Govt. Exams
Entrance Exams
SCC requires slump flow between 600-800 mm to flow and compact under its own weight without vibration.
Slump test is the most common field test to measure the workability and flow characteristics of fresh concrete.
IS 456:2000 recommends minimum 14 days of moist curing for normal Portland cement in normal temperature conditions.
Abrams' Law states that compressive strength decreases exponentially with increase in water-cement ratio.
Retarders delay the setting time of concrete, allowing more time for placement and compaction in large structures.
M25 designation means the concrete will achieve 25 MPa minimum compressive strength at 28 days with 95% probability.
C3A reacts rapidly with water and is responsible for flash setting. Gypsum is added to control this reaction.
Concrete gains approximately 40-50% strength in 7 days due to rapid hydration, then strength gain slows down gradually.
IS 456:2000 is the Indian Standard for plain and reinforced concrete - Code of Practice.
For reinforced concrete beams, nominal maximum coarse aggregate size is typically 20 mm to ensure proper placement around reinforcement.
