Final Report Independent Laboratory Evaluation of Zinc- Aluminum-Magnesium (ZAM ) Coating Verses Hot-Dip Galvanizing KTA Project No. 350519-R1 Presented to: Mr. Evan Rothblatt, EIT Associate Program Manager, Materials American Association of State Highway & Transportation Officials 444 North Capital Street NW, Suite 249 Washington, DC 20001 erothblatt@aashto.org Prepared by: Valerie D. Sherbondy KTA-TATOR, INC. 115 Technology Drive Pittsburgh, PA 15275 412.788.1300 Ext. 183 phone 412.722.0976 fax vsherbondy@kta.com email www.kta.com Valerie D. Sherbondy Technical Manager Analytical Laboratory Services March 28, 2016 VDS/WDC:tbr JN350519 (350519-R1 AASHTO APEL.doc) R1- Changes to properly reference with the registered mark and editorial changes. i
TABLE OF CONTENTS Introduction and Purpose of the Study... 1 Executive Summary... 1 Products for Evaluation... 3 Sample Acquisition Process... 3 Cutting HDG Blanks into Test Coupons... 5 Specimen Identification Procedures... 5 Measurement of Coating Thickness... 5 Edge Preparation... 5 Test Coupon Scribing Procedure... 6 Salt Fog Exposure... 6 Immersion Exposure... 7 Test Results Salt Fog Exposure... 7 Appendices 1. Mill Test Reports and Certificates of Conformance 2. Test Matrix 3. Coating Thickness Data 4. Edge Protection Illustration 5. Digital Images of Test Coupons 6. Rusting Evaluations 7. SEM-EDS Images NOTICE: This report represents the opinion of KTA-TATOR, INC. This report is issued in conformance with generally acceptable industry practices. While customary precautions were taken to insure that the in gathered and presented is accurate, complete and technically correct, it is based on the in, data, time, materials, and/or samples afforded. This report should not be reproduced except in full. ii
INTRODUCTION AND PURPOSE OF THE STUDY According to a draft Test Proposal provided to KTA-Tator, Inc. (KTA) by the American Association of State Highway and Transportation Officials (AASHTO) Product Evaluation List Council (APEL) titled, Development of Practical Testing Protocol and Preliminary Materials Durability Evaluation of Continuous Hot-Dipped Zinc-Aluminum-Magnesium Alloy Coatings for Highway Applications, the development of Hot Dipped Zinc-Aluminum-Magnesium Alloy (ZAM ) coatings (91% Zn, 6% Al, 3% Mg) for steel components has been made and introduced to the market as an alternative for hot dipped galvanized steel. Standardization of ZAM coatings has been made in ASTM A1046, Standard Specification for Steel Sheet, Zinc- Aluminum-Magnesium Alloy-Coated by the Hot-Dip Process. Product literature from the manufacturer of ZAM describes a significant amount of favorable testing results (including mechanically induced deficiencies such as scribing, bending and drawing) in laboratory salt spray and outdoor exposure environments. The available technical in on material durability from the manufacturer has created interest in the material for highway design and construction. Development of testing protocols to assess the durability of the material in applicable environments and independent evaluation of the material was needed to identify possible future application for highways. The APEL Council sought an independent evaluation of the resistance properties of the ZAM coating compared to the resistance properties of traditional hot-dip galvanizing (HDG) for use in highway construction applications, including traffic barriers, cable posts, sign posts and paneling, and for coating of reinforcing bar (rebar) in contact with concrete. Specifically, there was interest in assessing the comparative performance of these two materials in both an undamaged condition and in a condition where mechanical damage had been intentionally induced in a controlled manner. This test report describes the sample acquisition process, and describes the, specimen preparation procedures, test environments, evaluation procedures and test results. Appendices to this report include coating thickness measurements, digital images (photographs) of the test specimens, SEM-EDS images and EIS data. EXECUTIVE SUMMARY KTA subjected steel coated with two thicknesses of ZAM (ZM90 and ZM115) and two thicknesses of HDG (Type 1 and Type 2) to 3,000-hours salt fog exposure (ASTM B117), as well as immersion for 90 days in distilled water (adjusted to ph 8-9), a 5% solution of sodium chloride (neutral ph) and a 5% solution of sodium chloride (adjusted to ph 8-9). The test coupons included scribed and un-scribed coating, as well as protected and un-protected edges. Evaluations included visual observations, Electrochemical Impedance Spectroscopy (EIS), and Scanning Electron Microscopy/Energy-Dispersive Spectroscopy (SEM-EDS) to compare baseline to post-exposure elemental properties and assess degradation of the coating (i.e., of oxides, evidence of iron oxide indicating lack of galvanic protection of the base steel, etc.). AASHTO APEL 1 of 15 March 28, 2016
