Question 1

Quicklime (calcium oxide) in building works – behavior and uses Which statements about quicklime (CaO) are correct in civil engineering practice?

Accepted Answer

Introduction: Quicklime (calcium oxide, CaO) is a foundational material in construction chemistry. Its hydration and carbonation reactions underpin uses such as mortar preparation, soil stabilization, and production of whitewash after slaking. The item checks multiple core behaviors of CaO relevant to site practice. Given Data / Assumptions: Material: quicklime (CaO), not hydrated lime. Water addition refers to slaking carried out safely with adequate water and mixing control. Whitewashing refers to using the product of slaking (Ca(OH)2) as a coating. Concept / Approach: Two principal reactions define quicklime on site: (1) hydration to slaked lime (calcium hydroxide) with heat evolution, and (2) subsequent carbonation of hydroxide to calcium carbonate in air. Correct handling converts CaO into a usable binder or wash. Step-by-Step Solution: 1) Hydration: CaO + H2O → Ca(OH)2 + heat (exothermic), hence temperature rise.2) Product: Ca(OH)2 is slaked lime; suitable for making putty, mortars, and whitewash.3) Carbonation: Ca(OH)2 + CO2 → CaCO3 + H2O; this sets/hardens lime coatings and mortars. Verification / Alternative check: Observed site practice shows vigorous heat release during slaking. Whitewash recipes begin with well-slaked lime. Over time, surfaces harden through carbonation, consistent with the chemistry above. Why Other Options Are Wrong: Each listed behavior (heat on hydration, reaction with CO2, production of slaked lime, suitability for whitewashing after slaking) is correct; thus the combined statement “All of the above” is true. Common Pitfalls: Confusing quicklime (CaO) with hydrated lime (Ca(OH)2), and attempting whitewashing with un-slaked CaO, which is unsafe and unsuitable. Proper slaking and aging improve workability and finish. Final Answer: All of the above

Question 2

Glaziers’ putty – composition, use, and handling in building works What is correctly stated about traditional putty used around window glass panes?

Accepted Answer

Introduction: Putty, especially traditional glaziers’ putty, remains a practical material for bedding and sealing glass panes. Understanding its composition and handling ensures durable, weather-tight glazing in doors, windows, and skylights. Given Data / Assumptions: Composition refers to classic putty, not modern polymer mastics. “Softened” means reconditioning for removal or rework, not daily service. Concept / Approach: Classic putty is a plastic sealant produced by mixing whiting (finely ground chalk/calcium carbonate) with linseed oil to a doughy consistency. It cures by slow oxidation of the oil, forming a firm yet slightly flexible seal around glass edges. Step-by-Step Solution: 1) Composition: whiting + boiled/raw linseed oil → malleable compound.2) Use: roll into fillets, press around the rebate to bed glass, tool to a neat arris for weathering.3) Maintenance: aged putty can be softened/loosened using appropriate solvents or alkaline solutions to aid removal; care is required to avoid damaging timber or glass. Verification / Alternative check: Traditional building practice and conservation handbooks consistently specify chalk + linseed oil recipes, with rework methods using controlled softening or mechanical removal where needed. Why Other Options Are Wrong: Each of the first three statements is correct in the traditional context. Therefore, the combined statement “All of the above” is the right choice. Common Pitfalls: Confusing modern acrylic/silicone mastics with classic putty; applying paint too soon before oxidation cure; or neglecting proper bevel for water shed, which shortens service life. Final Answer: All of the above

Question 3

Mastic asphalt in buildings and civil works – typical application Mastic asphalt is normally used for which primary purpose on site?

