Observation

Most candidates were able to:

state the three ways of locating a building line;

state the three advantages and disadvantages of batching concrete materials by weight and by volume;

state the functional requirements of a timbering system for trench excavation.

  However majority of the candidates failed to:

use the appropriate terms to explain the advantages and disadvantages of batching by weight and volume;

state the functional requirements of timbering system for trench excavation.

The expected response to question 2 is as given below:

Three ways of locating a building line:

by measuring the required set-back approved by town planning authority for the area;

by using the frontage line of existing building as reference;

by using the road/street kerb line;

by using the corner pillars as established by ordnance survey.

 

 

Advantages of batching concrete materials by weight over by volume:

greater accuracy in measuring the materials;

higher quality concrete is obtained;

accurate/correct mix proportion is obtained;

no allowance for bulking of damp sand is required;

reliability in measurement.

Functional requirements of timbering system:

to prevent the soil from falling inside the trench;

to protect the person working inside the trench;

to allow workmen to operate safely along the edges of trench;

strength and stability;

resistance to insect attack.