A combination of small-angle and inelastic neutron scattering studies are presented to elucidate the different effects of Class F and Class C fly ash additions on microstructure development in hydrating cement (and concrete). Small angle neutron scattering (SANS) measures the overall effect of fly ash on the microstructure while inelastic neutron scattering (INS) measures the purely pozzolanic reaction. It is shown that, while the traditional F and C classification delineates part of the difference in the microstructure development, it does not take full account of the calcium content in fly ash, which controls the fly ash self-cementing property. Nor does it account for all of the physical effects associated with fly ash addition. It is concluded that the overall effect of fly ash addition should be considered, rather than the pozzolanic reaction alone, in determining how best to recycle fly ash material into cement for maintenance of the concrete infrastructure.
Citation: Journal of Materials Research
Pub Type: Journals
cement, fly ash, inelastic neutron scattering, microstructure characterization, pozzolans, small-angle neutron scattering