Question 1

Brick Mould Dimensions – Allowance for Drying and Burning Shrinkage In order that the finished, burnt bricks meet the specified nominal size after drying and firing, the size of the green brick mould is generally kept how, relative to the specified …

Accepted Answer

Introduction: Bricks shrink during drying and burning. If the mould matched the final size exactly, the fired brick would end up undersized. Hence, moulds are made slightly oversize to compensate. This question checks that you understand that practical allowance. Given Data / Assumptions: Green (freshly moulded) bricks lose moisture and undergo sintering. Both stages produce dimensional shrinkage. Specifications demand finished bricks within tight tolerances. Concept / Approach: The mould must be dimensioned to offset expected shrinkage so that the final product meets the nominal standard upon completion of burning and cooling. The exact percentage varies with clay composition and process, but the qualitative rule is that the mould is slightly larger than the finished size. Step-by-Step Solution: 1) Recognize shrinkage from moisture loss and vitrification.2) Choose an oversize mould so that the final, fired dimensions match nominal values.3) Avoid excessive oversize that would cause wastage or out-of-tolerance variation.4) Therefore, the correct choice is 'a little larger than specified'. Verification / Alternative check: Brickmaking manuals specify typical shrinkage allowances (often a few millimetres depending on mix and process), confirming oversize mould practice. Why Other Options Are Wrong: Smaller or equal moulds would yield undersized bricks; fixed 10% or 20% oversize is unrealistic and excessive for most clays. Common Pitfalls: Assuming a single percentage suits all clays; ignoring quality control adjustments based on measured shrinkage. Final Answer: A little larger than the specified size to allow for shrinkage

Question 2

Cement Storage – Effect of Aging on Strength When ordinary Portland cement is stored for extended periods under average site conditions, what typically happens to its potential strength?

Accepted Answer

Introduction: Cement is hygroscopic. With time, especially in humid climates, it reacts slowly with atmospheric moisture and carbon dioxide even inside bags. This premature reaction reduces reactivity during actual mixing and lowers the achievable strength of mortar and concrete made from aged cement. Given Data / Assumptions: Storage is in typical warehouses where some humidity exposure is inevitable. No special vacuum packing or desiccation is assumed. Strength refers to standardized test strength achievable at equal water content. Concept / Approach: Partial hydration and carbonation of clinker compounds occur during storage. These irreversible changes consume reactive phases and create agglomerates that do not fully participate in later hydration, lowering ultimate strength. Hence, specifications often limit storage time or require re-testing before use. Step-by-Step Solution: 1) Recognize cement’s sensitivity to moisture and CO2.2) Understand that reactions during storage reduce the fraction of reactive clinker available later.3) Infer that, at equal mix proportions, aged cement yields lower test strengths.4) Conclude that strength decreases with storage. Verification / Alternative check: Standards require periodic re-testing of stored cement and recommend first-in-first-out usage to mitigate strength loss. Why Other Options Are Wrong: Increase in strength does not occur in sealed bags; exact sameness is unrealistic; 'none' and 'random oscillation' ignore known chemistry. Common Pitfalls: Using old cement without re-testing; ignoring the need to adjust water demand due to caking and reduced reactivity. Final Answer: It decreases as the cement partially reacts with moisture and carbon dioxide

Question 3

Engineering Geology – Rock Class Formed from Molten Magma Rocks that originate by crystallization or solidification of molten magma are classified as which rock type?

