No abstract

Fired-clay materials such as brick, tile and ceramic artefacts are found widely in archaeological deposits. The slow progressive chemical recombination of ceramics with environmental moisture (rehydroxylation) provides the basis for archaeological dating. Rehydroxylation rates are described by a (time) 1/4 power law. A ceramic sample may be dated by first heating it to determine its lifetime water mass gain, and then exposing it to water vapour to measure its mass gain rate and hence its individual rehydroxylation kinetic constant. The kinetic constant depends on temperature. Mean lifetime temperatures are estimated from historical meteorological data. Calculated ages of samples of established provenance from Roman to modern dates agree excellently with assigned (known) ages. This agreement shows that the power law holds precisely on millennial time scales. The power law exponent is accurately 1 / 4 , consistent with the theory of fractional (anomalous) 'single-file' diffusion.

No abstract

We analyse rising damp using the concepts and methods of unsaturated flow theory. A simple first-order Sharp Front model is developed which uses clear physical principles and includes the effects of evaporation and gravity. We find that the simple model captures well the observed features of capillary rise in walls and is supported by the underpinning nonlinear capillary diffusion theory. For most cases, capillary forces are dominant and the effects of gravity can be neglected.

No abstract