The thickness of the treatment on each test coupon was measured prior to testing. The thickness of the HDG Type 1 ranged from 1.9 to 3.0 mils; the thickness of the HDG Type 2 ranged from 3.1 to 5.0 mils. The thickness of the ZM90 ranged from 0.7 to 1.2 mils; the thickness of the ZM115 ranged from 0.9 to 1.3 mils. The visual examinations and the analytical methods revealed similarities and differences between the performance of the ZAM and HDG materials. For the salt fog exposure, all four materials initially developed similar during the first 1,000 hours of exposure. The most notable difference between the was slightly more white at the scribe on the test coupons protected with the ZAM, which was not visually evident in the scribe on the coupons protected with the HDG. After 2,000 hours exposure to salt fog, the HDG Type 1 showed the highest amount of white, and started to reveal spots of red rust at the top of the coupons. After 3,000 hours of salt fog exposure there was a significant visual difference in the amount of red rust on the test coupons protected with HDG Type 1, with pinpoint rusting evident on the test coupons protected with HDG Type 2. Scraping of the scribed areas revealed additional red rust occurring under the white rust on the coupons protected with HDG, with creepage (undercutting) at the scribe present in spots that ranged up to 1/8 from the scribe line on the coupons protected with HDG Type 1. The coupons protected with HDG Type 2 contained a lower amount of rusting and there was no visible undercutting from the scribe. Other than 0.1-0.3% pinpoint rusting on one panel, there was no visual evidence of red rusting on the coupons protected with the ZM90 and the ZM115. All four appeared to adequately protect exposed edges. The SEM-EDS elemental scans of the s of the coupons (all four ) after 90-days immersion in the three test solutions revealed that the majority of the was zinc oxide. There was no variation in the that could be attributed to the immersion solution or the of the panel. The elemental scans produced from the s of the test coupons exposed to salt fog revealed an increase in chlorine levels in the, but it was relatively consistent over the 3,000 hours of exposure. The EIS analysis was interesting due to the nature of the treatment. EIS is typically used to evaluate the barrier properties of an applied film. However, ZAM and HDG are not typically regarded as barrier type coatings. Rather, these protect using a galvanic process and create an oxide layer during exposure that subsequently protects the base metal. So for this study the EIS analysis assessed the effectiveness of the barrier layer once formed. The initial testing of the unexposed coupons produced varying data. The data remained variable at subsequent test intervals, but when analyzed as trend data, there is indication of of a protective layer that can be measured. The EIS data acquired from the test coupons exposed to salt fog indicated that the barrier protection of the increased between 1,000 and 2,000 hours exposure, but then decreased. The level of increase was from ohms to Kohms for the HDG materials and from ohms to Kohms and Mohms for the ZAM materials. The decrease in protection at 3,000 hours took the HDG materials back to the ohms levels, while the ZAM materials stayed in the Kohms level for some of the test coupons, and in the ohms level for others. This coincides with the visual evidence of red rust that occurred on the coupons protected with HDG. AASHTO APEL 2 of 15 March 28, 2016
The barrier protection levels of the that formed in the immersion exposure varied by solution type and the length of exposure. Independent of the protection product, the coupons immersed in solution 1 (distilled water adjusted to ph 8-9) developed the most visible layer of white, but never developed an increase in the barrier protection. The test coupons protected with ZM90 and HDG Type 1 immersed in test solution 2 (5% sodium chloride, ph neutral) remained at the ohm level, while the test coupons protected with ZM115 and HDG Type 2 showed an increase in barrier protection after 90-days immersion. The test coupons immersed in solution 3 (5% sodium chloride, adjusted to ph 8-9) developed