On this page
- The challenges of using recycling glass fines
- Using glass fines in new products
- Sorting and cleaning glass fines
- Environmental benefits
- RMIT’s research report
- Projects that have successfully used recycled glass fines
Glass fines are the small glass particles (typically between 3 and 8 millimetres in size) that are broken during commingled recycling collection, transportation and processing.
The market for using glass fines in new products is relatively undeveloped, so RMIT University partnered with leading sustainable materials producer Alex Fraser Group, and glass designer Mark Douglass, to examine ways to overcome the barriers of recycling glass fines and provide tangible insights for business and investors on the various uses of this low-cost but high-value material.
The project was supported by Sustainability Victoria through a Research, Development and Demonstration grant and resulted in a final report (PDF, 9.7MB).
Glass fines are considered unsuitable for recycling or remanufacturing into glass for a number of reasons.
- Contamination in recycling bins – Glass fines are difficult to process after they mix with other materials present in commingled recycling bins, including ceramics, stoneware, Pyrex and plastics.
- Difficult to sort at facilities – Glass fines have sharp edges and come in various sizes and colours. These characteristics make the material difficult to sort at material recovery facilities (MRFS), as current machinery is often not built for glass fine specifications.
- Low economic value – Due to the affordability of imported virgin glass, recycled glass fines are a high-supply, low-demand material that give businesses little financial incentive to use recycled glass.
One of the major challenges for refining recovered glass fines is the mixing of colours that occur through the commingled recycling system.
– RMIT glass fines report
The challenges associated with recycling glass fines often lead to the otherwise valuable glass material being stockpiled or landfilled.
The research project focused on understanding the properties of glass fines and identifying contaminates present from the commingled kerbside recycling process.
Alex Fraser Group provided a range of glass fine samples and a series of technical explorations were undertaken by the RMIT research group to define the characteristics.
The research found that:
- The most common type of glass fine is from soda lime glass, predominantly used in food and beverage packaging.
- Glass fines are mixed in with ceramics, stones, porcelain, borosilicate and other non-recyclable glass types found in the commingling bin.
- Contaminants are primarily composed of carbon, sodium, calcium, sulphur, iron, potassium, aluminium and chlorine.
Left: Polished glass fine cement sample; Right: Patterned green polished recycled glass fine tile
The research identified and explored a diverse range of new uses for glass fines. These included using glass fines in:
- construction materials and products such as:
- thermal insulation for prefabricated panels
- concrete aggregate
- cement replacement
- cementitious glass
- lightweight bricks
- building products made from glass foam.
- consumer products such as:
- decorative objects (for example, lighting fixtures)
- tiles and bricks
- porcelain and stoneware
And harnessing glass fines for:
- artisanal purposes such as:
- marving (glass blowing)
- environmental uses such as:
- water filtration systems
- an alternative to granitic sand and gravels for landscaping
- glass structures that support sea-bed erosion and artificial reef structures
- feed stock for mycelium biocomposites.
This otherwise unutilised material could be used for a range of potential low cost, high-value product development opportunities.
– RMIT glass fines report
Left: Green and grey coloured recycled glass fine lampshade
Right: Rounded decorative containers with a solid recycled glass fine base and curved glass lids