KTU CE 204 Construction Technology - Module 4

CONSTRUCTION
TECHNOLOGY
Module 4
Fr. Dr. Bennet Kuriakose
Department of Civil Engineering

Syllabus
Lintels and arches – types and construction details
Floors and flooring – different types of floors and floor
coverings
Roofs and roof coverings – different types of roofs –
suitability – types and uses of roofing materials
Doors, windows and ventilators – types and construction
details
Finishing works – plastering, pointing, white washing, colour
washing, distempering, painting. Methods of providing DPC.
Termite proofing
Department of Civil Engg., SJCET Palai 2

LINTELS

Lintels
• A lintel or lintol (older spelling) is a structural horizontal block
that spans the space or opening between two vertical supports
• Now it is defined as the member (width equal to that of wall)
placed across openings like doors and windows
• Uses:
– Carry load from masonry above the lintel level and bridge
between the gaps of doors or windows
– Provide support and fixity to the sunshade (cantilever slab)
– Provide integrity to masonry
– Provides space for architectural beauty. Lintels used for
ornamental purposes are called “architrave” or “epistyle”

Lintels
Stonehenge
(post and lintel)
Ornamental lintel
(Ellora Cave)

Lintels (Classification)
1. Timber Lintels
– Timber member is used as lintel
– Cannot handle spans
– If more span is required „flitched lintels‟ are often
provided (with steel plates)
– Vulnerable to fire

2. Stone Lintels
– Abundantly used before invention of concrete
– Used as single piece or double piece.
– Give architectural beauty to stone masonry buildings

2. Masonry Lintels
– These are used when the opening
is less than 1m and lesser loads
are acting.
– Bricks with frogs are more suitable
than normal bricks

3. Reinforced Brick Lintels
– These are used when loads are heavy and span is
greater than 1m.
– The depth of reinforced brick lintel should be equal to 10
cm or 15 cm or multiple of 10 cm.

4. Steel Lintels
– used when the superimposed loads are heavy and
openings are large.
– consist of rolled steel joists.
– Sometimes used for retrofitting works

5. RCC Lintels
– widely used to span the openings for doors, windows, etc.
in a structure because of their strength, rigidity, fire
resistance, economy and ease in construction.
– These are suitable for all the loads and for any span.
– Easy to support sunshades

ARCHES

Arches
• An arch is a vertical curved structure that spans a space and
support the weight over it.
• From Greek word “arxi” (chief) or high
• Structural behaviour  “arch action” (maintaining
compressive stress within the arch – maintaining zero or
very nominal tensile stress)
• This can span larger span compared to beam
• Has higher strength – to – weight ratio compared to
beam/lintel

Arches

Arches – Parts
• Intrados/ Soffit: The inner curve of an arch
• Extrados: The outer curve of an arch
• Voussoirs: The wedge-shaped units of masonry which are
forming an arch
• Crown: The highest part are peak point of extrados
• Keystone: The wedge shaped unit which is fixed at the crown
• Springings: support points of the arch
• Springing Line: The imaginary line joining the springing points of
either ends

Arches – Parts
• Springer: The first voussoir after springing level
• Span: The clear horizontal distance between the piers/
abutments
• Rise: The clear vertical distance between the highest point on
the intrados and the springing line
• Depth or Height: The perpendicular distance between the
intrados of arch to the extrados of arch

Arches – Parts
• Thickness: breadth of soffit which is
measured perpendicular to the front
and back faces of an arch
• Skew Back: This is an inclined
surface or splayed surface on
abutment, from which arch curve
starts or ends.
• Impost: The projecting course
provided on the upper part of a pier
or abutment to stress the springing
line
• Center of an Arch: Geometrical
points based on which the arcs
forming intrados of arch. Arch can
have one or multiple centers.

Arches – Parts
• Pier and Abutment: The
intermediate support of an arch is
called as pier. The end support of an
arch is called as abutment.
• Bed Joints: The joints between the
voussoirs are called bed joints.
These bed joints are radiate from
center of arch.
• Spandrel : If two arches are
constructed side by side, then a
curved triangular space is formed
between the extrados with the base
as horizontal line through the crown.
This space is called as spandrel.

Arches - Taxonomy
A. Based on Shape
1. Flat / French/ Jack Arch
– For flat arch, the intrados and extrados are apparently flat
and it acts as a base of equilateral triangle which was
formed by the horizontal angle of 600 by skewbacks.
– slight rise of camber of about 10 to 15 mm per meter
width of opening is allowed for small settlements.
– generally used for light loads, and for spans up to 1.5m.