Accepted Answer

Introduction: Engineering geology divides rocks into three major genetic classes: igneous, sedimentary, and metamorphic. Correctly identifying the origin class helps predict mechanical properties, weathering behavior, and suitability for use as building stones and aggregates. Given Data / Assumptions: Molten magma cools either intrusively (slowly underground) or extrusively (rapidly at the surface). Crystallization produces interlocking mineral textures. Examples include granite (intrusive) and basalt (extrusive). Concept / Approach: Rocks formed directly from magma are classed as igneous. Their coarse or fine textures reflect cooling rate, which in turn affects properties such as strength and durability—key considerations in civil works. Step-by-Step Solution: 1) Map the formation process (magma → solid rock) to the appropriate class.2) Recognize that neither sedimentary (deposition) nor metamorphic (solid-state alteration) fits this origin.3) Therefore select 'igneous rocks' as the correct class.4) Use examples to validate: granite/basalt are quintessential igneous rocks. Verification / Alternative check: Standard geology texts define igneous rocks as those formed by magma solidification and contrast them with sedimentary and metamorphic categories. Why Other Options Are Wrong: Sedimentary: formed from sediments by deposition/lithification. Metamorphic: formed by heat/pressure acting on pre-existing rocks. Evaporitic: a subset of sedimentary formed by chemical precipitation. Common Pitfalls: Confusing metamorphosed igneous rocks with original igneous class; using textural terms (e.g., crystalline) without considering genesis. Final Answer: Igneous rocks

Question 4

Quarrying Methods – Wedging for Costly Stratified Stones In stone quarrying, the wedging method (drilling narrow holes and inserting wedges/feathers) is especially adopted for which costly stratified stones to obtain blocks along bedding planes with…

Accepted Answer

Introduction: Different quarrying methods are chosen based on rock structure, bedding, and value. Wedging is a low-explosive, controlled technique well-suited to stratified stones where clean separation along planes is desired to preserve block quality and reduce wastage. Given Data / Assumptions: Rocks considered: marble, limestone, sandstone, laterite. They commonly exhibit bedding/foliation or planes of weakness. Objective: economical extraction of intact dimension blocks. Concept / Approach: Wedging relies on driving wedges into pre-drilled holes to propagate splits along natural planes. It offers precision and control compared to blasting, which can cause shattering. This makes it suitable for costly, stratified stones where surface finish and block integrity are important. Step-by-Step Solution: 1) Identify stones with bedding/lamination facilitating guided splitting.2) Match technique: wedging and feather-and-wedge systems exploit these planes.3) Evaluate economics: reduced damage improves yield of saleable blocks.4) Conclude wedging is appropriate for the listed stratified stones. Verification / Alternative check: Quarrying manuals describe wedging for marble/limestone/sandstone and even laterite where bedding controls extraction, reserving blasting for massive, non-stratified bodies. Why Other Options Are Wrong: Each single stone listed is indeed compatible; hence 'All of the above' captures the general applicability across these stratified materials. Common Pitfalls: Assuming blasting is always cheaper; neglecting quality loss due to cracks and shatter. Final Answer: All of the above

Question 5

Rapid Hardening Cement – Reason for Early Strength Gain Rapid hardening cement develops higher early strength compared to ordinary Portland cement primarily because of which factor?

Accepted Answer

Introduction: Rapid hardening cement (RHC) is selected where early formwork removal or quick strength development is required, such as in precast yards or cold weather concreting with time constraints. Understanding why RHC gains early strength helps engineers choose appropriate cement for project needs. Given Data / Assumptions: RHC is chemically similar to OPC but optimized for early hydration. Early strength correlates strongly with C3S content and particle fineness. Final 28-day strengths can be comparable to OPC for properly cured mixes. Concept / Approach: Increasing C3S accelerates formation of C-S-H gel at early ages. Finer grinding increases surface area, raising hydration rate and early heat evolution. Together, these factors yield higher early strengths without relying on excessive gypsum or solely on aluminates. Step-by-Step Solution: 1) Compare clinker phase proportions between OPC and RHC—RHC has higher C3S.2) Recognize that finer particles hydrate faster due to higher specific surface.3) Exclude mechanisms that do not primarily drive early compressive strength (e.g., gypsum beyond set regulation).4) Conclude that higher C3S plus fine grinding explains RHC’s early strength. Verification / Alternative check: Standards and manufacturer datasheets show higher early strength and fineness values for RHC versus OPC, consistent with the mechanism above. Why Other Options Are Wrong: Lower lime/coarser grinding reduces early strength; extra gypsum risks flash set; aluminates affect set/heat more than sustained early strength; pozzolana alone is not the basis of rapid-hardening behavior. Common Pitfalls: Confusing rapid hardening cement with rapid setting formulations; assuming gypsum increase alone ensures early strength. Final Answer: Higher tricalcium silicate (C3S) content and much finer grinding than OPC

Question 6

Stone Masonry – Effect of Bed Orientation Relative to Load When stones in masonry are placed so that their natural bedding layers are parallel to the direction of the applied compressive load, what is the likely behavior in service?