a variable protective layer on random replicates early in the immersion process, and then a more consistent barrier on all of the test coupons (independent of the product) after 90 days immersion. PRODUCTS FOR EVALUATION The product evaluation program involved four from two manufacturers. Each manufacturer supplied two coating weights for each product. Wheeling-Nisshin, Inc. supplied pre-cut coupons (see below) containing two coating weights of the ZAM product, including ZM90 (0.90 oz/ft 2 ) and ZM115 (1.15 oz/ft 2 ). Gregory Industries, Inc. supplied four-foot blanks containing two coating weights of HDG, including Type 1 (1.8-2.0 oz/ft 2 ) and Type 2 (3.6-4.0 oz/ft 2 ). SAMPLE ACQUISITION PROCESS Wheeling-Nisshin, Inc. supplied KTA with 100 1/8 x 3 x 6 ZM90 and 100 1/8 x 3 x 6 ZM115 test coupons. The test coupons were reportedly cut from strip (after coating), resulting in four unprotected edges on each test coupon. Additional (spare) coupons of each coating weight were also provided. The test coupons were delivered to KTA by Mr. Sujai Sukumar of Wheeling-Nisshin, Inc. on July 14, 2015. Mill test reports for the steel used to fabricate the ZM90 and ZM115 test coupons are attached to this report in Appendix 1. KTA personnel did not witness the deposition processes used to prepare the ZM90 or ZM115 test coupons. KTA issued Purchase Order No. 15PO-273 on July 14, 2015 to Gregory Industries, Inc. (Canton, Ohio) for 4 4-foot 0-inch lengths of 12 gauge WB T1 Type 1 galvanized guardrail strip (un-pierced blanks) and 4 4-foot 0-inch lengths of 12 gauge WB T2 Type 2 hot-dip galvanized guardrail strip (un-pierced blanks). KTA instructed Gregory Industries to exclude any post-treatment processes. The shipment of HDG blanks was received on July 27, 2015. Mill test reports for the steel and a Certificate of Compliance for the galvanizing process are attached to this report in Appendix 1. KTA personnel did not witness the HDG deposition processes used to prepare the blanks. The chemistry of the base steel used for the HDG, ZM90 and ZM115 test samples (extracted from the Mill Test Reports) is shown in the table below, Steel Chemistry (Weight %). The Atmospheric Corrosion Index (ACI) was calculated according to ASTM G101, Standard Guide for Estimating the Atmospheric Corrosion Resistance of Low-Alloy Steels. According to the Guide, the higher the ACI is, the greater the resistance of the steel. AASHTO APEL 3 of 15 March 28, 2016
Steel Chemistry (Weight %) Coating C Mn P S Si Cu Ni Cr Mo Sn HDG 0.22 0.75 0.01 0.007 0.01 0.03 0.02 0.04 0.01 0.004 ZM90 0.03 0.30 0.006 0.008 0.009 0.03 0.01 0.02 0.002 0.008 ZM115 0.04 0.28 0.006 0.009 0.007 0.03 0.01 0.02 0.002 0.010 Steel Chemistry (Weight %), continued Coating Al V Cb N B Ti Sb Ca ACI HDG 0.056 0.001 0 0.0068 0.0001 0.001 0 0.0003 1.06 ZM90 0.035 0.001-0.008-0.001 - - 0.93 ZM115 0.036 0.001-0.006-0.001 - - 0.92 AASHTO APEL 4 of 15 March 28, 2016
CUTTING HDG BLANKS INTO TEST COUPONS The blanks containing the Type 1 and Type 2 HDG coating were cut into 3 x 6 test coupons (100 of each type) using an industrial band saw. Since the blanks were already formed as guardrail sections, KTA selected coupons with minimal curvature from the forming process. The coupons were cut dry without the use of lubricants. The coupons were carefully segregated into two pre-identified boxes; one box for each type of galvanizing. SPECIMEN IDENTIFICATION PROCEDURES A matrix was designed by KTA to manage the numbering and disposition of the test coupons. The test matrix is attached to this report in Appendix 2. The table below illustrates the numbering system used to uniquely identify each test coupon, prior to measurement of coating thickness. Product ZAM ZM90 ZAM ZM115 HDG Type 1 HDG Type 2 Numbering Sequence 1Za 100Za 1Zb 100Zb 1H-I 100H-I 1H-II 100H-II MEASUREMENT OF COATING THICKNESS The thickness of the coating on the un-numbered side of each test coupon was measured using a PosiTector 6000-F1 nondestructive, magnetic induction coating thickness gage with calibration traceable to the National Institute of Standards and Technology (NIST) and verified for accuracy prior to use using traceable coated standards. Measurements were obtained in accordance with ASTM D7091, Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals. Thickness data are appended to this report in Appendix 3. The thickness of the HDG Type 1 ranged from1.9 to 3.0 mils; the thickness of the HDG Type 2 ranged from 3.1 to 5.0 mils. The thickness of the ZM90 and ZM115 ranged from 0.7 to 1.2 mils and 0.9 to 1.3 mils, respectively. EDGE