Arches - Taxonomy
2. Segmental Arch
– This is the basic type of arch used for buildings in which
Centre of arch lies below the springing line.
– In segmental arch, the thrust is transferred in inclined
direction to the abutment.

Arches - Taxonomy
3. Semicircular/ Roman Arch
– The shape is semi-circle
– the thrust transferred to the abutments is perfectly vertical
direction since skewback is horizontal.
– In this type of arch, the Centre lies exactly on the
springing line.

Arches - Taxonomy
4. Horseshoe/ Keyhole/ Moorish Arch
– Horse Shoe Arch is in the shape of horse shoe which
curves more than semi-circle.
– This is generally considered for architectural provisions.

Arches - Taxonomy
5. Pointed / Gothic Arch
– In this type of arch, two arcs of circles are met at the apex
– A triangle is formed with apex and the springings as
triangle - either isosceles or equilateral.

Arches - Taxonomy
6. Venetian (Venetian Gothic) Arch
– Venetian arch is also pointed arch but its crown is deeper
than springings.
– It contains four Centres, all located on the springing line.

Arches - Taxonomy
7. Ogee Arch
– Consists of two ogees (ogee  S-shape)
– 4 centres

Arches - Taxonomy
8. Semielliptical Arch
– Three centres
– Rise is very less

Arches - Taxonomy
9. Bull’s eye Arch
– Perfectly circular shape

Arches - Taxonomy
B. Number of Centres
1. One Centred Arches
– Segmental, semi-circular,
flat, horse-shoe arches, Bull-
eye
2. Two Centred Arches
– Gothic
3. Three Centred Arches
– Semielliptical arch
4. Four Centred Arches
– Venetian arch, Ogee arch

Arches - Taxonomy
C. Material and Workmanship
1. Rubble Stone Arches
– Rubble arches are very weak
and used only for inferior work.
– These are made of rubble
stones which are hammer
dressed, roughly to shape and
size and fixed in cement mortar.
2. Ashlar Stone Arches
– the stones are cut to proper
shape of voussoirs (a wedge-
shaped or tapered stone used
to construct an arch) and fully
dressed, joined with cement
mortar.Department of Civil Engg., SJCET Palai 30

Arches - Taxonomy
3. Brick Arches
– bricks are cut into voussoirs
– (a) Rough brick (b) axed brick
4. Concrete Arches
– (a) precast concrete block
– (b) cast – in-situ

FLOORS

Floors
• Horizontal elements of buildings which
divide buildings into different levels and
provide support for occupants, furniture
and equipments.
• Levels:
– Basement floor (below ground level)
– Ground floor (plinth level)
– Upper floors (above GF)
– Mezzanine Floor (A floor in
between two regular floors)
– Roof Floor

Requirements (Selection) of a Floor
• Appearance: aesthetic appeal matching with the building
• Hardness: (Resistance to abrasion) to be high
• Offer proper friction: mainly in bathrooms or floor subjected
to dampness
• Smoothness: should give proper smooth and even surface
• Durability: should be high
• Damp resistance: should be damp resistant, especially
when used in ground floor
• Should not disintegrate under temperature
• Should not make sound while walking
• Should be cost effective

Floor - Types
1. Ground Floor
• Red earth/ sand is compacted
• Damp proof material (polythene sheet) is provided if required
• Layers of brickbats and stones laid (or quarry waste) and compacted
• PCC (1:4:8) is laid. If it is an industrial floor or floor with loads, rebars
are provided (RCC)
• Required finish is provided
• DPC is provided for brick wall – basement interface

Floor - Types
2. RCC Floor System
– Versatile and widely used
– Types (a) normal slab (b) flat slab
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Cranking
Reinforcement details of slab

Floor - Types
– Flat slab system, beams are not
provided
– Provided when
• More clear height
• Flat soffit required for
architectural purpose
• If HVAC conduits are difficult to be
laid
– Drop panels are provided to resist
punching shear

Floor - Types
3. Hollow Core Slab System
– Slab with hollow hole throughout the length
– Reinforced with prestressed strands
– This is a type of precast (prefab) slab
– Stacked according to requirement on beams and
reinforced screed is provided at the top to have integrity

Floor - Types
4. Timber Floor
– Provides thermal insulation
– Sometimes heating pipes are provided inside
– Will not be cold and slippery
– Highly susceptible to fire

Floor - Types
5. Steel – concrete composite floor
– Concrete is poured over corrugated steel deck
– Light weight
– Only less rebars required compared to conventional slabs
– Easy to construct – no formwork required

FLOORINGS

Flooring - Types
• Flooring or Floor Finish (floor covering) is the finish that is
applied on the floors
1. Mud Flooring
– used in rural India
– Moist earth is mixed with chopped straw or sand
– Sometimes thin wash of cow dung is provided

Flooring - Types
2. Muram Flooring
– Mine waste is called „muram‟
– Look almost like mud flooring
– 150 mm thick muram is laid. Water is sprinkler over it and
rammed. The surface is leveled.
– If required, cow dung wash is provided.

