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Recycled glass aggregate concrete : thermal, dimensional and strength behaviour

The aim of the work presented in this thesis is to examine the thermal, dimensional and strength behaviour of glass concrete. The type of concrete used for this study differed significantly from those of other researchers. Firstly, the particle size distribution of glass identically matched the grading of natural aggregate. Secondly the glass used was free of sharp edges, uncontaminated, and produced by a unique implosion technique. The results showed that the process of cement hydration produces a much higher temperature in concrete made with glass cullet. Furthermore, when such concretes were allowed to hydrate under freezing conditions (-10°C or -20°), glass concrete was able to withstand freezing much longer than control concrete. The exposure of glass concrete to both high (60 °C) and low (-20°C) temperatures maintained greater temperature stability. This behaviour is attributed to the thermal properties of glass and the pore structure of glass concrete. These findings suggest that concrete made with recycled glass could have two important applications, namely, cold temperature concreting and in buildings where it is important to maintain greater temperature stability. The benefits of glass aggregate exceeded the enhanced performance of the best available accelerator with natural aggregate. Glass concrete probably has a lower drying shrinkage than any natural aggregate. Because of its low shrinkage, glass concrete is more affected by a change in water to cement ratio. The reduction in shrinkage was related to the glass content of the concrete. A mathematical model is suggested for the prediction of drying shrinkage of concrete made with a mix of glass and natural aggregates. This model produced a very good correlation with the experimentally obtained results. The 28 day compressive strength of standard cured glass concrete was lower than that of control concrete. However, significantly higher rates of strength development are achieved during the first 7 days due to the early acceleration of hydration resulting from the thermal properties of glass. There is also a much greater gain in the strength of glass concrete between the ages of 28 days and 1 year. As a result of these trends, the early age and long term strength of glass concrete is higher than that of control concrete. The post 28 day gain in strength is mainly attributed to better bonding of glass aggregates and the pozzolanic activity of the finest glass particles. When glass concrete is cured at either a high (40°C) or low (-10°C and -20°C) curing temperature, the 28 day compressive strength is higher than control concrete. Glass concrete that had been cured at low temperatures and then subsequently allowed normal curing recovered 100% of its strength, while the recovery for control concrete was just 50%. Thus it can be concluded that glass is better suited for both hot and cold weather concreting.
Date January 2007
CreatorsPoutos, Konstantinos I.
PublisherUniversity of Portsmouth
Source SetsEthos UK
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation

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