Trials confirm benefits of recycled glass in concrete-block production
Scottish concrete-block manufacturers Brand & Rae have found the evidence they were looking for after successful trials showed that recycled glass does provide a commercially viable and environmentally friendly alternative to the use of primary aggregates in the manufacture of higher-value blocks.
The Fife-based company received funding from the Scottish Executive, through WRAP (the Waste & Resources Action Programme), to carry out commercial-scale trials at their main plant at Russell Mill in Fife and a mobile plant at Bonnyrigg, near Edinburgh.
The six-month trial, involving the manufacture of 75,000 concrete blocks at both sites, confirmed that crushed recycled glass can be used as a replacement for primary aggregates in the manufacturing process and, in certain cases, blocks containing recycled glass perform better than conventional ones in terms of strength and performance in adverse weather conditions.
Trials at the Bonnyrigg site tested blocks traditionally used in standard or cavity wall construction produced on a mobile concrete-block making system, while at the Russell Mill site, lightweight, paint- and masonry-grade blocks were produced on a static plant, allowing comparisons between the two methods.
The Bonnyrigg trials found that the optimum percentage of recycled crushed glass in place of primary aggregates is 30%. This is the percentage at which strength is at a maximum and drying shrinkage is at a minimum — the lower the drying shrinkage, the less prone a concrete block is to crack.
At Russell Mill the trials concluded higher levels of replacement glass can be achieved at a static plant. The findings showed that, as the glass levels increased, the strength of the manufactured blocks improved. Up to 80% recycled glass was used as a direct alternative for natural aggregates without any detrimental effect on performance or handling, however the best outcome for drying shrinkage was found to be 45% replacement glass.
Commenting on the trials, Gary Bell, managing director of Brand & Rae, said: ‘The advantages have been clearly demonstrated through better strength and lower drying shrinkage. We have already commenced production at Bonnyrigg of a block containing 30% glass.’
The Fife-based company received funding from the Scottish Executive, through WRAP (the Waste & Resources Action Programme), to carry out commercial-scale trials at their main plant at Russell Mill in Fife and a mobile plant at Bonnyrigg, near Edinburgh.
The six-month trial, involving the manufacture of 75,000 concrete blocks at both sites, confirmed that crushed recycled glass can be used as a replacement for primary aggregates in the manufacturing process and, in certain cases, blocks containing recycled glass perform better than conventional ones in terms of strength and performance in adverse weather conditions.
Trials at the Bonnyrigg site tested blocks traditionally used in standard or cavity wall construction produced on a mobile concrete-block making system, while at the Russell Mill site, lightweight, paint- and masonry-grade blocks were produced on a static plant, allowing comparisons between the two methods.
The Bonnyrigg trials found that the optimum percentage of recycled crushed glass in place of primary aggregates is 30%. This is the percentage at which strength is at a maximum and drying shrinkage is at a minimum — the lower the drying shrinkage, the less prone a concrete block is to crack.
At Russell Mill the trials concluded higher levels of replacement glass can be achieved at a static plant. The findings showed that, as the glass levels increased, the strength of the manufactured blocks improved. Up to 80% recycled glass was used as a direct alternative for natural aggregates without any detrimental effect on performance or handling, however the best outcome for drying shrinkage was found to be 45% replacement glass.
Commenting on the trials, Gary Bell, managing director of Brand & Rae, said: ‘The advantages have been clearly demonstrated through better strength and lower drying shrinkage. We have already commenced production at Bonnyrigg of a block containing 30% glass.’
