Rebound Hammer Test

CAHAYA METRO SDN BHD Standard Operation Procedure

METHOD OF STATEMENT FOR REBO#ND HAMMER TEST

Prepared by: Nur Farah Atia! "  Chec by: $a%&an A Tan'ah Pa'e Re+i,ion ( o) * -

Method for determination of the compressive strength of concrete 1.0

SCOPE

This test method method covers covers the determin determinatio ation n of reboun rebound d number number of hardene hardened d concrete using a spring-driven steel hammer (Concrete Test Hammer Type N). It is not intended as the basis for acceptance or rejection of concrete because of  the inherent uncertainly in the estimated strength.

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REFERENCED DO DOCMEN!S

 !T" C#$%& !tandard !tandard Test est for 'ebound Numbers of Hardened Hardened Concrete& provides some standard procedures procedures so that the user can have consistency hen using the rebound hammer.

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S#$N#F#C%N C%NCE %ND S SE

This test method is not intended as the basis for acceptance or rejection of  concrete because of the inherent uncertainty in the estimated strength. This test method is intended as non-destructive test.

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%PP%R %!S

 pparatus  pparatus included included rebound hammer that consisting consisting of a spring-loaded spring-loaded steel hammer that hen released stries a steel plunger in contact ith the concrete surf surfac ace. e. The The spri spring ng-l -loa oade ded d hamm hammer er must must trav travel el ith ith a cons consis iste tent nt and and reproducible velocity. The rebound distance of the steel hammer rom the steel plunger is measured on a linear scale attached to the frame of the instrument. *se type N rebound hammer that are commercially available to accommodate testing of various si+es and types of concrete construction. brasive stone that consisted of medium grain te,ture silicon carbide or euivalent material.

'ebound hammer shall be serviced and verified annually and henever there is reason to uestion their proper operation. erify the functional of a rebound hammer using the test anvil. CAHAYA METRO SDN BHD Standard Operation Procedure

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METHOD OF STATEMENT FOR REBO#ND HAMMER TEST

Prepared by: Nur Farah Atia! "  Chec by: $a%&an A Tan'ah Pa'e Re+i,ion . o) * -

!ES! %RE% %ND #N!ERFERENCES

i. !election of test surface should be determined such as concrete members to be tested shall be at least /$$mm thic and fi,ed ithin a structure. !maller  specimens must be rigidly supported. void areas e,hibiting honeycombing& scaling& or high porosity. 0o not compare test results if the form material against hich the concrete as placed is not similar. Troeled surfaces generally e,hibit rebound numbers than screeded or formed finished. If possible& test structural slabs from the underside to avoid finished surfaces. ii. 1reparation of test surface area shall be at least /%$mm in diameter. Heavily te,tured& soft& or surfaces ith loose mortar shall be ground flat ith the grind and finished ith abrasive stone. !mooth-formed or troeled surfaces do not have to be ground prior to testing. 0o not compare results from ground and unground surfaces. iii. 0o not test fro+en concrete. "oist concrete at $2C or less may e,hibit high rebound value. Concrete should be tested only after it has thaed. iv. 3or reading to be compared& the direction of impact& hori+ontal& donard& upard& or at another angle& must be the same or established correction factors to be applied to the readings.

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PROCEDRE •

Hold the instrument firmly so that the plunger is perpendicular to the test surface. 4radually push the instrument toard the test surface until the hammer impacts. fter impact& maintain pressure on the instrument and& if 

necessary& depress the button on the side of the instrument to loc the plunger in its retracted position.

CAHAYA METRO SDN BHD Standard Operation Procedure

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'ead the rebound number on the scale to the nearest hole number and record the rebound number. Tae ten to telve reading from each test area. No to impact tests shall be closer together than 5%mm. 6,amine the impression made on the surface after impact& and if the impact crushes or breas through a near-surface air void& disregard the reading and tae another reading.

C%*C*%!#ON •

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METHOD OF STATEMENT FOR REBO#ND HAMMER TEST

Prepared by: Nur Farah Atia! "  Chec by: $a%&an A Tan'ah Pa'e Re+i,ion / o) * -

0iscard readings differing from the average of ten to telve readings by more than si, units and determine the average of the remaining readings. If more than to readings differ from the average by si, units& discard the entire set of  readings and determine rebound numbers at ten ne locations ithin the test. 6,pression of results.

%!!%C,MEN! • • •

!ample 'esult 3orm Compressive strength against the rebound number graph !ample photo