Activated Fly Ash-ash and Nano-silica Blends for Sustainable Self-consolidating Concrete
Mentor 1
Dr Konstantin Sobolev
Mentor 2
Dr Marina Kozhukhova
Location
Union Wisconsin Room
Start Date
28-4-2017 1:30 PM
End Date
28-4-2017 4:00 PM
Description
The production of portland cement is a carbon intensive process releasing considerable amounts of CO2. Because of the scale involved, reduction in the amount of cement used in concrete can have significant effect on carbon dioxide emissions. Utilizing a by-product such as fly-ash is an ideal way to supplement the binder, but doing so while replacing portland cement without sacrificing the performance of concrete is challenging. The implementation of activation can convert this by-product to a higher-grade material capable of replacing portland cement. The combination of nano-engineered cement (NEC) and mechano-chemical activation (MCA) of fly ash with chemical admixture was realized, with the MCA being achieved through vibro-milling. Supplementary cementitious materials (SCM's) such as super-plasticizers and viscosity modifying admixtures were optimized to achieve critical properties such as workability, viscosity, and mechanical performance. Mortars with nano-silica and SCMs such as fly ash C and F were produced and studied for flowability and compressive strength. The activation of fly ash through vibro-milling accelerated the hydration of cementitious systems with fly ash and reduced setting time, enhancing early strength of blended cementitious composites of up to 30% fly ash. Results indicate that mortars based on activated class C fly ash had better performance than reference portland cement in all ages of curing. The effects of activation can be seen in the improvement of 1 and 7-day strength. While systems with 20% activated class F fly ash had 7 and 28-day compressive strength comparable to reference portland cement, 1 day performance was about 50% lower than the reference. Results also indicate that nano-silica can be effectively used to boost performance of systems with activated fly ash. Further research into the effect of class F fly ash, activation of fly ash, and its effect on composition and morphology beyond 28 days must be investigated.
Activated Fly Ash-ash and Nano-silica Blends for Sustainable Self-consolidating Concrete
Union Wisconsin Room
The production of portland cement is a carbon intensive process releasing considerable amounts of CO2. Because of the scale involved, reduction in the amount of cement used in concrete can have significant effect on carbon dioxide emissions. Utilizing a by-product such as fly-ash is an ideal way to supplement the binder, but doing so while replacing portland cement without sacrificing the performance of concrete is challenging. The implementation of activation can convert this by-product to a higher-grade material capable of replacing portland cement. The combination of nano-engineered cement (NEC) and mechano-chemical activation (MCA) of fly ash with chemical admixture was realized, with the MCA being achieved through vibro-milling. Supplementary cementitious materials (SCM's) such as super-plasticizers and viscosity modifying admixtures were optimized to achieve critical properties such as workability, viscosity, and mechanical performance. Mortars with nano-silica and SCMs such as fly ash C and F were produced and studied for flowability and compressive strength. The activation of fly ash through vibro-milling accelerated the hydration of cementitious systems with fly ash and reduced setting time, enhancing early strength of blended cementitious composites of up to 30% fly ash. Results indicate that mortars based on activated class C fly ash had better performance than reference portland cement in all ages of curing. The effects of activation can be seen in the improvement of 1 and 7-day strength. While systems with 20% activated class F fly ash had 7 and 28-day compressive strength comparable to reference portland cement, 1 day performance was about 50% lower than the reference. Results also indicate that nano-silica can be effectively used to boost performance of systems with activated fly ash. Further research into the effect of class F fly ash, activation of fly ash, and its effect on composition and morphology beyond 28 days must be investigated.
