Utilization of imploded glass in concrete

Abstract

Land-filling waste has become a problem and a waste in itself. A lot of material that is being landfilled can be reused with minimal processing reducing demand on natural resources and landfills. In the last years local public awareness on the reuse of waste has started to rise and larger amounts of reusable material are collected each year. Concrete is an ideal material for the reuse of glass and other waste materials due to its wide use and demand for material of not such a high quality while also creating a long term solution. When used as large particles glass has proved to be deleterious to concrete forming a poor bond and also exhibits alkali silica reaction (ASR). In concrete effected by ASR an expensive gel that causes the concrete to crack is formed. The use of glass less the 1 mm In diameter resulted in concrete that did not suffer from ASR. Glass ground to a fine powder proved to have pozzolanic properties and was beneficial as a partial cement replacement. Crushing to such a fine powder proved to be a high energy procedure and its environmental and economical benefits are doubtful. The recent introduction of the Implosion Technology allowed waste glass to be processed producing a cleaner product which is free of sharp edges, uses less energy than the impact crushers which are used normally, making glass much easier to handle and of a much better quality to reuse. Investigations were carried out to compare the contaminated mixed glass collected at bring in sites reduced either by a standard impact crusher or by a glass imploder. The glass was used in various proportions as cement replacement and the resultant concrete was tested in both compression and flexure. The feasibility of using glass with a particle size varying from dust to about O.S mm as a partial cement replacement produced through an industrial crusher was assessed. Such tests lead to better interpretation of the balance that exists between pozzolanic activity and processing energy. Results showed that there was pozzolanic activity, 10-20% cement replacement gave compressive and flexural strength results similar to that of normal concrete while 30-40% cement replacement still produced concrete of good quality. When tested for durability and the susceptibility to chloride attack the concrete with 10-40% replacement showed a significantly higher resistance making such a concrete ideal for areas exposed to or in sea water. It can be concluded that a widespread use of waste glass in concrete is possible, and can be done with the technology that is already available locally.