CHAPTER 1: SUB-STRUCTURE
LECTURE 1 - SOIL INVESTIGATIONS
LECTURE 2 - CHOICE OF FOUNDATION IN RELATION TO SOIL CONDITION
LECTURE 3 - SHALLOW FOUNDATIONS: PAD, STRIP & RAFT
LECTURE 4 - BASIC UNDERSTANDING OF PILING DEEP FOUNDATIONS
LECTURE 5 - BASEMENT CONSTRUCTION & WATERPROOFING
LECTURE 5 BASEMENT CONSTRUCTION
BASEMENT
Basement
Defined as a storey with a floor which is more than 1.2 m below the highest level of ground adjacent to the outside wall.
The structural wall of a basement below ground level are in fact retaining walls
They have to offer resistance to soil and groundwater pressure as well as assisting to transmit superstructure load to foundations.
BASEMENT
Waterproofing
Presents the greatest problem in basement construction
There are 3 basic method of waterproofing
monolithic structure
drained cavities
membranes
BASEMENT
Monolithic Structure
Basement made of dense reinforced concrete using impervious aggregates for walls and floors
Great care must be taken with the design of the mix
Actual mixing placing together with careful selection and construction of formwork
Shrinkage cracking can largely be controlled by forming construction joints at regular intervals
Though providing adequate barrier to passage of water, they are not always vapour proof.
BASEMENT
Drained cavities
Provides excellent barrier to moisture penetration
Allows any moisture which has passed through the structural wall to drain down within a cavity formed between inner face of structural wall and an inner load bearing wall
The internal wall is built of special triangular precast concrete tiles which allows moisture from the cavity to flow under the tiles to a sump where it is discarged into a drainage system
BASEMENT
Drained cavities
BASEMENT
Membranes
Relatively a thin material placed either on external or internal face of basement wall or floor to provide resistance to passage of moisture to inside of basement
If applied internally, it is called INTERNAL TANKING
If applied externally, it is called EXTERNAL TANKING
BASEMENT
External Tanking
Advantages Protection is given to structural elements
(hydrostatic pressure will keep them in place)
Disadvantages reasonable working space
required at perimeter of basement membrane can easily be damaged during backfilling
Internal Tanking
Advantages No extra cost and time incurred for excavation work
Disadvantages Gives no protection to structural elements
Membrane may be forced away
from wall surface by water pressure unless adequately loaded.
BASEMENT
BASEMENT
BASEMENT
END OF LECTURE THANK YOU