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Past Questions — 2025
Which of the following materials is used to fill joints in masonry walls?
A)
Grout
B)
Mortar
C)
Putty
D)
Cement paste
In masonry construction, mortar is the primary binding material used to fill the joints between individual masonry units (such as bricks or stones). Its primary functions are to bond the units together, distribute the load evenly across the wall, and seal the joints against air and water penetration.
Analysis of other options:
- Grout (a): While similar to mortar, grout is a fluid mixture used primarily to fill voids or gaps in concrete blocks or to reinforce masonry walls by filling the cores of blocks; it is not the standard material for filling the horizontal and vertical joints during the laying of masonry.
- Putty (c): Putty is used for filling small holes, cracks, or smoothing surfaces (typically in woodwork or plastering) before painting; it has no structural capacity for masonry joints.
- Cement paste (d): This is a mixture of cement and water only. It lacks the aggregate (sand) found in mortar, which is necessary to prevent shrinkage cracking and provide the required volume and strength for masonry joints.
Which of the following wood products is made by gluing thin layers of wood together?
A)
Particle board
B)
Block board
C)
Plywood
D)
Fiberboard
Step-by-step reasoning:
1. **Plywood**: This is an engineered wood product made by gluing together thin layers of wood veneers. These layers (plies) are glued with their grains oriented perpendicular to each other (cross-graining), which provides high strength, stability, and resistance to splitting.
2. **Particle board**: This is made from wood chips, sawmill shavings, or sawdust bonded together with a resin under heat and pressure. It does not consist of 'thin layers' of wood veneers.
3. **Block board**: This consists of a core of solid wood strips (blocks) sandwiched between two layers of veneer. While it uses veneers on the surface, the core is not made of thin layers glued together, but rather solid blocks.
4. **Fiberboard (MDF/HDF)**: This is made by breaking down wood residuals into fibers, combining them with wax and resin, and forming panels under high temperature and pressure. It is a homogeneous material rather than a layered veneer product.
Therefore, the product specifically defined by gluing thin layers (veneers) together is Plywood.
The grade of cement generally used for RCC works is-
A)
33 grade
B)
43 grade
C)
53 grade
D)
22 grade
The grade of cement is defined by its compressive strength after 28 days of curing (measured in MPa).
1. **53 Grade Cement (Option c):** This is an Ordinary Portland Cement (OPC) with a minimum compressive strength of 53 MPa. Due to its high early strength and superior load-bearing capacity, it is the standard choice for Reinforced Cement Concrete (RCC) works, high-rise buildings, and heavy structural components where high strength is critical.
2. **43 Grade Cement (Option b):** This has a strength of 43 MPa. While it can be used for RCC, it is more commonly used for general construction, plastering, and masonry work where extreme strength is not the primary requirement.
3. **33 Grade Cement (Option a):** This has a strength of 33 MPa. It is generally used for low-strength works, such as small-scale residential masonry or non-structural elements, and is rarely used for modern RCC works.
4. **22 Grade Cement (Option d):** This is not a standard grade for Ordinary Portland Cement used in structural engineering.
Therefore, for RCC works, where structural integrity and high compressive strength are paramount, 53 grade cement is the most generally preferred and used grade.
Which of the following is a protective coating for metals?
A)
Whitewash
B)
Lacquer
C)
Galvanization
D)
Emulsion paint
Step-by-step reasoning: 1. The question asks for a protective coating specifically for metals. 2. Galvanization is the process of applying a protective zinc coating to steel or iron to prevent rusting. The zinc acts as a sacrificial anode, protecting the underlying metal from corrosion. 3. Analyzing other options: (a) Whitewash is a mixture of slaked lime and water used primarily for walls and ceilings, not for metal protection. (b) Lacquer is a resin-based coating used for furniture or decorative finishes; while it can be used on some metals, it is not the primary industrial protective coating compared to galvanization. (d) Emulsion paint is a water-based paint used mainly for interior and exterior walls. Therefore, Galvanization is the most authoritative and standard protective coating for metals in civil engineering and materials science.
Which of the following woods is most resistant to termite attack?
A)
Pine
B)
Teak
C)
Cedar
D)
Sal
Termite resistance in wood is primarily determined by the presence of natural oils, resins, and extractives (like tannins and silica) that act as chemical deterrents to insects.
1. **Teak (Tectona grandis):** Teak is world-renowned for its exceptional durability and resistance to termites and decay. This is due to its high content of natural oils and silica, which make the wood unpalatable and toxic to termites.
