unit-ii basic civil engg
TRANSCRIPT
UNIT-IIMATERIALS AND CONSTRUCTION
[A] BASIC CONSTRUCTION MATERIALS
Materials
CementBrick, StoneNatural & Artificial sandReinforcing steel – mild, tor & high tensile steelConcrete types– PCC, RCC, Prestressed & precastIntroduction to smart materialRecycling of materials
Basic materials and their uses
Basic materials used in construction are cement, sand, bricks, stone and steel
Cement –As a binding materialSand- used in mortar or concreteBricks and stones – for masonry work.Steel- for reinforcement concrete and
fabrication of steel doors, windows, fixtures and fastners
7
Cement binder a very fine in size Compose of various ratio of chemical When water is added to the cement, a hydration reaction occurs,
producing a solid gel that bond the aggregate particle
•3CaO+Al2O+SiO2+3CaO+SiO2+4CaO
• +Al2O3+Fe2O3+other minerals
Cements
1-CEMENT
lime stone + clay physical properties of cement 1- fineness-OPC-Surface area not less than 2250cm2/gm 2-setting time-a) Initial setting time-30minb) Final setting time-3 to 6 hrs 3-compressive strength -3days-16N/mm2 7days-22 N/mm2 4-soundness-not more than 10 mm
9
Cements
The composition on the cement helps determine the rate of curing and the final properties of the concrete
e.g. 3CaO . Al2O3 and 3CaO . SiO2 Rapid setting but low strengths
2CaO . Al2O3 Slowly during hydration but higher strengths
Str
eng
th
Time
•2CaO . Al2O3
•3CaO . Al2O3
•3CaO . SiO2
10
Cements
The concrete is expected 28 days for nearly complete curing Some additional curing may continue for years
Types of cement Type 1: General purpose Type 2: Low rate of heat generation, moderate resistance to
sulphate Type 3: Rapid setting Type 4: Very low rate
of heat generation Type 5: Good sulphate
resistance + =
11
Cements Reaction
Cement
Water
Sand
Aggregate
•Hydration reaction occur
3CaO . Al2O3+6H2O -> Ca3Al2(OH)12 + heat
2CaO . SiO2+xH2O -> Ca2SiO4 . xH2O + heat
3CaO . SiO2+ (x+1)H2O -> Ca2SiO4 . xH2O +Ca(OH)12 + heat
types of cement
A) Portland cements- 1-ordinary Portland cement-all types of constn,less resistance
to chemical attack 2-rapid hardening Portland cement-after 3 days it is same as 7
days strength of OPC 3- low heat cement –slower rate of reaction 4-sulphate resisting cement- 5-portland blast furnace slag cement-used for dams,bridges &
foundation & more resistant to sulphate attack-decoration & architectural finish,it is costly
6-white and colored cement
B) Super Sulphate cement-resistant to sea water
C) Natural cement- not used D) High alumina cement-it is not attacked by
carbon dioxide therefore for manufacture of RCC pipes
Field testing of Cement
Uses of Cement
1) OPC is used for preparation of cement mortar & constn of bldgs
2) Manufacturing of tiles3) Used as a base in paints4) White & coloured cement uesd in plastering &
decorative finish5) Sulphate resisting cement is used in constn of
surfaces exposed to sulphate action6) construction of highway slabs
2-BRICK
properties of brick 1-size and shape 2-water absorption 3-strength-35 kg/cm2 4-colour
Manufacture of bricks
Selection of site Preparation of clay Moulding of bricks Drying of bricks Burning of bricks
TYPES OF BRICKS
first class second class third class uses of bricks-1) In masonry work2) Flooring material3) Constn of roads4) First class bricks used in face work of the bldg5) Broken bricks used as a aggregate in lime concrete
Stone
Stone is always obtained from rocks, which a solid portion of earth crust.
The rocks quarried from quarries is called as stone.
Quarried stone may be in the from of stone slab, stone blocks, stone aggregates, stone lintels, stone flags.
Stone has to be properly dressed & shaped before it is used at the place of work.
20
Aggregate
Gravel & Rock Aggregate must be clean, strong, and durable Angular aggregate particles provide strength due to mechanical
interlocking between particles More surface on angular particles may form voids or cracks The large size of aggregate is preferred Aggregate particles should not be larger than about 20% of the
thickness of the structure or it will cause the holding defect
Classification of rocks
Geological classification:- Igneous rocks, Sedimentary rocks, metamorphic rocks.