Flooring - Types
3. Brick Flooring
– Normally used in godowns and factories
– 75 mm thick layer sand is laid, over which brick is laid
with lean concrete.
– Polished if required to avoid wear and tear

Flooring - Types
4. Flagstone Flooring
– Laminated sandstones or slates of 20 – 40 mm thickness
are known as flagstones
– flagstone tiles are available with different sizes
– These tiles are spread over 20- 25 mm thick mortar
– Joints are finished with rich mortar

Flooring - Types
5. Terrazzo/ Mosaic Flooring
– Marble chips or glazed stones
– Marble chips are mixed in cement
with proportion 1:2 and 6mm thick
toping with cement / lime mortar is
laid
– The top is tamped and rolled
– Additional marble chips are added
during the tamping operation
– It is cured for 2 – 3 days
– The layer is ground, finished and
polished

Flooring - Types
7. Tile Flooring
– Tiles are manufactured in factory out of mainly clay
(kaolin) burnt at high temperature  Porcelain
– Three types: (a) unglazed (b) glazed (c) Vetrified
– Glazed  coat of enamel or glass is applied to top of tiles
– Vitrified  hydraulic pressing the clay and other
ingredients to get vitreous (glassy ) surface

Flooring - Types
8. Marble Flooring
– Marble is cut as tiles and placed on mortar
– Polished to get glossy surface
9. Granite Flooring
– Granite rocks are cut into tiles and placed on mortar
– Polished

Flooring - Types
10. Timber Flooring
– Costly and make sound
– Sustain heat inside room, not
slippery
11. Linoleum Flooring
– Linoleum sheets are
manufactured by mixing
oxidized linseed oil, resins,
pigments and filler material
(wood flour)
– Durable and cheap

Flooring - Types
12. Vinyl Flooring
– Continous flexible sheets which can be printed
– Vinyl flooring is extensively used because it is water-
impervious, fairly durable, insulating, easy to install,
available with a variety of appearances, and inexpensive.
– Lot of environmental issues regarding manufacturing and
disposal
– Catch fire easily, emit poisonous gas upon heating. Vinyl
fires are hard to extinguish

Flooring - Types
13. Vacuum Dewatered Flooring (VDF)
– Excess water is removed from concrete by suction
– Strong (since water – cement ratio is less) Hard and
smooth (no shrinkage cracks) concrete is obtained.
– The concrete is polished and used directly without any
finish - initial cost and maintenance cost for finish is
reduced

Flooring Types
14. Interlocking Rubber Tiles
– Rubber - regular or foamed
– Easy to install and remove
– No need of mortar

ROOFS

Roofs
• Topmost portion of a building which protects the building and
its inhabitants.
• it provides protection against rain, snow, sunlight, extremes
of temperature, and wind
• Also give additional living space: ex. Roof garden, party
space (patio)
• Considerations of selection of roofing:
1. Climatic condition – rainy (sloping), snowy (sloping),
tropical without much rain (flat), windy (slightly sloping),
dusty (shell – dome)
2. Span of space to be accommodated
3. Materials locally available
4. Architectural requirement

Roofs
Features of Good Roof (roofing material)
1. Structural stability – under the service loads
2. Proper insulation for cold, heat and sunlight
3. Fire resistance
4. Damp-proof and leak proof
5. Durability
6. Aesthetics suitable for the building architecture
Taxonomy of Roofs
1. Flat / Terraced Roofs
2. Pitched/ Sloping Roofs
3. Folded plate Roofs
4. Shell Roofs
5. Membrane/ fabric roofs
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Roofs - Taxonomy
Flat (Terrace) Roofs
• Flat or slight slope (< 10°)
• Normally adopted for moderate rainfall region, however, also
adopted for high-rainfall regions with proper waterproofing
• Advantages:
– Roof can be used as terrace ( extra living space)
– Add another storey any time
– Overhead water tanks can be located easily
• Disadvantages:
– Self weight is large
– Not suitable for high snowfall or rainfall regions
– Requires costly water-proofing treatments