Accepted Answer

Introduction: Natural stones are anisotropic due to bedding or foliation planes formed during geological processes. The orientation of these planes relative to structural loads significantly affects performance in masonry. This question examines the risks when layers run parallel to the applied load direction. Given Data / Assumptions: Many stones have distinct bedding/lamination planes. Load is applied vertically (e.g., in a wall or column stone). Moisture may penetrate along planes of weakness. Concept / Approach: When bedding planes are parallel to the load, shear and splitting can occur along those planes, reducing effective compressive capacity. Moisture ingress along layers fosters deterioration (freeze–thaw, salt crystallization), further weakening the stone. Standard practice is to place stones so that bedding planes are normal to the principal compressive load where possible. Step-by-Step Solution: 1) Identify planes of weakness (bedding).2) Consider stress alignment with planes—parallel orientation encourages sliding/splitting.3) Factor moisture transport along layers, increasing decay risk.4) Therefore both splitting and moisture effects are likely, making option (c) correct. Verification / Alternative check: Stone masonry guides recommend orienting beds normal to load to exploit compressive strength across layers and reduce delamination risks. Why Other Options Are Wrong: Choosing only one effect ignores the coupled mechanical and durability impacts; claiming increased strength contradicts practice. Common Pitfalls: Ignoring anisotropy; orienting for appearance instead of structural performance; underestimating moisture transport along bedding. Final Answer: Both (a) and (b)

Question 7

In timber selection for civil and structural works, where is high-quality teak wood especially suitable due to its durability, dimensional stability, and resistance to decay? Choose the single best overall use-case set from the options below.

Accepted Answer

Introduction / Context: Teak (Tectona grandis) is one of the most prized hardwoods used in civil engineering and carpentry. This question checks whether you know why teak is preferred across multiple demanding applications, not just decorative furniture. Given Data / Assumptions: Teak contains natural oils and silica that enhance decay and termite resistance. It exhibits good dimensional stability and moderate to high strength. Applications considered: sports gear, furniture, and railway sleepers. Concept / Approach: Materials selection balances strength, durability, workability, and environment. Teak’s natural oils resist moisture ingress and biological attack; its grain and strength support shock-loaded uses. Historically, well-seasoned teak has been used even for sleepers where availability and cost permitted, and widely for marine/furniture uses due to weathering resistance. Step-by-Step Solution: Assess sports articles: teak’s shock resistance and sweat/oil resistance make it suitable for select items.Assess furniture: excellent choice for long-life indoor/outdoor furniture.Assess sleepers: durable hardwood use is documented; though alternatives like sal are common, teak remains suitable. Verification / Alternative check: Service records in humid/tropical climates show teak’s superior life against decay and borers; marine decks and exterior joinery further confirm its robustness. Why Other Options Are Wrong: Only furniture: too narrow; it ignores other valid uses. Individual options omit teak’s broader suitability. Common Pitfalls: Assuming cost equals unsuitability; suitability refers to performance, not economics. Confusing “common today” with “suitable” historically and technically. Final Answer: All the above

Question 8

In architectural painting practice, which primer/base is most traditionally used on timber before finishing coats? Select the most appropriate historic/standard choice used on wood.

