High volume utilization of waste glass powder as a cement replacement in the composition of self-compacting concrete.
Thesis DisciplineCivil Engineering
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The principle objective of this research was to assess the capability of self-compacting concrete utilizing waste glass as partial replacement for GP cement and as an alternate to class F and class C fly ashes and limestone filler. The viability of using this self-compacting concrete was assessed by conducting various tests. The incorporation of glass powder, whether finer/coarser or in less/more proportions, influenced rheology of self-compacting concrete. A better rheological performance was achieved by the mixes containing glass powders of finer sizes and added at lower contents. However, excessive use of superplasticizer beyond a certain limit resulted in strength loss due to microstructural damage and increase in pore areas. The use of finer glass powder at lower replacement levels in self-compacting concrete resulted in higher compressive strength, splitting tensile strength and elastic modulus than coarser glass powder used at higher contents. The durability was also improved particularly with the addition of smaller sizes of glass powder and lower glass powder contents. Glass powder improved concrete properties by reactive filler effect and pozzolanic action that led to reduction in pore sizes and well packed concrete mix. The improved particle distribution of glass powder also resulted in reduction of the thickness of transition zone leading to densely packed stronger concrete. On the other hand, the mechanical properties of concrete containing unwashed glass powder worsened compared to washed glass incorporated mixes. In addition, the replacement of cement with unwashed glass powder resulted in concrete with inadequate durability properties. Accelerated cured mix incorporating washed glass powder achieved its target strength and improved the microstructure, irrespective of the following curing regime. Conversely, elevated cured self-compacting concrete containing unwashed glass powder could not reach its design strength even with subsequent water-curing. Hence, GP cement, class F and C fly ashes and limestone filler can successfully be replaced by glass powder of fineness 10 μm added up to 30% and 20 μm added up to 20%-30%, in a self-compacting concrete mix, particularly where both strength and durability are essential requirements. Moreover, limestone filler can be replaced by glass powder of fineness 20 μm added up to 40% and 40 μm added up to 30% in a self-compacting concrete mix, where durability is of a greater concern and strength can be compromised. The present research will benefit concrete producers and consumers and will increase economic and environmental advantages for concrete industry by limiting the production of cement and utilizing waste glass resources in New Zealand and around the globe.