Novel Recycled Waste Glass-Based Material with Geopolymerisation

The concept of green construction with recycled materials has been widely discussed and investigated lately. This paper introduces a sustainable option of a lightweight, porous, composite material with recycled waste glass (RWG) that can be used specifically for geotechnical applications such as columnar inclusions to support embankments for transport infrastructure constructed over soft ground. The material proposed here is a combination of RWG aggregates and RWG-based binder where the aggregate part is a coarse mix of poorly graded RWG ranging from 75 μm to 9.5 mm. An environmentally friendly binding mechanism with fine glass powder-based geopolymerisation is proposed here to substitute the traditional cement-based binders. General fine ground soda-lime glass powder (GP) was used as the precursor of the geopolymerisation, activated with 10 M sodium hydroxide and cured at 85 °C. Commercially available class F fly ash (FA) and cleaned waste aluminium foils (AF) were examined under two trials to evaluate the possibility of catering for the deficiency of aluminium in GP for a successful geopolymerisation process. AF pre-dissolved in sodium hydroxide in 2:1, Na:Al ratio proved to be the ideal filler of aluminium required for the geopolymerisation process. Further investigation on the above combinations showed that 24 h of curing at 85 °C results in the maximum compressive strength of the hardened composite mix. The mineralogical characterisation of the finalised binder mix with X-ray diffraction (XRD) and stagewise microstructure analysis with scanning electron microscopy (SEM) confirmed the geopolymerisation with the formation of an alkaline aluminosilicate (N–A–S–H) gel.