PREPARATION All test coupons (ZAM and HDG) contained four bare edges after cutting to the 3 x 6 coupon size. Three of four edges on all of the HDG test coupons (Type 1 and Type 2) were fully protected using a commercially available epoxy coating applied by dipping. The remaining vertical edge of each HDG coupon was sealed along the top four inches only, leaving the bottom 2-inches bare (protected by masking tape). The masking tape was removed after the epoxy coating cured. The unsealed portion was intended to simulate transverse cuts or punched holes on galvanized before fabrication, while the sealed top two thirds of the coupon simulated post dipped (galvanized after fabrication) product. AASHTO APEL 5 of 15 March 28, 2016
The top horizontal edge of the ZAM coupons selected for salt fog testing was sealed with the same epoxy coating to prevent (that may run down from the top edge) from interfering with scribe or face evaluations. All three remaining sides of the ZAM test coupons designated for salt fog exposure remained unsealed to simulate uncoated edges as intended for highway construction applications of ZAM. The edges of all ZAM test coupons designated for immersion testing remained unsealed. See edge protection illustration, in Appendix 4. TEST COUPON SCRIBING PROCEDURE One hundred forty-four (144) of the test coupons were scribed to expose the base steel using a lathe cutting tool described in ASTM D1654, Standard Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments. The scribing implement was mounted in the grip of a milling machine and the scribe generated using the machine, rather than attempting to scribe through the ZAM and HDG coatings by hand. A single 4 diagonal scribe was cut into each designated coupon. The scribe enabled the evaluation of the galvanic protection afforded by the two coating weights of ZAM when damaged in service, compared to the two types of HDG coating. Each test coupon was photographed prior to testing. The photographs can be referenced in Appendix 7. SALT FOG EXPOSURE Three sets of duplicate or triplicate test coupons representing each variable (scribed and non-scribed ZM90 and ZM115; scribed and non-scribed Type 1 and Type 2 HDG) were subjected to salt fog exposure in accordance with ASTM B117, Standard Practice for Operating Salt Spray (Fog) Apparatus. Test coupons were exposed for 3,000-hours of cumulative exposure (18 weeks), with one full set of coupons removed from exposure at 1,000-hour intervals (i.e., after 1000, 2000 and 3000 hours of cumulative exposure). The type and frequency of red/brown (when visually evident) was rated in accordance with SSPC-VIS 2, Standard Method of Evaluating Degree of Rusting on Painted Steel s (rating scheme shown below). The s that had the intentional defect of the scribe were rated after removal of the. The area around the scribe was assigned a rust rating, if applicable and any creepage from the scribe was measured and included in the Rusting Evaluations included in Appendix 6. SSPC-VIS 2 Rating System Rating % Rusting Rating % Rusting 10 0.01 5 > 1 to 3 9 > 0.01 to 0.03 4 > 3 to 10 8 > 0.03 to 0.1 3 > 10 to 16 7 > 0.1 to 0.3 2 > 16 to 33 6 > 0.3 to 1 1 > 33 to 50 Type: G: Rusting; P: Pinpoint Rusting; S: Spot Rusting AASHTO APEL 6 of 15 March 28, 2016
The test coupons containing the intentional scribe (and unprotected edges) were visually evaluated for resistance to undercutting at 1,000-hour intervals. The non-scribed test coupons were examined at 1,000-hour intervals using Scanning Electron Microscopy Energy- Dispersive Spectroscopy for elemental analysis of the s. The analysis was compared to the baseline spectra obtained from the s of unexposed ZAM and HDG test coupons. A second set of non-scribed test coupons were analyzed at 1,000-hour intervals using Electrochemical Impedance Spectroscopy (EIS), which provides an indication of the barrier properties afforded by ZAM verses HDG and reveals changes at the interface between the ZAM coating or the HDG coating and the base steel. Changes in barrier properties are measured in ohms, kilo-ohms (Kohms) and mega-ohms (Mohms). A Kohm is 1,000 ohms; a Mohm is one million ohms. IMMERSION EXPOSURE Three sets of duplicate or triplicate test coupons representing each variable (scribed and non-scribed ZAM ; scribed and non-scribed HDG) were subjected to 100% immersion in three different aqueous solutions (listed below) at room temperature for 90 days. Each test solution was aerated; the solutions were changed monthly. The ph of the test solutions was monitored and adjusted weekly. One