Transport properties of high-volume fly ash concrete: capillary water sorption, water sorption under vacuum and gas permeability

Studying concrete’s resistance to carbonation-induced corrosion usually involves exposing the material to CO2 for quite some time. To estimate the performance of high-volume fly ash (HVFA) concrete more quickly, two key properties governing this process can be studied, namely water penetrability and gas permeability. With respect to HVFA mixtures optimized for usage in an environment exposed to carbonation with wetting and drying, we adopted the latter approach. This paper presents a full assessment of concrete mixtures with varying fly ash amounts. A 50% fly ash mixture by mass with a binder content of 400 kg/m3 and a water-to-binder ratio of 0.4 had a lower capillary water uptake (−32.6%), water sorption under vacuum (−10.7%) and gas permeability (−78.9%) than a proper reference normally used in this environment. The fly ash applied had an excellent quality regarding loss on ignition (3.5%) and fineness (19% retained on a 45 μm sieve).

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