ASTM_D_7234_-_12.pdf

Designation:D723412Standard Test Method forPull-Off Adhesion Strength of Coatings on Concrete UsingPortable Pull-Off Adhesion Testers1This standard is issued under the fixed designation D7234;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers procedures for evaluating thepull-off adhesion strength of a coating on concrete.The testdetermines the greatest perpendicular force(in tension)that asurface area can bear before a plug of material is detached.Failure will occur along the weakest plane within the systemcomprised of the test fixture,adhesive,coating system,andsubstrate,and will be exposed by the fracture surface.1.2 This test method uses a class of apparatus known asportable pull-off adhesion testers.2They are capable of apply-ing a concentric load and counter load to a single surface sothat coatings can be tested even though only one side isaccessible.Measurements are limited by the strength of adhe-sion bonds between the loading fixture,coating system and thesubstrate or the cohesive strengths of the adhesive,coatinglayers,and substrate.1.3 Pull-off adhesion strength measurements depend uponboth material and instrumental parameters.There are differentinstruments used that comply with this test method.Thespecific instrument used should be identified when reportingresults.This test is destructive and spot repairs may benecessary.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:3C1583 Test Method for Tensile Strength of Concrete Sur-faces and the Bond Strength or Tensile Strength ofConcrete Repair and Overlay Materials by Direct Tension(Pull-off Method)D16 Terminology for Paint,Related Coatings,Materials,andApplicationsD2651 Guide for Preparation of Metal Surfaces forAdhesiveBondingD3933 Guide for Preparation of Aluminum Surfaces forStructural Adhesives Bonding(Phosphoric Acid Anodiz-ing)D4541 Test Method for Pull-Off Strength of Coatings UsingPortable Adhesion TestersE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE178 Practice for Dealing With Outlying ObservationsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 The terms and definitions in Terminology D16 apply tothis test method.3.2 Definitions:3.2.1 adhesive,n(with respect to this test method)adhe-sive refers to the material that bonds the bottom of the loadingfixture to the top surface of the coating to be tested.3.2.2 loading fixture,n(also referred to as dollies or studs)a metal structure that is flat on one end for bonding to thecoating surface and shaped on the other end for attachment tothe adhesion tester and is used to determine the pull-offadhesion strength of coatings.3.2.3 portable pull-off adhesion testers,ninstruments thatare capable of applying a concentric load and counter load to1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.46 on Industrial Protective Coatings.Current edition approved July 1,2012.Published October 2012.Originallyapproved in 2005.Last previous edition approved in 2005 as D7234 05.DOI:10.1520/D7234-12.2The term adhesion tester may be somewhat of a misnomer,but its adoption bytwo manufacturers and at least two patents indicates continued usage.3For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 a single surface so that coatings can be tested even though onlyone side is accessible.4.Summary of Test Method4.1 The general pull-off adhesion test is performed byscoring through the coating down to the surface of the concretesubstrate at a diameter equal to the diameter of the loadingfixture(dolly,stud),and securing the loading fixture normal(perpendicular)to the surface of the coating with an adhesive.After the adhesive is cured,a testing apparatus is attached tothe loading fixture and aligned to apply tension normal to thetest surface.The force applied to the loading fixture is thenuniformly increased and monitored until a plug of material isdetached.When a plug o