Roofs - Taxonomy
1. Mud Terrace roof
2. Punjab Terrace Roof
3. Maharashtra Terrace Roof
4. MP (Madhya Pradesh) Terrace Roof
5. Madras (brick jelly) Terrace Roof
6. Bengal Terrace Roof
7. RCC Roofs
Mud Terrace roof Punjab Terrace roof
Madras Terrace roof
Bengal Terrace roof

Roofs - Taxonomy
Pitched (Sloped) Roofs
• Preferred in areas with heavy rainfall or snowfall
• Slope ranges from 10° to 60° (30° common in kerala)
• Different roofing sheets are used over the sloped roofs
• Elements of a sloped roof:

Roofs - Taxonomy
Parts of a pitched roof

Roofs - Taxonomy
1. Single Roofs
• Rafters are placed at ~ 1 m spacing
• Rafters are the main members which take load
• Suitable for span is very less
• No purlins are provided
• Only for wooden type
a) Lean-to Roof
b) Couple Roof
c) Couple-Close roof
d) Collar – beam roof
2. Double Roof (Purlin Roof)
• Purlins are provided
• Can span more than single roofs
• Material – wood or steel

Roofs - Taxonomy
2. Trussed Roof
– Can accommodate large spans
– Truss – is a framework of slender members
– Purlins support the roof covering – purlins are supported
on over trusses
– Wood and steel
– In case of steel, joints are made by rivetting, bolting or
welding
– Steel is most commonly used world-wide

Roofs - Taxonomy
Parts of a typical Wooden Truss
(king-post type)

Roofs - Taxonomy
Parts of a typical Steel Truss
(Fink – type)

Roofs - Taxonomy
• Different Shapes of trusses

Roofs - Taxonomy

Roofs - Taxonomy
Folded Plate Roof
– Folded plate is a slab with number of folds.
– This is also known as hipped plate or Faltwerke
– Because of the folds, the plate achieve inherent stiffness
when compared to flat plates

Roofs - Taxonomy

Roofs - Taxonomy
Shell Roof
– Shell roofs are curved roofs with thickness is very small
– Load is transferred by „membrane action‟ (compressive
membrane force)
– It can span large space , but formwork is costly
– Different types are: dome, paraboloid, ellipsoid,
hyperbolic paraboloid etc.

Roofs - Taxonomy
Cylindrical
ellipsoidal
spherical
paraboloidal
Hyperbolic
paraboloidal

Roofs - Taxonomy
Membrane Roof
– Membrane / Fabric roof transfer load by membrane action
(tensile membrane force)
– Very versatile – architectural beauty
– Used for temporary structures

ROOFINGS

Roofings (Roof Coverings)
Taxonomy of roofings for pitched roof :
1. Thatch Covering
– Dried plant stems, straw, reeds, palm leaves, coconut
leaves
– Truss may be wooden or bamboo
– Now a days used for architectural purpose

Roofing
2. Tiled Roof
• Roof tiles are designed mainly to keep out rain, and are
traditionally made from locally available materials such as
terracotta or slate.
• Modern materials such as concrete and plastic are also used
and some clay tiles have a waterproof glaze.

Roofings
3. AC Sheet
– Width of AC sheet vary from 1 m to 1.2 m, length 1.75 to
3 m.
– Two types : (a) corrugated (b) Trafford
– Fixed on to steel purlins using J-bolts and washers
– Will not provide thermal comfort
– Occasional cleaning is necessary

Roofings
4. GI Sheets
– Galvanization of iron make it rust-proof
– Fixed to steel purlins with J-bolt and washers
– Durable, fireproof and lightweight
– Noisy during rain

Roofings
5. Aluminium Sheets
– Aluminium and aluminium composite form
– Highly corrosion resistant – can be used for highly
corrosive industrial environment
– Though the metal is a good conductor of heat, its high
reflectivity of radiant heat and light – provide more
thermal comfort
– Environmental friendly – manufacturing process and
disposal (recycling)

Roofings
6. Shingles
– roof covering consisting of individual overlapping
elements.
– Shingles are made of various materials such as wood,
slate, flagstone, metal, plastic, and composite materials
such as fibre cement and asphalt shingles.
– Usually nailed or pasted to existing roof
– Not very suitable for tropical climate

DOORS

Doors
• Definition of door :
– A door may be defined as “an openable barrier or as a
framework of wood, steel, aluminum, glass or a
combination of these materials secured in a wall
opening”.
• Function of door :
1. It is provided to give or deny access to the inside of a
room or portion of a building.
2. Provide lighting and ventilation of rooms.
3. They act as a barrier to noise and heat