Accepted Answer

Introduction / Context: Before finish coats are applied to wood, a compatible base/primer is used to seal pores, improve adhesion, and provide opacity. Historically, building practice relied on certain pigments for the base on timber. The question tests recognition of that conventional choice (not modern health regulations). Given Data / Assumptions: Focus is on traditional/common practice in civil engineering texts. Substrate is timber, not metal or plaster. Primers must provide sealing, adhesion, and a good key for subsequent coats. Concept / Approach: White lead (basic lead carbonate) was historically the most commonly specified base/primer for timber because it offered excellent coverage, flexibility with oil vehicles, and good sanding properties. While modern practice often replaces it with safer titanium dioxide systems, exam standards referencing classic materials usually identify white lead as the canonical answer for timber bases. Step-by-Step Solution: Identify substrate: wood needs a sealing/priming base.Match to historical choice: white lead in oil as the standard base on timber.Separate from anti-corrosives: red lead is primarily for ferrous metals. Verification / Alternative check: Older specifications and handbooks list white-lead priming on joinery before puttying and finishing coats. Why Other Options Are Wrong: Red lead: metal anti-corrosive primer. Zinc white and titanium white: used in modern primers but not the classic “most commonly used” in traditional texts. Shellac alone lacks hiding power and build of a pigmented base. Common Pitfalls: Answering by today’s environmental regulations rather than traditional specification context. Final Answer: White lead

Question 9

In lime classification for construction, the lime containing a high percentage of calcium oxide (nearly pure, low clay) is generally called what? Pick the standard term used in civil engineering.

Accepted Answer

Introduction / Context: Limes are grouped by composition and setting behavior. Recognizing the name for high-calcium, low-impurity lime is basic in materials courses and site practice for mortar selection and plastering work. Given Data / Assumptions: High CaO content, minimal clay/insolubles. Air-setting (carbonation) behavior predominates; poor underwater setting. Common synonyms appear in literature. Concept / Approach: High-calcium lime is traditionally termed “fat lime” because it is plastic and workable, “rich” in lime content. Some texts use “rich lime” as a synonym, but “fat lime” is the standard term in exam keys and specifications. It contrasts with hydraulic lime, which contains reactive silicates/aluminates enabling setting under water. Step-by-Step Solution: Identify composition: predominantly CaO → plastic, high workability.Map to term: “fat lime”.Differentiate from hydraulic lime (impure with clay) and generic descriptors. Verification / Alternative check: Traditional plastering specs refer to fat lime putty for high-finish work requiring slow set and fine workability. Why Other Options Are Wrong: Rich lime: sometimes used synonymously but not the standard single best choice. White lime: color descriptor, not classification. Hydraulic lime: compositionally different due to clay. Common Pitfalls: Thinking “rich” is a separate category; in most exam contexts, “fat” is the accepted name for high-calcium lime. Final Answer: Fat lime

Question 10

In engineering materials, brass is the alloy formed from which metals? Choose the single correct pair.

Accepted Answer

Introduction / Context: Recognizing common industrial alloys is essential for specifying fittings, fasteners, and architectural hardware. Brass and bronze are frequently confused, yet their compositions and properties differ meaningfully for corrosion behavior and machinability. Given Data / Assumptions: We are identifying the principal alloying pair only. Minor additions (lead, tin) are ignored for the definition. Concept / Approach: Brass is primarily copper + zinc. Varying Zn content tunes strength and color; free-cutting brasses may contain a little lead for machinability, but the defining pair remains Cu–Zn. By contrast, bronzes are copper + tin (and sometimes other elements), and other pairs listed do not define brass. Step-by-Step Solution: Identify the alloy family by major constituents: Cu–Zn → brass.Exclude non-brass combinations (Zn–Pb, Zn–Ni, Sn–Ag, Sn–Pb).Confirm typical applications: valves, taps, door hardware confirm corrosion-resistant Cu–Zn use. Verification / Alternative check: Standards for brass compositions (e.g., IS/ASTM) list copper and zinc as the major elements. Why Other Options Are Wrong: Zinc–lead and zinc–nickel describe other alloy types; tin–silver and tin–lead relate to solders, not brass. Common Pitfalls: Confusing brass with bronze (Cu–Sn); remember: brass = Cu + Zn and bronze = Cu + Sn. Final Answer: Copper and zinc

Question 11

In protective coatings for civil works, what is the principal benefit provided by bitumen paints on metal, concrete, or wood surfaces? Pick the most accurate effect.