Physical classification:- Stratified rocks, unstratified rocks, laminated rocks
Chemical classification:- Siliceous rocks, argillaceous rocks, calcareous rocks
Classification based on hardness of the stones:-Very hard rock, hard rock, medium rock and soft rock.
Uses of stones
Broken stones & stone chips are used in foundation, for floor of buildg. Railway ballast & road metal
Stone blocks are mainly used In walls & for ornamental facing work.
Quartzite is used for rubble masonry, road metalling & also used as a aggregates
Lime stone slabs used for flooring, paving,roofing
Granite:-for bridge abutments, piers & kitchen ota
Marble :- for extreme superior work eg. TajMahal
23
Sand
Sand
Sand
It is a form of silica (siliceous+ argillaceous), formed due to decomposition of sandstones due to various weathering actions.Natural (obtained from pits, river beds, shores)& artificial sand (by crushing of stones)Fine sand (sand which pass through IS. 4.75mm size sieve) & coarse sand( that retain on IS.4.75mm size sieve)Increases volume of mortar & makes the mortar economical.
Requisites for Good Sand
1) The gains should be sharp,angular & coarse
2) Sand should be free from clayey materials
3) It should free from salts
4) The grains should be of durable minerlas
Uses of sand
In cement mortar for stone, brick masonry & plastering work.
Used in PCC, RCC. & in Prestressed conc.
Coarser sand used for face plastering for external walls.
STEEL
It is an alloy of iron & carbon, containing carbon- 0.25 to 1.25%
Steel is highly elastic, ductile, malleable, forgeable & weldable.
Generally mild steel: (designated as Fe250, ie. Yield strength in N/mm2), Tor steel: used in RCC. structures (Fe415 & Fe500)) & High tensile steel: (used in prestress conc. costruction.) used in construction.
Steel is of diff. sections like I, T, O, & channel sections
Uses of steel
Structural material in trusses, beams in the form of various sections.Non structural components like stairs, grills, windows & doors.In fabrication of steel pipes, tubes, tanks, ducts etc.Mild steel- used as distribution steel in RCC.Tor steel- used as main steel in RCC.High tensile steel cables used in prestressed conc. Girders.
6-CONCRETE
CEMENT+SAND+COARSE AGGREGATES+WATER
It is workable mixture which can be easily transported, placed & compacted to attend maximum strength.
Properties of concrete depends upon properties of ingredients.
32
Concretes
Common construction material Strong hard but brittle Heavy and can not be recycle All ingredients compose of diminishing raw
material
33
Concretes Concretes = a particular composite in which both the
particular and the matrix are ceramic material Concretes = Portland Cement + Sand +Aggregate (A cementation reaction between water and the mineral in cement provide a
strong matrix and good compressive strength)
CementsCements SandSand AggregateAggregate
34
Properties of Concrete
The water cement ratio
35
Properties of Concrete
The amount of air entrainment
36
Properties of Concrete
The amount of air entrainment A small amount of air is entrained into concrete during pouring 1-2.5% (sometimes up to 8%) by volume of the concrete may
be trapped by air The entrained air - improves workability of concrete - minimise problems with shrinkage and freeze thaw
conditions, but – cause lower strength
37
Concrete Construction
Grades of concrete
M10 1:3:6(culvert, retaining walls, conc. floors)
M15 1:2:4(for general RCC. work) M20 1:1.5:3(water tank & bridge
construction) M25 1:1:2(heavily loaded RCC. structures) M30 and above (heavy structures)
Classification of concrete
1-Plain cement concrete (PCC)2-Reinforced cement concrete (RCC)3-Precast concrete4-Prestress concrete-Pre-tensioning-Post-tensioning
1-Plain cement concrete (PCC)
It is a mixture of cement, fine+coarse aggregates & water
The proportion of these ingredients depends upon grade of mix required & for requirenent of particular job
The PCC is strong in compression & weak in tension. It has good weathering resistance property.
It has good resistance to abrasion.
Uses of PCC.
Used in foundation masonry, Base for foundation, flooring base
In gravity dam & retaining walls
Reinforced cement concrete (RCC)
Mixture of concrete with steel.
Equally strong in tension & in compression
Due to bonding between steel & concrete, stresses are transferred from one material to another material.
Minimum M20 grade of concrete is required for the construction
Uses of RCC.
