Basic Civil Engineering

1

This section covers the properties, types, characteristics, composition, selection, and usage of the major engineering materials used in civil engineering construction.

2

Properties of Engineering Materials Property Category Examples Physical properties Density, specific gravity, porosity, water absorption, colour, texture, durability Chemical properties Chemical composition, resistance to acids/alkalis/salts, corrosion resistance, reactivity with environment Mechanical properties Strength (compressive/tensile/shear), elasticity, plasticity, hardness, toughness, brittleness, ductility, fatigue resistance Thermal properties Thermal conductivity, thermal expansion, fire resistance, specific heat Common Engineering Materials Material Characteristics & Usage Stone Natural material, high compressive strength, used for masonry, foundations, flooring, cladding; selection based on hardness, durability, and workability Bricks Manufactured from clay by moulding and burning; used for masonry walls, partitions, paving; classified by class/grade based on strength and water absorption Tiles Burnt clay or manufactured units used for roofing, flooring, and cladding; lighter than brick, various shapes for specific functions Cement Binding material (commonly Ordinary Portland Cement, OPC) that hydrates and hardens with water; used in concrete, mortar, and plaster Lime Traditional binding material obtained by burning limestone; used in mortar, plaster, and soil stabilization; weaker but more flexible than cement Timber Natural organic material, good strength-to-weight ratio, used for formwork, roofing, doors/windows, temporary structures; susceptible to decay/fire/insects Metals/alloys Steel (most common structural metal, high tensile strength), reinforcing bars, structural sections; aluminium and other alloys for specific applications (lightweight, corrosion-resistant components) Paints/varnishes Surface coatings providing protection (against weather, corrosion, decay) and aesthetic finish; varnish is typically a clear/transparent protective coating Asphalt/bitumen/tar Bituminous materials used for waterproofing, road pavement construction, and damp-proofing; derived from petroleum (bitumen/asphalt) or coal (tar) Material selection for a given application balances required strength, durability, availability, cost, and compatibility with other materials and the environment (exposure conditions).

1

This section covers the standard laboratory tests used to verify the quality and properties of key civil engineering materials — bricks, cement, aggregate, and reinforcement steel — as governed by Nepal Standards (NS) and Indian Standards (IS).

2

Tests of Brick Test Purpose Water absorption test Measures the percentage increase in weight of a brick after 24-hour immersion in water, indicating porosity/durability; lower absorption generally indicates better quality/durability Compressive strength test A brick specimen is crushed under a compression testing machine to determine its crushing (compressive) strength, the primary indicator of load-bearing capacity and used for brick grading/classification Tests of Cement Test Purpose Consistency test Determines the standard (normal) consistency — the water content required to produce a cement paste of standard penetration resistance, using the Vicat apparatus; used as a reference for other cement tests Setting time test Determines initial setting time (when the paste begins to stiffen, loses plasticity) and final setting time (when the paste has fully hardened), also using the Vicat apparatus; ensures adequate working time yet timely hardening Soundness test Checks for excessive free lime/magnesia that could cause the cement to expand after setting (unsoundness), typically using the Le Chatelier apparatus Compressive strength test Cement mortar cubes (cement + standard sand, specified water-cement ratio) are cast, cured, and crushed at specified ages (e.g.

3

3, 7, 28 days) to determine strength development and grade compliance Test of Aggregate & Test of Rebar Bulking of sand test: determines the increase in volume of moist (damp) fine aggregate (sand) compared to its dry volume, caused by surface moisture films that push sand particles apart — important because bulking must be accounted for when batching concrete/mortar by volume (bulking can be significant, sometimes 20–30% at certain moisture contents, and reduces again as the sand becomes saturated).

4

Tensile test of rebar (reinforcement steel): a steel bar specimen is pulled in a universal testing machine to determine its yield strength, ultimate tensile strength, percentage elongation, and other mechanical properties, verifying compliance with the relevant grade specification (e.g.

5

Fe415, Fe500) before use in reinforced concrete.

