| dc.description.abstract | Using CO2 as an addition in concrete is a technological advancement made possible by CO2 curing techniques and injection of CO2 during mixing. The benefits involve potential for CO2 storage by hydration, reduction of clinker cement use or stronger concrete. Previous research has shown that compressive strength increases as CO2 produces more calcium carbide in the concrete through hydration, as well as increase the rate of hydration. Fly ash, a bi-product of coal power plant operation, has been used as a pozzolan in concrete since the 1970s, providing an opportunity to reduce the use of clinker cement. This thesis studies the effects of combining these practices, and their potential as an improvement to the sustainability of concrete. 0 wt%, 1 wt% and 2 wt% CO2 per binder weight is injected in a concrete mixer for 0 wt%, 20 wt%, 30 wt% and 70 wt% (of total binder weight) fly ash concrete designs.
Unlike previous findings for normal concrete, results indicate a negative rela- tionship between compressive strength and CO2 additions for fly ash concrete. For extreme amounts of fly ash the results also show a negative effect on compressive strength of CO2 curing in atmospheric pressure. A decrease in workability from CO2 additions is shown for fly ash concrete, similarly to normal concrete. Contrary to the effect on normal concrete, it is shown that the degree of hydration and production of calcium carbonate is reduced by adding CO2 to fresh fly ash concrete. It appears from the results and hypothesis presented that fly ash concrete is unsuitable for carbon storage. | |