Accepted Answer

Introduction / Context: Bituminous coatings are widely used in damp-proofing, underground structures, tanks, and exposed steel where economical protection from moisture and certain chemicals is required. The question asks you to identify the core function of a bitumen paint film. Given Data / Assumptions: Coating binder is bitumen/asphalt cutback or solution. Applied on metal, masonry, or wood where water-proofing and chemical resistance are desired. Finish quality (gloss/smoothness) is secondary. Concept / Approach: Bitumen forms a continuous, hydrophobic film that resists water ingress, many salts, and weak acids/alkalis. It shields substrates from corrosion and moisture-driven deterioration. While it can look uniform, its primary value is barrier protection, not high decorative appeal or extreme hardness. Step-by-Step Solution: Relate composition to performance: hydrocarbon matrix blocks moisture and ions.Map to application: damp-proof courses, tank exteriors, buried pipes.Select “protective surface” as the primary benefit. Verification / Alternative check: Product datasheets emphasize water resistance, corrosion protection, and chemical splash resistance. Why Other Options Are Wrong: Aesthetic/hard/rough claims do not capture the principal service function; smoothness depends on substrate and application, not inherent to the coating. Common Pitfalls: Overestimating bitumen’s UV durability; top-coats or shielding may be required in sunlight. Final Answer: Protective surface (moisture and chemical resistance)

Question 12

Fire resistance of building stones: select the correct set of statements about mineral changes and stone types under heating. Choose the most comprehensive correct option.

Accepted Answer

Introduction / Context: Understanding stone behavior in fire helps engineers select facing and structural masonry where thermal shock and decomposition are concerns. This question ties mineral transformations to practical fire performance of common stones. Given Data / Assumptions: Quartz undergoes a known phase transition near 573°C causing volume change. Limestone decomposes on strong heating, affecting integrity. Siliceous vs argillaceous compositions influence fire resistance differently. Concept / Approach: Mineralogy governs thermal stability. Quartz-bearing stones may experience internal stress near the 573°C transition, but siliceous sandstones generally remain more fire-resistant than calcareous stones that calcine. Argillaceous stones, though weaker mechanically, often show better resistance to fire damage than limestones because they lack the calcination decomposition that generates CO2 and disrupts the matrix. Step-by-Step Solution: Confirm a): quartz transition and expansion below 600°C.Confirm b): limestone calcination → CaO + CO2 above ~800–900°C.Confirm c): siliceous sandstones generally outperform in fire compared with limestones.Confirm d): argillaceous stones can resist fire fairly well despite lower strength. Verification / Alternative check: Fire test data and manuals consistently warn of limestone spalling due to calcination; quartz transition is a standard property, and clays/silicates manage heat differently. Why Other Options Are Wrong: Choosing anything less than “All the above” omits one or more true statements. Common Pitfalls: Assuming highest compressive strength equals best fire resistance; overlooking chemical decomposition under heat. Final Answer: All the above

Question 13

Styrene (polystyrene) resins in building products and consumer goods: identify the correct set of characteristics and sources. Choose the most comprehensive correct option.

Accepted Answer

Introduction / Context: Styrenic polymers (e.g., polystyrene, high-impact polystyrene, ABS blends) are widely used in interiors, appliances, and packaging. This question checks your understanding of their source, typical properties, and general performance in everyday chemical environments. Given Data / Assumptions: “Styrene resin” here refers to polystyrene-based materials. Comparisons are with common alternatives like metals and glass. We are discussing household/architectural contexts, not extreme chemicals. Concept / Approach: Styrene is derived industrially from ethylbenzene (benzene + ethylene from petroleum). Polystyrene has low density, enabling light components. Optical grades are transparent and can transmit visible and some UV (though yellowing/UV degradation can occur without stabilizers). For domestic use, many styrenics resist water, salts, and mild acids/bases, making them suitable for certain utensils and containers, while they are not resistant to aromatic solvents or strong chemicals. Step-by-Step Solution: Source: petroleum route via ethylbenzene → styrene → polymerization.Property: low density → lightweight parts.Optics: clear polystyrene transmits visible and some UV; additives affect stability.Use: many household chemicals do not attack styrenics; avoid strong solvents. Verification / Alternative check: Material datasheets show density ~1.04–1.06 g/cm^3, optical clarity, and compatibility charts for typical reagents. Why Other Options Are Wrong: Each individual statement is true; picking fewer than all ignores other correct attributes. Caveat: resistance is not universal—context matters. Common Pitfalls: Assuming universal chemical inertness; polystyrene is attacked by hydrocarbons like toluene and gasoline. Final Answer: All the above

