Stones have to be selected for a specific work based on the strength and other properties including durability. Stones needed for building exposed to different environments and stones needed for other civil engineering works are discussed below.
General Building Works
Stones are used for foundations, walls and superstructure. Stones with a high mechanical strength and pleasant colours are widely used which are also highly durable. Sandstone is in general used for the above purpose.
Buildings Exposed to High Wind
Such buildings are those constructed near the sea or locations where more wind prevails. Here, apart from the general requirements the stones will be subjected to high weathering action. Hence, stones with a high crushing strength and the presence of silica in addition to hardness should be preferred. Granite and basalt may be used.
Buildings in Industrial Areas
Here the buildings may be subjected to polluted atmosphere which may contain harmful gases, acids and moisture. These elements adversely affect the stones leading to deterioration. Stones that could sustain the effect of acidity and smoke on them are preferred. Granite and compact sandstone may be used.
Buildings Exposed to Heat and Fire
Buildings constructed in regions where hot weather conditions are prevalent throughout the year and chemical factories which may have hot air which are susceptible for frequent fires. For such cases, the stones should have high fire-resisting properties. In general, stones are free from calcium carbonate can resist fire.
Heavy Engineering Works
Heavy engineering works include docks, harbours, bridges, etc. These are constructed in general in an open area and on the seashore. Structures constructed for the above purposes should be able to resist thrust, salt environment, must be strong and highly durable. Granite and quartzite are generally preferred for such purposes, and gneiss is also used for the inside purposes of such structures.
Road Metals and Railway Ballasts
Road metals and railway ballasts are subjected to high compression and abrasion. Further, railway ballasts are exposed to atmosphere throughout their lifespan. Stones selected for such purposes should be hard, tough and highly abrasive resistant. Generally, igneous rocks are preferred for this purpose, viz., granite and basalt.
Facing and Architectural Items
Facing slabs and stones, parts of stairs and landings, parapets and guard rails are made of slabs sawn or split from natural stone and worked on by mechanical means. Sandstone, slate and marble are used for these purposes.
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