Project Description
Cement production is a highly energy-intensive and environmentally polluting process, however, despite the detrimental effects, the production rates are increasing annually to meet the ever-rising demand. Hence, it is imperative to look out for materials that can be used in place of cement for promoting green construction and sustainability. On the other hand, glass, post-consumption, is dumped in landfills instead of recycling due to factors such as high recycling cost, cheap imports and lack of awareness to name a few. Since glass is a non-biodegradable material, the practice of dumping waste glass in the landfills is environmentally unsustainable. Recently it has been revealed that glass at particular fineness exhibits pozzolanic characteristics. The focus of this study is to investigate the pozzolanic attribute of a coarse glass powder (<150 µm) used as a cement replacement; the substitution levels employed were 15% and 30% by weight of cement. In addition to the basic compressive strength testing, durability tests such as drying shrinkage, resistance to chloride ion penetration and heat of hydration were evaluated. The test results indicate that 30% is the ideal replacement level, providing a strength activity index (SAI) of 117%, a 32% higher resistance to chloride ion permeability and a 24% reduction in heat from hydration.
Project Personnel and Beneficiaries
There are multiple benefits of using waste gasss power as cement replacement: firstly, using a waste material would reduce the load on the landfills, secondly, the total cost would be less as recycled waste gasss power is replacing the costly cement; and finally, the use of waste gasss power would lead to sustainable construction as a consequence of a decrease in cement manufacturing.
Outcomes to Date
These positive outcomes were decisive in selecting coarse waste glasss powder(<150 µm) in the subsequent stages of the research project. Another purpose for choosing coarse waste glasss powder was to optimise the grinding energy, as a considerable amount of energy would be used to pulverise the coarse glass particles into fine particles, and the energy saved would thereby lead to a decrease in harmful CO2 emissions and reduced costs. In summary, a coarse waste glasss powder exhibiting a good compressvie strength at 30% glass powder replacement was preferred for the following research project.
Project Significance
Concrete is one of the most used materials in the world, and global production rates are rising annually to meet the ever-increasing demand. Cement, which is the main ingredient in concrete, is manufactured in enormous quantities. It is estimated that around 85.9 million metric tonnes of cement are produced in the United States (US) compared with 4,200 million metric tonnes worldwide (US Geological Survey, 2017). Cement production adversely affects the environment because it releases carbon dioxide into the atmosphere. Hence, it is crucial to find methods to curb these negative environmental effects. Pozzolanic materials such as fly ash, silica fume and blast furnace slag have been successfully used to reduce cement consumption and increase performance. However, these materials are by-products of other industrial processes, so industry experts are researching other alternatives to cement.