CREATED BY :RAHUL RAJ TANDON5TH SEMESTER CIVIL BRANCH

GUIDED BY :Er V.C.BHAGHELPWD BILASPUR

MINOR TRAINING

CEMENT CONCRETE Concrete is product obtained

artificially by hardening of mixture of cement , sand, gravel and water in predetermined proportion.

CLASSIFICATION AND COMPOSITION OF CEMENT

[1.] Portland cement [2.] High Alumina cement [3.] Super sulphate cement [4.] natural cement [5.] Special cement

SUBDIVISION OF PORTLAND CEMENT

PORTLAND CEMENT 1 ordinary portland cement 2 rapid hardening cement 3 extra rapid hardening cement 4 low heat portland cement 5 portland blast furnace slag cement 6 portland pozzolana cement 7 sulphate resisting portland cement 8 white portland cement 9 coloured portland cement

Special cement 1 masonary cement 2 trief cement 3 expansive cement 4 oil well cement

Chemical constituents of portland Name formula percentage

Lime CaO 60 - 67

Silica SiO2 17 - 25

Alumina Al2O3 3 - 8

Iron Oxide Fe2O3 0.5 – 6

Magnesia MgO 0.1 – 4

Sulphar Trioxide SO3 1 - 2

Soda And Potash Na2O+K2O 0.5 -1.3

BOUGE COMPOUNDNAME FORMULA ABBREVIATION

Tricalcium Silicate 3CaO.SiO2 C3S

Dicalcium Silicate 2CaO.SiO2 C2S

Tricalcium aluminates 3CaO.Al2O3 3CaO.Al2O3

Tetra Calcium Aalumino ferrate

4CaO.Al2O3.Fe2O3 C4AF

COMPOSITION AND COMPOUND CONTENTs :

NAME NORMAL RAPID LOW HEATCOMPOSITION %LIME 6301 64.5 60SILICA 20.6 20.7 22.5ALUMINA 6.3 5.2 5.2IRON OXIDE 3.6 2.9 4.6

COMPOUND:PRESENT

C3S 40 50 25C2S 30 21 45C3A 11 9 6C4AF 12 9 14

Properties of concrete 1.Strength 2.durability 3.workability 4.economy

Properties : DURABILITY OF CONCRETE : durability is

property of concrete by virtue of which it is capable of resisting it’s disintegration and decay.

AFFECTING FACTORS: 1. Use of unsound cement 2.Use of less durable aggregate 3.Entry of harmful gasses 4.freezing and thawing of water sucked

through cracks 5. expansion and contraction

properties WORKABILITY OF CONCRETE: workability of

concrete is that property of concrete which determine the amount of internal work necessary to produce full compaction.

Factors affects workability : 1.water in the mix 2.maximum size of particle 3.ratio of coarse and fine aggregate 4.particles interference 5.particle interlocking 6.admixtures

CONCRETE MIX PROPORTIONING Mix Proportion : The mix proportions shall be

selected to ensure the workability of the fresh concrete and when concrete is harden, it shall have the required strength , durability and surface finish.

The determination of proportion of cement, aggregate and water to attend the required strength shall be made as follows :

CONCRETE MIX

[a] By designing the concrete mix; such concrete shall be called ‘Design Mix Concrete’

[b] By adopting nominal concrete mix ; such concrete shall be called ’ Nominal Mix Design’

INFORMATION REQUIRED for concrete mix

1.Type of mix: design or nominal mix 2.grade designation 3.type of cement 4.maximal nominal size of aggregate 5.minimum cement content 6.maximum water cement ratio 7.workability 8.mix proportion 9.exposure condition 10 maximum temperature 11.method of placing 12..degree of supervision 13.type of aggregate 14. maximum cement content 15. use of admixtures or not

Tests of cements

1. Workability test2.Test for compressive strength3.Test for flexural strength4.Test for module of elasticity5.Test for analysis of fresh concrete6.Test for cement content of hardened

portland cement concrete.