1

This section covers the fundamental building construction technologies and techniques used in civil engineering practice, along with the role of building by-laws in regulating construction.

2

Building Construction Technology Technique Description Brick masonry Construction of walls/structures using bricks bonded together with mortar in defined patterns (bonds, e.g.

3

English bond, Flemish bond) to ensure structural stability and avoid continuous vertical joints Stone masonry Construction using natural stone units bonded with mortar; classified as coursed/uncoursed and rubble/ashlar masonry depending on stone dressing and arrangement Carpentry Construction/fabrication work in timber, including formwork, roof trusses, doors, windows, and other wooden building components Painting Application of protective/decorative coatings to building surfaces, requiring surface preparation and appropriate paint type selection for substrate and exposure Plastering Application of a thin mortar/plaster coat (typically cement or lime-based) to wall/ceiling surfaces to provide a smooth, protective, and finished surface Concrete roofing Construction of roof slabs/structures using reinforced concrete, providing durability, fire resistance, and design flexibility compared to traditional roofing Flooring Construction of floor surfaces/finishes (concrete, tile, stone, timber, etc.), selected based on function, durability, aesthetics, and maintenance needs Damp proof course (DPC) A moisture-impermeable layer (commonly cement concrete with waterproofing admixture, or a bituminous/plastic membrane) installed in a wall (typically just above plinth level) to prevent rising dampness from the ground into the superstructure Building By-laws Building by-laws are the local regulatory rules governing building construction — covering setbacks, maximum height/floor area ratio, plot coverage, parking requirements, structural safety, fire safety, and sanitation provisions — that must be satisfied for a building permit to be granted.

4

By-laws ensure buildings are constructed safely, in an organized manner compatible with surrounding infrastructure and community needs, and in compliance with applicable building codes (such as the National Building Code).

1

This section covers the fundamental geometric properties of cross-sections used in structural analysis and design — axes of symmetry, centre of gravity, moment of inertia, and radius of gyration.

2

Axes of Symmetry & Centre of Gravity An axis of symmetry is a line about which a section's shape is a mirror image on either side; a section may have zero, one, two, or more axes of symmetry (e.g. a circle has infinite axes, a rectangle has two, an unequal-leg angle section has none).

3

The centre of gravity (centroid) of a section is the point at which the entire area of the section may be considered to be concentrated for purposes of calculating moments; for a built-up (composite) section, the overall centroid is found by dividing the section into simple parts, computing each part's area and centroid location, and taking the area-weighted average: x = Σ(Aixi)/ΣAi (similarly for y).

4

For standard steel sections (I-sections, channels, angles, etc.), centroid location is tabulated in standard section handbooks based on the section's standard geometry and is essential for stress and deflection calculations.

5

Moment of Inertia The moment of inertia (second moment of area), I, of a section about a given axis measures the section's resistance to bending about that axis, and is calculated as I = ∫y² dA, where y is the distance of an elemental area dA from the reference axis.

6

For a composite/built-up section, the moment of inertia about the centroidal axis is found using the parallel axis theorem:

7

I = Ic + Ad², where Ic is the moment of inertia of a part about its own centroidal axis, A is the part's area, and d is the distance between the part's centroidal axis and the overall section's centroidal axis.

8

A larger moment of inertia (for a given material and area) indicates greater bending stiffness/resistance — which is why structural sections such as I-beams concentrate material away from the neutral axis to maximize I for a given amount of material.

9

Radius of Gyration The radius of gyration, k (or r), of a section about a given axis is defined as k = √(I/A), representing the distance from the axis at which the entire area could be concentrated to give the same moment of inertia as the actual distributed area.

10

Radius of gyration is a key parameter in column design/buckling analysis (e.g. in slenderness ratio calculations, slenderness ratio = effective length / least radius of gyration), since a section with a larger radius of gyration about its weakest axis provides better resistance to buckling for a given area.

1

This section covers the fundamentals of surveying and levelling, measurement techniques, topographic surveying, simple circular curves, and the principles and applications of GPS/GIS.

