Alkali-silica reaction in alkali-activated concretes: the tempering effect of fly ash in slag/fly ash systems

Author(s): Alexandre Rodrigue, Josée Duchesne, Benoit Fournier, Benoit Bissonnette
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: 184-191
Total Pages: 813
Language: English

Abstract: Alkali-silica reaction in concrete can result in severe cracking and lead to loss in serviceability of the affected infrastructures. To occur, the reaction needs alkali ions in the pore solution, reactive silica in the aggregates and high relative humidity. Alkali-activated systems require high pH activators to dissolve the aluminosilicates used as binders and could represent an aggravating factor to ASR. Dimensional changes of prismatic concrete specimens were monitored over time for a range of alkali-activated concrete mixtures prepared with slag, fly ash and slag/fly ash binders. Extremely reactive, highly reactive and non-reactive aggregates were used. Different fly ash contents (20, 30 and 40%) were investigated in slag/fly ash concretes prepared with the same aggregates and with a moderately reactive aggregate. With slag as unique binder, concrete prism expansions of 0.12% and 0.15% were recorded after two years for extremely and highly reactive aggregates, respectively. With fly ash as unique binder, expansions of -0.01% and 0.02% respectively were obtained after 2 years. For slag/fly ash mixtures, increasing the fly ash replacement level results in decreasing expansions for all tested aggregates. After one year of testing, only specimens from the mixtures with 20% fly ash and extremely reactive aggregates exceeded the 0.040% limit.

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