Tests on hardened concrete :

1. Compressive strength (cylinder , cube ,core)

2. Tensile strength ; direct tension 3. modulus of rupture 4. INDIRECT SPLITTING TEST 5. density 6. shrinkage 7. creep 8. modulus of elasticity 9. absorption

Tests : 10. PERMEABILITY TEST ON CONCRETE 11. Freeze / thaw resistance 12. Resistance to aggregates 13. Bond to reinforcement 14. Analysis for cement content and

proportion 15. IN SITU TEST : schmidt hammer ,

concrete pull out, break off , cones etc 16. Ultrasonic or nuclear

Tests on fresh concrete : 1. workability test (slump test) 2. bleeding test 3. air content 4. setting time 5. segregation resistance 6. unit weight 7. wet analysis 8.temperature 9.heat generation

test for cements concrete 1. Slump test 2. Compacting factor test 3.Vee-Bee test 4.Vibro workability test

concrete tests details 1. SLUMP TEST : this test is simple and

commonly used tests. In this test concrete is compacted in a vessel of the shape of the frustum of the cone and open at both the ends.

concrete is compacted with the help of standard tamping rod , in four equal layers. Immediately after the vessel is filled, it is raised vertically , without giving any jerks etc.

the concrete in the vessel becomes free and therefore slump. The vertical settlement measured in mm , is termed as slump.

Workability of concrete in terms of slump

TYPE OF WORK SLUMP ( MM)

1. Concrete for road 20 -30

2.Ordinary R. C . C . Work for beams and slab 50 -100

3.Colums ,retaining walls and thin vertical section 75 -150

4. Vibrated concrete 12 -25

5. Mass concrete 25 -50

tests THE COMPACTION FACTORS : This tests measures

the workability of concrete in terms of internal energy required to compact the concrete fully.

In this test the concrete is compacted in cylindrical mould by making it fall through two vertically placed hoppers. The weight of concrete in mould is determined . The theoretical weight of material required to fill the mould without air voids is also calculated from the knowledge of the proportion of the mix.

observed weight of concrete Compaction factor = theoretical weight

Grades of concreteGROUP GRADE

DESIGNATIONCOMPRESSIVE STRENGTH OF 150MM CUBE AT 28 DAYS

ORDINARY CONCRTE M10 10M15 15M20 20

STANDARD CONCRETE

M25 25

M30 30M35 35M40 40M45 45M50 50M55 55

HIGH STRENGTH CONCRETE

M60 60

M65 65M70 70M75 75M80 80

CHARACTERISTIC STRENGTHS : TENSILE STRENGTH OF

CONCRETE : Estimate of tensile strength from compressive strength.

Flexural strength = 0.7√fck n/mm2

Where fck is characteristic cube compressive strength of concrete in N/mm2

Strengths : ELASTIC DEFORMATION : The

modulus of elasticity is primarily influence by the elastic properties of aggregate and to lesser extent by method of curing and age of concrete, the mix proportion and type of cement.

Modulus of elasticity ( Ec ) = 5000√fck

Properties : SHRINKAGE : it is depend upon the

constituents of concrete , size of member and environment condition i.e. humidity , temperature.

shrinkage of concrete is most influenced by total amount of water present in the concrete at the time of mixing.

Total shrinkage strain is taken as 0.0003

Properties : CREEP OF CONCRETE :creep is

defined as the plastic deformation under sustain load. Creep strain depends primary on the duration of sustained loading , according to the code, the value of the ultimate creep coefficient is taken as 1.6 at 28 days of loading.

Modular ratio

Short term modular ratio is the ratio of modulus of elasticity of steel to the modulus of elasticity of concrete.

Short term modular ratio = Es/ Ec Where Es =2*10 5N/mm2 Ec = 5000*SQRT(fck)N/mm2 Long term modular ratio = 280/(3fcbc) Where Fcbc is permissible compressive

stress due to bending in concrete in N/mm2

Poisson’s ratio Poisson’s ratio varies between

0.1 for high strength concrete and 0.2 for weak mixes . It is normally taken as 0.15 for strength design and 0.2 for serviceability criteria.

