Alkali Activated Green Building Materials – Selected Case Study of Alkali Activated Aggregate

Abstract

Alkali activated materials (AAM) are obtained trough the reaction of aluminosilicate materials, preferably waste, with alkali activation solutions what results in materials with properties comparable to ceramic or concrete but at the same time with a  significant lowering of CO2 footprint. One such example which could consume a huge amount of waste is production of aggregate. Alkali activated aggregate (AAA) within this research was obtained from fly ash by granulation on a pelletization plate and curing at room conditions or elevated temperature. The density, porosity, compressive strengths, and alkali silica reactivity of so obtained AAA were determined. Density is below 2000 kg/m3, what classified this aggregate into lightweight aggregates (EN 13055-1:2002). Compressive strength depends greatly on the curing regime, and it amounts to 2.6 MPa if aggregate is cured at room conditions, by application of curing at 65 °C the compressive strength is 4.7 MPa. If aggregate is fired then the corresponding compressive strength increases up to 11.4 MPa. Alkali silica reactivity test confirmed that certain expansion is to be expected if such aggregate is used in concrete.