2. **Sal (Shorea robusta):** While Sal is a very hard, heavy, and durable wood often used for railway sleepers and heavy construction, it is generally considered slightly less resistant to certain types of termite attacks compared to the high oil content of Teak, although it is still highly durable.
3. **Cedar:** Cedar contains natural oils that repel insects, but it is a softer wood and generally less resistant to heavy-duty termite infestations compared to Teak.
4. **Pine:** Pine is a softwood and is highly susceptible to termite attacks and decay unless it is chemically treated (pressure-treated).
Therefore, among the given options, Teak is the most resistant to termite attack.
A retaining wall fails mainly due to-
A)
Wind pressure
B)
Overturning or sliding
C)
Snow accumulation
D)
Thermal expansion
A retaining wall is designed to resist the lateral earth pressure exerted by the soil it retains. The primary stability checks for any retaining wall involve ensuring it does not fail due to the following modes: 1. Overturning: This occurs when the lateral pressure causes the wall to rotate about its toe. 2. Sliding: This occurs when the lateral force exceeds the frictional resistance between the base of the wall and the foundation soil. 3. Bearing Capacity Failure: When the pressure exerted by the wall exceeds the allowable bearing capacity of the soil.
Analyzing the options:
- Option (a) Wind pressure: While wind acts on structures, it is negligible compared to the lateral earth pressure for a retaining wall.
- Option (b) Overturning or sliding: These are the fundamental failure modes analyzed in geotechnical and structural engineering for retaining walls.
- Option (c) Snow accumulation: This may add a surcharge load, but it is not a primary cause of failure for the structure itself.
- Option (d) Thermal expansion: This can cause cracking in concrete but does not lead to the overall structural failure (collapse) of the wall in the way sliding or overturning does.
Which of the following is not a type of slope movement?
A)
Slides
B)
Tectonic shift
C)
Flows
D)
Falls
Slope movement, commonly referred to as mass wasting, is the downward movement of soil, regolith, and rock under the direct influence of gravity. The primary types of slope movements are categorized based on the material involved and the nature of the movement:
1. Slides (Option a): This occurs when a distinct zone of weakness exists, and a block of material moves along a well-defined surface (e.g., translational or rotational slides).
2. Flows (Option c): This occurs when material moves as a viscous fluid, often saturated with water (e.g., mudflows, debris flows).
3. Falls (Option d): This occurs when material detaches from a steep slope and descends primarily through the air via free-fall, bouncing, or rolling (e.g., rockfalls).
In contrast, a Tectonic Shift (Option b) is a large-scale geological process caused by the movement of the Earth's lithospheric plates. While tectonic activity (like earthquakes) can trigger slope movements, the shift itself is a crustal movement driven by internal planetary heat and pressure, not a surface slope movement driven by gravity. Therefore, it is not classified as a type of slope movement.
The standard size of a modular brick excluding mortar in India is-
A)
190mm x 90 mm x 80 mm
B)
190mm x 90 mm x 90 mm
C)
200 mm x 100 mm x 100 mm
D)
230mm x 110mm x 70mm
In India, the Bureau of Indian Standards (BIS) defines the dimensions for modular bricks.
1. **Modular Brick (Standard Size):** The standard size of a modular brick excluding mortar is 190 mm x 90 mm x 90 mm.
2. **Nominal Size:** When mortar joints (usually 10 mm) are added to the modular size, the nominal size becomes 200 mm x 100 mm x 100 mm. This is the size used for calculating quantities and planning layouts in construction.
Analyzing the options:
- Option (a) 190mm x 90mm x 80mm is incorrect as the height is not 80mm.
- Option (b) 190mm x 90mm x 90mm is the correct standard modular size.
- Option (c) 200mm x 100mm x 100mm is the 'Nominal Size' (including mortar), not the modular size.
- Option (d) 230mm x 110mm x 70mm refers to traditional/non-standard brick sizes used in some regions, not the BIS modular standard.
Which is a suitable foundation for a retaining wall?
A)
Clay bed
B)
Soft silt
C)
Compacted granular base
D)
Organic soil
A retaining wall is subject to significant lateral earth pressure, which translates into both vertical loads and horizontal sliding forces at the base. To ensure stability against overturning and sliding, and to prevent excessive settlement, the foundation must have a high bearing capacity and good drainage characteristics.
1. **Compacted granular base (Correct):** Granular soils (like well-graded sand or gravel) provide high shear strength and high bearing capacity when compacted. They also allow for efficient drainage, reducing the buildup of hydrostatic pressure behind and beneath the wall, which is critical for stability.
