Building Material Questions (BM 11)

In this post, I will share some important questions which are frequently asked in competitive examinations such as SSC, UPSC and state PSCs.



  1. The turning of timber tissues to almost a dry powder is called ...


    1. dry rot
    2. wet rot
    3. rind gall
    4. none of the above

    View Answer
    Answer: a

  2. The disintegration of tissues of timber due to alternate wetting and drying is called ...


    1. shakes
    2. rind gall
    3. wet rot
    4. knots

    View Answer
    Answer: c

  3. Select the correct statement.


    1. heart shakes are wider at centre and diminish outwards
    2. star shakes are wider at the circumference and narrower at centre
    3. cup shakes separate annual rings
    4. all of the above

    View Answer
    Answer: d

  4. After a branch has broken or cut off from the tree, a dark patch develops, called ...


    1. rind gall
    2. knots
    3. foxiness
    4. deadwood

    View Answer
    Answer: b
    When a branch is improperly cut off or removed, a peculiar curved swelling portion develops on that area, known as rind gall.

  5. If the timber has a red or yellow tinge or reddish brown stains or spots around the pith, then the defect is called ...


    1. burls
    2. callus
    3. druxiness
    4. foxiness

    View Answer
    Answer: d
    Burls: they are formed when a tree had received shock or injury in its young age. Due to such injury, the growth of a tree is completely upset and irregular projections appear on the body of timber.
    Callus: It is the soft tissue which covers the wound of a tree
    Druxiness: White decayed spots which are concealed by healthy wood.

  6. Select the incorrect statement.


    1. A bow is a curvature of the timber in the direction of its length.
    2. Cup is a curvature in the transverse direction of the timber.
    3. When a piece of timber has twisted out of shape it is said to be collapsed.
    4. A check is a crack which separates fibres of wood due to rapid drying.

    View Answer
    Answer: c
    When a piece of timber has twisted out of shape it is said to be wrapped.
    Collapse: Due to uneven shrinkage, the wood sometimes flattens during drying.

  7. Consider the following methods of preservation of timber and arrange them in increasing order of their effectiveness.


    1. dipping
    2. pressure application
    3. open tank application
    4. brush application

    1. 1,3,4,2
    2. 4,1,3,2
    3. 1,2,3,4
    4. 2,3,4,1

    View Answer
    Answer: b

  8. To make timber fire resistance ...


    1. soak it in ammonium sulphate
    2. coat it with tar paint
    3. season it well
    4. pump creosote oil into the timber

    View Answer
    Answer: a

  9. The strength of timber is maximum when the load is applied ...


    1. inclined at $45^\circ$ to grains
    2. perpendicular to grains
    3. parallel to grains
    4. inclined at $60^\circ$ to grains

    View Answer
    Answer: c

  10. The expansion and shrinkage of plywoods are comparatively very low as ...


    1. they are held in position by adhesives
    2. they are glued under pressure
    3. piles are placed at right angle to each other
    4. they are prepared from veneers

    View Answer
    Answer: c
    The cross binding and odd numbers of piles make the plywood of less shrinkage and the shrinkage stresses are symmetrical about the middle ply which reduces the warping tendency.

  11. Wood is impregnated with creosote oil in order to ...


    1. change its colour
    2. protect against termites
    3. protect the annular layers
    4. fill up the pores

    View Answer
    Answer: b

  12. Timber is ...


    1. isotropic
    2. anisotropic
    3. homogeneous
    4. heterogeneous

    View Answer
    Answer: b

  13. What is the modulus of elasticity of group A timber in $\times 10^3 N/mm^2$?


    1. greater than 12.6
    2. 9.8 to 12.6
    3. 5.6 to 9.8
    4. none of the above

    View Answer
    Answer: a
    As per IS 883, timber is classified in 3 groups.
    Group A: elasticity greater than $12.6 \times 10^3 N/mm^2$
    Group B: elasticity in between $9.8 \times 10^3 N/mm^2$ and $12.6 \times 10^3 N/mm^2$
    Group C: elasticity in between $5.6 \times 10^3 N/mm^2$ and $9.8 \times 10^3 N/mm^2$





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