Presentation on theme: "Stones Stone a natural, hard substance formed from minerals and earth material which are present in rocks. Rock the portion of the earth’s crust having."— Presentation transcript:
Stone a natural, hard substance formed from minerals and earth material which are present in rocks. Rock the portion of the earth’s crust having no definite shape and structure
Uses of Stones 1. Foundation Works 2. Flooring 3. Walls 4. Bridges, Dams, Arches 5. Preparation of Concrete(Aggregates) 6. Pavements, Platforms 7. Railway Tracks (Ballast) 8. Columns, Lintels, Sills etc
5 Types of Stone Fieldstone Fieldstone Rubble Stone Rubble Stone Dimension Stone Dimension Stone
6 Stone Masonry Patterns Laid in Mortar Rubble (Unsquare pieces) Rubble (Unsquare pieces) Ashlar (Square Pieces) Ashlar (Square Pieces) Coursed or Random Coursed or Random
Types of Stone Masonry Walls: (i) Solid masonry wall made by laying stone masonry over a prepared bed of mortar, and proceeding in a similar manner to increase the height; (ii) Composite wall made of an outer wall of large stone slabs, attached to a backing of structural frame or brick/concrete masonry wall; and (iii) Cavity wall made by two different types of masonry wall separated by a cavity, which is either insulated or empty and connected together by metal ties Laying of stone masonry blocks in a wall: (a) Rubble Masonry - Composed of unsquared pieces of stones; mason has to choose carefully each stone so that it can fit into the available space - (b) Ashlar masonry - Made of squared pieces of stones; mason has to carefully lift the heavy stones by a hoist and lower it into place - (c) Coursed stone masonry: has continuous horizontal joints - (d) Uncoursed or random masonry : Does not have defined bedding planes for the wall TYPES OF STONE MASONRY WALLS AND THEIR CONSTRUCTION
Quarrying – the process of extracting stone from natural rock bed is known as quarrying of stone.
Seasoning of stone or quarry sap : Before placed in structure – removing – moisture Dressing the stone: – the act or process of surfacing and shaping blocks of stone.
Testing of Building stone: – 1.Acid Test: – a sample of stone weighing about 50 to 100 gm is taken - It is placed - hydrophobic acid having strength of one percent and is kept there for 7 days - – A good building stone maintains its sharp edges and keeps its surface free from powder at the end of this period. – If the edges are broken and powder is formed on the surface, it indicates the presence of calcium carbonate and such a stone will have poor weathering quality. This test is usually carried out on sandstones.
Attrition Test: – This test is done to find out the rate of wear of stones, which are used in road construction. – The results of the test indicates the resisting power of stones against the grinding action under traffic - Devil’s attrition test machine\
Crushing Test: Samples of stone is cut into cubes of size 40x40x40 mm. sizes of cubes are finely dressed and finished. Maximum number of specimen to be tested is three. Such specimen should be placed in water for about 72 hours prior to test and therefore tested in saturated condition.
Crystalline Test: – At least four cubes of stone with side as 40mm are taken. They are dried for 72 hrs and weighed. – They are then immersed in 14% solution of Na2SO4 for 2 hours. – They are dried at 100 degree C and weighed. Difference in weight is noted. – This procedure of drying, weighing, immersion and reweighing is repeated atleast 5 times. – Each time, change in weight is noted and it is expressed as a percentage of original weight. – Crystallization of CaSO4 in pores of stone causes decay of stone due to weathering.
Freezing and thawing test: – Stone specimen is kept immersed in water for 24 hours. – It is then placed in a freezing machine at -12 degC for 24 hours. – Then it is thawed or warmed at atmospheric temperature.
Hardness Test: – Dorry’s testing machine Impact Test For determining the toughness of stone, it is subjected to impact test in a Page Impact Test Machine
Microscopic Test: The sample of the test is subjected to microscopic examination. The sections of stones are taken and placed under the microscope to study the various properties such as i. Average grain size ii. Existence of pores, fissures, veins and shakes iii. Mineral constituents iv. Nature of cementing material v. Presence of any harmful substance vi. Texture of stones etc.
Smith’s Test: – This test is performed to find out the presence of soluble matter in a sample of stone. – Few chips or pieces of stone are taken and they are placed in a glass tube. – The tube is then filled with clear water. – After about an hour, the tube is vigorously stirred or shaken. – Presence of earthy matter will convert the clear water into dirty water. – If water remains clear, stone will be durable and free from any soluble matter. Water Absorption Test:
Requirements/Qualities of Good Stone 1. Crushing Strength > 100 N/mm2 2. Water Absorption(in 24 hours) should be < 5% 3. Specific gravity > 2.7 4. Coefficient of Hardness>14 5. Toughness Index < 13 6. Should be durable (long lasting) 7. Uniform Colour and Pleasing Texture 8. Should be easily carved 9. Should be dressed economically 10. Should be fire resistant
1. Appearance: The stones to be used for face work must have a uniform and pleasing color. It must be free from cavities, cracks, flaws and patches of loose and soft material etc. 2. Strength: A good building stone should have sufficient crushing strength to withstand the load of superstructure. In general, compressive strength should not be less than 100N/mm 2. It should be strong. 3. Durability: A good building stone must be durable enough to resist the effect of weathering agencies e.g. rain, wind, temperature etc. It should have fine grained, compact and crystalline structure. 4. Hardness: The stone used in floors, pavements and aprons of bridges, should be able to resist the abrasive forces caused due to wear and friction. For good stone wear should be equal or less than 3%. It terms of co efficient of hardness, it should be more than 14
5. Workability: The stone to be used should be easy to cut and dress into different sizes and shapes. 6. Toughness: Building stones should be tough enough to withstand stresses developed due to vibrations of machinery and moving loads over them. The stones used in the construction of roads should be hard as well as tough. 7. Seasoning: The stone to be used for an important interior work should be well seasoned. Presence of moisture makes the stone soft and it is liable to an early decay when used in structural work. 8. Resistance to fire: A good building stone should be able to resist high temperature. Its mineral constitutes should have equal co-efficient of expansion.
9. Porosity: A good building stone should be less porous. It should not absorb more than 5% of water. Any stone absorbing 10% of water should be rejected. 10. Specific gravity: The stone to be used on heavy engineering works docks, harbous, gravity dams etc. must have high specific gravity. In general, it varies from 2.4 to 2.8. For a good building stone specific gravity should be more than 2.7. 11. Texture: A good building stone should have a close grained and compact texture. It should be free from cavities and cracks. 12. Availability: It should be easily available and cheap.