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Progress Report: Using Thermal

Modification Technology to Add

Value to Small-Diameter Logs

from Underutilized Species

Duluth Laboratories & Administration 5013 Miller Trunk Highway Duluth, Minnesota 55811 Coleraine Laboratories One Gayley Avenue P.O. Box 188 Coleraine, Minnesota 55722

Submitted by: Patrick Donahue

Matthew Aro

Date: March 2018

Report Number: NRRI/TR-2018/07

Collaborators:

Michigan Technological University US Forest Service, Forest Products Laboratory

UC Coatings

Funders: USDA Wood Education and Resource Center

Table of Contents Progress Achieved in Accomplishing Project Goals and Objectives ............................................... 1 Activity Anticipated Next Reporting Period .................................................................................... 5 Outcomes, Accomplishments, Results ............................................................................................ 5

Outcomes .......................................................................................................................... 5 Accomplishments .............................................................................................................. 6 Results ............................................................................................................................... 7 pH ............................................................................................................................ 7 Hardness ................................................................................................................. 7 Compression Strength Parallel to Grain ................................................................. 9 Equilibrium Moisture Content .............................................................................. 10 Dimensional Stability ............................................................................................ 11

Length Change .......................................................................................... 11 Width Change ........................................................................................... 12

Thickness Change ...................................................................................... 14 Volume Change ......................................................................................... 15

Durability ............................................................................................................... 17 Soil-Block ................................................................................................... 17 Field-Testing: Ground-Proximity Test ...................................................... 18 Field-Testing: Lap Joint Test .................................................................... 19

Field-Testing: L-Joint Test......................................................................... 20 Appendix 1 AWPA Annual Meeting Presentation and Abstract .............................................. 22 Appendix 2 WDMA Technical & Manufacturing Conference Presentation ............................. 51 Appendix 3 Minnesota Department of Natural Resources, Marketplace Newsletter .......... 103

Appendix 4 Year 1 Inspection Report, Ground-Proximity Test .............................................. 107

Appendix 5 Year 1 Inspection Report, Lap Joint Test ............................................................ 122

Appendix 6 Year 1 Inspection Report, L-Joint Test ................................................................ 137

Progress Report: Using Thermal Modification Technology to Add Value to Small-Diameter Logs from Underutilized Species

Date: 3/31/2018

Report Period: 01/01/2017-12/31/2017

Grant Project Period: 07/01/2015 – 06/30/2020

Grant Recipient: University of Minnesota

Grant Number: 15-DG-11420004-082

Recipient Contact Person: Elizabeth Rumsey

Principal Investigator/Project Director: Patrick Donahue

Progress Achieved in Accomplishing Project Goals and Objectives

Overarching Goals and Objectives

1. Define product performance benchmarks by identifying mechanical, physical, andbiological durability performance targets for the selected thermally-modified materials.

2. Develop effective thermal-modification treatment schedules for each species.3. Transfer knowledge concerning performance benchmarks and thermal-modification

treatments to stakeholders, including those in commercial and other building markets.

Goal/Objective 1.1

Planned: Secure small clear specimens (as described in ASTM D143) of 4/4 (1-inch) and 8/4 (2-inch) kiln-dried (6-12% moisture) yellow poplar, red maple, white ash, balsam fir, Eastern hemlock, and ponderosa pine (benchmark species).

Actual: Worked with two regional wholesale lumber companies (Midwest Hardwood Lumber and Lake States Lumber) to secure all sample materials except for Eastern hemlock. After further researching optimal thermal-modification processing protocols, the project team determined that all the wood would be conditioned to a uniform moisture content of 12% prior to thermal-modification processing – this conditioning step caused a delay in processing the samples.

Difficulties Encountered: We were unable to initially find a commercial supplier of Eastern hemlock lumber with sufficient quality; however, we expanded our search and secured Eastern hemlock logs from Longyear Natural Resources and had them custom sawn into 4/4 and 8/4 dimensions.

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Goal/Objective 1.2

Planned: Categorize all lumber by weight and dimension, and scan with WoodEye® technology to identify possible wet pockets and/or internal defects.

Actual: We were unable to find an appropriate electronic scanning technology to provide meaningful information on the presence of wet pockets in the wood, nor could we locate a commercial partner who would help execute this task.

Resolution/Corrective Action Plan: The project team did not want to delay progress with this bottleneck, so this task was removed from the work plan.

Goal/Objective 1.3

Planned: Process lumber into sample sets for thermal modification.

Actual: Complete.

Goal/Objective 2.1

Planned: Categorize all lumber by weight and dimension, and scan with WoodEye® technology to identify possible wet pockets and/or internal defects.

Actual: We were unable to find an appropriate electronic scanning technology to provide meaningful information on the presence of wet pockets in the wood, nor could we locate a commercial partner who would help execute this task.

Resolution/Corrective Action Plan: The project team did not want to delay progress with this bottleneck, so this task was removed from the work plan.

Goal/Objective 2.2

Planned: Determine degree of wood modification at both the 170°C and 180°C treatment levels utilizing electron spin resonance spectroscopy (ESR).

Actual: Specimens have been sent to Firmolin (The Netherlands) for ESR analysis. Due to unforeseen circumstances at Firmolin, we continue to wait for final results.

Problem(s): There has been an unexpected delay at Firmolin.

Resolution/Corrective Action Plan and Schedule:

1) Continue to inquire with Firmolin bi-weekly to ensure results are presented as soon as

possible.