2. **Clay bed (Incorrect):** Clay is cohesive and prone to long-term consolidation settlement. It has lower shear strength compared to compacted granular soil, increasing the risk of bearing capacity failure or tilting.
3. **Soft silt (Incorrect):** Soft silts are highly compressible and have very low bearing capacity, making them unsuitable for supporting the heavy concentrated loads of a retaining wall.
4. **Organic soil (Incorrect):** Organic soils (like peat) are highly compressible, unstable, and decompose over time, leading to severe differential settlement and structural failure.
Which wall is used along slopes to support the cut portion of the hill?
A)
Breast wall
B)
Toe wall
C)
Revetment wall
D)
Grouted wall
In civil engineering and hill road construction, retaining structures are categorized based on their position relative to the slope:
1. **Breast Wall (Option a):** This is a wall constructed on the hill side of a road or a cut slope. Its primary purpose is to support the cut portion of the hill to prevent landslides or soil slippage from the upper slope onto the road. It 'breasts' the slope.
2. **Toe Wall (Option b):** This is constructed at the base (toe) of a slope or embankment to prevent the soil from sliding down and to provide stability to the slope's foot. It supports the fill portion rather than the cut portion.
3. **Revetment Wall (Option c):** This is a facing of stone, concrete, or turf used to protect a slope from erosion (e.g., by water or wind). While it stabilizes the surface, it is not specifically designed as a structural wall to support a deep cut portion of a hill in the same way a breast wall is.
4. **Grouted Wall (Option d):** This refers to a method of stabilization where grout is injected into the soil or rock to fill voids and increase strength; it is a technique rather than a specific type of wall used for supporting cut slopes.
Therefore, the wall used specifically to support the cut portion of a hill is the Breast Wall.
Which of the following tests determines the toughness of aggregates?
A)
Impact Test
B)
Aggregate Impact Value Test
C)
Soundness Test
D)
Los Angeles Abrasion Test
In the context of building materials and aggregate testing, it is crucial to distinguish between toughness, hardness, and soundness:
1. **Toughness** is defined as the ability of an aggregate to resist failure under repeated impact or shock loading. The **Impact Test** (specifically the Aggregate Impact Test) is used to determine the toughness of aggregates. It measures the resistance to sudden shock or impact.
2. **Aggregate Impact Value (AIV) Test** (Option b) is the *method* or the *metric* derived from the Impact Test. While closely related, the 'Impact Test' is the general category of test that determines toughness. However, in many technical contexts, 'Impact Test' and 'Aggregate Impact Value Test' are used interchangeably. Between the two, 'Impact Test' is the fundamental test for toughness.
3. **Soundness Test** (Option c) determines the resistance of aggregates to weathering actions, such as freeze-thaw cycles or chemical reactions (using sodium or magnesium sulfate).
4. **Los Angeles Abrasion Test** (Option d) determines the **hardness** (resistance to surface wear and abrasion) of the aggregates, not the toughness.
Therefore, the test specifically designed to determine the toughness (resistance to impact) is the Impact Test.
The primary use of varnish is to-
A)
Color the surface
B)
Fill gaps
C)
Provide protective and glossy finish
D)
Act as an adhesive
Varnish is a transparent, hard, protective finish or film primarily used in woodworking. It consists of a resin dissolved in a solvent.
1. Why Option (c) is correct: The primary purpose of varnish is to protect the underlying surface (usually wood) from moisture, heat, and scratches while enhancing the natural beauty of the grain by providing a glossy or semi-glossy transparent finish.
2. Why Option (a) is incorrect: Varnish is typically transparent. If the goal is to change the color of the surface, paints or stains are used.
3. Why Option (b) is incorrect: Filling gaps is the function of wood fillers, putties, or sealants, not varnish.
4. Why Option (d) is incorrect: While some resins used in varnish have adhesive properties, the primary application of varnish as a building material is as a top-coat finish, not as a structural adhesive.
Which foundation is suitable when the bearing stratum lies at a greater depth?
A)
Pile foundation
B)
Mat foundation
C)
Spread footing
D)
Grillage foundation
In soil mechanics and foundation engineering, foundations are categorized into shallow and deep foundations.
1. **Pile Foundation (Deep Foundation):** When the surface soil or the immediate layers are too weak to support the structural load, and the strong bearing stratum (hard rock or dense sand) lies at a significant depth, deep foundations like piles are used. Piles transfer the load to the deeper, stronger strata through skin friction or end-bearing capacity.
