Dawn T. Nicholson
The results
are reported of four experimental weathering tests: freeze-thaw, wetting and
drying, slake durability and salt weathering, on five different types of limestone.
Effective porosity, mercury intrusion porosimetry and SEM were used to evaluate
changes in pore properties, while weight loss and fracture density were used
to assess deterioration severity. A primary aim was to observe modifications
in porosity due to weathering and to draw inferences about the internal rock
deterioration mechanisms taking place.
It is concluded
that the five limestones not only show a wide range of resistance to weathering
in general but considerable difference in resistance to particular weathering
processes. Consequently, when assessing durability it is essential to consider
rock properties in the context of the weathering process to which the rock is
subject. The type of deterioration indicator used is also important in interpretation
of durability. A variety
of pore modification mechanisms operate, including changes in pore connectivity,
pore infilling, and the introduction of additional void space. There are indications
that changes to the internal pore structure of rocks due to weathering may be
a pre-cursor to more substantial macro-deterioration. Keywords: Porosity,
limestone, weathering, breakdown mechanisms, durability