full set of coupons was removed from immersion at 30-day intervals. The scribed coupons (and unprotected edges) were evaluated for resistance to undercutting; the non-scribed coupons were evaluated by EIS and SEM-EDS (described above). Each test coupon was photographed after removal from immersion and prior to evaluation. Test Solution 1: Distilled water with alkalinity adjusted to ph 8-9 Test Solution 2: Distilled water containing sodium chloride (5%); neutral ph Test Solution 3: Distilled water containing sodium chloride (5%); alkalinity adjusted to ph 8-9 TEST RESULTS SALT FOG EXPOSURE The results of the visual evaluations of the four subjected to salt fog exposure are provided in Tables 1-6, below. Table 1: Comparison of Performance at Scribe 1,000-hours Exposure ZM90 HDG Type 1 ZM115 HDG Type 2 White 1/16 1/8 from scribe Scribe not visible due to white White 1/16 1/8 from scribe Scribe not visible due to white Table 2: Comparison of Performance at Scribe 2,000-hours Exposure ZM 90 HDG Type 1 ZM115 HDG Type 2 White extends approximately 1/8 from scribe Scribe not visible due to white White extends approximately 1/8 from scribe Scribe not visible due to white AASHTO APEL 7 of 15 March 28, 2016
Table 3: Comparison of Performance at Scribe 3,000-hours Exposure ZM 90 HDG Type 1 ZM115 HDG Type 2 Scribe partially masked due increased white. Approximately 1/8 from scribe Scribe not visible due to white Scribe partially masked due increased white. Approximately 1/8 from scribe Scribe not visible due to white Table 4: Comparison of Performance Non-scribed Areas 1,000-hours Exposure Evaluation ZM 90 HDG Type 1 ZM115 HDG Type 2 Oxidation White Heavy white White Heavy white Rust No red rust One panel rated 7-S No red rust One panel rated 6-S Edge Rusting None None None None Table 5: Comparison of Performance Non-scribed Areas 2,000-hours Exposure Evaluation ZM 90 HDG Type 1 ZM115 HDG Type 2 White White White White Oxidation Most prevalent at top Top of panel rated of panel, rated 3-G. Rust None None 6-G. None on Lower half of panel lower half of panel rated 6-G Edge Rusting None None None None Table 6: Comparison of Performance Non-scribed Areas 3,000-hours Exposure Evaluation ZM 90 HDG Type 1 ZM115 HDG Type 2 Oxidation Rust Increased evidence of white Pinpoint rusting (7-P) on one panel Heavy white rust at top of panel (2-G). Lower half of panel rated 5-G Increased evidence of white None Edge Rusting None None None Heavy white rust on top of panel (4-G). Lower half of panel rated 6-G Evident on one exposed edge AASHTO APEL 8 of 15 March 28, 2016
Elemental Analysis (verses baseline analysis) via SEM-EDS The SEM-EDS analysis was performed on the s prior to exposure. The coupons with the HDG revealed the presence of zinc. The coupons with the ZAM coatings revealed the presence of zinc with lower levels of aluminum and magnesium. The analysis performed after exposure revealed some variation in the elements present. The presence of silicon was noted intermittently on the test coupons containing HDG. The aluminum and the magnesium in the ZAM coatings were infrequently detected on the scans produced by analysis of the s of the exposed test coupons. The SEM-EDS elemental scans of the s of the test coupons exposed in the salt fog chamber revealed that the chlorine peaks became larger relative to the size of the zinc peaks on the HDG Type 1 as the exposure time increased, while the chlorine levels remained reasonably consistent on the s of the test coupons with the HDG Type 2, ZM90 and ZM115 after 1000, 2000 and 3000 hours of exposure. This variation was not significant and indicates that the majority of the salt was zinc oxide. Barrier Property Analysis via EIS The electrochemical impedance spectroscopy was performed using a Gamry Potentiostat with a calomel electrode. A glass cylinder was attached to the of the coupons using a rubber washer and a clamp. The cylinder was filled with a 5% sodium chloride solution for testing. The solution was in contact with the of the test coupons long enough to verify that the seal was not leaking and then the testing was initiated. Once the test coupons were exposed, the on the would wick the salt solution out of the cylinder, so a ring of was removed at the attachment point of the washer. The in the center of the tested area were not removed intentionally during this process. In some cases, the were fragile enough that the removal occurred while handling. One of the edges of each of the tested coupons was also sanded to complete an electrical connection with the EIS test equipment. The