Accepted Answer

Introduction: Mastic asphalt is a dense, void-free asphaltic material prepared from bitumen and carefully graded mineral fillers. Its key engineering value lies in forming seamless, impermeable layers. The question asks for the most typical, primary site use. Given Data / Assumptions: We consider standard building and civil applications. “Normally used” implies the common, dominant application. Concept / Approach: When applied hot and finished properly, mastic asphalt creates a monolithic, watertight sheet that adheres well to substrates. This makes it ideal for roofs, podium decks, basements, and water-retaining or water-excluding structures where impermeability is vital. Step-by-Step Solution: 1) Identify properties: zero voids, high density, durable under traffic (with protection), highly impermeable.2) Map properties to needs: roofs and wet areas require continuous waterproofing membranes.3) Therefore, the principal application is waterproofing. Verification / Alternative check: Specifications for roofing and tanking frequently list mastic asphalt grades as waterproofing layers, sometimes protected with tiles or screeds. Sound or fire insulation are secondary or unrelated functions compared with its waterproofing role. Why Other Options Are Wrong: Sound insulation: Not a primary function; mass helps, but better acoustic systems exist. Fire proofing: While asphalt has some fire-related considerations, it is not primarily a fireproofing material. None of these: Incorrect because waterproofing is a standard, mainstream use. Common Pitfalls: Confusing mastic asphalt (dense, void-free) with asphalt concrete or polymeric membranes; overlooking the need for proper expansion detailing and protection from high service temperatures. Final Answer: Waterproofing

Question 4

First-class bricks – minimum compressive strength requirement What is the minimum compressive strength specified for first-class bricks?

Accepted Answer

Introduction: Brick classification includes performance thresholds for compressive strength, water absorption, and dimensional tolerances. Knowing the minimum compressive strength for first-class bricks helps in selecting suitable masonry units for load-bearing and high-quality work. Given Data / Assumptions: We refer to traditional Indian practice values used in many exam standards. Answer seeks the minimum threshold, not typical or average strengths. Concept / Approach: First-class bricks are made from good clay, properly molded, burnt uniformly, and conform to strength and absorption limits. Historic exam references commonly quote a minimum compressive strength of about 100 kg/cm^2 for first-class bricks, with higher classes demanding more. Step-by-Step Solution: 1) Identify the benchmark: many texts list first-class bricks ≥ 100 kg/cm^2.2) Compare options: 100 kg/cm^2 matches the widely taught minimum.3) Therefore select 100 kg/cm^2 as the minimum value. Verification / Alternative check: Some codes and newer standards may specify in N/mm^2; 10 N/mm^2 is approximately 102 kg/cm^2. In MCQ traditions, 100 kg/cm^2 is accepted as the minimum for first-class in many question banks. Why Other Options Are Wrong: 75 or 90 kg/cm^2: Below the common first-class threshold. 120 or 130 kg/cm^2: These are higher than the minimum and may describe better grades or typical strengths but not the minimum requirement. Common Pitfalls: Mixing minimum values with typical test results; not converting consistently between N/mm^2 and kg/cm^2 when comparing sources. Final Answer: 100 kg/cm^2

Question 5

Plywood – behavior, sizes, and directional properties Which statements about commercial plywood are generally correct in construction practice?

Accepted Answer

Introduction: Plywood is a widely used engineered wood product. Alternating veneer directions give it stability and relatively uniform in-plane properties, making it reliable for formwork, sheathing, furniture, doors, and partitions. The item checks multiple true characteristics commonly cited in civil engineering texts. Given Data / Assumptions: “Commercial plywood” refers to general building grades, not specialized structural plywood. Typical maximum panel sizes in the market are being referenced. Concept / Approach: Cross-lamination reduces anisotropy and minimizes splitting along grain. It also moderates dimensional changes due to moisture fluctuations. Market availability often includes large panels, reducing joints and speeding installation. Step-by-Step Solution: 1) Splitting/cracking: Cross plies resist propagation of checks caused by humidity and temperature changes.2) Sizes: Large panels, commonly around 1.2–1.5 m wide by 2.4–3.0 m long, are widely available, matching the statement.3) Directional strength: Cross-grain stacking yields relatively uniform in-plane tensile behavior compared with solid wood.4) Weight: Lower density species and thinner veneers make plywood comparatively light for its stiffness and size. Verification / Alternative check: Common product data sheets corroborate the general size ranges and the cross-laminated behavior that resists splits and warping. Why Other Options Are Wrong: Each individual statement is broadly correct for commercial plywood; thus “All of the above” is the correct combined choice. Common Pitfalls: Assuming plywood is completely isotropic; it is only more uniform than solid timber. Ignoring panel orientation during installation can still lead to performance differences. Final Answer: All of the above

Question 6

Brick earth composition – dominant constituent for good quality bricks The main ingredient that should dominate in a good brick earth is which of the following?