Doors
• Consideration while selecting location:
– Doors shall be preferably at the corners of the room
– If two doors necessary for passage, shall be given on
opposite walls, facing each other.
– Toilet door shall be arranged without disturbing the utility
of the room

Anatomy of a Door

Taxonomy of Door (summary)
• Method of Construction
– Battened
• Battened and ledged
• Battened, ledged and
braced
• Battened, ledged and
framed
• Battened, ledged,
framed and braced
– Panelled
– Flushed
– Glazed
– Louvered
– Wire Gauzed
• Working Operation
‾ Casement
‾ Revolving
‾ Sliding
‾ Swing
‾ Collapsible
‾ Rolling Shutters
• Material
‾ Glass
‾ Mild steel
‾ Metal covered plywood
‾ Timber

Taxonomy of Door
A. Method of Construction
1. Battened Doors
(a) Battened and Ledged (BL)
Doors
– Simplest and cheapest
– Only battens are provided
– Normally used for temporary
buildings or low cost buildings

Taxonomy of Door
(b) Battened, Ledged and Braced (BLB) Doors
– Bracings are added to BL doors for integrity
– This is also cheap

Taxonomy of Door
(c) Battened, Ledged and Framed (BLF) Door
– Frames are provided for BL Doors, it will become BLF
doors

Taxonomy of Door
(d) Battened, Ledged, Braced and Framed (BLBF) Door
– Bracing is added to BLF door

Taxonomy of Door
2. Panelled Doors
– strong and pleasing appearance compared to battened
doors
– This will be always framed – thus called as Panelled and
framed doors
– Can be (a) single leaf (shutter) (b) double leaf (shutter)

Taxonomy of Door
3. Flush Doors
– Wood doors flushed with plywood or veneer
– Sometime provided with peep hole

Taxonomy of Door
4. Glaze/ Sash Doors
– Glass is provided for architectural beauty and for vision
– (a) fully glazed (b) partially gazed

Taxonomy of Door
5. Louvered Doors
– Louvered doors are provided to enhance ventilation with
privacy
– Louver material can be (a) glass (b) wood
– Louver mobility : (a) movable (b) fixed

Taxonomy of Door
7. Wire Gauzed Doors
– Permits natural ventilation and light, but restrict the entry
of flied and mosquitoes

Taxonomy of Door
B. Working Operation
1. Casement doors
– Two shutters with hinges on sides

Taxonomy of Door
B. Working Operation
2. Revolving doors
– Provided in public buildings, theatres and malls for
constant visitors

Taxonomy of Door
3. Sliding Doors
– with the help of runners and guide rails, the door slides to
sides
– Provided when space is not sufficient for normal opening

Taxonomy of Door
4. Swing Doors
– Swing door can rotate to either sides – easy for a person
to move inside or outside
– Normally always glazed
– Attached with springs
– (a) single shutter (b) double shutter

Taxonomy of Door
5. Collapsible doors
– acts like a metallic curtain which can get opened and
closed by horizontal pull or push
– (a) single shutter (b) double shutter
– Provided for extra security in public buildings, lifts, glazed
doors…

Taxonomy of Door
6. Rolling Shutters
– Consist of a frame, drum and a shutter made of thin steel
plates
– Shutter moves on steel guides
– Counterbalancing is made with helical springs in the drum
– Very strong and provide safety to the property

Taxonomy of Door
C. Material
1. Glass Doors
– Full glass - used
2. Mild Steel Doors
– Joists/ corrugated sheets
plates
– Paintings can be done
3. Metal covered Plywood
doors
4. Timber Doors

WINDOWS

Windows
• Vented barrier in a wall opening to admit light and air
• Also provide outside/inside view
• Enhance appearance to building by breaking the monotony
of walls
• Consideration of selection and placement:
1. Location of room
2. Size of room
3. Direction of wind
4. Cross ventilation
5. Architectural point of view

Windows
A. Method of Construction
1. Panelled
2. Glazed
3. Louvered
– (a) movable louver (b) fixed louver
B. Type of Opening
1. Fixed
– Does not open
2. Sliding
– The panel can be slide
– (a) single panel (b) double panel
(c) triple panel
3. Pivoted
– The shutters are rotated on a
pivot to open
(a) vertically pivoted
(b) horizontally pivoted

Windows
4. Casement Window
– Shutters hinged on sides like door like casement door
5. Single hung and Double Hung
– Double-Hung windows have two operating sash that
move up and down allowing for ventilation on the top,
bottom or both.
– Single-Hung windows allow ventilation through a single
operable lower sash.