of the test coupons was known to be reactive, so the intent of this analysis was to evaluate the barrier protection of the resulting layer that formed during exposure. This layer varied in both consistency and thickness between the materials. The initial EIS readings were variable, with most of the values falling in the range of 7 to 407 ohms for the four materials. This indicated that the barrier properties were consistent between the materials at the initiation of the testing. The test coupons exposed to ASTM B117 salt fog produced a visible layer of white, and red rusting occurred on the HDG Type 1 and Type 2 test coupons as the duration of the testing increased. Based on the EIS data there was an increase in the barrier protection between 1000 and 2000 hours of exposure for all four materials. The increase was approximately 1,000-fold for the barrier protection. The HDG Type 1 and HDG Type 2 showed an increase in the level of protection afforded by the layer of about 100- fold at 3,000-hours exposure (compared to the protection afforded at 1,000-hours), but had decreased approximately 1,000-fold relative to the protective properties measured after 2,000 AASHTO APEL 9 of 15 March 28, 2016
hours exposure. The protection increase and subsequent decrease was less repeatable on the HDG Type 1, with the fluctuation likely caused by variations in the developed oxide layer. The protective properties afforded by the ZM90 and ZM115 increased about 1000-fold between the 1,000-hour and 2,000-hour exposure, and maintained a protective layer with a level in the Kohm region after 3,000-hours exposure. The overall indication was that the ZAM materials produced a protective layer that maintained their barrier properties throughout the exposure, while the HDG materials appeared to lose some of their protective properties after the same exposure period. This appears to correlate with the visual evidence of red rust on the HDG Type 1 after 2000-hours and on both HDG materials (Type 1 and 2) after 3000 hours of salt fog exposure. TEST RESULTS Immersion in SOLUTION 1 (Distilled water with PH adjusted to 8-9) The results of the visual evaluations of the panel, the scribe area and the exposed edges of the four subjected to immersion in distilled water with the ph adjusted to 8-9 are provided in Tables 10-13, below. Table 10: Comparison of Performance 30-Days Exposure Scattered white rust Scattered white rust Scattered white rust Scattered white rust Scribe Exposed Edge rust rust rust rust Table 11: Comparison of Performance 60-Days Exposure Scribe Exposed Edge Scattered white rust Inconsistent white rust rust Scattered white rust Inconsistent white rust rust Scattered white rust Inconsistent white rust Scattered white rust Inconsistent white rust AASHTO APEL 10 of 15 March 28, 2016
Table 12: Comparison of Performance 90-Days Exposure Scribe Exposed Edge on Inconsistent white rust rust on Inconsistent white rust rust on Inconsistent white rust Table 13: Comparison of Performance at Scribe after Scraping on Inconsistent white rust Time Period ZM90 HDG Type 1 ZM115 HDG Type 2 30 Days 60 Days 90 Days Elemental Analysis (verses baseline analysis) via SEM-EDS (Solution 1) The SEM-EDS analysis was performed on the s prior to exposure. The coupons protected with HDG revealed the presence of zinc. The coupons with the ZAM coatings revealed the presence of zinc and lower levels of aluminum and magnesium. The analysis performed after exposure revealed some variation in the elements that were present, but the changes in the elemental analysis were consistent. The change in the treatment did not reveal a change in the elemental findings. The s of the test coupons contained primarily zinc oxide. Occasionally, a relatively low amount of calcium was also detected on the Type 1 and Type 2 HDG test coupons and is probably a result of the water used for testing. The quantity of calcium was indicated by the size of the peaks relative to the zinc peaks on the elemental scans. There was a small chlorine peak on the test coupons treated with ZM90 at 30 and 60 days that was not present on the same product exposed for 90 days. The HDG Type 1 test coupons revealed a small peak associated with silicon at 60 and 90 days exposure. Barrier Property Analysis via EIS (Solution 1) Based on the EIS analysis, all test coupons (independent of the type of protection) developed a layer of white, but never developed an increase in barrier protection. That is, there was no significant difference in barrier protection measurements between the baseline and post-90-day immersions test coupons. All of the results remained in the ohms levels. AASHTO APEL 11 of 15 March 28, 2016
