Natural stone – beautiful and sustainable in the long term
Natural stone has a host of positive qualities. It is climate smart, sustainable and durable, while also offering a low life cycle cost. And just as importantly, its aesthetic qualities mean that it contributes to a better environment for our planet and the beings that live on it.
Natural stone is a strategic resource
Rock as a raw material is necessary to a functioning infrastructure in the shape of roads, railways, ports and airports, and therefore to employment and development in trade and industry. Every year around 80 million tonnes of rock material are produced and delivered in Sweden, making it one of the nation’s biggest industrial products.
Different types of rock
What we call natural stone actually encompasses different types of rock found in the earth’s crust. A rock is defined by its constituent minerals, its chemical composition and the way it was formed. Rock types are generally divided into three main categories – igneous, metamorphic and sedimentary – as well as meteorites.
Natural stone has been used for thousands of years as a construction material, but also for monuments, decoration and in industrial processes.
Granite is an igneous rock type
Granite (from the Latin granum, grain) is one of the most common rock types on the continental crust. Granite is an igneous plutonic rock, which means it is formed when magma deep inside the earth undergoes a slow cooling process. Large parts of Sweden’s bedrock is comprised of granite, particularly in the southern province of Småland and the northern half of Sweden.
Granite can be a range of colours from white to red and black, depending on differences in mineral composition and texture. Some minerals are just a few millimetres in size while others can be several centimetres.
Granite is hard, solid and very durable
Granite is a very hard rock that doesn’t crack and is uncommonly resistant to pressure, impact and deformation. It is also insusceptible to acid rain. It is almost always completely solid as it generally lacks an inner structure. Granite is known as a hard stone, unlike marble, limestone and other types which are called soft stones. Thanks to its hardness and resulting durability, granite enjoys a reputation as a stone with fine properties. The Pyramid of Menkaure at Giza, one of Egypt’s best-preserved pyramids, is partly made of granite. Classic curling stones are also made of granite.
Natural stone – the most environmentally neutral choice
Quarrying stone in Sweden is associated with all kinds of regulations which ensure quarries follow strict environmental guidelines. But natural stone is in itself also a sustainable product with excellent properties, especially when it comes to climate impact and life cycle analyses.
This is demonstrated for example in an EU project, which aims to establish standards for sustainable construction. Within the project international ISO standards are used to produce EPDs (Environmental Product Declarations) which consider energy consumption, environmental impact, product durability and other aspects. There are more than 500 EPDs for different types of construction materials, and this data makes it easier for architects, for example, to choose the most environmentally friendly option. This kind of comparison was used, for instance, when natural stone was chosen for the facade of the Opera Tower in Frankfurt rather than a combination of glass and concrete. The natural stone was shown to reduce costs by 40% over 50 years, primarily thanks to lower maintenance costs.
SP Technical Research Institute of Sweden (now RISE) has also conducted in-depth life cycle analyses comparing Swedish natural stone to concrete and imported Chinese natural stone. Considering life span, production and transport, it has been shown for instance that natural stone kerbstones have a total climate impact equivalent to around 3 kg CO2 equivalents/m, as opposed to 60 kg CO2equivalents/m for concrete kerbstones.
Natural stone means a better living environment
Natural stone is not only sustainable from a climate and cost perspective, it also contributes to a better environment for residents in urban areas in purely qualitative terms.
Increased urbanisation and a climate with more precipitation mean that the physical surface quality in a city is taking on ever greater importance. Paved, sealed surfaces create problems when precipitation increases, and more and more cities are formulating strategies for dealing with ‘one hundred year rains’, i.e. extreme downpours which don’t happen that often, but do have serious consequences for society. Natural stone has advantages here as it always has seams, and therefore working drainage which reduces the risk of large amounts of water collecting.
Natural stone also creates a better, more vibrant environment than concrete in purely aesthetic terms; a town centre with natural stone paving feels more alive and exciting. In Denmark, for example, investments have been made in replacing concrete for natural stone in housing areas that have had problems with vandalism, the result being that residents spend more time outdoors and the quality of life has increased. In northern Sweden too, one hospital has remodelled its courtyards by replacing concrete with natural stone, and these areas are now used more by patients.