Tests on Alkali-Activated Slag Foamed Concrete with Various Water-Binder Ratios and Substitution Levels of Fly Ash

Keun-Hyeok Yang, Kyung-Ho Lee

Department of Architectural Engineering, Kyonggi University Graduate School, Seoul, Korea.
Department of Plant & Architectural Engineering, Kyonggi University, Suwon, Korea.

DOI: 10.4236/jbcpr.2013.11002                

Abstract

To provide basic data for the reasonable mixing design of the alkali-activated (AA) foamed concrete as a thermal insulation material for a floor heating system, 9 concrete mixes with a targeted dry density less than 400 kg/m³ were tested. Ground granulated blast-furnace slag (GGBS) as a source material was activated by the following two types of alkali activators: 10% Ca(OH)₂ and 4% Mg(NO₃)₂, and 2.5% Ca(OH)₂ and 6.5% Na₂SiO₃. The main test parameters were water-to-binder (W/B) ratio and the substitution level (R_FA) of fly ash (FA) for GGBS. Test results revealed that the dry density of AA GGBS foamed concrete was independent of the W/B ratio an R_FA, whereas the compressive strength increased with the decrease in W/B ratio and with the increase in R_FA up to 15%, beyond which it decreased. With the increase in the W/B ratio, the amount of macro capillaries and artificial air pores increased, which resulted in the decrease of compressive strength. The magnitude of the environmental loads of the AA GGBS foamed concrete is independent of the W/B ratio and R_FA. The largest reduction percentage was found in the photochemical oxidation potential, being more than 99%. The reduction percentage was 87% - 93% for the global warming potential, 81% - 84% for abiotic depletion, 79% - 84% for acidification potential, 77% - 85% for eutrophication potential, and 73% - 83% for human toxicity potential. Ultimately, this study proved that the developed AA GGBS foamed concrete has a considerable promise as a sustainable construction material for nonstructural element.

Keywords

Alkali-Activated Foamed Concrete; Granulated Ground Blast-Furnace Slag; Fly Ash; Water-to-Binder Ratio; Environmental Load

Conflicts of Interest

The authors declare no conflicts of interest.

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