Abstract

ANGULO-RAMIREZ, Daniela E.; VALENCIA-SAAVEDRA, William G.  and  MEJIA DE GUTIERREZ, Ruby. Alkali-activated concretes based on fly ash and blast furnace slag: Compressive strength, water absorption and chloride permeability. Ing. Investig. [online]. 2020, vol.40, n.2, pp.72-80.  Epub Dec 18, 2020. ISSN 0120-5609.  https://doi.org/10.15446/ing.investig.v40n2.83893.

Concretes based on alkali-activated binders have attracted considerable attention as new alternative construction materials, which can substitute Portland Cement (OPC) in several applications. These binders are obtained through the chemical reaction between an alkaline activator and reactive aluminosilicate materials, also named precursors. Commonly used precursors are fly ash (FA), blast furnace slag (GBFS), and metakaolin. The present study evaluated properties such as compressive strength, rate of water absorption (sorptivity), and chloride permeability in two types of alkali-activated concretes (AAC): FA/GBFS 80/20 and GBFS/OPC 80/20. OPC and GBFS/OPC* concretes without alkali-activation were used as reference materials. The highest compressive strength was observed in the FA/GBFS concrete, which reported 26,1% greater strength compared to OPC concrete after 28 days of curing. The compressive strength of alkali-activated FA/GBFS 80/20 and GBFS/OPC 80/20 was 61 MPaand 42 MPaat 360 days of curing, respectively. These AAC showed low permeability to the chloride ion and a reduced water absorption. It is concluded that these materials have suitable properties for various applications in the construction sector.

Keywords : alkaline activated concrete; fly ash; blast furnace slag; mechanical and permeability properties.

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