Question 14

In oil-based paints used for buildings and metalwork, which solvent/thinner is most commonly used to adjust brushing/spraying viscosity and aid drying? Select the best traditional choice.

Accepted Answer

Introduction / Context: Oil paints are formulated with drying oils (e.g., linseed), pigments, and volatile solvents to achieve workable viscosity and film formation. Field painters universally use a standard thinner to condition these coatings for brush or spray. This question targets that practical solvent choice. Given Data / Assumptions: We refer to oil-based (not water-borne) paints. Solvent should be compatible with oil vehicles and resins. Traditional practice is considered. Concept / Approach: Turpentine (or mineral turpentine substitutes/white spirit) is the common solvent for oil paints. It lowers viscosity for application, improves flow and leveling, and evaporates at a controlled rate to allow oxidative curing of the film. Alcohol (spirit) is not suitable for oil vehicles; water cannot thin oil paints; coal tar and generic petroleum fuels are inappropriate solvents. Step-by-Step Solution: Identify binder: drying oil based → needs hydrocarbon/terpene solvent.Select turpentine/white spirit family as standard thinner.Eliminate incompatible solvents and fuels. Verification / Alternative check: Paint manufacturer datasheets specify turpentine or mineral spirits as recommended thinners/cleanup solvents. Why Other Options Are Wrong: Alcohol/water do not dissolve oil vehicles; coal tar/petroleum fuel fractions are unsuitable and unsafe for consistent paint performance. Common Pitfalls: Confusing solvent roles in oil vs spirit/latex systems; over-thinning which can reduce hiding and gloss. Final Answer: Turpentine

Question 15

Dry rot in timber: which environmental conditions most strongly favor rapid fungal growth and decay in service? Choose the most comprehensive correct option.

Accepted Answer

Introduction / Context: Dry rot is a misnomer; the causative fungi require moisture to colonize and digest wood. Recognizing risk conditions guides prevention in floors, roofs, and joinery, especially in humid climates or water-leak locations. Given Data / Assumptions: Timber can be seasoned or unseasoned. Environmental control (light, ventilation) varies among structures. Fungi need moisture, oxygen, and food (cellulose/hemicellulose) to grow. Concept / Approach: Fungal spores germinate when the wood moisture content exceeds fiber saturation thresholds typical for decay fungi (often > 20%). Darkness or absence of sunlight lowers temperatures and UV exposure that otherwise inhibit growth. Poor ventilation maintains humidity; unseasoned or sappy timber provides nutrients that speed colonization. Therefore, the combination of dampness, stagnant air, nutrient-rich wood, and lack of sunlight is ideal for dry-rot fungi. Step-by-Step Solution: Identify moisture as the primary driver; ensure MC stays below safe limits.Note that darkness and stagnant air sustain high humidity.Recognize that sappy, improperly seasoned wood accelerates fungal metabolism. Verification / Alternative check: Building pathology guides show dramatic reduction in decay when ventilation and damp-proofing improve and when timber is well seasoned and isolated from wet masonry. Why Other Options Are Wrong: Each single factor is contributory; the correct comprehensive choice is all of them together. Common Pitfalls: Believing “dry rot” occurs without moisture; ignoring hidden leaks and cold bridges that raise local humidity. Final Answer: All the above

Building Materials Questions