Observation

 

         A good number of candidates were able to:

-           state two desirable properties of fresh concrete and hardened concrete;
-           sketch the 3: 4: 5 methods of setting out right-angle corner of a building;
-           state the  two desirable properties of fresh concrete and hardened concrete;
-           describe how the 3: 4: 5 methods is used to set out the right-angle corner of a building.

However, some of them failed to:

(a)   

  (i)  Properties of fresh State concrete:

•       correct cement/aggregates ratio;
•       should be well mixed;
•       should be well cured;
•       should be workable;
•       should be of correct mix proportion;
•       correct water-cement ratio

(ii) Properties of  hardened concrete:

-           it must be durable;
-           it must be fire resistant;
-           it must resist indentation;
-           it should be impermeable to water;
-           it should be resistant to wear;
-           it must be sound resistant.                 

(b )       Setting  out a right angle corner using 3 : 4 : 5 method:

• along the axis Y - Y measure distance AB equal to 3 units;
• along the axis X - X measure the distance AC equal to 4 units;
• move the peg D up and down until the distance AC measures 5 units
• drive the peg D down permanently to establish the right angled comer of the building i.e. angle CAB = 90°