Assessing Local and Long-Range Structural Disorder in Aggregate-Free Lime Binders

For aggregate-free, calcite-containing lime binders, we correlate long-range crystallinity parameters from X-ray diffraction measurements (lattice constants, crystalline domain sizes, and microstrain fluctuation values) with short-range structural parameters from extended X-ray absorption fine structure data (coordination environments, attenuation factors, and fit stabilities). In doing so, we reveal a correlation between unit cell contraction and a more ideal local calcite structure. Using Fourier transform infrared spectroscopy and X-ray absorption near edge spectroscopy, we rule out the possibility of contributions from amorphous calcium carbonate and show that the structural disorder is likely related to localized regions of incomplete carbonation. Thus, by using data from this judicious combination of structural characterization tools, we demonstrate that short-range structural distortions occur in calcitic lime binders and that these distortions can be detected even in multiphase mixtures.