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Transcript of Sand
Construction Materials
• Sand
• Lime
• Cement
Sand
• Definition: Naturally occurring granular
material composed of finely divided rock
and mineral particles
• Constituents: Varies on location and
availability of local rock sources
Silica, calcium carbonate
Sources
• Pit sand : free from salt, good for mortar, no stains, sharp
angular grains
• River sand: banks or beds of river, finely rounded grains,
almost white, clean
• Sea sand: sea shores, finely rounded grain, light brown in
colour, contains salt : causes moisture absorption from
atmosphere , filling of basements, not useful for mortar and
other work
Classification
• Fine sand: pass through
screen 1.5875mm, for
plastering
• Coarse sand: 3.175mm
screen, masonry work
• Gravelly sand: 7.62mm,
concrete work
Bulking of sand
• Presence of moisture
increase in volume of
sand
• with 5-8%, increase of
volume is 20-40%
• Finer the material , more
is the volume increase
Properties
• Chemically inert
• Clean, coarse, free from organic or vegetable
matter, 3-4% of clay is permitted
• Should contain sharp angular coarse and durable
grain
• No salts
• Well graded, to suit various sizes and proportion
Function
• Bulk: acts as adulterant, volume of mortar is increased,
reduction in cost, doesn’t increase strength of mortar
• Shrinkage: prevents excess shrinkage of mortar,
cracking of mortar during setting is prevented
• Strength: resistance of mortar against crushing
• Surface area: more surface area is offered for
spreading
• Setting: if fat lime is used in mortar, setting time is
increased
Tests
• Adding of water: layer of clay settle down
• Taste: no salts should be present
• Rubbing against fingers should leave no
stains
• Colour and sharpness of sand
• Other mechanical analysis
Substitutes
• Stone screenings:
Sharp, more strenght
for huge quantity, big
construction projects,
• Burnt clay or surkhi:
finely grinding burnt clay
Lime
• Definition: Due to calcination of limestone, the
moisture and carbon dioxide are removed from it.
The product which remains thereafter is known as
lime
• Limestone is a sedimentary rock
• It is mainly made up of calcium carbonate
• It is actually a mixture of substances
Terminology
• Calcination: heating to redness in contact with air
• Hydraulicity: property of lime to set or harden in
damp places, water or thick masonry walls where
there is no free circulation of air
• Setting: Process of hardening of lime after it has
been converted into paste form (different from
drying where water evaporates)
Quick lime
• obtained by calcination of comparatively pure
limestone, great affinity for moisture, amorphous, not
crystalline and highly caustic having no affinity for
carbon acid
Slaked (hydrated) lime
• Product obtained by slaking of quick lime, (hydrate of lime)
• White powder form
• The thin pourable suspension of slaked lime in water is known as milk
of lime.
• Should be kept in damp place
• Should be used fresh,
• Slaking of lime:
sufficient quantity of water added to quick lime
due to chemical reaction , quick lime cracks,
swells and falls into powder form,
Classification
• Fat lime
• Hydraulic lime
• Poor lime
Fat lime
• Fat lime: high calcium lime , rich lime,
pure lime or white lime
• Slakes vigorously, volume is increased to
about 2 to 2 ½ times the volume of quick
lime.
• Hardens very slowly, high degree of
plasticity, soluble in water which is
frequently changed
• Perfectly white colour, sets slowly in
presence of air
• Impurities is less than 5%
• Used in whitewashing and plastering, for
lime mortar in brick and stone masonry
• Whith surkhi, lime mortar posses good
setting and hydraulic properties, used for
foundations, thick masonry walls etc
Hydraulic lime (water lime)
• It sets under water
• Contains some amount of ferrous oxide
• Increase in %age of clay making slaking
difficult and increases hydraulic property
• Presence of 30% of clay resembles
hydraulic lime to natural cement
• Used for thick walls where there is no free
air circulation, plaster work
• Colour is not perfectly white
• Forms thin paste with water
• Does not dissolve in water though it is
frequently changed
Poor lime
• Impure lime or lean lime,
• Contains more than 30% of clay
• Slakes slowly
• Sets very slowly
• Poor binding properties , so poor mortar
• Muddy white colour
• It forms thin paste with water
• Does not dissolve in water though it is
frequently changed
Comparision
Item Fat lime Hydraulic lime
composition Obtained from pure carbonate of lime, only
5% of impurities
Obtained from limestone
containing clay of about 5 to
30% + some amount of ferrous
oxide
Slaking action Slakes vigorously, volume is increased to
about 2 to 2 ½ times the volume of quick
lime.