Concreting for general work like beam, column, slabs, footing etc
Construction of multistoried buildings
Construction of road pavements
Construction of water, oil tanks, bridges,concrete pipes
Machine foundations
Marine structure, hydraulic structure
Precast concrete
Concrete which is cast in separate forms before they are placed in position
It may be casted at building site or some distance from building site
Then with help of equipments & cranes they are transported on site.
Simplest form of precast concrete are hollow & solid concrete blocks for the construction of external & internal walls.
45
Reinforced and Pre-post-stressed Concrete
Concrete for construction material Reinforced Concrete Pre-stressed Concrete Post-stressed Concrete
Uses of precast concrete
For casting various building elements such as beam, column, slabs, water tank etc.
For manufacturing of compound poles, electric poles
Fabrication of RCC. Pipes, bridge girder, bridge pier & concrete piles
Prestressed Concrete (P.S.C.)
This is a reinforced concrete in which concrete is subjected to compressive stress before the external load applied to conteract tensile stress caused in concrete due to external loads
Used for M30 & above grades of concrete.
Prestressing is of two types- 1)Pre-tensioning
2) post-tensioning
Prestressing force is applied with the help of hydraulic jacks.
1)Pre-tensioning
In this the tendons are prestressed in place before concrete is poured,
2) Post-tensioning- In this the tendons are given the required tension after the concrete has attained desired strength.
Uses of Prestressed Concrete (P.S.C.)
Girders for bridgesBeams for larger spansRailway slippersElectrical polesUsed in constn of nuclear power stations,steel plants ,piles
ADVANTAGES
1) It permits the use of large spans with shallow member even when heavy loads are encounted
2) High quality materials are used
3) The size of structural member are reduced
Precast blocks
The cement concrete blocks which are cast in rectangular shape mould, which is hollow or solid.
Uses of pre-cast blocks
For light weight structure
In partition walls
As size of precast block is more it required less material & hence economical.
Strong, Durable, & having High strength
Difference between mortar & concrete
Mortar Cement+fine
aggregates+water Mortar used for
masonry work & plastering works, also used for grouting
Concrete Cement+fine
aggregates+coars aggregates+water +water
Used for RCC. & PSC. works
Introduction to smart material
Smart materials are the materials which have the capability to respond to change in their condition or the environment to which they are exposed
Eg. Photocromatic material that change in colour with response to light, alloys & polymers change their shape with response to heat, fluids that changes its viscosity with respect to electric or magnetic stimuli.
Different smart materials
Piezoelectric material
Electrostrictive material
Magnetostrictive material
Shape memory alloy
Optical fibres
56
Asphalt Asphalt is bitumen. Bitumen is the organic binder, composed of
HC with low melting point thermoplastic polymers and oils.
Asphalt mix is composite of aggregate and bitumen.
57
Asphalt Mix
The aggregate use as in the concrete that should be clean and angular.
Aggregate should have distribution of grain sizes to provide a high packing factor and good mechanical interlock between aggregate grains.
A B
58
Operation of Asphalt Mix
59
Asphalt construction
Electrostrictive material
This material has same properties to that of piezoelectric material, but only the change is that mechanical change is equal to square of electrical field
Piezoelectric material
When subjected to an electrical field or electrical voltage piezo-electric material will undergo some mechanical change
Wi
Magnetostrictive material
When subjected mechanical field this material under goes mechanical strain
Shape memory alloy
When subjected to thermal field it undergoes some thermal shape change.
Optical fibres
Fibres that use intensity, phase, frequency to measure strain, temperature, electric & magnetic field.
Applications of smart materials
Used in aircrafts & space crafts to measure vibrations & excessive deflections.
Smart concrete used in smart structures to detect smaller cracks.
Catalytic materials that increase or decrease the rate of reaction
All senser materials that can detect signals & adjust sensitivity according to environment
Noise control
Recycling of material
Recycling is the process in which we can utilize the material left on construction site or demolition of structure.
Because of this supply of fresh material required can be reduced
And ultimately reduce environmental pollution
1) Crushed concrete used for road base,general fill or pavement aggregate
2) Asphalt pavement can be crushed & recycled back into asphalt or in hot mix asphalt plant
3) Metal can be melted down & uesd for metal products
4) Bricks can be used in base material in water proofing treatment
68
Woods Most familiar materials to mankind. Not a high-technology materials but fantastic. The only material that can be reproduced and give oxygen
to human. Woods is very strong but yet lightweight.
