CE-302 Construction Materials - Jun 2025 Question Paper

Under each question, How to answer lists the points an answer should cover, outlined by CampusPrep from the syllabus. Check the details against your textbook.

1. 7 Marks
   aClassify rocks based on their geological origin and provide examples of each type with their typical uses in construction.
   How to answer

   • Classification into Igneous, Sedimentary, and Metamorphic rocks based on formation process.
   • Igneous rocks: Formation from magma/lava; examples (Granite, Basalt); uses (foundations, ballast, aggregate).
   • Sedimentary rocks: Formation from deposition/weathering; examples (Sandstone, Limestone); uses (masonry, cement manufacture).
   • Metamorphic rocks: Formation under heat and pressure; examples (Marble, Slate); uses (flooring, roofing, ornamental works).
2. 7 Marks
   bExplain the steps involved in the quarrying and dressing of stones. Why is dressing necessary before using stones in construction?
   How to answer

   • Methods/steps of quarrying: Digging, wedging, heating, and blasting.
   • Steps and types of stone dressing: Pitch-faced, hammer-dressed, chiseled, fine tooled, rubbed finish.
   • Importance/necessity of dressing: Provides regular shape, uniform joint thickness, aesthetic appeal, ease of handling, and stability in masonry.
3. 7 Marks
   aClassify bricks based on their properties and uses. What are the distinguishing characteristics of each class?
   How to answer

   • Classes: First class, Second class, Third class, and Fourth class (Jhama).
   • Distinguishing characteristics: Compressive strength limits, water absorption percentage, ringing sound, sharpness of edges, color, and surface texture.
   • Uses of each class in structural masonry, temporary works, or concrete aggregate.
4. 7 Marks
   bExplain the common defects found in timber. How do these defects affect the strength and durability of timber?
   How to answer

   • Classification of defects: Natural forces (knots, heart shakes, star shakes, ring shakes), fungal decay (dry rot, wet rot), conversion defects, and seasoning defects (bow, warp, cup, twist).
   • Effect on strength: Discontinuity of fibers, stress concentration, and load-carrying reduction caused by knots and shakes.
   • Effect on durability: Moisture retention, susceptibility to insect attack, decay, and rot.
5. 7 Marks
   aWhat is timber seasoning and why is it important? Describe different seasoning methods.
   How to answer

   • Definition of seasoning: Controlled reduction of moisture content in freshly felled timber.
   • Importance: Prevents warping and shrinkage, increases strength and durability, prevents decay, and improves workability/finishing.
   • Methods: Natural seasoning (Air seasoning, Water seasoning); Artificial seasoning (Kiln, Chemical, Boiling, Electrical seasoning).
6. 7 Marks
   bDiscuss the effects of coatings on glass. How do coatings modify the performance of glass in terms of energy efficiency and durability?
   How to answer

   • Types of coatings: Low-Emissivity (Low-E), solar reflective, anti-reflective, and self-cleaning coatings.
   • Energy efficiency: Reflection of infrared radiation, reduction of U-value, lowering solar heat gain coefficient (SHGC), and maintaining natural light transmission.
   • Durability: Protection against chemical weathering, scratch resistance, resistance to moisture and UV degradation.
7. 7 Marks
   aWhat are the different types of roofing materials used in construction? Explain the characteristics of each type.
   How to answer

   • Overview of roofing materials: Thatch, clay tiles, slates, AC sheets, GI/corrugated metal sheets, and modern polymeric/bituminous membranes.
   • Characteristics of clay tiles: Traditional, thermally insulating, brittle, and heavy.
   • Characteristics of GI and metal sheets: Lightweight, durable, fire-resistant, prone to corrosion if zinc wears off.
   • Characteristics of AC and composite sheets: Weather-resistant, economical, health hazard concerns.
8. 7 Marks
   bDescribe the properties and common applications of PVC, asbestos and stoneware pipes.
   How to answer

   • PVC pipes: Lightweight, corrosion-resistant, smooth interior (low friction), easy installation; used in domestic plumbing, irrigation, and rainwater conveyance.
   • Asbestos pipes: High tensile strength, resistant to corrosion and fire; used for water mains, drainage, and vents (declining due to environmental regulations).
   • Stoneware pipes: Highly resistant to chemical attacks, acids, and abrasion, but brittle; widely used in underground sanitary sewage and drainage networks.
9. 7 Marks
   aWhat factors should be considered when choosing flooring for residential and commercial buildings and how do these factors impact the selection?
   How to answer