2

Fundamentals of Surveying & Measurements Surveying is the science and art of determining the relative positions of points on, above, or beneath the earth's surface, used to produce maps/plans and to set out engineering works accurately on the ground.

3

Linear distance measurement methods range from simple tape/chain measurement to electronic distance measurement (EDM); vertical distance (elevation) measurement is achieved through levelling instruments; angle and direction measurement uses instruments such as the theodolite/total station to measure horizontal and vertical angles and establish bearings/azimuths.

4

Levelling Levelling is the process of determining the elevation (height above a datum) of points, or the difference in elevation between points, typically using a levelling instrument (level) and a graduated staff; common methods include simple/differential levelling (a series of instrument setups and staff readings to carry elevation from a known benchmark to unknown points) and profile/cross-section levelling (for road/canal alignment design).

5

Key levelling terms:

6

Bench Mark (BM) — a point of known/assumed elevation used as reference;

7

Back Sight (BS) — staff reading taken on a point of known elevation;

8

Fore Sight (FS) — staff reading taken on a point whose elevation is to be determined (often the last reading before moving the instrument);

9

Height of Instrument (HI) — elevation of the instrument's line of sight.

10

Topographic Survey, Circular Curves & GPS/GIS A topographic survey maps both the horizontal positions and elevations of natural and man-made features on the ground, producing contour maps/plans essential for engineering planning and design (roads, drainage, site grading).

11

Simple circular curves are used to connect two straight alignments (e.g. in road or railway design) with a smooth curved transition of constant radius, characterized by elements such as radius, tangent length, length of curve, and degree of curve, calculated from the deflection angle between the straights.

12

GPS (Global Positioning System) uses satellite signals to determine precise geographic position (latitude, longitude, elevation) of a receiver anywhere on earth;

13

GIS (Geographic Information System) is a computer-based system for capturing, storing, analyzing, and displaying spatially-referenced (geographic) data — together, GPS provides field position data that GIS can store, analyze, and present as maps/layers for planning and infrastructure management.

1

This final section of the chapter covers the types and methods of construction cost estimating, rate analysis, specifications, and the principles of property valuation.

2

Types of Estimate Estimate Type Purpose Preliminary (approximate) estimate A rough, quick cost estimate prepared in the early planning stage, often based on unit rates (per unit area/volume/capacity) or historical cost data, for budgeting/approval purposes before detailed design is complete Detailed estimate A precise estimate prepared from complete drawings and specifications, calculating exact quantities of each item of work and applying corresponding rates — the basis for tendering and contract cost Revised estimate Prepared when the original sanctioned estimate is exceeded (e.g. due to scope change, price escalation) beyond a permissible limit, requiring fresh approval Supplementary estimate Prepared for additional work not included in the original estimate, required to complete the project as intended Methods of Estimating & Rate Analysis Common methods of estimating quantities include the detailed (item-wise) method (measuring each item of work — excavation, concrete, masonry, etc. — from drawings), and approximate methods such as plinth area method, cubic content (cubic rate) method, and unit/service rate method, used for quick preliminary estimates.

3

Rate analysis determines the cost per unit of a specific item of work (e.g. cost per m³ of concrete) by systematically accounting for the cost of materials, labor, equipment/machinery, overheads, and contractor's profit required to complete one unit of that item.

4

Specifications Specifications are the detailed written description of the quality, quantity, and workmanship of materials and construction methods to be used in a project, supplementing the drawings.

5

Purpose/importance: specifications ensure the desired quality of work and materials, provide a clear basis for cost estimation and contractual obligations, guide the contractor's execution, and serve as a reference for quality control/inspection and dispute resolution.

6

Common types: general specifications (broad description of materials/workmanship standards for the whole project, without exact quantities) and detailed (particular) specifications (item-by-item description of materials, proportions, and workmanship for each specific component of work).

7

Valuation Valuation is the process of estimating the fair present market value (or other defined value, e.g. for taxation, insurance, mortgage, or compensation purposes) of a property (land and/or building), considering factors such as location, condition, age, construction cost, income potential, and prevailing market rates.