2. **Spread Footing (Shallow Foundation):** These are used when the bearing stratum is located at a shallow depth. They distribute the load over a small area of the soil.
3. **Mat/Raft Foundation (Shallow Foundation):** These are used when the soil bearing capacity is low or the column loads are very heavy, spreading the load over the entire footprint of the building. However, they are still considered shallow foundations as they do not reach deep strata.
4. **Grillage Foundation (Shallow Foundation):** These are typically used to support heavy concentrated loads (like steel columns) by using beams of steel to spread the load over a larger area of the soil at a shallow depth.
Therefore, when the bearing stratum is at a 'greater depth', a pile foundation is the only suitable choice among the options provided.
The triaxial shear test provides information about-
A)
Plasticity
B)
Shear strength under controlled drainage
C)
Specific gravity
D)
Consolidation characteristics
The triaxial shear test is one of the most versatile and widely used methods for determining the shear strength parameters (cohesion 'c' and angle of internal friction 'φ') of soil. Its primary advantage over other tests (like the direct shear test) is the ability to control the drainage conditions and the pore water pressure. Depending on how the drainage valves are operated and the rate of loading, the test can be conducted as an Unconsolidated Undrained (UU) test, a Consolidated Undrained (CU) test, or a Consolidated Drained (CD) test.
Why other options are incorrect:
- a. Plasticity: This is determined using Atterberg limits tests (Liquid Limit, Plastic Limit).
- c. Specific gravity: This is determined using a pycnometer or a density bottle.
- d. Consolidation characteristics: These are determined using an Oedometer (one-dimensional consolidation test).
Which is not a component of surface water?
A)
Rivers
B)
Aquifers
C)
Lakes
D)
Reservoirs
Surface water refers to any body of water found on the Earth's surface, such as streams, rivers, lakes, and reservoirs.
1. Rivers (Option a): These are natural flowing watercourses on the surface of the earth.
2. Lakes (Option c): These are large bodies of surface water surrounded by land.
3. Reservoirs (Option d): These are artificial lakes created by dams to store surface water.
4. Aquifers (Option b): An aquifer is an underground layer of water-bearing permeable rock, gravel, sand, or silt from which groundwater can be extracted. Because aquifers are located beneath the Earth's surface, they are a component of 'Groundwater,' not 'Surface Water.'
Therefore, aquifers are not a component of surface water.
Which is a short-term slope stabilization method?
A)
Shotcrete or gunite
B)
Soil nailing
C)
Toe buttress
D)
Gabion wall
Slope stabilization methods are categorized based on their duration of effectiveness and the mechanism of support.
1. **Shotcrete or Gunite (Option a):** This involves spraying concrete or mortar at high velocity onto a slope surface. While it provides immediate surface sealing and prevents weathering or minor surface sloughing, it is primarily considered a short-term or surface-level stabilization method. Over time, water pressure can build up behind the shotcrete layer (unless extensive weep holes are provided), and it does not address deep-seated rotational failures. It is often used as a temporary measure or as a facing for other reinforcement systems.
2. **Soil Nailing (Option b):** This is a long-term reinforcement technique where steel tendons are inserted into the soil mass to create a coherent gravity structure. It is designed for permanent stability.
3. **Toe Buttress (Option c):** This involves placing a heavy mass of material (like rockfill) at the toe of the slope to resist rotational failure. This is a permanent structural modification to the slope geometry.
4. **Gabion Wall (Option d):** These are wire mesh cages filled with rocks. They are flexible, permeable, and designed as permanent retaining structures to stabilize the base of a slope.
Therefore, compared to the structural reinforcement provided by nailing, buttressing, or gabions, shotcrete is the most appropriate answer for a short-term/surface stabilization method.
Which of the following is not a form of precipitation?
A)
Rain
B)
Snow
C)
Condensation
D)
Hail
Precipitation is defined as any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds to the Earth's surface.
1. Rain (Option a): This is liquid precipitation occurring when water droplets in clouds collide and grow large enough to fall.
2. Snow (Option b): This is frozen precipitation occurring when water vapor turns directly into ice crystals (deposition) and falls as flakes.
3. Hail (Option d): This is solid precipitation consisting of balls or irregular lumps of ice, formed by strong updrafts in thunderstorms.
4. Condensation (Option c): This is the physical process by which water vapor (gas) changes into liquid water. While condensation is a necessary prerequisite for precipitation to occur (it forms the clouds), it is the process of phase change, not the act of water falling to the ground. Therefore, condensation is not a form of precipitation itself.
