A novel eco-friendly foaming technique for developing sustainable glass foams from the waste glass

The complex waste glass (WG) coming from the automotive vehicle industry has very low recycling potential and goes mainly to landfills. This research aims to develop a sustainable and eco-friendly method to prepare lightweight glass foams using this waste. Glass foams are porous, lightweight materials and are extensively used in various industry sectors. Gel-casting technique is known as an eco-friendly method for making glass foams by vigorous mechanical foaming. In gel-casting, the pore structure of the foam is initially stabilized by gelation of alkali-activated precursors and then strengthened by viscous flow sintering. However, the gelation process requires a prolonged activation and precuring processes of precursors at a raised temperature which is not energy-efficient. Therefore, this research aimed to reduce the gelation time and improve the pore characteristics in glass foams by a novel combined mechanical and chemical foaming technique. After quick alkali-activation of precursors and foaming, the hardened glass foams were sintered at 700-800 degrees C temperatures. It is concluded that the lengthy gelation process can be replaced by quick activation and combined foaming technique to develop desirable pore characteristics. The low-speed mechanical foaming imposes low shearing stress on the activated paste, which reduces pore coalescing. Additionally, chemical foaming by low-concentration hydrogen peroxide reduces anisotropic pore formation. Consequently, the pore structure in glass foam improves. The proposed ecofriendly foaming method is useful for producing glass foams in large scale with desirable density (300-400 kg/m(3)), thermal conductivity (<0.10 W/(mK)) and compressive strength (similar to 2 MPa).

Automated summary

This research aims to develop a sustainable method to prepare lightweight glass foams using waste glass from the automotive vehicle industry. By utilizing a novel combined mechanical and chemical foaming technique, the gelation time can be reduced and the pore characteristics in glass foams can be improved. This ecofriendly foaming method is useful for producing glass foams in large scale with desirable properties.