week 3 Flashcards
(19 cards)
Why is steel reinforcement needed in reinforced concrete (RCC)?
Because concrete is strong in compression but weak in tension, steel reinforcement carries tensile stresses in structural members like beams, slabs, and joists.
What role does steel reinforcement play in resisting shear stresses?
Shear reinforcement is used to resist shear stresses that concrete alone cannot withstand, especially in beams under load.
How does steel reinforcement help control cracks in concrete?
Steel limits the width of cracks caused by shrinkage and thermal changes by holding the concrete together and distributing stresses.
How are reinforcement bars classified?
Bars are classified by surface profile (deformed or plain), strength grade (e.g., 500N), ductility class (L, N, E), and diameter in millimeters.
What is the purpose of deformations (ribs or indentations) on reinforcement bars
Deformations improve the bond between steel and concrete, enhancing the composite action of RCC.
When and why is mesh reinforcement used in RCC?
Mesh reinforcement is used in slabs, footpaths, and suspended slabs to provide tensile strength; it consists of welded longitudinal and transverse bars.
What is concrete cover and why is it important?
Concrete cover is the minimum distance between reinforcement and the outer concrete surface; it protects steel from corrosion and fire exposure.
Why is fire protection important in RCC despite concrete being non-combustible?
Because steel loses strength at high temperatures, adequate concrete cover is necessary to protect steel reinforcement from heat during a fire.
What is development length in reinforced concrete?
Development length is the minimum embedded length of rebar required to transfer tensile forces effectively to the surrounding concrete.
What is a splice in reinforcement bars, and why is it used?
A splice is an overlapping section where two bars are joined to achieve the required length; splices are staggered to maintain strength and avoid weak points.
What are the main components of concrete?
Concrete is made of cement, water, fine aggregates, and coarse aggregates such as crushed stone. Admixtures are often added to enhance its performance.
What are some important properties of concrete?
important properties include strength, workability, setting times, and durability.
What is the purpose of mix design in concrete?
Mix design specifies the proportions of concrete ingredients to achieve the desired properties.
What type of water should be used in concrete?
Water used in concrete should be clean and free from contaminants such as suspended solids, organic matter, and salts. Potable water is generally used.
Why is particle size distribution important in concrete?
Particle size distribution affects the selection of fine and coarse aggregates, which influences the concrete’s quality and performance.
What is the importance of timing during concrete placement?
Concrete should be batched, transported, placed, compacted, and finished within its initial setting time, which can be modified by admixtures.
Why is curing necessary for concrete?
Proper curing is essential to achieve the required quality and strength in concrete.
When should formwork be removed from concrete?
Formwork should only be removed after the concrete has gained sufficient strength and cured properly.