Accompanied by Sound and heat
slaking slowly, volume is
slightly increased, No sound
and heat
Setting action Hardens very slowly in presence of air
Sets fast under water
hydraulicity Does not possess hydraulic property Posses hydraulic property
colour Perfectly white colour, sets slowly in
presence of air
Not so white
strength Not very strong Very strong
CEMENT
• Natural cement: Obtained by burning
and crushing the stones containing clay,
carbonate of lime and some amount of
carbonate of magnesia
• Colour: brown, best variety known as
roman cement
• Not as strong as artificial cement , limited
use in practice
Properties
• Gives strenght to
masonry
• Excellent binding material
• Easily workable
• Good resistence to the
moisture
• Possesses good plasticity
• Stiffens and hardens early
Setting action of
cement
• Setting action: when water is added,
chain of chemical reactions between
ingredients and water results in a
chemical compounds, its long ,
• Sticky paste gradually thickening till it
achieves a rock like state
• Ordinary cement achievies 70% of its
final strenght in 28dsy, and 90% in a
year
Functions
• Lime: excess lime makes unsound, causes to expand and disintegrate .
Less of lime decreases the strength and causes cement to set quickly
• Silica: imparts strength ,Excess silica increases strength but prolongs
setting time
• Alumina: imparts quick setting property to cement: acts as flux and
lowers the clinkering temperature. excess alumina weakens the cement
• Calcium sulphate in the form of gypsum, increases initial setting time
• Iron Oxide: imparts colour, hardness and strength
• Magnesia: in small quantity imparts hardness and colour. High content
makes cement unsound
• Sulphur: small amount is used to make cement become sound. In
excess makes it unsound
• Alkalies: in excess causes alkali aggregate reaction, effloesecnce and
stating when used in mortar or concrete
Artificial cement
• The best variety of artificial cement is known
as portland cement or ordinary cement or
normal setting cement, finely ground material
consiting of lime, silica,iron alumina.
• When mixed with with water, it forms a paste
which hardens and binds the aggregate
togsther to form concrete
Rapid hardening
cement
• Attains high strength in early bcoz of increased lime
content in composition, burning at a higher temperature
and finger grinding.
• This type of cement is used in concrete when early high
strength area needed either to remove formwork quickly
or to carry out construction speedily or in cold weather
construction to reduce the period of protection against
temperature or to achieve economy for higher early
strengths
Quick setting
cement
• Starts setting within 5 min of water addition and becomes hard
like stone within 30 min or so.
• Produced by adding small percentage of aluminum sulphate as
an accelerator and also by reducing percentage of gypsum or
retarded along with finer grinding
• This type of cement is used where concrete work is to be
completed in very short period such as concreting in static o
running water
White cement
• Variety of ordinary cement and is prepared from
such raw materials which are practically free from
iron oxide it is more costly and s used widely only
for architectural purposes such as pre-cast curtain
wall and facing panels, terrazo surface, etc
Colour
• Cements of desired colour are produced by
intimately mineral pigments with ordinary cement,
coloured cement are widely used for decorative
works in floors, external surfaces, walls, etc
Pozzolona cement
• It is volcanic powder which when mixed with
portland cement clinkers forms pozzolanic
cement. This cement is largely used in marine
structures, sewege works, and for laying concrete
under water such as bridge piers, dams, etc
Field test for cement
• Colour : uniform, typical
grey with a light greenish
shade
• Physical properties:
smooth when touched or
rubbed in between two
fingers if rough indicates
adultration with sand,
• If ahnd is inserted
THE CEMENT MANUFACTURING PROCESS quarry
raw grinding and burning
grinding, storage, packing, dispatch
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THE CEMENT MANUFACTURING PROCESS
1. BLASTING : The raw materials that are used to manufacture cement (mainly limestone and clay) are blasted
from the quarry.