Windows
C. Position
1. Bay windows – provided on projected
walls
2. Corner windows – provided at corner
of a room – heavy lintels are necessary
3. Clerestory (Clear storey) Windows –
Windows above the eyelevel (provided
at landing of stairs, balcony of
churches)
4. Gable window – provided in the
gables
5. Skylight Window – for sloping roof
6. Dormer window – vertical windows on
a sloping roof

VENTILATORS

Ventilators
• Ventilators are openings provided for the exit of exhaust air
• Normally provided over lintel level
• Provides natural ventillation
• Should not provide on the windward direction (ex: West)

FINISHING WORKS

Introduction
• Finishing works include the last works done on a building to
improve the architectural beauty
• Includes:
– Plastering
– Pointing
– Puttying
– Colour washing
– Distempering
– Painting
– Varnishing
– DPC
– Antithermal Treatment
– Antitermite Treatment

Plastering
• Applying mortar coats on the surface of building elements
such as walls, columns, ceilings etc. to get smooth finish is
termed as plastering
• Cement mortar 1:4 or 1:6 is used
• Two to three coats of mortar are provided: first to get level
surface and subsequent to get smooth surface
• Thickness ~ 10 mm
• Uses:
– Smooth and pleasing surface
– To protect concrete against corrosion
– Protect other structures from rain and moisture
– Conceal inferior workmanship

Plastering
Requirements of Good Plaster
1. Should adhere to the surface irrespective of the climatic
changes
2. Prevent penetration of moisture and chemicals
3. Hard and durable

Plastering
Types of Plastering
1. Based on material used: Mud Mortar, Lime mortar, cement
mortar, gauged mortar, Gypsum
2. Based on Finish
a) Smooth Cast Finish
b) Rough Cast Finish
c) Sand Faced Finish
d) Pebble Dash
e) Scrapper Finish
f) Textured Finish

Plastering
Method of Plastering
1. Surface Preparation:
– RCC surface is chipped if not roughened before
– Brush and scrap the surface to make it free from mortar,
oil, efflorescence and loose materials
– The surface is washed and kept moist
2. Mixing ingredients of mortar
3. Applications:
– Primary coat applied
– Maintaining uniform thickness, first coat is applied
– Second Coat is provided if required
4. Curing

Plastering
Defects in Plastering
1. Blistering - formation of small patched of plaster swelling
out beyond the plastered surface
2. Cracking – especially shrinkage cracks
3. Efflorescence
4. Flaking – due to poor bond between surface and plaster

Plastering
5. Peeling – complete dislocation of some portion of the
plastered surface – due to imperfect bond
6. Rust Stains – when plaster is applied on metals
7. Uneven surface – due to poor workmanship

Pointing
• Finishing of mortar joints of masonry
• In exposed masonry finish, mortar joints are vulnerable spots
• In pointing, better quality mortar is used to fill these gaps in
finish
• Mortar : 1:3
• Procedure:
– Preparation of surface
• all joints are raked to depth 20 mm
• Cleaned and wetted
– Mortar is applied
– Cured

Pointing
Types of Pointing
1. Flush Pointing
– Pointing mortar is pressed hard in the raked joints and
finished flush with the edge of masonry units
2. Recessed Pointing
– Pointing mortar is pressed back by 5 mm or more from
the edges of masonry

Pointing
3. Beaded Pointing
– pointing done by a steel or iron with a concave edge
4. Struck Pointing
– face of the pointing is kept inclined to vertical, with its
upper edge pressed inside by 10 mm

Pointing
5. Rubbed (Keyed or grooved) Pointing
– Modification of flush pointing in which groove is formed at
its mid height by a pointing tool
6. Tuck Pointing
– Mortar is pressed in and finished flush
– A narrow groove is cut at the centre of groove
– This groove is then filled with white cement putty, kept
projecting beyond the face

Pointing
7. V- Pointing
– It forms V- groove with pointing tool
8. Weathered Pointing
– Made by making a projection in the form of V-shape

Whitewashing
• Whitewash (Calcimine or lime paint) is a low-cost paint made
from slaked lime (Ca(OH)2) and chalk(CaCO3 ) – Base
• Carrier - Water
• Whitewash cures through a reaction with carbon dioxide in
the atmosphere to form calcium carbonate in the form of
calcite, a reaction known as carbonation.
• It has got mild antibacterial property
• Occasionally colour is used, but not popular as it can rub off
onto clothing
• Lime Wash is pure slaked lime in water. Lime wash and
white wash both cure to become same material
• Additives: glue, water glass, egg white, linseed oil, cement
or pig‟s blood

