Building Materials (Civil)

Cement:

• OPC (Ordinary Portland Cement): most common. Grades 33, 43, 53 (28-day strength in MPa).
• PPC (Portland Pozzolana Cement): with fly ash, more durable.
• Initial setting time: ≥ 30 min. Final setting time: ≤ 600 min (10 hours).
• Soundness test: Le Chatelier apparatus.

Steel:

• Mild steel: 250-500 MPa. Used in RCC.
• HYSD (Fe-415, Fe-500): high-yield strength deformed bars.
• TMT bars: thermo-mechanically treated; commonly used now.
• Carbon content: mild steel ~0.15-0.25%; high carbon ~0.55-0.75%.

Bricks:

• Standard size: 190 × 90 × 90 mm.
• Class A, B, C (load capacity).
• Tests: compression, water absorption, efflorescence.

Aggregates:

• Fine aggregate (sand): <4.75 mm.
• Coarse aggregate (gravel/stone): 4.75 mm - 80 mm.
• Fineness modulus, gradation.

Concrete:

• M20, M25, M30 grades (28-day strength in MPa).
• Ratios: M20 = 1:1.5:3 (cement:sand:aggregate).
• Water-cement ratio: 0.40-0.55 typical.
• Slump test: workability.

Timber:

• Teak, sal, deodar: most common.
• Defects: knots, shakes, warps.

Other materials:

• Lime, paint, plaster, glass, tiles, paint.

RRB JE focus: cement grades, brick size, M20 concrete ratio, steel types.