Petrophysical and durability tests on sedimentary stones to evaluate their quality as building materials

摘要

Six types of sedimentary stone (four bioclastic calcarenites, one calcitic sandstone and one calcitic dolostone) commonly used as building materials were studied from a petrophysical point of view and their durability was evaluated. The following analytical techniques were used: X-ray diffraction, polarizing optical microscopy, hydric tests, mercury intrusion porosimetry, ultrasound, salt crystallization cycles, freeze-thaw cycles and colorimetry. The hydric behaviour of the stones is affected by their different textures. The most compact stone absorbs less water compared with the other samples and has the lowest open porosity; however, more porous and less compact stones achieved better results in terms of the degree of pore interconnection and the drying rate. All the stones have unimodal pore size distribution and most pores had radii of 10 urn or less. Accelerated ageing tests caused some changes in the colour of stones and, above all, the loss of fragments, especially during salt crystallization cycles. The main causes of decay were the different mineralogy between the grains and the matrix in the sandstone and a strong anisotropy owing to the presence of sedimentary planes in one calcarenite. On the basis of our results we then ranked the stones according to their quality as building materials.