Natural and accelerated carbonation rates of alkali-activated slag/fly ash blended concretes

Author(s): Susan Bernal, Jannie van Deventer, John Provis
Paper category: Proceedings
Book title: Proceedings of the International Conference on Sustainable Materials Systems and Structures (SMSS2019) Durability, Monitoring and Repair of Structures
Editor(s): Ana Baričević, Marija Jelčić Rukavina, Domagoj Damjanović, Maurizio Guadagnini
ISBN: 978-2-35158-217-6
e-ISBN: 978-2-35158-218-3
Publisher: RILEM Publications SARL
Publication year: 2019
Pages: 357-364
Total Pages: 813
Language: English

Abstract: Carbon dioxide present in the air is one of the main threats to our cement-based built environment. Its diffusion through mortars and concretes, and its dissolution in the pore water present in these materials, initiate acid-base reactions known as carbonation, leading to degradation or corrosion processes that can compromise the integrity of structures. In this study the carbonation rates of alkali-activated concretes produced with blast furnace slag/fly ash blends were determined. All concretes were designed to achieve a ompressive strength of 60 ± 5 MPa after 28 days of curing. The results are compared with those obtained for concretes solely based on alkali-activated blast furnace slag. Natural (0.04% CO2) and accelerated (1% CO2) carbonation was induced in the specimens under a controlled relative humidity of 65% at 23C. The partial substitution of slag for fly ash increased the carbonation rates of alkali- activated concretes when tested under accelerated carbonation conditions; however, under natural carbonation the partial replacement of slag seemed to have a negligible effect on the carbonation rate of these materials, at least during the period evaluated in this study (90 days).

Online publication :2019
Publication type : full_text
Public price (Euros) : 00