Question 2
(a) State three reason why it is necessary to remove a vegetable soil from a building site.
(b) Explain one reason for providing a concrete foundation to a load bearing wall.
(c) Sketch a cross-section through a raft foundation and label the following parts.
(i) ground beam;
(ii) reinforced concrete.
Observation
A good number of candidates were able to:
- state the reason why it is necessary to remove a vegetable soil from a building site.
- explain one reason for providing a concrete foundation to a load bearing wall.
However, many of them failed to sketch a cross-section through a raft foundation and label the following parts.
(i) ground beam;
(ii)reinforced concrete.
The expected response to question 2 is as given below:
2(a) Reasons why it is necessary to remove vegetable soil from a building site:
- to prevent instability of the building;`
- to prevent unreliable bearing capacity of the imposed load;
- to prevent organisms and chemicals necessary for the growth of plants or
- to prevent the growth of plants underneath the ground floor of a building;
- to prevent settlement.
(b) Reason for providing a concrete foundation to a load bearing wall:
- is to spread all the load from the building over sufficient areas of the soil to avoid undue settlement;
- is to provide a solid base for the wall.
(c) Sketch of a cross-section through a raft foundation and labelling of the parts:
