Quality Requirements of Good Building Stones

Quality requirements of good building stones will be discussed here. Stay with us.

Stone Industry

Stone industry refers to the part of the primary sector of the economy. It is similar to the mining industry, but concerned with excavations of stones, in particular granite, marble, slate and sandstone. Other products of the industry include crushed stone and dimension stone. Stone industry is one of the oldest industries in the world. Creation of stone tools in the region of South Africa has been dated to about 60,000–70,000 years ago. Granite and marble mining existing as far back as ancient Egypt. Crushed stone was used extensively by the first great road building civilizations, such as ancient Greece and ancient Rome.

Mining

Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef or placer deposit. These deposits form a mineralized commodity that is of economic interest to the miner. Ores recovered by mining include metals, coal, oil. shale, gemstones, limestone, chalk, dimension stone, rock salt, potash, gravel, and clay. Mining is required to obtain any material that cannot be grown through agricultural processes, or feasibly created artificially in a laboratory or factory. Mining in a wider sense includes extraction of any non-renewable resource such as petroleum, natural gas, or even water.

What Is the Best Stone for Building?

Many types of stones are available such as basalt, marble, limestone, sandstone, quartzite, travertine, slate, gneiss, laterite, and granite, which can be used as construction materials. The stones used for building construction should be hard, durable, tough, and should be free from weathered soft patches of material, cracks, and other defects that are responsible for the reduction of strength and durability. Stones for construction purposes are obtained by quarrying from massive solid rocks.

Quality Requirements 

Each type of stone lends itself to various construction applications based on its properties. For instance, certain types like basalt and granite have superior characteristics like high compressive strength and durability and hence employed in major construction works. However, there are stones that their characteristics such as low compressive strength and presence of harmful materials in their constituents makes them suitable for minor construction works, for example, gneiss. So, stones are used as a building material and also for decorative purposes.

Building with Natural Stone

Building with stone in an environmentally considerate way requires careful thought and planning. The returns from building with natural stone far outweigh the costs involved, though, pricing on this natural resource varies considerably. Conventional building demands large quantities of energy and water, which can create heavy amounts of pollution and waste. Building with stone and implementing green techniques is good for humans and the environment both in the construction phase, as well as for the lifetime of the home.

Stones are derived from the rocks which are naturally occurred as the portion of earth’s crust. Each rock has a different chemical composition and exhibits different properties. Some of these rocks are widely used in the construction industry. Some commonly used building stones along with their properties and uses are explained in this article.

Requirements of Good Building Stones

The following are the quality requirements of good building stones:

Cost

Cost is an important consideration in selecting a building material. The proximity of the quarry to the building site brings down the cost of transportation and hence the cost of stones comes down.

Durability

Building stones should be capable of resisting the adverse effects of natural forces like wind, rain and heat. It must be durable and should not deteriorate due to the adverse effects of the above natural forces.

Hardness

When stones are used in floors, pavements or aprons of bridges, they become subjected to wearing and abrasive forces caused by the movement of men or machine over them. So it is required to test the hardness of stone. The Mohs scale determines the hardness of stone.

Strength

Generally, most of the building stones have a high strength to resist the load coming on it. Therefore it is not of prime concern when it comes to checking the quality of stones. But when the stones are to be used in large structures, it becomes necessary to check the compressive strength of stones. Compressive strength of building stones generally fall within the range of 60 to 200N/mm2.

Fire Resistance

Stones should be free from calcium carbonate, oxides of iron, and minerals having different coefficients of thermal expansion. Igneous rock show marked disintegration principally because of quartz which disintegrates into small particles at a temperature of about 575°C. Limestone, however, can withstand a little higher temperature; i.e. up to 800°C after which they disintegrate.

No single stone can satisfy all the below-mentioned quality requirements. For example, strength and durability requirement contradicts ease of dressing requirement. Hence it is necessary that the site engineer looks into the properties required for the intended work and selects the stone accordingly.

Toughness

The toughness of stones means its ability to resist impact forces. Building stones should be tough enough to sustain stresses developed due to vibrations. The vibrations may be due to the machinery mounted over them or due to the loads moving over them. The stone aggregates used in the road constructions should be tough.

Specific Gravity

The more the specific gravity of stone, the heavier and stronger the stone is. Therefore stones having higher specific gravity values should be used for the construction of dams, retaining walls, docks and harbors. The specific gravity of good building stone is between 2.4 and 2.8.

Porosity and Absorption

The porosity of building stones depends upon the mineral constituent and structural formation of the parent rock. If stones used in building construction are porous, then rainwater can easily enter into the pore spaces and cause damage to the stones. Therefore building stone should not be porous.

Water absorption of stone is directly proportional to the porosity of the rock. If a stone is more porous, then it will absorb more water and cause more damage to the stone. In higher altitudes, the freezing of water in pores takes place, and it disintegrates the stone.

Dressing

Giving the required shape to the stone is called dressing. It should be easy to dress so that the cost of dressing is reduced. However, the care should be taken so that, this is not at the cost of the required strength and durability.

Appearance

In case of the stones to be used for face works, where appearance is a primary requirement, its color and ability to receive polish is an important factor. Light-colored stones are more preferred than dark-colored stones as the color are likely to fade out with time.

Seasoning

Good stones should be free from the quarry sap. Lateritic stones should not be used for 6 to 12 months after quarrying. They are allowed to get rid of quarry sap by the action of nature. This process of removing quarry sap is called seasoning.

Workability

The stone should be workable. Stone is said to be workable when the work involved in stone working such as cutting, dressing & shaping is economical and easy to conduct.

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Sources

en.wikipedia.org/wiki/Stone_industry

cmpstone.com.au/what-is-the-best-stone-for-building/