Physical Properties: Identified by visual observation & Hand tools

Chemical Properties: Identified based on the effect of different chemicals

Thermal Properties: Effect of Heat

Types of Building Materials

Stone

Stone is the naturally available construction material and is obtained from a quarry, process of extracting stones by excavating, wedging, heating & blasting is called quarrying and is composed of different minerals and with different processes.

Classification of stones:

Geological Classification:

Igneous Rocks

• Solidification of molten mass above or below the earth’s surface.

• Crystalline glossy or fussed texture

• Ex: – Granite, Basalt, Diorite, Trap dolerite, Syenite, Pegmatite, Gabbro etc.

Sedimentary Rocks

• Gradually deposition of sand, clay, debris, etc. by the action of rain, wind, sun etc.
• Stratified
• Ex: – limestone and sandstone, conglomerate, gypsum, dolomite, magnesite, chalk, shale, kankar,Tripoli, diatomite, etc.

Metamorphic Rocks

• Change in texture or mineral composition of rocks under heat and excessive pressure
• Ex: – marble, Gneiss, Quartzite, Slate, Schist, etc.

Physical classification:

Stratified Rocks:

• Distinct layers which can be separated
• E.g.: limestone, slate, and sandstone.

Unstratified Rocks:

• No sign of strata
• E.g.: granite, marble, etc.

Chemical classification:

Silicious Rocks

• Silica as the main constituents
• E.g.: granite, quartzite, gneiss etc.

Argillaceous Rocks

• Clay or Alumina as main constituents
• E.g. of silicious rock: slate, laterite, kaolin, etc.

Calcareous Rocks

• Lime or calcium
• E.g.: limestone, marble, etc.

Important building stones:

1. Granite

• mainly composed of quartz, felspar, mica

What is Feldspar?

“Feldspar is no other than silicate of aluminum with varying amounts of potash, soda, or lime.

• Sp. Gravity -= 2.64
• Compressive strength = 70 – 130 MN/m²
• color depends on felspar – brown, grey, green, pink
• Offer high resistance to weathering
• Easily polished and worked
• Used for the external facing of buildings

2. Slate

• Argillaceous rock
• Alumina + sand /carbonate of lime
• Sp. Gravity = 2.8
• Compressive strength = 60-7- MN/m²
• Grey/dark blue color
• Hard, tough, fine-grained
• Used in cisterns
• Slate as tiles, an excellent roof covering material.

3. Gneiss

• Gneiss:
• A silicious rock
• Composed of quartz and felspar
• More easily worked than granite
• Used for street paving

4. Sandstone

• Silicious sedimentary rock.
• Composed of quartz, lime, and silica
• Sp. Gravity = 2.65- 2.9
• Compressive strength = 35 -40 MN/m²
• White, grey, brown, pink, etc.
• Strong and durable
• Used for ashlar works, moldings, carvings, etc.

5. Limestone

• Sedimentary rock of calcareous variety
• Sp. Gravity = 2.6
• Brown, yellow, dark grey colors
• Used large quantities in blast furnaces
• Used as stone masonry for walls.

6. Marble

• Metamorphic rock of calcareous variety
• Sp. Gravity = 2.7
• Very hard, ornamental work, takes a fine polish
• Carving, decoration
• Kankar
• Impure limestone containing 30 % alumina & silica
• Used for foundations of buildings

7. Laterite

• Laterite contains a high percentage of iron oxide.
• Porous and cellular structure
• Sp. Gravity = 2 -2.2
• Laterite blocks are suitable for light roads, and inferior buildings.
•  a very good road metal

8. Moorum

• Decomposed laterite
• Deep brown or red color
• Used in  garden walks & paths

9. Quartzite

• Siliceous sandstones
• Strong, durable, used as road metal/ railway ballast

Bricks

Bricks are construction materials made by moulding the tempered clay to a suitable shape and size which is in a plastic condition, dried in sun, and burnt in a kiln or clamp.

Other constituents are lime, magnesia, sodium, potassium, manganese, and Iron oxide.

Excess of Alumina,Silica & Lime

Alumina – brick crack/warp on drying

Silica – brick brittle and weak

Lime –  brick to melt and distort during burning

Alkaline salt – efflorescence

Manufacture of Bricks:

Preparation of Brick clay

• Earth left for atmospheric action for a few weeks after digging called weathering.

• 1.5 – 2.5 m³ of brick soil – 1000 bricks

• Tempered in pug mills

• Process of mixing clay, water, and other ingredients is known as Kneading.

Moulding bricks:

• Handmade bricks superior to machine-made bricks

• Drying of Bricks:
• Bricks are arranged in rows on their edges on a slightly raised ground called hacks.

• Burning of bricks:
• Clamp burning = 60 % out-turn
• Kiln burning = 80 – 90 % out-turn
• Takes 24 hrs. at 1000 – 1200 ⁰c.
• Cool for 12 days

Classification of Bricks:

1. First Class:

• Well burnt, smooth, even surface, rectangular, uniform reddish.
• Water absorption (≤ 20 %) at 24 hrs.
• Min. crushing strength = 10.5 MN/m²

2. Second Class:

• Slightly overburnt, rough, no perfect rectangle
• Water absorption (≤ 22 %)

3. Third Class:

• Under burnt, soft, easily broken
• Water absorption (≤ 25 %)

4. Jhama bricks

• Over burnt, irregular, dark bluish color

What is the size of the Brick?

•  Size of Brick = (19 cm * 9 cm * 4 cm)

                          Or (19 cm * 9 cm * 9 cm)

• Sp. Gravity = 2

• For 1 m³ of brick masonry = 550 machine-made bricks

                                                  500 handmade bricks

Special Bricks:

Squint bricks: construction of acute and obtuse squint quoins

Paving bricks: used for street pavements

Round bricks: circular pillars

Perforated & Hollow: Partitions walls

Refractory Bricks: withstanding temperature, low Coeff. of expansion & contraction.

• Acid Bricks: (fire Bricks & silica bricks)
• Basic Bricks: ( Dolomite bricks, Magnesite bricks and bauxite bricks)
• Neutral Bricks: (Chrome bricks, chrome-magnesite Bricks, spinel Bricks)

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