NACE TM0105-2012 Evaluation of Organic-Based Conductive Coatings for Use as an Anode on Atmospherically Exposed Reinforced Concrete (Item No 21247).pdf

1、 Standard Test Method Evaluation of Organic-Based Conductive Coatings for Use as an Anode on Atmospherically Exposed Reinforced Concrete This NACE International (NACE) standard represents a consensus of those individual members who have reviewed this document, its scope, and provisions. Its acceptan

2、ce does not in any respect preclude anyone, whether he or she has adopted the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not in conformance with this standard. Nothing contained in this NACE standard is to be construed as granting any righ

3、t, by implication or otherwise, to manufacture, sell, or use in connection with any method, apparatus, or product covered by letters patent, or as indemnifying or protecting anyone against liability for infringement of letters patent. This standard represents minimum requirements and should in no wa

4、y be interpreted as a restriction on the use of better procedures or materials. Neither is this standard intended to apply in all cases relating to the subject. Unpredictable circumstances may negate the usefulness of this standard in specific instances. NACE assumes no responsibility for the interp

5、retation or use of this standard by other parties and accepts responsibility for only those official NACE interpretations issued by NACE in accordance with its governing procedures and policies which preclude the issuance of interpretations by individual volunteers. Users of this NACE standard are r

6、esponsible for reviewing appropriate health, safety, environmental, and regulatory documents and for determining their applicability in relation to this standard prior to its use. This NACE standard may not necessarily address all potential health and safety problems or environmental hazards associa

7、ted with the use of materials, equipment, and/or operations detailed or referred to within this standard. Users of this NACE standard are also responsible for establishing appropriate health, safety, and environmental protection practices, in consultation with appropriate regulatory authorities if n

8、ecessary, to achieve compliance with any existing applicable regulatory requirements prior to the use of this standard. CAUTIONARY NOTICE: NACE standards are subject to periodic review, and may be revised or withdrawn at any time in accordance with NACE technical committee procedures. NACE requires

9、that action be taken to reaffirm, revise, or withdraw this standard no later than five years from the date of initial publication. The user is cautioned to obtain the latest edition. Purchasers of NACE standards may receive current information on all standards and other NACE publications by contacti

10、ng the NACE FirstService Department, 1440 South Creek Dr., Houston, Texas 77084-4906 (telephone +1 281-228-6200) Revised 2012-06-23 Approved October 2005 NACE International 1440 South Creek Dr. Houston, Texas 77084-4906 +1 281-228-6200 ISBN 1-57590-200-1 2012, NACE International NACE Standard TM0105

11、-2012 Item No. 21247 TM0105-2012 NACE International i _ Foreword This standard provides a test method to evaluate organic-based conductive coatings for use as an anode on atmospherically exposed reinforced concrete. Organic-based conductive coatings are commonly applied to steel-reinforced concrete

12、surfaces for the purpose of supplying cathodic protection (CP) current to the embedded steel. The conductive coating systems used for this purpose are intended to serve as an anode material and are not intended to provide a protective barrier coating to the concrete. This standard is intended for us

13、e by consultants, suppliers, and users of CP systems intended to reduce corrosion of embedded steel in atmospherically exposed reinforced concrete. This standard is expected to be used primarily to qualify organic-based conductive coatings as an anode material, rather than as a quality control proce

14、dure. This standard was originally prepared in 2005 and revised in 2012 by NACE Task Group (TG) 045,“Reinforced Concrete: Anode Test Procedures,” which is administered by Specific Technology Group (STG) 01, “Reinforced Concrete.” TG 045 also is sponsored by STG 05, “Cathodic/Anodic Protection.” This

15、 standard is issued by NACE under the auspices of STG 01. In NACE standards, the terms shall, must, should, and may are used in accordance with the definitions of these terms in the NACE Publications Style Manual. The terms shall and must are used to state a requirement, and are considered mandatory

16、. The term should is used to state something good and is recommended, but is not considered mandatory. The term may is used to state something considered optional. _ TM0105-2012 ii NACE International _ NACE International Standard Test Method Evaluation of Organic-Based Conductive Coatings for Use as

17、 an Anode on Atmospherically Exposed Reinforced Concrete Contents 1. General . 1 2. Test Panels . 1 3. Determination of Coating Properties Before Electrochemical Test 3 4. Electrochemical Test . 4 5. Determination of Coating Properties After Electrochemical Test . 4 6. Reporting . 5 References 5 FIG

