निर्माण सामग्री – Construction Materials MCQ
निर्माण सामग्री – सिभिल इन्जिनियरिङ
Construction Materials · Civil Engineering · १,००८ प्रश्न
१,००८ प्रश्न उपलब्ध। मोड छान्नुहोस्:
निर्माण सामग्री: प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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Shellac, used for knotting and in French polish, is a resin obtained from:
सही उत्तर: ग) The secretion of the lac insect
Shellac is refined from lac, a resinous secretion deposited on trees by the lac insect.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Mastic asphalt, used for damp-proof courses and waterproofing flat roofs, is:
सही उत्तर: ख) A mixture of bitumen with fine mineral filler and aggregate that forms a dense, voidless, impermeable mass when laid hot
Mastic asphalt is laid hot and spread by hand floats, giving an impervious layer without needing compaction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A small amount of alkalis in brick earth acts as a flux during burning, but an excess of alkalis causes:
सही उत्तर: क) Melting and distortion of bricks during burning, and efflorescence in the finished bricks
Excess alkalis lower the fusion temperature, making bricks melt and warp, and soluble salts later appear as efflorescence.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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As per IS 456, concrete of grades M10 to M20 is classified as:
सही उत्तर: ग) Ordinary concrete
IS 456 groups M10–M20 as ordinary concrete, M25–M55 as standard concrete and M60 and above as high strength concrete.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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When an aggregate is found to be potentially alkali-reactive, a common precaution is to:
सही उत्तर: ख) Use low-alkali cement or replace part of the cement with a pozzolana such as fly ash
Limiting alkalis and using pozzolanas that bind alkalis reduce the expansive alkali-silica reaction.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Class F fly ash (as per ASTM C618) is:
सही उत्तर: क) A low-calcium fly ash, usually from burning bituminous or anthracite coal, with mainly pozzolanic properties
Class F is low in lime and is pozzolanic; Class C (from lignite or sub-bituminous coal) is high in calcium and partly self-cementing.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The pozzolanic reaction in concrete containing fly ash or silica fume is the reaction between:
सही उत्तर: घ) Reactive silica of the pozzolana and calcium hydroxide released by cement hydration, forming additional C-S-H
Pozzolanas consume the weak, soluble Ca(OH)2 and produce extra C-S-H, improving long-term strength and impermeability.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A 12 mm diameter steel bar carries an axial tensile load of 50 kN. The tensile stress in the bar is about:
सही उत्तर: ग) 442 N/mm²
Area = π/4 × 12² = 113.1 mm²; stress = 50,000/113.1 ≈ 442 N/mm².
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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For a cement whose standard consistency is 30%, the water to be added to 400 g of cement for the initial and final setting time test (0.85P) is:
सही उत्तर: ख) 102 ml
Water = 0.85 × 30% × 400 g = 25.5% × 400 = 102 ml.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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In a tensile test on a steel bar, the gauge length of 200 mm becomes 236 mm at fracture. The percentage elongation is:
सही उत्तर: क) 18%
Elongation = (236 − 200)/200 × 100 = 18%.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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