Natural Stone

Limestone is one of the most frequent building stones used in monuments in Egypt from ancient Egyptian times and salt weathering is one of the main threats to these monuments. During this work, cylindrical limestone samples (2 cm diameter and approx. 4 cm length) from Mokattam group, one of the most frequent materials in historic Cairo, were subjected, in a purpose-made simulation chamber, to laboratory salt weathering tests with a 10% weight NaCl solution at different temperatures (20, 30, 40 °C). During each test, temperature was kept constant and salt solutions flowed continuously imbibing samples by capillary rise resembling the way they get into building stone in many real cases. Air temperature, relative humidity inside the simulation chamber and also samples weight were digitally monitored and recorded. Results show the influence of temperature and the ratio between imbibitions and evaporation on the dynamics of salt crystallization in the samples.
KEYWORDS: Stone decay; Salt weathering; Limestone; Durability

The paper deals with the theme of environmental issues connected to marble quarries, focusing the attention on extraction processes, on waste disposal of this activity and on transports and infrastructures. The marble extraction is an energy-intensive process and is characterized by a significant production of waste (on average, 1 ton of blocks generates about 1 ton of waste that usually goes to local special dump). The research applies to few marble quarries located in Puglia (Italy). Unfortunately in this area uncontrolled processes are leading to serious environmental emergencies. The study aims to emphasize the negative consequences due to transports development and the production of high quantities of residuals. The situation could be improved through a careful management of mining processes and the control of energy and materials flows. The study identifies strategies aiming to implement a system for the re-use of the waste through the development of new networks of local factories that reuse residuals deriving by marble and stone extraction and cutting. In order to compare the environmental improvement related to the different scenarios and strategies, the study proposes a model of evaluation based on a simplified set of environmental indicators. The method takes some parameters from the Life Cycle Assessment and contextualizes the evaluation with indicators that quantify and assess the territorial modifications engaged with marble quarries activities (for example land use). The study proposes a model to evaluate impacts and to support decisions, oriented to the stakeholders (public and private) of the various production processes, in order to guide their choices and to enable the comparison of different alternatives whit explicit criteria (environmental performances).