18、URES Figure 1: Test Panel Construction Details with Bottom Side (Form Side) Up 2 _ TM0105-2012 NACE International 1 _ Section 1: General 1.1 This standard provides a test method to evaluate organic-based conductive coatings for use as an anode on atmospherically exposed reinforced concrete. The test

19、 method primarily consists of exposing concrete test panels coated with the organic-based conductive coating to an electrochemical (EC) test under defined laboratory conditions that are intended to simulate the conditions present when cathodic protection (CP) current discharges from the anode in a w

20、orking CP system. The evaluation of the coating is based on determination of coating properties (i.e., appearance, adhesion, resistivity, visual inspection, and water vapor transmission) before and after the EC test. 1.2 Accelerated tests are not possible because of the nature of organic-based condu

21、ctive coatings used as anodes. Therefore, this test does not reflect the accelerated whole-life performance of a conductive coating anode. 1.3 Full round-robin testing on a wide range of organic-based conductive coatings has not been performed, but a number of products were tested in the original te

22、st program on which this test method is based and by a laboratory in Europe.1 1.4 The results of this test method cannot be used to guarantee the performance of a product in any given field exposure condition. The product also should be field tested, or existing field performance data should be coll

23、ected whenever possible to demonstrate its suitability for the particular application intended. _ Section 2: Test Panels 2.1 Three concrete test panels shall be prepared for each organic-based conductive coating to be tested. 2.2 The concrete mix used to prepare the test panels shall be as follows:

24、2.2.1 Cement (Type 1): 385 kg/m3 (649 lb/yd3). Reference ASTM(1) C150M.2 2.2.2 Potable Water: Water-to-cement ratio = 0.45. 2.2.3 Fine aggregate (silica sand): 961 kg/m3 (1,620 lb/yd3). Reference ASTM C33.3 2.2.4 Crushed limestone aggregate (nominal 10 mm): 777 kg/m3 (1,310 lb/yd3). Reference ASTM C

25、33. 2.2.5 Chloride: 2.0% by weight of cement (7.7 kg/m3 13 lb/yd3) added as sodium chloride. 2.2.6 Air-entraining additive: Used in accordance with the air-entraining manufacturers directions to provide an air content of 3 to 5%. Reference ASTM C260.4 2.3 Test panel size shall be 750 x 750 x 50 mm (

26、30 x 30 x 2 in). A 13 x 13 mm (0.50 x 0.50 in) steel wire mesh grid shall be embedded near the top of the test panel on one 750 x 750 mm (30 x 30 in) side to act as the cathode. The cathode shall be placed near the top of the test panel, opposite the anode, which shall be applied to the bottom (form

27、 side) of the test panel. The spacing between the anode and the wire mesh grid shall be 32 mm (1.3 in) minimum. To make the electrical connection, a contact point for the wire mesh grid shall be allowed to extend beyond the edge of the test panel. Test panel construction details are shown in Figure

28、1. 2.4 The test panels shall be cured 28 days in accordance with the following cycle: 7 days wet cure (100% relative humidity RH) followed by 21 days at 50% RH). 2.5 After the concrete has been cured and removed from the form, the surface of the form side (the side next to the form during casting) o

29、f each test panel shall be prepared for coating with a light grit blast, or in accordance with the conductive coating manufacturers recommendations to remove surface laitance and provide sufficient roughness to promote coating adhesion. The surface shall then be vacuum cleaned. (1)ASTM International

30、 (ASTM), 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959. TM0105-2012 2 NACE International 2.6 A nonconductive epoxy coating shall be applied to all four 50 mm (2 in) sides of each test panel and cured according to the epoxy coating manufacturers application instructions. 2.7 Before the cond

31、uctive coating is applied, a primary anode shall be attached to one end of each test panel, as shown in Figure 1. Two acceptable primary anode materials are platinum-clad titanium wire and carbon fiber. Other primary anode materials may be used based on the conductive coating manufacturers recommend

32、ations. The primary anode may be attached to the test panel by any of the following methods: (a) Conductive epoxy; (b) Conductive coating and fiberglass mesh tape as recommended by the manufacturer of the coating anode; or (c) Conductive mastic or paste as recommended by the manufacturer of the coat