   • Factors: Traffic intensity/durability, initial cost, maintenance requirements, aesthetic appearance, slip resistance, fire resistance, sound and thermal insulation, and damp resistance.
   • Impact on residential selection: Emphasis on comfort, warmth, aesthetics, ease of cleaning (e.g., vitrified tiles, timber, marble).
   • Impact on commercial selection: High wear resistance, heavy foot-traffic handling, slip resistance, low long-term maintenance (e.g., granite, terrazzo, vinyl, industrial screed).
10. 7 Marks
    bCompare enamels, distempers, water wash in terms of their properties, applications and advantages in painting.
    How to answer

    • Properties: Enamels provide hard, glossy, impermeable film; Distempers provide matte, breathable finish; Water wash is lime/chalk based, thin, and permeable.
    • Applications: Enamels for wood and metal surfaces, doors/windows; Distempers for interior plaster walls; Water wash for budget interior/exterior walls and basements.
    • Advantages: Enamels are washable and durable; Distempers are economical and aesthetically pleasing; Water wash is cheap, disinfectant, and easy to apply.
11. 7 Marks
    aDescribe the characteristics of an ideal paint. What properties should it possess to be effective for various applications?
    How to answer

    • Key characteristics: High opacity and covering power, uniform consistency, reasonable drying time, elasticity to accommodate expansion/contraction.
    • Resistance properties: Resistance to weathering, moisture, chemical action, cracking, flaking, and discoloration.
    • Application properties: Easy brushing/spraying without brush marks, long-lasting aesthetic gloss or finish, harmless to applicator.
12. 7 Marks
    bExplain the steps involved in painting wooden surfaces. What specific considerations should be taken into account to ensure a durable finish?
    How to answer

    • Sequence of steps: Surface preparation (smoothing/cleaning), knotting treatment (patent or ordinary), priming coat application, stopping/filling defects with putty, applying undercoats, and final finishing coat.
    • Specific considerations for durability: Moisture content of timber should be low (<15%), seasoning must be complete, dust-free environment, sufficient drying time between successive coats.
13. 7 Marks
    aWhat are the properties of tar and what are the advantages and disadvantages of using tar in various applications?
    How to answer

    • Properties of tar: Viscous black liquid produced by destructive distillation of coal/wood, higher temperature susceptibility than bitumen, strong odor, high carbon content.
    • Advantages: Excellent adhesion to aggregate, good waterproofing capability, cheaper than petroleum bitumen, effective preservative action for wood/iron.
    • Disadvantages: Highly temperature sensitive (becomes brittle in cold, melts/flows in hot weather), volatile constituents evaporate quickly causing brittleness, potential health/carcinogenic hazards.
14. 7 Marks
    bWhat are thermal insulating materials and why are they important in construction?
    How to answer

    • Definition: Materials possessing very low thermal conductivity that resist the transfer of heat through conduction, convection, or radiation.
    • Examples: Glass wool, expanded polystyrene (EPS), rockwool, cellular glass, polyurethane foam.
    • Importance in construction: Reduction in HVAC energy consumption, maintaining thermal comfort inside buildings, prevention of moisture condensation, and fire protection.
15. 14 Marks
    Write short notes on (any two): a) Grades of Concrete b) Key properties of aluminium c) French polish d) Water proofing materials
    How to answer

    • a) Grades of Concrete: Ordinary (M10-M20), Standard (M25-M55), High Strength (M60-M80); designated by characteristic 28-day compressive cube strength in N/mm².
    • b) Key properties of aluminium: Low density, high strength-to-weight ratio, excellent corrosion resistance (oxide layer), high ductility, high thermal and electrical conductivity.
    • c) French polish: Solution of shellac in methylated spirit; produces high-gloss transparent finish on fine wood furniture; applied in thin coats using a rubbing pad.
    • d) Waterproofing materials: Bituminous felt, APP/SBS modified membranes, polyurethane/acrylic liquid coatings, integral waterproofing admixtures, and bentonite clay liners.