TEST OF HARDENED TEST OF HARDENED CONCRETECONCRETE

Types of TestTypes of TestDestructive test – Destructive test – compressive compressive strength, flexural strength, flexural strength, cylinder strength, cylinder splitting strengthsplitting strength

Non-destructive test Non-destructive test – – Ultrasonic Pulse Ultrasonic Pulse Velocity, Rebound Velocity, Rebound Hammer, Hammer, CovermeterCovermeter

Compressive strength testCompressive strength test

To determine the compressive strength To determine the compressive strength of concreteof concrete

Samples – 100 or 150 mm cube or Samples – 100 or 150 mm cube or cylindercylinder

150 mm cube – 3 layers – 35 strokes150 mm cube – 3 layers – 35 strokes

100 mm cube – 2 layers – 25 strokes100 mm cube – 2 layers – 25 strokes

Hand compaction or external vibrator Hand compaction or external vibrator (poker)(poker)

Cont.Cont.

Hand compaction – steel bat 25 mm Hand compaction – steel bat 25 mm square face, 380 mm long, 1.8 kgsquare face, 380 mm long, 1.8 kg

After compaction, the surface of After compaction, the surface of sample is trowel as smooth as possiblesample is trowel as smooth as possible

Curing – cover the samples using wet Curing – cover the samples using wet gunny for 24 hoursgunny for 24 hours

Demould after 24 hours and placed in Demould after 24 hours and placed in water tank for further curingwater tank for further curing

CompactionCompaction

CuringCuring

Compressive Strength TestCompressive Strength Test

Mode of FailureMode of Failure

Cont.Cont.

Test the samples at the required age – Test the samples at the required age – 3, 7, 28 days3, 7, 28 days

Three samples per test ageThree samples per test age

Load the sample until failureLoad the sample until failure

Compressive strength = Compressive strength = (Ult. Load)(Ult. Load)

AreaArea

Flexural testFlexural test

Determine the modulus of rupture of concreteDetermine the modulus of rupture of concrete

Sample – Sample – 150x150x750 mm or 100x100x500 150x150x750 mm or 100x100x500 mmmm

150x150x750 mm – 3 layers – 170 strokes150x150x750 mm – 3 layers – 170 strokes

100x100x500 mm – 2 layers – 100 strokes100x100x500 mm – 2 layers – 100 strokes

Compaction – by hand or vibratorCompaction – by hand or vibrator

Curing will be the same as concrete Curing will be the same as concrete cube/cylindercube/cylinder

Cont.Cont.

Test under four-point loadTest under four-point load

Record the ultimate loadRecord the ultimate load

Modulus of Rupture = Modulus of Rupture = PlPl

bdbd22

Cylinder splitting testCylinder splitting test

Determine the tensile strength of Determine the tensile strength of concreteconcrete

Sample – 100x200 mm or 150x300 mmSample – 100x200 mm or 150x300 mm

Compaction – vibrator or by handCompaction – vibrator or by hand

Curing – the same as cube/prismCuring – the same as cube/prism

Test until failureTest until failure

Tensile Splitting Strength = Tensile Splitting Strength = 2P2P

ππLdLd

Not Properly CompactedNot Properly Compacted

NON-DESTRUCTIVE TESTNON-DESTRUCTIVE TEST

Ultrasonic Pulse VelocityUltrasonic Pulse Velocity

Measure the velocity of pulse through Measure the velocity of pulse through solid materialsolid material

Transmitter generate pulse, receiver Transmitter generate pulse, receiver receive the pulsereceive the pulse

Time (microsecond) taken by the pulse Time (microsecond) taken by the pulse to travel from point a to B is recordedto travel from point a to B is recorded

Velocity = Velocity = DistanceDistance

TimeTime

Methods of propagating and Methods of propagating and receiving ultrasonic pulsereceiving ultrasonic pulse

Direct transmissionDirect transmission

Semi-direct transmissionSemi-direct transmission

Indirect or surface transmissionIndirect or surface transmission

Concrete QualityConcrete Quality

Rebound HammerRebound Hammer

Also known as Schmidt hammer testAlso known as Schmidt hammer test

Based on the principle that the rebound Based on the principle that the rebound of an elastic mass depends on the of an elastic mass depends on the hardness of the surface against which hardness of the surface against which the mass impingesthe mass impinges

The test is sensitive to the presence of The test is sensitive to the presence of aggregate and voids immediately aggregate and voids immediately underneath the plungerunderneath the plunger

Cont.Cont.

Take 10 to 12 readings over the area to Take 10 to 12 readings over the area to be testedbe tested

No unique relation between hardness No unique relation between hardness and strength of concreteand strength of concrete

BUT experimental relationships can be BUT experimental relationships can be determined for a given concretedetermined for a given concrete

Higher value indicate better quality of Higher value indicate better quality of concreteconcrete

Covermeter testCovermeter test

Can be used to determine the depth of Can be used to determine the depth of concrete cover and locating the concrete cover and locating the direction and size of reinforcementdirection and size of reinforcementConsist of searcher unit connected to Consist of searcher unit connected to the main unit containing the cells, the main unit containing the cells, circuits and indicator scalecircuits and indicator scaleHas the working range of up to 100 mm Has the working range of up to 100 mm depthdepthAccuracy of ± 15%Accuracy of ± 15%

Thank YouThank You