Accepted Answer

Introduction: Brick performance depends strongly on the proportion of its raw constituents. Understanding the dominant component in a suitable brick clay (brick earth) helps ensure strength, shape retention, and resistance to shrinkage and warping during drying and burning. Given Data / Assumptions: We refer to ordinary burnt clay bricks. “Dominant” means the largest proportion by percentage among the listed constituents. Concept / Approach: Good brick earth typically contains silica and alumina as major constituents, with silica usually the predominant fraction. Silica controls shrinkage, imparts hardness, and helps retain shape by preventing excessive warping during drying and firing. Minor constituents (lime, magnesia, iron oxide, alkalies) fine-tune vitrification and color. Step-by-Step Solution: 1) Identify common composition ranges: silica often ~50–60% (varies), alumina ~20–30%.2) Lime/magnesia are minor; over-dosage can cause lime blowing or expansion defects.3) Therefore, silica is the main ingredient in good brick earth. Verification / Alternative check: Standard texts consistently emphasize silica as the largest component for dimensional stability, while alumina gives plasticity for molding. Controlled lime aids fusion but remains a small fraction. Why Other Options Are Wrong: Magnesia: Usually minor; excess causes color change and potential durability issues. Lime: Needed in small amounts; too much causes popping/spalling due to unsoundness. Alumina: Important for plasticity but typically secondary to silica in proportion. Common Pitfalls: Assuming alumina should dominate because it provides plasticity; without sufficient silica, bricks can warp and shrink excessively. Final Answer: Silica

Question 7

In highway maintenance, where is plastic bitumen most appropriately used? (Add practical context: choose the application that benefits from a flexible, gap-filling, and water-resisting bituminous mix blended with fillers.)

Accepted Answer

Introduction: Plastic bitumen (often called bituminous mastic when loaded with mineral fillers) is designed to be workable at placement, then set into a dense, slightly deformable mass. The concept tested here is the correct field application where this mix's flexibility and adhesion are most valuable. Given Data / Assumptions: Plastic bitumen is bitumen blended with fillers to improve stiffness, adhesion, and water resistance. It is placed in confined small volumes rather than as a continuous structural layer. Traffic loads demand a material that accommodates slight movements without raveling. Concept / Approach: Bituminous mastics excel at sealing voids and bridging small movements. They bond to the sides of cracks and reduce water ingress, protecting the sub-layers from moisture damage and preventing crack propagation under traffic. Step-by-Step Solution: 1) Identify candidate uses: wearing course, expansion joints, crack sealing, general waterproofing.2) Evaluate property–use match: plastic bitumen = adhesive + flexible + gap-filling.3) Wearing course requires graded aggregate mixes with high stability, not mastics.4) Expansion joints typically use elastic sealants designed for large joint movements.5) Crack sealing needs a flowable, adhesive, water-resisting compound that tolerates micro-movements.6) Therefore, the best match is crack filling and patch repair. Verification / Alternative check: Maintenance manuals place bituminous mastics under crack treatment and localized patching rather than as primary surfacing. Field practice confirms longevity when cracks are cleaned, dried, primed (if specified), and filled flush. Why Other Options Are Wrong: Road pavements (main wearing course): Needs dense/stone mastic or asphalt concrete with graded aggregates for stability. Expansion joints: Prefer polysulfide, silicone, or specialized elastomeric joint sealants with designed movement capacity. General waterproofing of basements: Uses membranes/coatings tailored for hydrostatic pressure; pavement mastics are not the design solution. Common Pitfalls: Confusing stone mastic asphalt (a wearing course) with bituminous mastic used for sealing; using plastic bitumen as a structural layer; neglecting crack cleaning and drying leads to poor bonding. Final Answer: Crack filling and patch repair in flexible pavements

Question 8

For low-voltage electrical accessories, what are the common applications of porcelain components? (Consider domestic-grade parts such as lamp holders, switch blocks, and protective insulating pieces.)

