12 Questions
What is the main function of a slab in a building structure?
To provide support to upper parts of the building
How are beams and slabs differentiated in terms of dimension?
Beams are 1-dimensional and slabs are 2-dimensional
What provides direct support to the loads in a building structure?
Columns, walls, and foundations
How is the load generally transferred in a structured member like a beam?
Vertically from top to bottom
In the context of a building structure, where do beams transfer the imposed loads?
To the endpoints of the beams
What is the role of foundations in a building structure with respect to columns?
Foundations act as supports for columns
What does a PCC or RC of ratio 1:2:4 indicate?
Cement content is 1 part out of 7
What does a water-cement ratio (W/C ratio) of 0.45 mean?
45 litres of water for every 100 kgs of cement
What is the size of a standard burnt clay brick?
228 x 114 x 75 mm
Why are the sizes of beams and columns usually decided based on the brick wall thickness?
To ensure structural stability
Which members contribute to resisting applied loads in a structure?
All members - slabs, beams, walls, columns, and foundations
What does the water-cement ratio (W/C ratio) consider when specifying the amount of water to be added?
The weight of water with respect to cement
Study Notes
Concrete Mix Proportions
- A PCC or RC ratio of 1:2:4 means: 1 part cement, 2 parts sand, and 4 parts coarse aggregate by weight.
- Water content is specified separately as a fraction of the weight of cement (e.g., W/C ratio of 0.45 means 45 kg water for 100 kg cement).
- Extra water is added to account for absorption by aggregate during mixing, transportation, and compaction.
Bricks and Blocks
- Standard size of burnt clay brick: 228 x 114 x 75 mm (9 x 4 1/2 x 3 in.) including average mortar thickness on both sides.
- Hollow block or stone masonry may have different sizes.
- Beam and column sizes are decided based on brick wall thickness, which varies in multiples of 114 mm (4 1/2 in.).
Load Transfer Mechanism
- Structures carry various types of loads and transfer them to the soil or rock underneath.
- Different members (slabs, beams, walls, columns, and foundations) contribute to resisting applied loads.
- Slabs provide a horizontal roof surface, beams support slabs and upper parts of the building, and columns and walls provide direct support to loads.
- Gravity loads pass from top to bottom through the structure until they reach the soil underneath.
- Members and supports are defined relative to each other (e.g., beams are supported by columns, and columns are supported by foundations).
Test your knowledge on the proportions of cement, sand, and coarse aggregate in a concrete mix, as well as the water-cement ratio. Understand how to calculate the parts of each component and determine the ideal mix for different types of concrete.
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