Which soil has the highest permeability?
A)
Silt
B)
Gravel
C)
Clay
D)
Loam
Permeability (hydraulic conductivity) refers to the ease with which a fluid (usually water) can flow through a porous medium. In soil mechanics, permeability is primarily governed by the size of the soil particles and the size of the interconnected voids (pores) between them.
1. **Gravel (Option b):** Consists of the largest particles among the choices. Large particles create large, interconnected pore spaces, offering minimal resistance to water flow. Therefore, gravel has the highest permeability.
2. **Silt (Option a):** Particles are smaller than sand and gravel. The smaller pore spaces increase the frictional resistance to water flow, resulting in lower permeability than gravel.
3. **Clay (Option c):** Consists of the smallest particles (colloidal size). Clay has very small pores and a high specific surface area, which creates strong electrostatic attractions between water molecules and particle surfaces, making it nearly impermeable.
4. **Loam (Option d):** A mixture of sand, silt, and clay. While it has better permeability than pure clay, it is significantly lower than that of pure gravel because the smaller particles (silt/clay) fill the gaps between larger particles, reducing the effective pore size.
In summary, the order of permeability from highest to lowest is: Gravel > Sand > Silt > Clay.
Which component prevents leakage at construction joints in water tanks?
A)
Steel bar
B)
Water bar (PVC or rubber)
C)
Formwork
D)
Lining
In the construction of water-retaining structures like water tanks, construction joints are inevitable due to the pouring of concrete in stages. These joints are potential paths for water leakage. To prevent this, a 'Water bar' (also known as a waterstop) is used. A water bar is a flexible strip made of PVC or rubber that is embedded halfway into one concrete pour and halfway into the next. It creates a physical barrier that blocks the flow of water through the joint.
Why other options are incorrect:
- a. Steel bars: These provide structural strength and reinforcement against tension but do not create a watertight seal.
- c. Formwork: This is the temporary mold used to shape the concrete; it is removed after the concrete sets and does not prevent leakage.
- d. Lining: While lining (like epoxy or membranes) can be applied to the interior surface of a tank to reduce permeability, it is a surface treatment rather than a specific component designed to seal construction joints.
The purpose of providing reinforcement in foundation is to-
A)
Reduce dead load
B)
Resist tensile stresses
C)
Prevent shrinkage
D)
Increase soil strength
Step-by-step reasoning: 1. Concrete is a composite material that is very strong in compression but very weak in tension (its tensile strength is typically only 10% of its compressive strength). 2. Foundations are subject to various loads, including vertical loads from the superstructure and differential settlement of the soil. 3. These loads often induce bending moments within the foundation slab or footing. 4. Bending causes one side of the concrete member to be in compression and the opposite side to be in tension. 5. Since concrete cannot effectively resist these tensile stresses, steel reinforcement (which has high tensile strength) is embedded in the tension zone to carry those loads and prevent the concrete from cracking or failing.
Analysis of other options:
- (a) Reduce dead load: Reinforcement (steel) actually increases the dead load because steel is denser than concrete.
- (c) Prevent shrinkage: While specific 'shrinkage reinforcement' exists, the primary structural purpose of reinforcement in foundations is load-bearing (tensile resistance). Shrinkage is primarily controlled by curing and joint design.
- (d) Increase soil strength: Reinforcement is placed within the concrete foundation, not the soil. To increase soil strength, techniques like soil stabilization, compaction, or piling are used, not concrete reinforcement.
Which of the following plastics is used in making water storage tanks?
A)
Bakelite
B)
Polyethylene
C)
PVC
D)
Nylon
Step-by-step reasoning:
1. **Polyethylene (PE)**: Specifically High-Density Polyethylene (HDPE) and Linear Low-Density Polyethylene (LLDPE), these plastics are widely used for water storage tanks because they are chemically inert, non-toxic, durable, and resistant to corrosion and UV radiation. They are food-grade materials, making them safe for potable water.
2. **Bakelite**: This is a thermosetting phenol-formaldehyde resin. It is hard, brittle, and heat-resistant, typically used for electrical switches, handles of cooking utensils, and telephone casings, not for large water storage containers.
3. **PVC (Polyvinyl Chloride)**: While PVC is extensively used for water pipes and fittings due to its rigidity and strength, it is generally not used for the main body of large domestic water storage tanks because it is more brittle than polyethylene and can be more difficult to mold into large, seamless tank shapes.