Accepted Answer

Introduction: Porcelain is a ceramic with high dielectric strength, heat resistance, and dimensional stability. The question checks knowledge of typical low-voltage applications where porcelain's insulating properties are advantageous. Given Data / Assumptions: Context: domestic or low-voltage installations. Required properties: insulation, heat resistance, non-combustibility. Typical parts: switch blocks, insulating tubes/bushings, lamp holders. Concept / Approach: Electrical porcelain provides electrical isolation and mechanical support. In low-voltage fittings, it prevents arcing and charring at contact points exposed to heat and small sparks. Step-by-Step Solution: 1) Identify common low-voltage fixtures that heat up or carry current.2) Map porcelain's strengths: high dielectric and heat resistance.3) Check each item: switch blocks, insulating tubes, lamp sockets all require insulation and heat tolerance.4) Conclude that all listed items appropriately use porcelain. Verification / Alternative check: Standards and catalogs for wiring accessories list porcelain variants for lamp holders and certain switch/fuse bases where thermal performance and safety are critical. Why Other Options Are Wrong: Switch blocks only: ignores other common porcelain parts. Insulating tubes only: incomplete; does not reflect full range. Lamp sockets only: incomplete; omits switch and tube applications. Common Pitfalls: Confusing porcelain with bakelite or modern thermosets; while plastics are common today, porcelain remains a suitable choice where heat and flame resistance are prioritized. Final Answer: Switch blocks, insulating tubes, and lamp sockets (all of these)

Question 9

In pattern making and general workshop practice, which timber is most commonly chosen for wooden moulds? (Add context: consider dimensional stability, workability, and resistance to wear during repeated use.)

Accepted Answer

Introduction: Wooden moulds/patterns in foundry and workshop contexts must balance stability, machinability, and durability. This question probes recognition of a timber that consistently meets these demands in instructional and field practice. Given Data / Assumptions: Patterns experience abrasion and humidity cycles. Dimensional accuracy is important for repeat castings or formwork. Cost and availability matter but are secondary to stability and durability. Concept / Approach: Teak contains natural oils and silica, giving excellent dimensional stability, resistance to moisture changes, and a good finish when machined. These properties reduce warping and extend service life compared with many local hardwoods or softwoods. Step-by-Step Solution: 1) List candidate timbers and typical properties.2) Compare stability and wear: teak > deodar ≈ sheesham > generic hardwood/plywood.3) Evaluate surface finish and tool wear: teak machines cleanly and holds detail.4) Conclude teak as the preferred standard for durable wooden moulds/patterns. Verification / Alternative check: Teaching manuals and foundry texts routinely cite teak and mahogany as benchmark pattern woods due to balanced workability and dimensional stability. Why Other Options Are Wrong: Plywood: adequate for temporary forms, but exposed plies and glue lines wear quickly. Sheesham: hard and durable but tends to move with moisture; heavier to shape. Deodar: lighter and easy to work, but less durable compared to teak. Generic hardwood: unspecified properties; not a dependable choice for precision. Common Pitfalls: Choosing solely on cost or availability; ignoring movement across grain; neglecting surface sealing which all woods (including teak) still require for longevity. Final Answer: Teak wood (Tectona grandis)

Question 10

In brickwork, what is the name of the brick portion cut to form plan angles other than 90 degrees? (Think of special bricks used at corners or splayed openings.)

Accepted Answer

Introduction: Special shapes in brick masonry ensure proper bonding and neat arrises at corners that are not right angles. The question checks recognition of the correct term for such cuts. Given Data / Assumptions: Angle in plan is not 90 degrees. Objective is to maintain bond and reduce mortar wedges/gaps. Standard terminology from building construction practice applies. Concept / Approach: When walls meet at oblique angles, a squint brick (a brick cut or moulded with a splayed face) creates a proper junction. It differs from closers that adjust bond at right-angle corners and ends. Step-by-Step Solution: 1) Identify whether the problem concerns an oblique angle in plan.2) Recall brick types: queen closer (half brick cut lengthwise), king closer (nearly triangular after removing a triangular portion), and squint bricks (faces cut to angle).3) Match need: for angles ≠ 90°, the specialized unit is a squint brick. Verification / Alternative check: Construction handbooks illustrate squint bricks for 45°, 60°, and other common angles to preserve bond continuity. Why Other Options Are Wrong: Queen closer: used near quoins at right-angle corners to maintain bond, not for oblique corners. King closer: similar application at right-angle corners. Closer (generic): not specific to oblique angles. Common Pitfalls: Using ordinary headers and large mortar wedges at acute/obtuse corners, leading to weak joints and poor appearance. Final Answer: Squint brick

Question 11

Steelmaking processes: pick the single correct statement about open-hearth and Bessemer practices. (Focus on homogeneity and impurity removal, especially phosphorus and sulphur.)

