Building Material & Construction - 2 - GATE Civil Engineering SSC JE Free

Good quality stones must possess durability, be free from clay, and resist the action of acids. This ensures that the stone can withstand various weather conditions and maintain its structural integrity over time.

A good quality stone should absorb water less than 5%. This is because a stone with low water absorption is less prone to cracking, discoloration, and other forms of damage caused by water infiltration.

A stone is rejected if it absorbs water more than 10%. High water absorption can lead to the weakening of the stone, making it less durable and more susceptible to damage over time.

Stones used for ornamental work must be soft. Soft stones are easier to carve and shape into intricate designs, making them ideal for decorative purposes.

The presence of the original rounded surface on the manufactured piece of timber is called wane. Wane occurs when the outer surface of the log is still present on the finished piece of wood.

Stones used for the construction of retaining walls must be heavy. Heavy stones provide the necessary stability and strength to support the weight of the soil being retained.

In stone masonry, stones (stratified rocks) are placed so that the direction of pressure to the plane of bedding is at right angles. This placement ensures that the stones can effectively distribute and withstand the pressure.

In stone masonry, if stones are placed so that their layers are parallel to the direction of load, they are more likely to split easily and be affected by moisture. This can weaken the overall structure and reduce its longevity.

In arches, stratified stones are placed so that their lanes are radial. This arrangement allows the stones to effectively distribute and support the load in the arch.

The tendency of a stone is to split along its cleavage. Cleavage refers to the natural planes of weakness within the stone, which makes it more likely to break along those lines.

The standard size of masonry bricks is 19 cm x 9 cm x 9 cm. This size allows for consistent and efficient construction of brick structures.

Considering the volume lost in mortar between joints, 470 modular bricks are required per cubic meter of brickwork. This takes into account the nominal size of the bricks and the volume lost due to mortar.

The term frog refers to a depression on the face of a brick. Frogs are used to create a better bond between the bricks and the mortar, improving the overall strength of the brick structure.

The frog of a brick is normally made on its top face. This allows the mortar to fully fill the frog when the next brick is placed on top, creating a strong bond between the bricks.

The size of the mould for brick is generally kept a little larger than the specified size. This is because bricks shrink as they dry, so a slightly larger mould ensures that the finished brick meets the desired dimensions.

For one cubic meter of brick masonry, 500 bricks are required. This takes into account the standard size of masonry bricks and the space needed for mortar.

The minimum compressive strength of 1st class bricks should be 100 kg/cm². This ensures that the bricks can withstand the required loads and maintain their structural integrity.

The minimum compressive strength of 2^nd class bricks should be 75 kg/cm². This is a lower strength requirement than 1st class bricks but still provides sufficient strength for various construction applications.

Water absorption should be 12-15% of its dry weight when immersed in cold water for 24 hours. The crushing strength of the brick should not be less than 10 N/mm2. This limit varies with different Government organizations around the country.

Good brick earth should contain 50 – 60% of silica. It prevents cracking, shrinking, and wrapping of raw bricks. Silica imparts a uniform shape to the bricks. The excess of silica makes the bricks brittle..

Clay and silt content in a good brick earth must be at least 50%. This provides the necessary plasticity and workability to the brick earth, allowing for efficient brick production.

A bullnose brick is not used for arches. Bullnose bricks have a rounded edge, making them suitable for rounding off sharp corners and decorative purposes, but not for the structural requirements of an arch.

Second class bricks produce a metallic sound when struck. This indicates that the bricks are well burnt and have a sufficient hardness for use in construction.

Jumbo bricks are over burnt. This means that they have been subjected to excessive heat during the firing process, resulting in a dark, brittle, and less desirable brick.

Dolomite is a limestone that contains carbonate of magnesia up to 45%. This type of limestone is valued for its high magnesium content, which can be used in various industrial and agricultural applications.