69
Woods structure
Wood surface Cross sectional • portion of a round cross
section, clearly reveals a nnual growth rings.
Radial Surface•cutting along a radius
of a round cross section
Tangential Surface•cutting at a tangent to the growth rings, or the surface you would see if you were to view the outside of a log
70
Annual Ring trees grow in both diameter and height during growth
periods that are interrupted by periods of rest.
Woods structure
Raining seasonHigh water time
Summer seasonLower water time
71
Woods VS water Water caused negative effect to wood
Wood, if not predried, will dry while in use under uncontrolled conditions giving rise to warp, bow, twist, and similar defects.
Wet wood is susceptible to attack by decay and stain fungi. Water must be removed to provide
void space for preservatives if wood is to be treated for prevention
against fungal
attack.
72
Wood shrinkage
Wood is an anisotropic material (having different properties in 3 dimensions)
Three Dimensions in which Wood Shrinks
Longitudinal
Shrinkage
= 0.1% to 0.3%
Radial
Shrinkage
= 2.1% to 7.9%
Tangential
Shrinkage
= 4.7% to 12.7%
R RR
T
T
T
L
73
Mechanical Properties of woods Wood strength depends on density Given a high efficiency when subject to tensile strength
parallel to the fiber direction
Wood species Tensile // fiber
(MN.m-2)
Tensile radial
(MN.m-2)
Compress // fiber
(MN.m-2)
Compress radial
(MN.m-2)
Maple 108 8 54 10
Oak 78 6 43 6
Pine 73 2 33 3
74
Comparison of the specific strength
Specific strength (SF)= strength/density
Material SF strength(kg.m2.s-2)
SF modulus(kg.m2.s-2)
Clear wood 178 2.4E4
Aluminum 127 2.7E4
1020 steel 50 2.7E4
Copper 38 1.4E4
Concrete 15 0.9E4
75
Wooden house
Unit-II
Chapter no-4
Sub structure or foundation
Components of Substructure
1) Foundation2) Plinth-3) D.P.C.-Layer between substr &
superstr
foundation
Definition of foundation Bearing capacity ultimate bearing capacity:- It is the capacity of
soil before to failure in shear Safe bearing capacity= ultimate bearing capacity/
factor of safety F.O.S. for temporary structure=1.5 to 2, For
footing= 2 to 3, for piles=2 to 6 & for rocky strata=5 to 10
Sketch of foundation
Functions of foundation
1) To support the str 2) To distribute the load over a wide spread
area to prevent buildg frm any movement 3) To prevent unequal settlement 4) To increse the stability of str. 5) To transfer the load to thw sub soil
Settlement of foundation
Vertical downward movement of structure. Settlement is mainly due to change in volume. Amount of settlement is different for diff. soil &
stata Eg. Clay soil settlement is more, Hard rock less
settlement is there.
Settlement of foundation
Vertical downward movement of structure. Settlement is mainly due to distortion of soil or
change in volume. Amount of settlement is different for diff. soil &
stata Eg. Clay soil settlement is more, Hard rock less
settlement is there.
Types of settlements
1)Uniform settlement _ It will not cause any damage to str,but excessive settlement will damage undergroung utility services like water supply,drainage lines,telephone & electric cables
2) Differential settlement – The diff in magnitudes of settlement at any two points is known as D.S,
Uniform settlement
Differential settlement
Causes of settlement
Loose soil strata below foundation
Excessive expansion & contraction of swelling soil (Black cotton soil)
Excavation & pile driving in neighboring construction
Lowering of water table
due to earthquake
Causes of Failure of foundn
1) Unequal settlement of sub soil2) Withdrawal of Moisture from sub soil3) Horizontal movement of soil mass4) Atmospheric action5)Transpiration of trees & shrubs
Types of foundation Shallow & deep foundation
TYPES OF SHALLOW FOUNDATIONS
1.Spread Footing
2.Wall Footing/Strip footing
3.Isolated Column Footing/Pad footing
4.Combined Footing
5.Cantilever or strap Footing
6.Mat or Raft Foundation
7.Grillage foundation
Deep foundation
1.Spread Footing
Are used to distribute concentrated load from the superstr over a wide area so as to enable
the soil bed to provide safe support
2.Wall Footing/Strip footing
Used for light strs such as garden walls or compound walls
1) Simple footing 2) Stepped footing
3.Isolated Footing/Pad footing
These are used to support individual column. It is most commom used in modern
R.C.C.buildings It may be square,rectangular,circular or
sloped depending upon distribution of load
Isolated Footing
Isolated Footing
4.Strap footing/Cantilever
Sometimes it is not possible to provide footing exactly below the column due to its projection beyond the column in that case seprate footing is provided for interior & exterior column
Strap footing
5.Combined Footing
When loads on adjacent columns are very high or bearing capacity of the soil is less then two columns are grouped together to form combined footing.