Accepted Answer

Introduction: This question contrasts classic steelmaking routes. Open-hearth (Siemens–Martin) historically offered superior control over temperature and composition, yielding homogeneous steels favored for structural members. Bessemer routes varied in impurity removal capability depending on lining (acid vs basic). Given Data / Assumptions: Open-hearth permits prolonged refining and sampling. Bessemer's rapid blow limits fine compositional control. Phosphorus removal requires a basic slag; sulphur is more difficult and typically not removed effectively in Bessemer. Concept / Approach: Homogeneity and control are key in structural steel. Historically, open-hearth produced reliably uniform steel, while phosphorus removal is effective only with basic linings (Thomas process). Sulphur removal is limited and usually addressed in other stages or by selecting low-S raw materials. Step-by-Step Solution: 1) Evaluate A: claims open-hearth is less homogeneous — contradicts practice; reject.2) Evaluate B: aligns with the rationale for structural preference — accept as correct.3) Evaluate C: sulphur removal is not effectively handled by Bessemer; reject.4) Evaluate D: basic Bessemer is specifically developed to handle high-phosphorus iron; reject. Verification / Alternative check: Historical specs and texts cite open-hearth's uniformity and the role of basic slags for phosphorus; sulphur control typically requires separate desulphurization or basic open-hearth/BOF practices, not acid Bessemer. Why Other Options Are Wrong: A: Inverts the widely accepted comparison. C: Overstates Bessemer's ability; sulphur remains problematic. D: Thomas (basic) process is precisely to treat high-P pig iron. Common Pitfalls: Assuming “all processes remove all impurities”; ignoring the difference between acid and basic linings; conflating phosphorus and sulphur behavior in slag chemistry. Final Answer: Engineers prefer open-hearth steel for structural work because it is more homogeneous and better controlled.

Question 12

Which statement about cast iron is correct in standard materials practice? (Consider composition, manufacture, and typical remelting route.)

Accepted Answer

Introduction: Cast iron is an iron–carbon alloy with relatively high carbon content and accompanying impurities (Si, Mn, P, S). The question checks recognition of a compositionally accurate and contextually correct statement. Given Data / Assumptions: Cast irons solidify with graphite or cementite depending on composition and cooling. Manufacturing practice commonly involves remelting pig iron with scrap and flux in a cupola or induction furnace. Carbon range for cast iron exceeds that of steels. Concept / Approach: Cast irons are not “purified” pig iron; instead, they retain higher carbon and are cast into shape. Typical total carbon is about 2–4.5 percent, with silicon often 1–3 percent to promote graphitization. Step-by-Step Solution: 1) Review A: “purifying pig iron” is misleading; cast iron keeps high C and impurities; reject.2) Review B: Casting into shape is true but incomplete alone and could be ambiguous versus steels; we seek the most precise, unambiguous statement.3) Review C: The composition range 2–4.5% C accurately characterizes cast iron; accept.4) Review D: Cupola remelting is common; the statement saying “never remelted” is false; reject. Verification / Alternative check: Textbook data tables list typical carbon ranges and standard melting routes (cupola/induction). Casting shops routinely remelt charge mixes to pour into moulds. Why Other Options Are Wrong: A: Suggests purification, which contradicts the retained high carbon nature. B: Partly true but not as defining as composition; also many alloys are cast, so this is not unique. D: Opposite of common practice; cupola remelting is traditional. Common Pitfalls: Confusing cast iron with steelmaking; equating “purifying” with standard remelting; ignoring that composition definition is the clearest differentiator. Final Answer: Cast iron generally contains about 2 to 4.5 percent carbon along with other impurities.

Question 13

Which steelmaking route produces steel that characteristically shows fissures and cavities (blistered appearance)? (Identify the process known for creating blister steel.)

