions at different dosages and water/binder ratios which have been exposed to accelerated carbonation at 1% CO2-concentration at different ages. The results show that exposing the specimens to accelerated carbonation at a young age will result in an increased scaling but that the carbonation depths corresponds to 10 year natural exposure. By increasing the age before the accelerated carbonation exposure the scaling is significantly reduced and the salt frost scaling resistance seems to correlate better with field observations. 1. Introduction The resistance of concrete to salt frost scaling is tested by accelerated methods such as CEN/TS 12390-9 [1] and SS 137244 [2], which originally were developed based on the experience of Portland cement concrete [3] [4]. The testing regime is being under review, partly due to that it does not consider ageing effects, such as changes to pore structure, micro cracking, leaching and the effect of carbonation [3] [4] [5]. With increasing use of mineral additions, such as slag (GGBS) and fly ash (FA), for reducing the environmental footprint and improve resistance to reinforcement corrosion this type of test methods need to be modified so that it can safely and adequately be used for concrete with mineral additions. Moreover, the test results also need to be correlated with the performance in field conditions [6] [7].