Whitewashing
• Process:
– Preparation of white wash – White wash is prepared
from fat lime. 5 litres of water added to 1 kg lime allowed
to stand for 24 hrs.
– Preparation of surface – The new surface should be
thoroughly cleaned off all dirt, dust mortar and other
foreign matter before white wash is applied.
– Application of White wash – It is applied with brush, to
the specified number of coats(generally 3). Operation in
each coat should consist of a stroke of the brush given
from top downwards, another from the bottom upwards.

Colour Washing
• Colour wash is a painting technique that adds a thin layer of
darker colour over a previously painted surface in the same
colour group.
• Colour washing creates soft, muted tones that can dress up
drab, plain walls.
• The technique involves mixing paint with glaze; the glaze
thins the paint and slows its drying time to make it easier to
work with.
• Color washing your walls gives them a warm, textured look.

Distempers
• Distempers are the cheaper variety of paints in which chalk
is used as base and water is used as carrier
• These are also called „water paints‟ available in powder
• It is made by mixing whiting and glue boiled water
• A Binder commonly used is glue or casein.
• Application:
– Preparation of surface: thoroughly rubbed and cleaned.
Cracks if found filled with putty
– Priming coat
– Final coats: two or three coats. Each coat applied only
after previous coat is dried.

Distempers
Types:
1. White distempers
2. Coloured distempers
3. Oil bound distempers
4. Acrylic Distempers

Painting
• Coatings of fluid materials applied as a final finish to all
surfaces.
• Functions of paints:
– Protect the coated surface against chemical attack
– Decoration with smooth and colourful finish
– Resist formation of bacteria and fungi colonies
Paint
Base Pigment Binder Driers Solvents

Painting
1. Base
– A solid substance in a form of fine powder, forming the bulk of
a paint.
– It is generally a metallic oxide.
– A base in a paint provides opaque coating to hide the surface
to be painted.
– Commonly used Bases are White Lead, Red Lead, Oxides of
Iron and Zinc.
2. Pigment
– Natural colours - Orches, Umbers and iron oxides.
– Calcined colours - Lamp Black, Indian Red, Carbon Black
– Precipitates – Prussian Blue, Chrome green and yellow
– Lakes – Prepared by discolouring barytes or china clay with the
help of suitable dyes.

Painting
3. Binder
– These are liquid substances which hold the different in
gradients of a paint in liquid suspension.
– It makes the paint to spread evenly on the surface.
– Commonly used Binders are Tug oil, Linseed oil, poppy oil.
4. Driers
– aid drying as well as hardening
5. Solvents
– Solvents are added to paint to make it thin so that it can be
easily applied on surfaces.
– It also helps the paint in penetrating through the porous
surface of the background.
– Commonly used solvents are Alcohol, Naphtha, Benzene.

Painting
Characteristics of good paint
1. It should stick well to the surface and should be able to seal
the porous substrata.
2. Good consistency
3. The thickness of the paint film should be adequate for good
protection and decoration of the surface.
4. The paint film should dry rapidly.
5. The dried paint film should be able to withstand the adverse
weather effect for a long time without losing gloss.
6. It should posses good moisture resistance.
7. Its colour should not fade with the passage of time

Painting
Types of Paints
1. Aluminium Paints
– Contains finely ground aluminium in spirit or oil varnish
– Give nice protection to iron and steel against corrosion
– Does not oxidise and fade
2. Oil Paint
– General type of paint soluble in oil
– Normally three coats are applied
3. Enamel Paint
– Contains white lead, oil, petroleum spirit and resin
– Dry slowly forming hard tough elastic film
– Enamel painted surfaces are washable

Painting
4. Synthetic Rubber Paint
– Prepared from resisns
– Dries quickly and little affected by weather and sunlight
– This paint can be applied even on fresh concrete
5. Anti-corrossive paint
– Oil + strong drier + lead or zinc chrome + finely ground
sand
– Black in colour
6. Bituminous paint
– Dissolving asphalt in petroleum oil
– Black in colour
– Resist corrosion

Painting
7. Emulsion Paint
– Emulsion paint consists of tiny polymer particles within
which the pigments are trapped.
– The particles are suspended in water, then as the paint
dries the particles fuse together creating a film of paint on
the wall.
8. Cement Paint
– White cement, pigment and additives
– Should be applied on rough surface
– Exhibit excellent decorative appearance