TEST RESULTS Immersion in SOLUTION 2 (5% Sodium Chloride - neutral PH) The results of the visual evaluations of the flat, the scribe area and the exposed edges of the four subjected to immersion in 5% sodium chloride solution in distilled water with the ph adjusted to 7 are provided in Tables 14-17, below. Table 14: Comparison of Performance 30-Days Exposure Scribe Exposed Edge on Random spots white rust on Random spots white rust on Random spots white on Random spots white Table 15: Comparison of Performance 60-Days Exposure Scribe Exposed Edge on Increase in white on Increase in white on Increase in white Table 16: Comparison of Performance 90-Days Exposure on Increase in white on on on on Scribe White White White White Exposed Edge Table 17: Comparison of Performance at Scribe after Scrape Time Period ZM90 HDG Type 1 ZM115 HDG Type 2 30 Days 60 Days 90 Days AASHTO APEL 12 of 15 March 28, 2016
Elemental Analysis (verses baseline analysis) via SEM-EDS (Solution 2) The SEM-EDS analysis was performed on the s prior to exposure. The coupons protected with HDG revealed the presence of zinc. The coupons with the ZAM coatings revealed the presence of zinc and lower levels of aluminum and magnesium. The s of the test coupons in 5% sodium chloride maintained at ph 7 revealed the presence of a small amount of chlorine that did not show a trend in the relative amounts during the 90 day exposure. The only changes noted were the relative amounts of chlorine, but replicate test coupons did not confirm that these changes were a result of the material, so the increase may be due to the site selected for analysis. Barrier Property Analysis via EIS (Solution 2) The barrier protection levels of the formed during the immersion in 5% sodium chloride solution (ph adjusted to 7) remained at the ohm level except for the ZM115 and the HDG Type 2 test coupons evaluated after 90 days of immersion. Both of these materials showed an increase in their inherent barrier properties, indicated by EIS readings on these two materials that measured in the Mohms range. There was no visual indication that this increase in protection was occurring. TEST RESULTS Immersion in SOLUTION 3 (5% sodium chloride with PH adjusted to 8-9) The results of the visual evaluations of the flat, the scribe area and the exposed edges of the four subjected to immersion in 5% sodium chloride in deionized water with the ph adjusted to 8-9 are provided in Tables 18-21, below. Table 18: Comparison of Performance 30-Days Exposure Scribe Exposed Edge Light Slightly more white than rust Light Slightly more white than Light Slightly more white than Light Slightly more white than AASHTO APEL 13 of 15 March 28, 2016
Table 19: Comparison of Performance 60-Days Exposure Scribe Exposed Edge Light White Light White Light White Table 20: Comparison of Performance 90-Days Exposure Light White Scribe Exposed Edge Light White at scribe White Light White at scribe White Light White at scribe White Light White at scribe White Table 21: Comparison of Performance at Scribe after Scrape Time Period ZM90 HDG Type 1 ZM115 HDG Type 2 30 Days 60 Days 90 Days Patches of pinpoint rust around scribe Elemental Analysis (verses baseline analysis) via SEM-EDS (Solution 3) The SEM-EDS analysis was performed on the s prior to exposure. The coupons protected with HDG revealed the presence of zinc. The coupons with the ZAM coatings revealed the presence of zinc and lower levels of aluminum and magnesium. The s of the test coupons immersed in test solution 3 revealed the presence of a small amount of chlorine that varied throughout the 90 day exposure. Occasionally, a relatively low amount of aluminum was also detected on the test coupons protected with ZM115. This variation was most likely the result of the area selected for analysis and the thickness of the zinc oxide layer in that area. AASHTO APEL 14 of 15 March 28, 2016
Barrier Property Analysis via EIS (Solution 3) The barrier protection levels of the formed during the immersion in test solution 3 was evaluated via EIS. A protective layer that developed on the ZM90 test coupons after 30 days was not evident at the 60 day evaluation. A more consistent barrier was evident on the test coupons after 90 days of immersion. All four materials tested in the range of Mohms and Kohms after 90 days if immersion indicating protection of the underlying. There was no visual indication that this protection was occurring. AASHTO APEL 15 of 15 March 28, 2016