Unit load Unit load of concrete depends on

percentage of reinforcement, type of aggregate , amount of voids and varies from 23 – 26 kN/m2. the unit weight of plain and reinforced concrete as specified by IS: 456 are 24 and 25kN/m3 respectively.

AGGREGATESAggregate is general term applied to

those inert or chemically inactive materials which when bonded together by cement form concrete.

classification

1.Coarse aggregate 2. fine aggregate

COARSE AGGREGATE : The aggregates which are more than 4.75mm in size are known as coarse aggregate.

FINE AGGREGATE : The aggregate which is less than 4.75mm in size are known as fine aggregate.

Quality of aggregates 1.strength 2.size 3.particle shape 4.surface texture 5.grading 6.impermeability 7.cleaniness 8.chemical inertness 9.physical and chemical stability 10.coefficient of thermal expansion 11. cost

Various tests of aggregates

Aggregate play an important role in pavement construction. Aggregate influence to a great extent , the load transfer capacity of pavements. Hence it is essential that they should be thoroughly tested before construction.

[1.]crushing test [2.] abrasion test [3.] impact test [4.] soundness test [5.] shape test [6.] specific gravity test [7.] water absorption test [8.] bitumen adhesion test

Tests of aggregates with is codesPROPERTY OF AGGREGATE

TYPE OF TEST TEST METHOD (IS)

CRUSHING STRENGTH

CRUSHING TEST IS2386(PART 4)

HARDNESS LOS ANGLES ABRASION TEST

IS2386(PART 5)

TOUGHNESS AGGREGATE IMPACT TEST

IS2386(PART 4)

DURABILITY SOUNDNESS TEST IS2386(PART 5)

SHAPE FACTOR SHAPE TEST IS2386(PART 4)

SPECIFIC GRAVITY AND POROSITY

SPECIFIC GRAVITY AND WATER ABSORPTIION TEST

IS2386(PART 3)

ADHESION TO BITUMEN

STRIPPING VALUE OF AGGREGATE

IS6241-1971

Crushing test One of the model in which pavement

material can fail is by crushing under compressive stresses . A test is standardized by IS-2386- 4 and used to determine the crushing strength of aggregates. The aggregate crushing value provides a relative measure of resisting to crushing under gradually applied crushing load

The test consist of subjecting the specimen of aggregate in standard mould.

Abrasion test Abrasion test is carried out to test the hardness property of aggregate

and to decide whether they are suitable for different pavement construction works .Los angles abrasion test is preferred one for carrying out the hardness property and has been standardized in India

The principle of Los Angle test is to find the percentage wear due to relative rubbing action between the aggregate and steel balls used as abrasive charge.

Los angels machine consist of circular drum of internal diameter 700mm and length 520mm mounted on horizontal axis enabling it to be rotated.

an abrasive charge consisting of cast iron spherical balls of 48mm diameters and weight 340 -445g is placed in the cylinder along with the aggregates. The number of abrasive sphere varies according to the grading of sample.

The quantity of aggregate is 5-10kg. The cylinder is locked and rotated with the speed of 30 -33 rpm for a total of 500 –1000 revolution depend upon gradation of aggregate.

Test VALUES : The maximum value of 40 percent is

allowed for WBM base coarse in Indian conditions

For bituminous concrete a maximum value of 35 percent is specified.

Impact testThe aggregate impact test is carried out to evaluate the

resistance to impact of aggregates. Aggregates passing 12.5mm sieve and retained on 10mm sieve is filled in a cylindrical steel cup of internal diameter 10.2mm and depth 5cm which is attached to a metal base of impact testing machine. The material is filled in three layers where each layer is tamped for 25 number of blows. Metal hammer of weight 13.5 – 14kg is arranged to drop with a free fall of 38cm by vertical guides and the test specimen is subjected to 15 number of blows. The crushed aggregate is allowed to pass through 2.36mm is sieve ,and the impact value is measured as percentage of aggregate passing through (w2) to the total weight of the sample (w1).

tests Aggregate impact value = w1/w2*100 Aggregate to be used for wearing coarse ,

the impact value shouldn’t exceed 30 percent.