Accepted Answer

Introduction: Different historical steelmaking routes generate distinctive microstructural and surface features. The question targets recognition of the route that yields blister steel with visible fissures and cavities on the surface. Given Data / Assumptions: Cementation involves carburizing wrought iron bars in a carbonaceous pack at high temperature. Absorbed carbon diffuses inward, creating gas evolution and surface irregularity. Products were historically termed “blister steel.” Concept / Approach: Carbon absorption and gas formation during cementation cause a blistered surface and internal fissures. Later remelting (crucible) could homogenize, producing higher quality steel (shear or cast steel), but the initial product is blistered. Step-by-Step Solution: 1) Map processes to product appearance: cementation → blister steel.2) Crucible process remelts to refine and homogenize; does not create blisters.3) Bessemer and open-hearth are bulk steelmaking routes with different impurity control; no characteristic blistered surface.4) Conclude cementation as the correct answer. Verification / Alternative check: Metallurgical histories consistently depict blister steel as the hallmark of the cementation era before crucible and modern furnaces. Why Other Options Are Wrong: Crucible: used to melt and homogenize; reduces defects. Bessemer: pneumatic refining, not producing blisters as a characteristic. Open-hearth: bath refining with controlled slag; no blister signature. Common Pitfalls: Confusing subsequent refining (crucible) with the initial blister-forming step; assuming any older process produces visible blisters. Final Answer: Cementation process

Question 14

In oil-based paints, which is the most commonly used thinner for adjusting brushability and viscosity on site? (Choose the solvent typically recommended for oil paints.)

Accepted Answer

Introduction: Oil-based paints require compatible thinners to modify viscosity, flow, and leveling. The question asks for the typical field-standard thinner used with traditional oil paints and primers. Given Data / Assumptions: Binder system: drying oils/alkyds in oil paints. Goal: improve brushability and penetration without harming film formation. Common site solvents: turpentine and petroleum distillates. Concept / Approach: Turpentine (gum or mineral turpentine depending on locale) has long been specified for oil paints due to compatibility with drying oils and favorable evaporation rate, promoting good film without excessive solvent retention. Step-by-Step Solution: 1) Identify solvent options compatible with oil binders.2) Compare practice guidelines: turpentine widely cited as the standard thinner for oil paints.3) Naphtha can be used in some alkyd systems but is not the universal standard for all oil paints.4) Conclude turpentine as the most commonly used thinner. Verification / Alternative check: Manufacturer data sheets for traditional oil/alkyd paints specify mineral turpentine/white spirit for thinning and cleaning, confirming ubiquity. Why Other Options Are Wrong: Naphtha: usable in certain cases but not the default standard across all oil paints. Both equally standard: overgeneralizes and ignores system-specific guidance. Neither: contradicts established paint practice. Common Pitfalls: Over-thinning which reduces hiding power and film thickness; mixing incompatible solvents; ignoring maximum thinning percentages on data sheets. Final Answer: Turpentine

Question 15

According to Indian modular brick practice, what is the standard actual size of a modular brick (excluding mortar thickness)? (Note: Distinguish between actual and nominal dimensions.)

Accepted Answer

Introduction: Masonry measurements often distinguish between actual unit size and nominal (including mortar). This question checks recall of the standard actual size of a modular brick used in India. Given Data / Assumptions: Modular brick systems in India specify both actual and nominal sizes. Mortar thickness is typically around 10 mm, leading to a larger nominal size. The question explicitly asks for actual size. Concept / Approach: Actual size is the physical brick dimension measured without mortar; nominal size adds the intended mortar joint to simplify layout modularity on site. Step-by-Step Solution: 1) Recall standard figures: actual = 19 × 9 × 9 cm; nominal ≈ 20 × 10 × 10 cm.2) Compare with given choices and select the exact actual dimensions.3) Confirm that other options do not match Indian modular standards. Verification / Alternative check: Codes and handbooks list 19 × 9 × 9 cm as actual, with 10 mm mortar joints giving nominal 20 × 10 × 10 cm module for coursing and openings. Why Other Options Are Wrong: 10 × 10 × 9 cm: not a recognized standard module. 22.5 × 10 × 8.5 cm and 22.5 × 8.0 × 9 cm: resemble non-modular or historical sizes; not the Indian modular actual size. Common Pitfalls: Confusing actual with nominal; ignoring mortar thickness when setting out openings and lintels; mixing regional sizes. Final Answer: 19 × 9 × 9 cm (actual size)

Question 16

In stone masonry using stratified rocks, how should stones be oriented relative to their bedding planes under service load? (Select the best practice for load direction versus bedding.)

