Chapter 2 Flashcards
Types of cement
- Ordinary Portland Cement
- Rapid Hardening Portland Cement
- Low-heat Portland Cement
Constituent materials of concrete
- Cement
- Aggregates
- Water
Production of concrete
- Batching
- Mixing
- Transporting
- Placing
- Compacting
- Curing
Testing of concrete
- Slump test
- Compacting Factor test
- Compressive Strength test
Testing apparatus for slump test
- Standard slump cone
- Base plate
- Temping rod
Placement of reinforcements
(B, T, NF, FF)
B: Bottom face
T: Top face
NF: Near face
FF: Far face
20H1303-150T
20, H, 13, 03, 150, T
20 - No. required
H - Type of bar
13 - Diameter
03 - Bar mark
150 - Spacing
T - Location
Types of foundation
- Strip foundation
- RC Pad foundation
- Raft foundation
- Pile foundation
End bearing
Shafts of the piles act as columns that carry the loads through the overlaying weak subsoil to a stronger and firmer lower strata
Skin friction
Held up by frictional resistance between the surface of the pile and adjoining ground
Replacement pile
Soil is removed by boring and the hole is filled with wet concrete
Displacement pile
Piles are driven down into the ground at spaced intervals
Advantages of replacement piles
- Lesser noise and vibration
- No risk of ground heave
- Drilling tools can break obstructions that cannot be penetrated by any form of displacement pile
Disadvantages of replacement piles
- Cast-in-situ underground, more difficult to construct and control properly
- Concrete cannot be inspected after installation
- Inflow of ground water may cause damage to the wet and unset concrete and may lead to reduced pile bearing capacity
Advantages of displacement piles
- Preformed before they are driven into the ground, quality can be controlled
- Can be driven into a predetermined set
- Any construction operations are unaffected by ground water level
Disadvantages of displacement piles
- Driving process generates unacceptable noise, dust and vibration
- Piles cannot be inspected after installation
- Piles may be damaged due to hard-driving
Materials used for sheet piles
- Timber
- Reinforced and pre-stressed concrete
Concrete cover for main bars in substructure
Not less than 50mm
Concrete cover for main bars in beams and walls
Not less than 25mm or not less than the diameter of the main bars
Concrete cover for main bars in column
Not less than 25mm
Concrete cover for main bars in slab
Not less than 20mm
Explain superstructure
Every element of the structure situated above the ground
Explain substructure
Every element of the structure below the level of ground
Explain backfills
Materials excavated from the site
Explain bearing capacity
Safe load per unit area which the ground can carry
Explain made ground
Refuse, excavated rock or soil deposited for the purpose or filling in a depression
Ground movement may be caused by (Settlement)
- Deformation of soul due to imposed load
- Volume changes of soil as a result of seasonal condition
- Mass movement of soil in unstable areas
General weight of concrete
30kN/m3
Factors that affect strength of concrete
- Water
- Aggregates
- Cement
Types of shallow foundation
- Strip foundation
- RC Pad foundation
Selecting types of foundation
- Nature and bearing capacity of subsoil
- Cost or economic consideration
- Distribution of loads from superstructure
- Total weight of the building and its parts
Types of reinforcement
- Fabric reinforcement
- Cold worked bars
- Hot-rolled rib bars
- Mild steel bars
Length of reinforcement
12m for bars Ø13 and above
Reasons for termination of reinforcing bar
- To fit the member
- To economise on steel
- To make construction easier
- Bars are made of stock lengths
Factors determining choice of piles
- Superstructure design and site area
- Depth of suitable load-bearing strata
- Availability of equipment and site constraints
Types of preformed displacement piles
- Bakau piles
- Tanalised piles
- Precast concrete piles
Types of sheet pile
- Timber piles
- Steel piles
- Precast concrete piles