For bituminous macadam the maximum permissible value is 35 percent.

For water bound macadam base coarse the maximum permissible value defined is 40 percent.

Soundness test Soundness test is intended to study the resistance of

aggregates to weathering action , by conducting accelerated weathering test cycles. The porous aggregate is subjected to freezing and thawing is likely to disintegrate prematurely. To ascertain the durability of such aggregates.

Aggregate of specified sizes are subjected to cycles of alternate wetting in a saturated solution of either sodium sulphate or magnesium sulphate for 16 – 18 hours and then dried in oven at 105 to 110 degree centigrade to a constant weight , after five cycles the loss in weight of aggregate is determine by sieving out all undersized particles and weighing.

Tests VALUES : The loss in weight should not exceeds

12 percent when tested with sodium sulphate and

18 percent with magnesium sulphate solution.

Shape test The particle shape of an aggregate is

determined by the percentage of flaky and elongated particles in it. aggregates which are flaky or elongated are detrimental to higher workability and stability of mixes.

The flakiness index is defined as the percentage by weight of an aggregate particles whose dimension is less than 0.6times their mean size. Flakiness gauge is used for this test.

Elongation index The elongation index of an aggregate

is defined as the percentage by weight of particle whose greatest dimension (length)is 1.8 times their mean dimension.

This test is applicable to aggregates larger than 6.3mm.elongation gauge is used for this test.

Specific gravity Specific gravity is the property of an

aggregate required for the design of concrete mix.

The specific gravity of a solid is the ratio of its mass to that of an equal volume of distilled water at a specified temperature. Because the aggregate may contain water permeable voids so two measures of specific gravity of aggregates are used.

1. Apparent specific gravity 2.bulk specific gravity

test Apparent specific gravity :- it is

computed on the basis of the net volume of aggregates ,the volume excluding water permeable voids . thus

Gapp = (Md/Vn )/W Where Md is dry ass of aggregate , Vn is net volume of aggregates W is density of water

Tests : Bulk specific gravity : it is computed

on the basis of the total volume of aggregates including water permeable voids .thus

G = ( Md / Vb)/W

Vb is the total volume of aggregates including the volume of absorbed water.

Water absorption The difference between the apparent and bulk specific

gravities is nothing but the water permeable voids of the aggregates . we can measures the volume of such voids by weighing the aggregates dry and in a saturated surface dry condition , with all permeable voids filled with water . the difference of above two is Mw

Mw is weight of dry aggregate minus weight of aggregates saturated surface dry condition.

Water absorption =(Mw/ Md)*100 The specific gravity of aggregates normally used in road

construction ranges from about 2.5 - 2.9 Water absorption values ranges from 0.1 – 2.0 percent

for aggregate normally used in road surface.

Bitumen adhesion test Bitumen adheres well to all normal types of road

aggregates provided they are dry and free from dust. In the absence of water there is practically no adhesion problem of bituminous construction.

Adhesion problems occurs when the aggregate is wet and cold . this problem can be dealt with by removing moisture from the aggregate by drying and increasing the mixing temperature. Further the presence of water causes the stripping of binders from the coated aggregates. This problem occur when bitumen is permeable to water.

test Static immersion test is one specified

test by irc and is quite simple . The principle of the test is by immersing aggregate fully coated with binder in water maintained at 40 degree centigrade for 24 hours.

CURING OF CONCRETE :The curing of concrete is done to keep the

moisture content intact for structures so that hydration process can continue and concrete gains strength without the any surface defects on members.

Different types of concrete construction required different types of curing methods. The curing method of RCC slab cannot applied to RCC column.

Curing of pavements and slabs : Airfield concrete pavements,

highway , canal lining , walkway , driveways , parking lots , ground floor slabs are largely exposed surface due to this evaporation rate is very high so this surface is covered with mats , wind breakers , sunshield and fog sprayers can be used after casting the concrete.

References : 1. ‘RCC DESIGN’ by B.C.Punmia. 2. ‘CONCRETE TECHNOLOGY ‘ by

A.M.Neville