DYNAMIC CHARACTERIZATION OF CEMENT AND CERAMIC CHEMISTRY. Paul Barnes, Industrial Materials Group, Dept. Crystallography, Birkbeck College, London, UK

Elucidating reaction/structural pathways requires a complementary approach: Conventional diffraction/refinement techniques (e.g. Rietveld-powder) can yield high resolution "structural snapshots", but such information needs to be allied to that from other structural probes (EXAFS, neutron-scattering, computer-modelling, NMR, EM) as well as from dynamic in-situ diffraction. This approach will be illustrated with examples taken from three areas:

(1) hydrothermal/autoclave synthesis of zeolites;

(2) high temperature furnacing of tetragonal/monoclinic zirconia from the amorphous hydroxide precursor;

(3) hydration of a variety of cements (Portland, calcium-aluminate, rapid) under conditions varying from ambient to autoclave.

In particular (3) will include a very recent dramatic example of a 3-phase scenario, anhydrous cement -> intermediate -> final hydrate, all occurring within 200 seconds.