In the UK, glass is by far the most recycled packaging material and it can be recycled indefinitely without loss of quality or performance. Glass can be reused in crushed or powdered form or in lightweight foamed materials or as an ingredient in ceramic products such as bricks.
Returning glass to the glassmaking process makes a great deal of sense in environmental terms, since it saves energy and primary mineral resources, as well as reducing waste and pollution emissions.
Since the first bottle bank was introduced in Barnsley in 1977, 7.7 million tonnes of glass have been recycled in the UK.
The main source of glass cullet is as a byproduct of recovery for recycling into the glassmaking process. This process is clearly a favourable one from a sustainability perspective, since it diverts waste away from landfill. Additionally, glassmaking with recycled cullet requires less energy and produces fewer emissions than the situation where only primary mineral resources are used as the feedstock.
In certain circumstances quantities of cullet may become available which cannot be recycled. It is in these situations that the use of glass cullet in alternative applications, such as in concrete, plays a sustainable role, since a use can be found for a material which is surplus to requirements. Glass is by nature a very hard and durable material which lends itself to being considered as a construction material.
In many regions of the UK, the reduced burden on primary aggregate resources through the use of secondary aggregate sources (such as glass cullet) is considered to be highly desirable.
WRAP, together with a consortium of partners, is sponsoring a project by the Concrete Technology Unit at the University of Dundee which aims to expand the market for processed glass cullet as a construction material by raising awareness of high value/high volume applications. This objective is in line with the WRAP target of diverting at least 200,000 tonnes of green cullet into construction applications. The project follows on earlier research which established a set of specifications for using recycled glass in construction, either as a cement compound or as a fine or filler aggregate in concrete.
The project aims to identify Best Practicable Environmental Options (BPEOs) for the use of recycled glass in construction. BPEOs are options which have the largest positive, or smallest negative, impact on the environment, with acceptable cost. Given the wide range of options which are available for using recycled glass in construction, it is essential that each of these options are assessed in terms of their environmental impact, and also their likely cost. From such assessments, BPEOs can be identified.
The project will use Environmental Life-Cycle Analysis (LCA) techniques (see diagram below). The main output from the project will be a document providing detailed analysis of the environmental impact of each recycled glass use option, and identifying BPEOs.