When load is same then use rect combined footing
Combined Footing
Combined Footing
6.Raft or mat Foundation
Mat or raft is a heavily reinforced inverse slab placed over the entire area using heavily beams from column to column
Is used when bearing capacity is so less Is used when heavy load on the
foundation
Raft or mat Foundation
7.Grillage foundation
Is suitable when load from the steel columns is very heavy & bearing capacity is so less
Grillage foundation
DEEP FOUNDATION
Pile foundation
A pile is defined as a slender column capable of transferring the structural load to the deep underlying layers.
1) End Bearing pile -When piles transfer the load of bldg to a grater depth
2) Friction pile - When piles transfer the load by means of skin frictionwithout any end
Pile foundation
[B] SUPERSTRUCTURE
It is the part which is above ground level
Superstructure
1) Structural component above plinth upto top
2) Transfers load from upper part to sub str
3) e.g.roof,beam floor
Substructure
1) Structural component below plinth uoto footing
2) Transfers load received from superstr to foundn
3) e.g.footing,basement & foundn
TYPES OF CONSTRUCTION
1-Load bearing structures
2-Framed structures
3-Composite structure
1-Load bearing structures
In this the load of the str is transferred through the walls
Economical upto 2-4 storeys Is used when hard strata is available at shallow
depths E.g,Shaniwarwadwa in pune COEP-these are stone walls If no.of storeys increases wall thk also increases &
reduces carpet area
Load bearing structure
2.Framed structure
Load transferred through a frame of slab,beam,column & footing to the underlying soil.
Constructed more than 100 storeys Used when hard strata is not available at
shallow depth. Speed of constn is fast
Framed structure
3.Composite structure
The outer walls of load bearing type where as column & beams provided internally
Is used for industrial sheds or warehouse where span is so large
Composite structure
TYPES OF LOAD
1.Dead load
2.Live load
3.Wind load
4.Earthquake load
TYPES OF LOAD
1.Dead load-load of material in the constn of bldg, self wt of diff comp.Dead load is calculated by multiplying its volm by unit wt.of material
material Unit wt(KN/m3)
P.C.C. 24
R.C.C 25
Bricks 22
Steel 78
Stone masonry
22
Brick Masonry
18
2.Live load
It is movable load acting on the str.i.e.furniture,equipment & machinery
Minimum L.L. is considered in design og bldg dpending upon the type of bldg
Sr No Type of bldg Minm L.L. in KN/m3
1 Residential 2.00
2 Office 2.45
3 Bank & reading room 3.00
4 Class room ,Assembly hall 4.00
5 Dining hall,Store room 5.00
6 factories ,Workshop 7.00
3.Wind load
Is considered in tall bldgs P=kv2
P=Wind pressure in KN/m2
K=Coeff of wind velo.
4.Earthquake load
4.Earthquakeforce = w.α/g
Α = accln due to earthquake =1/20g to 1/20g W = wt.of str G= gravitatational acccln
Comparison betn Load bearing & framed strSr No Load bearing framed str
1 Hard strata at shallow depth
Suitable for any strata
2 Allowed Upto 4 storeys
Multistoreyed
3 Slow & time consuming constn
Fast & speedy
4 Economical upto 2 storeys
Economical upto multisoreyedstoreys
5 It can not resist E.Q. foeces
Resist E.Q.forces
Masonry
Types 1) Brick 2) Stone
Sr No
Brick Stone
1 Used brick & mortar for constn
Used stone & mortar for constn
2 Lesser wall thk.(min 100mm)
Higher wall thk.(300mm)
3 Less durable More durable
4 Less costly & easy to construct
Costly & skilled Labor is required
Fundamental requirements of masonry
1) It should be strong enough to carry the load
2) It satisfies the I.S.for durability & strength 3) Proper bonds to be maintained while
laying masonry 4) It should be in level 5) Thk should be such that it will offer
resistance to water current