Environmental Earth Sciences - Call for Papers
Building stones and geomaterials through history and environments - from quarry to heritage. Insights of the conditioning factors
Guest Editors: Siegfried Siegesmund, Luís Sousa, Rubén Alfonso López
The relationship between man and rocks began already from the beginnings of the first groups of human beings, who used the rock formations as a refuge and den, to later be used as a construction material. The evolution of civilizations was accompanied by an evolution in the use of natural rocks as a building material, reaching the point of using them to build not only dwelling places but even to erect imposing buildings and monuments that today are part of the heritage cultural world. The advantage of using natural construction rocks lies in their availability and their great variety of textures, colors, and hardnesses, in addition to the fact that they do not need to be manufactured, as industrial construction materials currently are (Portland cement, bricks, etc.), the reason why its use is quite friendly with the environment.
Increasing economic, ecological and administrative restrictions as well as geological causes have led to selective supply shortages since the beginning of the 21st century.The problem with the introduction of new rocks with an equivalent decoration to a product introduced to the market is the equivalence of rock technical and rock physical properties. Possible differences can present themselves as damage or structural failure when used in buildings. To meet these requirements, dozens of new stones are presented on the market every year, while around 10000 different rock varieties may exist on the international market.
Ecologically, this globalization is problematic. A life cycle assessment study by the German Natural Stone Association (Natursteinverband 2010) shows, when comparing two typical façade constructions made of natural stone and glass over a period of 100 years, that natural stone façades require much less primary energy than glass elements both in production and in the use phase, so that - viewed over the entire life cycle - more than three times the amount of primary energy has to be used for glass façades. While only 4.4 kg CO2 per ton of natural stone are emitted for stones from Germany with a transport distance of 100 km from the quarry to the construction site, the transport- related CO2 emissions for stones from other European countries (2000 km transport distance) are already 88 kg CO2 and for stones from Southeast Asia (18,600 km transport distance) around 265 kg CO2 per ton. Therefore the environmental control and the climate change on the globalization are under discussion.
However, both historical buildings and heritage monuments and sculptures are exposed to weathering and decay not only of natural agents, but also to anthropogenic activity, both voluntarily and involuntarily, the damage that has increased in the last two centuries due to increasing in world population.
The problem of weathering of natural construction rocks in buildings and historical monuments has been well known since ancient times, and the methods and techniques both for extracting rock from quarries and for conserving, protecting, and restoring them have evolved. This Special Issue collects a series of chapters on the weathering of rocks used in historical heritage in urban areas and their relationship with pollution and anthropogenic erosive agents, as well as the effects of natural agents such as moisture, sun, salt crystallization, etc., in addition to discussing key characteristics of building stones like marbles, sandstones, volcanic tuffs, gypsum, etc.
In fact, the actual features shown by the rocks are related with the intrinsic factors, which can be observed at quarry scale, and also derivated from the extraction and processing techniques. Therefore, from quarry to heritage, several factors should be considered and studied in order to fully understand the actual weathering features and correctly prevent the heritage destruction.