Quarry face
1. BLASTING 2. TRANSPORT
3. CRUSHING AND TRANSPORTATION : The raw materials, after crushing, are
transported to the plant by conveyor. The plant stores the materials before they are
homogenized.
quarry
3. CRUSHING & TRANSPORTATION
2. TRANSPORT : The raw materials are loaded into a dumper.
crushing
conveyor
dumper
storage at
the plant
loader
THE CEMENT MANUFACTURING PROCESS
1. RAW GRINDING : The raw materials are very finely ground in order to produce the raw mix.
1. RAW GRINDING
Raw grinding and burning
2. BURNING
2. BURNING : The raw mix is preheated before it goes into the kiln, which is heated by a flame that can
be as hot as 2000 °C. The raw mix burns at 1500 °C producing clinker which, when it leaves the kiln, is
rapidly cooled with air fans. So, the raw mix is burnt to produce clinker : the basic material needed to
make cement.
conveyor Raw mix
kiln
cooling
preheating
clinker
storage at
the plant
Raw mill
THE CEMENT MANUFACTURING PROCESS
1.GRINDING : The clinker and the gypsum are very finely ground giving a “pure cement”. Other secondary
additives and cementitious materials can also be added to make a blended cement.
1. GRINDING
Grinding, storage, packing, dispatch
2. STORAGE, PACKING, DISPATCH
2. STORAGE, PACKING, DISPATCH :The cement is stored in silos before being dispatched either in
bulk or in bags to its final destination.
clinker
storage
Gypsum and the secondary additives are added
to the clinker.
silos
dispatch
bags
Finish grinding
MORTAR
• Mortar is a workable paste used to bind construction blocks together and
fill the gaps between them
• Paste prepared by adding required qty of water to a mixture of binding
material like cement or lime and fine aggregate like sand
1: Matrix:
binds the particles of
adulterant
durability, quality and
strength
Cement , lime
Mortar
2: Adulterant:
Particles that gives volume to
mortar
Sand, surkhi etc
classification • Bulk density: Heavy mortar
Light mortar
• Kind of binding material
lime mortar
surkhi mortar
cement mortar
gauged mortar
gypsum mortar
• Nature of application
Brick laying mortar
finishing mortar
• Special mortars
Fire resistant
Lightweight
Packing
Sound absorbing
X ray shielding
Bulk density:
• Heavy mortar :
density of 15kN/m3 or more prepared form
heavy quartz or other sand
• Light mortar:
density is less than 15kN/m3 , prepared form
light porous sands from pumice or fine
aggregate
Kind of binding material
• lime mortar : fat lime shrinks to great extent and require 2-3 times its
volume of sand, water logged areas and damp situations
hydraulic lime consumed within 1 hr after mixing, more strength ,used in
damp situations
high plasticity, easily placed, good cohesiveness, with other surface and
shrinks very little, durable, hardens slowly,
• surkhi mortar : used instead of sand, not chemically inert, cannot used
with cement ad matrix, for ordinary work in foundation and superstructure,
not for plastering
• cement mortar: 1:2 to 1:6 or more , proportion depends on durability, and
working conditions, high strength, water resisting properties for
underground construction,
• gauged mortar : to lime mortar cement is added to achieve early strength,
lime mortar is economical, bedding, thick brick walls
• gypsum mortar : gypsum binding materials
Nature of application
• Brick laying mortar :
for brick walls, depending on working conditions,
kind of binding material
• finishing mortar :
common plastering- cement or lime mortar
Architectural and ornamental effects
Consideration of mobility, water retention, resistance
to atmospheric actions etc
Special mortars
• Fire resistant :used with fire-bricks for lining
furnaces, fire places, ovens etc
• Lightweight : saw dust, wood powder etc is added
to lime or cement mortar,
• Packing : to pack oil wells, water resistance, to
form water proof plugs in cracks and voids. San
cement, sand loam, and sand cement loam
• Sound absorbing: to reduce noise level, sound
absorbing a material like jute fibres, coir, light
weight porous material
• X ray shielding: plastering coat to walls and
ceiling, heavy mortar -22kN/m3 bulk density