Post on 16-Nov-2014
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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