Block laying Paper 2 WASSCE (SC), 2019

Question 3

(a)        state two properties of a fresh concrete.

(b)        Sketch a section through a formwork for concrete lintel and label the following parts
            (i)    sole plate;
            (ii)   head tree.
(c)        State two operations involved in substructural works


Some candidates were able to state two properties of fresh concrete.

However, few of them failed to:
-   Sketch a section through a formwork for concrete lintel and label sole plate and head tree.
-   State two operations involved in substructural works.

The expected response to question 3 is as given below:

3(a) Properties of fresh concrete:

  • it should be workable (i.e have adequate workability);  
  • it should have correct water-cement ratio;
  • it should have correct cement aggregate ratio;                    
  • it  should uniformly and thoroughly mixed;              
  • it should not bleed after placing;                  
  • it should be easily placed;
  • it should be have a uniform colour;
  • it should be easily compacted;
  • it should set within the appropriate setting time;
  • it should be wet;
  • segregation;
  • plastic shrinkage;
  •  thermal shrinkage;
  • thermal expansion;
  • plastic nature.

(b) Sketch of a section through a formwork for concrete lintel and labeling of parts:

(c)        Operations involved in substructural works:
-  excavation of foundation trenches;
-  bottoming/ ramming of base of trench to obtain level surface;
-  construction of timbering to support foundation trenches;
-  placing of concrete in foundation trench;
-  laying of blockwall in foundation;
-  laying of damp-proof course/damp-proof membrane;
-  filling of hardcore materials;
-  backfilling of foundation trench where necessary;
-  formwork construction for solid ground floor, concrete wall and concrete column;
-  blinding of bottom of foundation trench;
-  transferring of lines from the profile board to the foundation.