Stone is a natural material for construction obtained in quarries and has been used as a building material since prehistoric days. Stones used for the construction of building structures is known as building stone. When constructing a residential house using building stones in Kenya, one should know which type of stone to use for the walling, foundation, lintels, floors, etc. Durability and costs take the center stage in the decision-making process
Properties of a good building stone in Kenya.
The quality of building stones depends on the locally available material.
For a stone to qualify to be used as a building material it is paramount to satisfy and meet the following properties;
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Hardness and toughness
The stone used should be hard and strong enough to withstand all the pressure and stresses applied by seismic forces, winds, and the load of the whole structure. The value of the toughness index in an impact test should be between 13 and 19. with a value exceeding 19 indicating that the stone is highly tough.
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Texture and appearance
Good building stones must compose a fine crystalline structure free from cavities, cracks, or patches and have a close-grained compact texture. It should also be decent in appearance and aesthetically pleasing to reduce the costs of polishing it.
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Crushing strength
A good building stone should be having a crushing strength of greater than 100N/mm3.
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Durability
A good building stone should be durable by lasting for a long time and resisting all defective forces and climatic conditions.
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Porosity
The stone used for building should be less porous and not allow rainwater or any acidic water to pass through. The stone must not show any absorption properties for any liquid.
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Workability
Workability refers to the ease of working with stone through cutting, dressing, and shaping. A good stone for building should be workable and easy to cut.
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Cost-effective
When selecting building materials, cost is an important factor. If the stone is locally available or the site has close proximity to the quarry then the transportation and overall cost of the stone will go down.
Types of building stones in Kenya
The building stones in Kenya are mainly divided into two that is ;
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Machine-cut stones in Kenya
Machine-cut stones are produced by a machine in different sizes with the main sizes being 4*9 and 6*9 .4*9 machine cut stones are mainly used for partitioning walls like bathroom walls while the 6*9 machine-cut stones are used to construct places like perimeter walls and fencing because they are considered to be stronger. The main advantage of machine-cut stones is that they are well-cut and proportional therefore requiring less mortar when finishing. Another advantage is that machine-cut stones are fast to build meaning the labor costs are less. The stones also do not need dressing therefore saving the costs of polishing them.
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Manual cut stones in Kenya
Unlike machine-cut stones, These building stone type is usually manually cut by people meaning no machine is used. The main advantage of manually cut stones is that they are cheaper compared to machine-cut ones.
Bottom line.
Building stone remains an impressive building material because of its strength and fire-resistant properties. Its requirement for little to no mortar makes it stand out from other building materials. Stone has a variety of applications including masonry work, decorative elements like pillars swags, porticos, floor tiles, and cladding also. Common building stone types for building construction in Kenya are granite, marble, quartz, limestone, sandstone, and travertine.
