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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 scanning electron microscopy were used to evaluate changes in pore properties, while weight loss and fracture density were used to assess deterioration severity. A primary aim was toobserve 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 inresistance to particular weathering processes. Consequently, when assessing durability it is essential to consider rock properties in thecontext 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 changesto the internal pore structure of rocks due to weathering may be a precursor to more substantial macrodeterioration. [ABSTRACT FROM AUTHOR]