Submitted byJafar Pharas

Introduction to non destructive techniques Penetration resistance test

BackgroundApparatusProcedureAdvantages and limitationsApplications of W.P.

Quantab testObtaining sampleQuantab stripTest procedure

References

Use of NDT for concrete Types of NDT methods • 1st type Surface hardness ,pull out and maturity method to estimate compressive strength of concrete• 2nd type Methods that measures other properties like

m.c. ,densityAchieved important place in quality

control of hardened concrete and evaluation of existing structures

Background Also called windsor prob

Based upon depth of penetration probe

Introduced in US for penetration of concrete in laboratory and field

RESISTANCE TESTING USING PROBES Driver unit

Probe

Measurement equipment

Positioning device

RESTISTANCE TESTING USING PINS Driver unit

Pin

Measuring equipment

RESISTANCE TESING WITH PROBES1. For coarse finishes surface must be ground

smooth in area to be tested2. Place the positioning device on the surface of

concrete at location to be tested3. Mount a probe in the driver unit , position the

driver in positioning device4. Fire a probe into concrete5. Remove positioning device and tap the probe

on exposed end with small hammer6. Measurement of the exposed probe length

RESISTANCE TESTING WITH PINS1.Concrete surface o be tested shall be ground

flat with abrasive stone2. Insert a new pin into spring actuated driver unit3.Load the driver unit by compressing the spring

until the trigger mechanism engages4.Place the driver unit firmly against the

perpendicular to surface of concrete5.Pull the trigger to drive the pin into concrete

surface , remove unit including pin6.Clean the pin hole and measure the depth

RESISTANCE TESTIG WITH PROBES Operation of driver unit Safety goggles ,hearing protection Case of reinforcing bars

RESISTANCE TESTING WITH PINS Injury from inadvertent firing of pin Safety goggles and other protective

equipments

Initial amount of probe energy is absorbed

Concrete fractured in cone shaped zone

Further penetration below this zone is resisted by compression of adjacent material and hardness of the aggregete

Prepare 150mm×300mm cylinders and 600mm×600mm×200mm concrete slab

Test 3 specimen in compression at specified age using standard procedure and take penetration test on slab

Repeat the above procedure for all test specimens

Plot the exposed probe length against compressive strength

The 95% confidence limits may also drawn

Driver unit identification number and energy level used in testing

Dimensions of probes Approximate thickness of member tested Exposed length of a probe Description of unusual conditions Identification and location tested in

concrete construction Description of surface finish Date and time of testing

Relatively quick test

Simple to operate and little mentainance

Access is only needed to one surface

Correlation with concrete strength

Represent the concrete at depth 25mm to 75mm

Minimum acceptance distance between 2 test location is limited to 150mm to 200mm

Minimum thickness of the member to be tested should be 3 times expected probe penetration

Leaves 8mm hole in concrete and older concrete heavily fractured

Damaged area should be repaired

Formwork removal◦ Estimate early strength◦ Simplicity◦ Time of formwork removal estimated

As a substitute for core testing◦ In case of older structure W.P. test superior than

taking core◦ In coring area needs to be soaked 40 h before◦ Transportation of core sample

INTRODUCTION Quantab test (Chloride determination) Corrosion Upto 0.01% chloride bye mass of concrete

present More chloride if CaCl2(as admixture) or sea

dredged aggregate Many methods like volard laboratory

method,X-ray fluorescence spectrometry, atomic titrators

Taken with 20mm masonry drill bit

Suitable means of collecting sample without loss of fines

Minimum mass of sample should be 25g

First 5mm drilled material rejected

Made of plastic material

75 mm long and 15mm wide

Vertical capillary column impregnated with silver dichromate

At top horizontal air vent containing yellow moisture sensitive indicator

Solution containing 5g powdered concrete obtained by described method

Lower end of test strip is placed in chloride solution until capillary is full

Reddish brown silver dichromate reacts with chloride to form white silver chloride

Tip of color change related to vertical scale Reading converted to mg chloride ion/litre

by reference to calibration table

Use of low range test strips for normal purpose

High range test strips may over estimate chloride concentration

Can be used by staff without specialist Sufficient accuracy Total time required approximately 30

minutes

ASTM C803 Guide to non destructive testing of

concrete(U.S. Department of transportation) Guide book on nondestructive testing of

concrete structures(International atomic energy agency , Vienna)

Testing of concrete in structures (by John H. Bungey,Stefen G. Millard and Michael G.Grantham)