Accepted Answer

Introduction: Stratified stones (e.g., sandstones, limestones) have planes of weakness along bedding. Masonry durability and capacity depend on placing these stones so that loads act favorably relative to bedding. Given Data / Assumptions: Service load is primarily compressive. Stratified rocks may split or shear along bedding if stressed unfavorably. Goal is maximum stability and weathering resistance. Concept / Approach: Best practice is to set stones so the load acts normal (at right angles) to bedding. This minimizes the tendency to delaminate and improves compressive performance, akin to loading timber perpendicular to grain for strength and stability. Step-by-Step Solution: 1) Identify bedding as planes of potential separation.2) Evaluate load orientation: normal vs oblique vs parallel.3) Normal (right angles) to bedding closes laminations and resists splitting.4) Conclude that right angles is the recommended orientation. Verification / Alternative check: Construction handbooks consistently specify “load normal to bedding” for stratified blocks in courses, particularly for weathered stones. Why Other Options Are Wrong: 45° or 60°: induce shear along bedding and stress concentrations. Parallel: highest risk of lamination separation and bending along weak planes. None of these: incorrect because a clear best practice exists. Common Pitfalls: Orienting stones for visual grain instead of structural performance; placing face-bedded stones in steps or copings where weathering rapidly exploits laminations. Final Answer: At right angles to the bedding plane (load normal to bedding)

Question 17

Kilns in brick manufacturing — which type can operate continuously throughout the year without seasonal shutdowns? Choose the most appropriate option.

Accepted Answer

Introduction / Context: In brick manufacturing, different kiln types are selected based on production capacity, fuel efficiency, product quality, and operational continuity. This question tests the understanding of which kiln design allows continuous, year-round operation, which is crucial for consistent output and uniform burning results. Given Data / Assumptions: We compare common kiln types used for bricks. Operational continuity (continuous vs batch) is the key criterion. No seasonal interruptions desired. Concept / Approach: The defining difference is between intermittent (batch) kilns and continuous kilns. In intermittent kilns, loading, firing, cooling, and unloading happen in cycles, causing downtime. In continuous kilns, these stages occur simultaneously in different zones, enabling non-stop operation. Step-by-Step Solution: 1) Clamp kiln is a temporary, open-to-atmosphere setup, fired in batches. It depends on weather and cannot ensure year-round, uniform results.2) Bull's trench kiln (BTK) is a continuous kiln with moving fire, but its operation can be affected by heavy rains and site conditions; still, it is designed for continuous firing.3) Hoffman's kiln is a fully continuous, permanent, annular tunnel-like arrangement with multiple chambers. Firing, drying, and cooling occur simultaneously in separate chambers as the fire front advances.4) Because Hoffman's kiln separates zones and recovers heat efficiently, it runs economically and continuously throughout the year. Verification / Alternative check: Textbook descriptions consistently classify Hoffman's as a continuous, annular kiln noted for steady, industrial-scale production and year-round operation. Why Other Options Are Wrong: Clamp kiln: Batch and weather-dependent; not continuous. Bull's trench kiln: While continuous, it is more sensitive to site/weather than Hoffman's and is not the canonical answer for all-season permanence. None of these: Incorrect because a known continuous option exists. Common Pitfalls: Confusing “continuous firing” in BTK with the industrial, chambered permanence of Hoffman's kiln; overlooking weather sensitivity and construction formality. Final Answer: Hoffman's kiln

Question 18

In building finishes, “water paint” refers to which material category? Select the most appropriate choice.

