Q.1) Deval attrition test is used to determine which of the following ?
A) Aggregate abrasion value
B) Aggreggate impact value
C) Aggregate roughness value
D) Aggregate crushing value
Deval Attrition Test is carried out to measure the rate of wear of a granular material.
Dorry Abrasion Test is carried out to determine abrasion resistance of an aggregate.
Los Angeles Test is carried out to measure the toughness resistance such as degradation, crushing and disintegration.
Q.2) Slump test for concrete is carried out to determine ?
C) Water Content
Workability of concrete is the ease with which it can be mixed, transported, molded and compacted.
Tests used for measuring workability :
- Slump test
- Compacting factor test
- Vee-bee consistmeter
- Flow table test
- Kelly ball test
Q.4) Which of the following is correct for Low Heat Cement ?
A) Suitable for use in cold weather areas
B) Heat of hydration is reduced by tri-calcium aluminate content
C) Initial strength gained is higher than that of OPC concrete
D) This cement contains high aluminate percentage usually between 35-55%
Q.5) The decomposition of felled timber caused by fungal attack is known as ?
B) Wet rot
C) Dry rot
Dry rot : It is the decomposition of felled timber caused by the action of various fungi results in reduction of fibres to a fine powder and hence, losses strength. Dry rot in timber occurs when the timber is not well seasoned.
Upset : It occurs when timber is subjected to crushing or compression due to natural forces.
Wet rot : It occurs due to alternate wet and dry.
Foxiness : Decoloring due to overmaturity.
Q.6) Resistance against freezing and thawing will be increased by :
A) Increasing C3S percentage
B) Decreasing C3S percentage
C) Increasing C2S percentage
D) Decreasing C2S percentage
Hydration of some constituent compound such as Tricalcium aluminate, Tricalcium silicate, Dicalcium silicate and Tetra calcium aluminoferrite is the reason behind setting and hardening of cement.
Tricalcium aluminate (C3A) or Celite is the quickest one to react with water, responsible for flash setting of cement. The heat of hydration is 865 J/cal.
Tricalcium silicate (C3S) or Alite is responsible for early strength gain of cement. The increase in C3S content in cement results in resistance against freeing and thawing. The heat of hydration is 500J/cal.
Dicalcium silicate (C2S) or Belite is reponsible for progressive strength of cement. The heat of hydration is 260 J/cal.
Tetra Calcium Alumino Ferrite (C4AF) or Felite is responsible for long term gain of strength of cement. The heat of hydration is 420 J/cal.
Q.7) Which of the following is the most efficient method of resisting sulphate attack on concrete?
A) use of high alumina cement
B) use of pozzolana
C) use of air-entrainment
D) use of sulphate resisting cement
Sulphate resistant cement consist of C3A < 5%, which reduces the formation of sulphate salts. The reduction of sulphate salts lowers the possibility of sulphate attack on concrete.
Sulphate resistant cement provides maximum resistance against chloride ions and minimize the risk of steel corrosion.
Sulphate resistant cement are used where structures are exposed to severe sulphate attacks by water like culverts, canals, piers etc.
Q.8) Which apparatus is used to perform the soundness test of cement?
A) Le-chatelier Apparatus
B) Vee-Bee Apparatus
C) Slump Apparatus
D) Compaction Apparatus
Q.11) As per IS:1077-1992, the standard modular size of common building bricks shall be –
A) 200 mm x 90 mm x 40 mm
B) 190 mm x 90 mm x 90 mm
C) 200 mm x 100 mm x 90 mm
D) 190 mm x 100 mm x 40 mm
Q.12) The defect which cause deformation of shape of brick by rain water falling on hot brick is called –
Blister is generally caused on surface of sewer pipes and drain tiles due to air imprisoned during their moulding.
Bloating is observed as spongy mass over surface of burned bricks, occurs due to presence of excess carbonaceous matter and sulphur.
Chuffs is observed when rain water falls over hot bricks results in shape deformation.
Laminations are caused by entrapped air in voids of clay.
Q.13) As per IS:3495 (Part-I), what is the loading rate used to find the compressive strength of bricks?
A) 45 N/m2 per minute
B) 32N/m2 per minute
C) 14 N/m2 per minute
D) 24 N/m2 per minute
Q.14) The radial splits which are wider on the outside of the log and narrower towards the pith are known as :
A) Heart shakes
B) Cup shakes
C) Star shakes
D) Rind galls
Star shakes : Radial splits or cracks wide at the circumference and diminishing towards the centre of the tree.
Heart shakes : Wider at centre and diminish outwards.
Cup shakes : appear as curved split that partly or wholly separates annual rings from one another.
Rind Galls : Swelling caused by the growth of layers of sapwood over wounds after branch has been cutoff in an irregular manner.
Q.17) The bricks used for lining of furnaces are :
A) 1st class brick
B) Over burnt brick
C) Under burnt brick
D) Refractory brick
Refractory Brick :
- Made from fire clay.
- They are yellowish or light brown in color.
- Made of materials having high melting point.
- 4 – 10% water absorption.
- 15 – 20N/mm2 compressive strength.
Q.18) Which of the following materials have high density?
C) Granite stone
Density of materials are as follows :
- Concrete (RCC) : 2500 kg/m3
- Concrete (PCC) : 2400 kg/m3
- Steel : 7850 kg/m3
- Granite stone : 2650 – 2750 kg/m3
- Cement : 1440 kg/m3
- Wood (teak) : 630 – 720 kg/m3
- Clay soil : 1900 kg/m3
- Gravel soil : 2000 kg/m3
- Bricks : 1500 – 1800 kg/m3
- Stainless steel : 7480 – 8000 kg/m3
Q.19) Wide and deep cracks in concrete members may be repaired by –
B) Shotcreting or guniting
C) Mortar replacement
D) Epoxy injection
Epoxy Injections : Used to fill cracks narrower than 0.05 mm. Under this method, cracks are sealed by injecting epoxy under concrete.
Routing and sealing : This method is used where only remedial crack repairing is required, not structural repairs. It involves enlarging the cracks and filling it with joint sealant.
Stitching the cracks : In this methods, holes are drilled to make entry and exit points across the cracked surface. A number of U-shaped metallic staples are then passed through the holes and anchored strongly in the holes with grout.