Anisotropic behaviour of White Macael marble used in the Alhambra of Granada (Spain): The role of thermohydric expansion in stone durability

One of the most commonly used marbles in Spain is “White Macael” marble, quarried in the Macael area of Almeria. Throughout Spanish history, White Macael has been in great demand as an ornamental stone and was used to build pieces of great importance and artistic beauty, such as the Fountain of Lions in the Alhambra (Granada).Over the centuries, such pieces have suffered from decay due to exposure to the elements, as has happened in many other marbles all over the world.The main purpose of this paper was to determine the durability of White Macael marble when subjected to changes in thermal conditions. It was observed that these changes in the presence of humidity were an important factor in marble decay. They produce a progressive loss of cohesion along grain boundaries and an increase in porosity, which are starting points for marble degradation and facilitate the development of other pathologies.