Accepted Answer

Introduction / Context: Painting and finishing materials are classified by binder and solvent. Water paint is a traditional, economical finish often used on interiors. The question checks whether you can distinguish between lime-based washes and true water-based paints like distemper. Given Data / Assumptions: We compare whitewash, colour wash, whiting, and distemper. “Water paint” implies a paint where water is the main thinner/vehicle. Focus is on standard construction terminology. Concept / Approach: Whitewash and colour wash are primarily lime-based surface washes, not paints in the modern sense. Whiting is finely ground chalk used as a pigment/filler. Distemper, however, is a water-based paint with chalk/whiting and a glue or casein binder, thinned with water and applied as a coating. Step-by-Step Solution: 1) Whitewash: Lime + water; acts as a wash, low durability, not a true paint film.2) Colour wash: Whitewash with pigment; still a wash.3) Whiting: A component (calcium carbonate), not a finished paint.4) Distemper: Water-based paint that forms a film; historically used for ceilings and internal walls. Verification / Alternative check: Standard textbooks define distemper as a water-borne paint using whiting and animal glue/casein binders; thus, it fits the definition of water paint. Why Other Options Are Wrong: Whitewash: A lime wash, not a bound paint film. Colour wash: Same mechanism as whitewash, just pigmented. Whiting: Raw material, not paint. Common Pitfalls: Assuming any water-thinned coating is a “paint”; distinguishing wash from paint is key. Final Answer: Distemper (water-based paint)

Question 19

Stones obtained by blasting are typically suitable for which engineering uses? Choose the best option.

Accepted Answer

Introduction / Context: Blasting in quarries produces broken rock in various sizes. The question evaluates knowledge of standard applications of blasted stone fragments in transportation and structural works. Given Data / Assumptions: Blasting yields angular fragments. Grading after crushing/screening can be controlled. Common uses include ballast, aggregate, and road metal. Concept / Approach: Angular, crushed fragments provide good interlock and load distribution. Suitability depends on rock type, durability, abrasion resistance, and gradation, but generally blasted stone, when properly processed, is ideal for ballast, concrete aggregate, and road base/surface courses. Step-by-Step Solution: 1) Railway ballast requires angular, strong, hard particles for track stability and drainage.2) Concrete aggregate must be clean, strong, and graded; many blasted stones, after processing, meet these requirements.3) Road metal needs abrasion-resistant, angular particles to resist traffic polishing and provide skid resistance.4) Therefore, blasted stones, after suitable selection and processing, serve all these roles. Verification / Alternative check: Codes and manuals list crushed, angular stone as preferred for ballast, aggregates, and pavement layers due to interlock and durability advantages. Why Other Options Are Wrong: Ballast only: Too narrow; other uses exist. Aggregates only: Ignores road applications. Road metal only: Ignores ballast and concrete uses. Common Pitfalls: Assuming “blasted” equals “unprocessed” and overlooking necessary screening/washing for specific applications. Final Answer: All of the above

Question 20

Pyroxene — identify the correct characteristic from the list below. Select the single best statement.

Accepted Answer

Introduction / Context: Pyroxenes are a major rock-forming group of single-chain inosilicate minerals found in igneous and metamorphic rocks. The question probes mineralogical properties to identify the single correct attribute among distractors with subtle errors. Given Data / Assumptions: We evaluate crystal habit, alteration behavior, density, and hardness. Only one statement is fully correct as written. Units and mineral names must be accurate. Concept / Approach: Typical pyroxene properties include two cleavages at ~90 degrees, prismatic habit, hardness around 5–6, and density generally near 3.2–3.6 g/cm³. Alteration may produce amphibole, chlorite, or serpentine, but not “chlorine.” Wording and units matter. Step-by-Step Solution: 1) Crystal habit: Pyroxenes are short prismatic; “octagonal crystals” is not a standard description.2) Alteration: Hydration can yield chlorite (a mineral), not chlorine (an element); the given statement is chemically incorrect.3) Density: The lower bound 2.3 g/cm³ is too low for typical pyroxenes; expected range is around 3.2–3.6 g/cm³. Also, unit should be g/cm³ (not g/cm2).4) Hardness: Mohs hardness 5–6 is a recognized property of pyroxenes, making this statement correct. Verification / Alternative check: Standard mineralogy references list pyroxene hardness approximately 5 to 6 and specific gravity roughly 3.2–3.6, confirming our evaluation. Why Other Options Are Wrong: Octagonal crystals: Mischaracterizes the common prismatic habit and cleavage. Converts to chlorine: Confuses chlorite with chlorine; incorrect process and product. Density 2.3–3.6 g/cm³: Lower bound too low and original units often misstated. All of the above: Fails because multiple statements are incorrect. Common Pitfalls: Overlooking unit accuracy and mistaking chlorite (mineral) for chlorine (elemental gas). Final Answer: Hardness on Mohs scale is 5 to 6

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