Painting
9. Varnish
– Varnish is a solution of resin in either oil, turpentine or
alcohol
– Dries after applying, leaving a hard, transparent and
glossy film or resin over the varnished surface
– Applied on wooden surface to protect against
atmospheric action
10. Zinc Paint (Luminous Paint)
– Applied on metallic surface to give luminosity and
flourescence
– Zinc oxide or zinc sulphate is the main content

Painting
Defects in Painting
1. Blistering
– Formation of bubbles like shapes on
the painted surface is known as
blistering. The primary cause of this
defect is water vapor. When water
vapor trapped under the paint layer, it
creates bubbles under the film of paint.
2. Blooming
– Formation of dull patches on the
painted surface is known as blooming.
The primary cause of this defect is
poor quality of paint and improper
ventilation.

Painting
3. Fading
– When there is a gradual loss of colour
from the pained surface, it is known as
fading. The main cause of this defect is
the reaction of sunlight on pigments of
paint.
4. Flaking
– In this type of defect, some portion of
the paint film is not sticked properly
with the surface; resulting flaking off of
the paint layer. This is cause due to
poor adhesion between paint and the
surface to be painted.

Painting
5. Running
– This type of defect is seen when the
surface to be painted is very smooth.
In case of smooth surface the paint
runs back and leaves small areas of
surface uncovered.
6. Sagging
– This type of defect is more prominent
when a thick layer of paint is applied
on a vertical or inclined surface.
7. Wrinkling
– This type of defect is more prominent
when a thick layer of paint is applied
on a horizontal surface.

Damp Proofing
• Dampness is defined as the access or penetration of
moisture
• Causes:
– Moisture from ground
– Splashing of rain
– Exposed top wall
– Condensation of atmospheric moisture
– Presence of salts in concrete

Damp Proofing
Effects of Dampness
• Efflorescence in mortar and brick, leeching in concrete
• Plaster softens and crumbles.
• Materials used for wall decorations are damaged.
• Stones ,bricks and tiles disintegrate
• Floor finish may be damaged
• Woodworks decays due to dry rot.
• Metal components of building corrodes.
• Electrical fittings are damaged
• Dampness leads to breeding of mosquitoes, growth of
termites and germs carrying diseases such as tuberculosis
• Growth of fungi

Damp Proofing
Damp Prevention Technique
1. Use of Damp Proof Courses (DPC)
– Provided at different parts of building to prevent
dampness to enter
– DPC consist of water repellent material like bitumen,
cement concrete, metal or plastic sheets

Damp Proofing

Damp Proofing
2. Integral damp-proofing Treatments
– Adding concrete and mortar with materials
– Concrete can be added with damp-proof admixtures
which have hydrophobic properties
– Addition of pozzolans reduce the porosity and shrinkage
cracks in concrete, thereby reducing chance of damping
– Chalk, fuller‟s earth etc. can be added to mortar to make
dense and water proof
3. Cavity Walls
– Prevent moisture to enter the inner wall leaf
– Cavity walls also hides efflorescence

Damp Proofing
4. Shotcreting (Guniting)
– Rich mortar (1:3) or concrete is sprayed on to the surface
to close the possible cracks or capillaries
– Spraying is done pneumatically
5. Pressure Grouting (Cementation)
– Forcing cement grout (cement + fine sand + water) under
pressure into cracks or voids

Antitermite Treatment
• Termite spoil wooden materials, make path through masonry
and create tubular mud formation through the surface of
plastered walls
• They attack household articles like furniture, books…

Antitermite Treatment Methods
1. Preconstruction Treatment
(a) Soil/ site Preparation
• All trees, stumps, logs and roots removed from
building site
• All the organic debris removed
(b) Soil Treatment
• Anti-termite chemicals are used to form barrier
between ground and structure
• Chemicals include BHC, Aldrin, Chlordane,
Chloropyrifos.

(c) Structural Barriers
• Physical structural barrier is provided continuously at
plinth level to prevent termite entry
• Concrete layer are normally provided with ~ 80 mm
thickness
• Copper or galvanised iron of ~ 1mm thick is also
provided
2. Post construction Treatment
– Maintenance of buildings already under attack
– The magnitude of attack is estimated and defective
points of colony are identified
– Antithermite emulsion is injected

KTU CE 204 Construction Technology - Module 4

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KTU CE 204 Construction Technology - Module 4