The durability of concrete structures is strongly affected by formation or decomposition and reformation of hydrated calcium aluminosulfate compounds, such as ettringite. The changes are caused by environmental factors, such as humidity, temperature, and the presence of sulfates and carbonates. The goal of this study is to determine the nature of the compound crystal structure changes with environmental variables and to determine the dynamics of water as a crystal-chemical structural member.
Neutron diffraction and NMR studies of compound structure will be combined with X-ray and TGA measurements to examine the formation and decomposition of the cement hydration compounds and to elucidate the effects of relative humidity, and of sulfate, silicate, and carbonate concentrations on compound structure. Of particular interest will be the orientation of the water in the hydrated molecules, its dependence on environmental factors, the dynamics of the structural water and the effects of its relatively easy ingress and egress on the migration of other impurities in the system. This will lead to better understanding and control of the deterioration of concrete structures due to environmental attack.