4. **Nylon**: This is a polyamide used primarily for fibers, textiles, gears, and mechanical parts due to its high strength and wear resistance. It is not used for water storage tanks as it is expensive and not the optimal material for such applications.
Therefore, Polyethylene is the most appropriate material for making water storage tanks.
An area with impermeable geology faces declining groundwater levels. Which approach is most suitable?
A)
Use of artificial recharge structures and recharge wells
B)
Open wells only
C)
Deep borewells
D)
Rooftop irrigation
Step-by-step reasoning: 1. Analysis of Geology: The problem specifies 'impermeable geology'. In such areas, natural infiltration of rainwater into the aquifer is restricted, leading to a lack of natural groundwater replenishment. 2. Problem Identification: Declining groundwater levels indicate that the rate of extraction exceeds the rate of natural recharge. 3. Evaluating Solutions: To combat declining levels in impermeable or semi-impermeable terrain, 'Artificial Recharge' is required. This involves man-made structures (like percolation tanks, recharge shafts, or recharge wells) that bypass impermeable surface layers to direct water directly into the permeable aquifer zones. 4. Evaluating Options: Option (b) Open wells and Option (c) Deep borewells are methods of extraction, not replenishment; using them further would accelerate the decline of groundwater levels. Option (d) Rooftop irrigation is a water-use method, not a groundwater recharge method. Therefore, artificial recharge structures are the only viable engineering solution to increase the water table in this scenario.
PVC used in building works is a type of-
A)
Composite material
B)
Natural polymer
C)
Synthetic polymer
D)
Ceramic
Step-by-step reasoning: 1. PVC stands for Polyvinyl Chloride. 2. Chemically, it is a polymer made from the monomer vinyl chloride. 3. Polymers are categorized as either natural (e.g., rubber, cellulose, DNA) or synthetic (man-made). 4. Since PVC is produced through a chemical process (polymerization) in industrial plants and does not occur naturally in the environment, it is classified as a synthetic polymer. 5. Evaluating other options: (a) Composite materials are combinations of two or more distinct materials (e.g., reinforced concrete); PVC is a single homogeneous plastic. (b) Natural polymers occur in nature; PVC is man-made. (d) Ceramics are inorganic, non-metallic solids (e.g., bricks, glass); PVC is an organic plastic.
The strength of concrete is primarily affected by-
A)
Color of cement
B)
Water-cement ratio
C)
Size of coarse aggregate
D)
Quantity of sand
The strength of concrete is governed by the 'Abrams' Law', which states that for a given water-cement ratio, the strength of the concrete is dependent on the water-cement ratio, provided the mix is workable.
1. **Water-Cement Ratio (w/c):** This is the ratio of the weight of water to the weight of cement used in a concrete mix. A lower w/c ratio generally leads to higher strength because there is less excess water to evaporate, which reduces the formation of capillary pores (voids) in the hardened cement paste. Higher porosity leads to lower compressive strength.
2. **Color of cement (Option a):** The color of cement is a physical characteristic and has no impact on the chemical hydration process or the mechanical strength of the concrete.
3. **Size of coarse aggregate (Option c):** While the size and grading of aggregates affect the workability and the amount of cement paste required to coat the particles, they do not 'primarily' determine the strength. Strength is a property of the cement paste and the bond between the paste and the aggregate.
4. **Quantity of sand (Option d):** The proportion of sand (fine aggregate) affects the density and workability of the mix, but it is not the primary driver of strength compared to the chemical relationship between water and cement.
Fine aggregates are defined as those which pass through-
A)
4.75 mm IS sieve
B)
4.75 mm IS sieve and retained on 75 micron sieve
C)
10mm sieve
D)
2.36mm sieve
According to IS 383 (the Indian Standard specification for coarse and fine aggregates from natural sources for concrete), aggregates are classified based on their particle size. Fine aggregate is defined as the material that passes through a 4.75 mm IS sieve. Coarse aggregate is defined as the material that is retained on a 4.75 mm IS sieve.
Analysis of options:
- Option (a) is correct as it aligns with the standard definition of fine aggregates.
- Option (b) is incorrect because while fine aggregates are generally retained on a 75-micron sieve (material passing 75 microns is considered 'silt' or 'clay'), the primary defining boundary for 'fine aggregate' is the 4.75 mm sieve.
- Option (c) and (d) are incorrect as 10mm and 2.36mm are specific sieve sizes used for grading and classification of coarse aggregates or specific sand zones, but they do not define the general boundary between fine and coarse aggregates.