The ongoing energy crisis has brought consideration of the circular economy in structural glass construction to the forefront. Although glass is theoretically a material that can be recycled an infinite number of times, virtually no glass that has been dismantled has been added back to flat glass production due to high quality requirements of the cullets to prevent contamination. The high energy consumption required to produce flat glass makes the re-use of glass without re-melting interesting. Since the strength of glass is determined by its surface defects, this prompts the questions of what the strength of deconstructed glass is, whether it can be restored, and what processes are suitable for that endeavor. Literature reports, that due to via heat treatment of defined mechanically? pre-damaged annealed soda–lime silicate glass can increase its fracture strength, which serves as the methodical starting point of this research.
In order to study this phenomenon in more detail, this paper investigates various temperature programs (different temperature levels and treatment durations) on pre-damaged soda-lime glass samples, whereby samples are pre-damaged with a defined crack depth and the samples are slowly cooled down after the heat treatment, so that they remain annealed. The initial surface damage is introduced with an universal surface tester and the characterization of this pre-damage is determined by the crack depth before and after heat treatment.
Double-ring bending tests are performed to determine the strength of the heat-treated samples. The results are compared with a reference series (pre-damaged, but without further treatment) to show the potential of this method and the possibility of healing cracks as restoring strength.