Sandstone reserves in India are spread over the states of Rajasthan and Madhya Pradesh,Over 90% of the deposits of sandstone are in Rajasthan, spread over the districts of Bharatpur, Dholpur, Kota, Jodhpur, Sawai-Madhopur, Bundi, Chittorgarh, Bikaner, Jhalawar, Pali, and Jaisalmer.
The sandstone from Kota Region is very similar to York Stone from England and thus it is very popular in England. Sandstone can be used both externally and for internal use.
The term sandstone is used to describe almost any stone of sedimentary origin with a granular texture. Some other types of stone that may fall under this classification include gritstones, siltstones, greywackes, conglomerates and marls. Aside from particle size variations, the dominant factor affecting sandstone performance is the grain cement that may be siliceous, calcareous, clay bearing or iron-rich.
Geologically it is a sedimentary type rock made up of various mineral particles mainly quartz, mica and felspar. All these minerals are bonded together with natural cements such as silicas, calcium carbonates, iron oxides and clays. The individual make up of each sandstone gives a wide range of colours. A pure silica sandstone is white with the colours arising from other minerals. Iron oxides can cause the stone to vary from buff or brown through to the deepest red. Grey colour stone is due to the presence of clay and green could indicate the presence of glauconite which contained potassium.
Sandstone is a natural material traditionally regarded as a building stone around the globe. Sandstone can be seen throughout the Europe, Asia and Middle East in many prestigious buildings from structures which form part of our heritage to modern office blocks.
Sandstone has many colours ranging from white, grey and buff to various shades of pink and red. The colour and texture of stone is self evident, however the colour of dry stone can change quite dramatically on wetting. Natural weathering can play a major part in the change of colour. Such colour change can sometimes be viewed on abandoned faces of the quarry although it is much more important to view existing buildings constructed from the same stone.
Sandstones generally have an even texture, which may vary from course to fine, but the stone from some quarries also show attractive natural markings.
Many types of sandstone are suitable for paving or flooring. Some can be split ("riven") otherwise the normal finish is sawn. Tooled, sandblasted and flame textured finishes are also available. There is a vast variety of surface finishes available from the traditional rubble walling to wrought stonework with its finishes to different forms ie. boasting, pitched, broached, hammer dressed and rusticated, to the very intricate looking vermiculated. But most importantly, credit must go to the craftsmen who hue the sandstone to all the various forms from large stones with a high degree of moulding to the most intricate of carving work. Sandstones are suitable for blcok construction in most building and engineering work and can now be cut to relatively thin sections for cladding to steel framed or concrete structured buildings. All in all sandstone is one of the few historic natural minerals still in use today. It provides excellent durability and is virtually maintenance free. It is aesthetically appealing to the eye whilst giving great value for money to the client.
Most sandstones have good load bearing and weathering properties. Correct detailling with regard to weathering is of prime importance, especially on buildings designed with sloping surfaces and without overhangs. Great care is required in the design of non-ferrous cramps and corbels for fixing to structures.
Types of Sandstone
There are two broad types of sandstone in India.
Solid blocks of sandstone which have to be cut on gangsaw or circular saws similar to marble or marble processing. The example for this type of sandstone is Rainbow and Teakwood. This is found in the Khatu region of Rajasthan.
Sedimentary sandstone which has natural cleft in it. The clefts are opened manually using chisel and hammer - RIVEN SANDSTONE. The blocks are first made into sheets of 25-40mm , and then these sheets of stone are cut into the required dimensions. The entire process is manual and no machines are involved. A recent development in this category of stone has been to calibrate the stone to 20mm and then tumble it to give it a aged look. This has become very popular in the recent times. The main mining area for this type of sandstone is in the region of Kota in Rajasthan.
Sizes being produced
Slabs : As mentioned earlier, in some of the sandstone like Rainbow and Teakwood, it is possible to produce slabs in sizes of 200x100 Cm , in the flaggy sandstone the slabs will have a maximum size of 60x90 Cm. Tiles : Sandstone tiles can be produced in sizes starting from 15x15 Cm to 60x90 Cm. As a inherent limitation with some of the products a mix of sizes has to be produced to minimize the cost. It may not be possible to product only 60x90 size in bulk. Normally a container load will have a equal break up in four sizes.
Cobbles: Sandstone cobbles come in various sizes. Starting from 10x10 Cm to 15x20 Cm. The thickness is normally 5-7 Cm on the cobbles. The cobbles are all handcdressd and unlike granite cobbles the edges are taper cut on cobbles. Cobble stones can be used for various purpose, from garden landscaping to paving of public spaces like town squares etc. Recent trend which has developed is to tumble the cobbles to give it a aged look. This is very effective for restoration work where the heritage of the site is to be maintained.
Sandstone Pebbles : Pebbles are normally collected from rivers up in the Himalayas. These come sizes ranging from 1' - 1.5' on the higher side, which may also be called river boulders. And the smappler sizes are normally 2-3 Cm 3-4 Cm etc. Apart from the natural pebbles processed pebbles are made by tumbling sandstone pieces.
Sandstone Blocks : Blocks of sandstone are used for various purpose. As block steps in garden landscaping, as features in public spaces, as benches in gardens and public spaces. The normal size for block steps is 100x30x15 Cm . These are normally natural cleft on all sides but can also be done in three sides sawn, thickness calibrated and two sides rock faced.
Sandstone Strips : A very contemporary design which is widely used in modern architectural designs is strips of sandstone. Also known as lenier paving. This product is used for indoor areas as well as decks and patios, or as swimming pool surrounds. The product is normally sawn on six sides and the sizes are 100x15x2 Cm.
Sandstone Block Paving : A natural alternative to monotonous concrete block paving. This very similar to sandstone cobbles but the difference being that these are sawn on all six sides. This gives them a more accurate size and hence they are more user-friendly for laying purpose. Unlike concrete block paving sandstone block paving can be produced in custom made sizes. The normal sizes are 10x15x5 Cm . These can be produced in simple six side sawn block paving or in sawn and tumbled block paving. Alternately the surface can be flamed to give it a anti skid property.