33、ing anode. NOTE: Whichever method is used, the attachment method must not extend more than 25 mm (1.0 in) beyond the end of the test panel where the primary anode is attached. 2.8 The conductive coating shall be applied to the prepared form side of each concrete test panel to the dry film thickness

34、(DFT) recommended by the conductive coating manufacturer, and shall completely cover the primary anode. The DFT of the conductive coating shall be determined using one of the following three methods: (a) By using a wet film thickness gauge and calculating the DFT based on the solids content of the c

35、onductive coating; (b) By coating a plastic panel and measuring the DFT with a mechanical gauge after the coating has cured in accordance with the conductive coating manufacturers recommendations; or (c) By coating a steel panel and measuring the DFT with a magnetic DFT gauge after the coating has c

36、ured according to the coating manufacturers recommendations. NOTE: For (b) and (c), the same application method used for coating the concrete test panels must be used to coat the plastic or steel panel. The conductive coating shall be allowed to cure in accordance with the manufacturers recommendati

37、ons before measuring the DFT. Figure 1: Test Panel Construction Details with Bottom Side (Form Side) Up (NOTE: All dimensions are in mm.) TM0105-2012 NACE International 3 2.9 The conductive coating shall be allowed to cure in accordance with the manufacturers recommendations. 2.10 A topcoat shall be

38、 applied over the conductive coating on one of the three test panels in accordance with the conductive coating manufacturers recommendations, and allowed to cure. _ Section 3: Determination of Coating Properties Before Electrochemical Test 3.1 Adhesion 3.1.1 Adhesion of the conductive coating shall

39、be measured using a pull-off tensile adhesion tester in accordance with ASTM D7234.5 The adhesive used shall not penetrate the conductive coating to the concrete. 3.1.2 A minimum of three measurements of adhesion strength shall be obtained from each panel. 3.1.3 All adhesion strength measurements sh

40、all be recorded, including the nature and location of any failure (e.g., within the conductive coating, coating to concrete, within the concrete). 3.1.4 Repairs to the conductive coating after the adhesion tests shall not be permitted. 3.1.5 The adhesion strength shall meet the conductive coating ma

41、nufacturers specification before performing the EC test. Any concrete test panel with a conductive coating that does not meet this adhesion requirement shall be discarded and another test panel shall be prepared in accordance with Section 2 to replace it. 3.2 Resistivity 3.2.1 Resistivity of the con

42、ductive coating shall be measured in two ways. (a) First, the resistivity shall be measured on the conductive coating that has been applied to a nonconductive surface, such as a glass or plastic plate, at the specified DFT and allowed to cure. This value is considered the true resistivity. (b) Secon

43、d, the resistivity of the conductive coating that has been applied to all three of the concrete test panels shall be measured. This value is considered the initial resistivity used as the basis to measure the effects of the EC testing. 3.2.2 The four-pin method in NACE SP03086 shall be used to measu

44、re the resistivity. This method uses four pins spaced 50 mm (2 in) apart on a spring-mounted device. The pins shall be placed a minimum of 100 mm (4 in) from the primary anode location or any edge of the test panel. The resistance (R) is measured by applying an alternating current (AC) between the t

45、wo outer pins, measuring the voltage generated between the two inner pins, and calculating R in accordance with Ohms law. Resistivity shall then be calculated from R in accordance with Equation (1): p = 4.32 x R x t/1,000 Where: p = resistivity in m R = measured resistance in t = DFT in mm. 3.3 Wate

46、r Vapor Transmission Water vapor transmission of the conductive coating shall be measured on each of the test panels in accordance with ASTM D1653.7 3.4 Coating Appearance The conductive coating on each test panel shall be given a visual inspection before the EC test is performed. The original color

47、 as well as the location and size of any coating flaw shall be noted. (1) TM0105-2012 4 NACE International _ Section 4: Electrochemical Test 4.1 The EC test shall be performed by applying a direct current (DC) at a current density of 21.5 mA/m2 (2.00 mA/ft2) of concrete test panel surface or 12.1 mA

48、 for the test panel shown in Figure 1. NOTE: Greater current densities may accelerate deterioration of the conductive coating film, leading to accelerated deterioration of the coating-to-concrete interface. 4.1.1 DC shall be applied with a constant current source with current variations of no greater