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Goal/Objective 3.1

Planned: Moduli of rupture (MOR) and elasticity (MOE), hardness, shear strength, nailholding strength, compression and impact strength, hygroscopicity, coating performance, adhesion, and dust particle size will be determined. Other tests may be included. Ponderosa pine (both unmodified and treated with soluble borate salts) will serve as a benchmark.

Actual: (1) Upon further discussion with industry stakeholders, we determined that shear, hygroscopicity, and nailholding strength testing data would not be useful for growth of the thermally-modified wood industry. The USDA WERC approved of removing these tests from the work plan. (2) MOR and MOE test specimens have been prepped and conditioned and are awaiting testing. (3) Hardness and compression testing is complete. (4) The coating performance and adhesion test specimens were quality-graded and coated by our industrial partner UC-Coatings (Buffalo, NY) and are awaiting the final adhesion and accelerated aging exposure testing. (5) Split resistance and screwholding strength test specimens are fully prepped and have been shipped to Michigan Technological University (MTU) for testing. (6) The pH of the thermally-modified wood was determined.

Problem(s):

1) Our initial project work plan neglected to include Eastern hemlock, a much underutilizedspecies, in our analyses.

2) There was a delay in completing some of the physical and mechanical testing. This delaywas due to two issues: (1) The NRRI has recently instituted a new Quality Controlprogram that requires all performance tests to have newly-written and -verified testprocedures and certified testing fixtures in place. This unexpected new requirementforced the testing work to be halted on more than one occasion. (2) There was afunding shortfall.

Resolution/Corrective Action Plan and Schedule:

1) We worked diligently to find kiln-dried Eastern hemlock lumber. Unfortunately, wecould not find a regional source of this material. Thus, we secured Eastern hemlock logsfrom Longyear Natural Resources (Figure 1) and had them custom sawn into 4/4 and 8/4dimensions. The lumber was then dried in the NRRI’s autoclave, followed by thermal-modification processing. At this time, all Eastern hemlock test specimens have beenprepared and have undergone or are awaiting testing.

2) We worked with the USDA WERC Program Officer to streamline the scope of themechanical testing.

3) New test procedures have been written and testing fixtures are in place to ensure thatall testing meets the NRRI’s new, rigorous Quality Control requirements.

4) MTU (project subawardee) will be completing the split resistance and screw withdrawaltesting for the project, speeding up the project timeline and reducing the NRRI’sbudgetary shortfall burden. We are also working with MTU to develop a plan to

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increase funding for NRRI’s testing responsibilities by adjusting MTU’s subaward contract.

5) We are also working with NRRI management to contribute additional hard funding resources to fully complete all the tasks. We expect all mechanical and physical testing to be completed in calendar year 2018.

Figure 1. Eastern hemlock logs sourced from Longyear Natural Resources.

Goal/Objective 3.2 Planned: Biological durability will be determined by MTU according to American Wood Protection Association (AWPA) standards. The thermally-modified wood will be subjected to laboratory soil-block testing with two white-rot and two brown-rot fungi. Long-term ground proximity, above-ground lap joint, and fenestration L-joint testing will be completed at MTU’s outdoor site (near Hilo, HI). ACQ-treated Southern pine (at three preservative-retention levels) will serve as a benchmark. Actual: (1) Soil-block testing is complete. However, due to unexpectedly promising results from MTU’s testing, further soil-block testing is currently being completed by the U.S. Forest Service Forest Products Laboratory (FPL) to generate more valuable test data. (2) In partnership with FPL, we are hoping to complete future soil-block testing on thermally-modified Eastern hemlock to determine if leaching has any effect on durability. (3) The first-year long-term ground proximity, above-ground lap joint, and L-joint testing field inspections at MTU’s outdoor site have been completed. Problem(s): None.

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Goal/Objective 4.1 Planned: Develop a structured plan targeting technical and non-technical reporting formats. Actual: (1) The soil-block decay results were presented at the American Wood Protection Association (AWPA) Annual Meeting (April 9-11, 2017; Las Vegas, NV), and the project abstract was included in the Proceedings. The presentation and abstract are shown in Appendix 1. (2) The results of the airborne dust study were presented at the Window and Door Manufacturers Association (WDMA) Technical and Manufacturing Conference (June 6-8, 2017; Minneapolis, MN). The presentation is shown in Appendix 2. (3) A summary of the balsam fir soil-block durability test results was presented in the Minnesota Department of Natural Resources (MN DNR) Spring 2017 Marketplace Newsletter (online). The article can be viewed in Appendix 3. Problem(s): None. Goal/Objective 4.2 Planned: Submit final report (also submit annual reports). Actual: The first three annual reports have been submitted. The final report will be submitted upon project completion. Activity Anticipated Next Reporting Period Goal/Objective: We expect 2.2 to be completed. Goal/Objective: We expect 3.1 to be substantially completed. Goal/Objective: We expect the second-year field durability inspections to be completed (3.2). Goal/Objective: We expect to disseminate more project results in a variety of technical and non-technical formats (4.1). Unexpected development: We are partnering with an architect and the University of Minnesota-Extension to design and install a wooden bike shelter in the Destination Medical Center area (Rochester, MN; www.dmc.mn). We expect the shelter will be cladded with thermally-modified ash (donated by a Minnesota company) and will successfully demonstrate the cladding product in a highly-visible environment. Outcomes, Accomplishments, Results Outcomes The greatest outcome is generation of public domain durability data on thermally-modified wood using accepted AWPA testing protocols. The laboratory soil-block durability tests demonstrate that at the higher modification levels (i.e., 180°C/5 bar pressure), the durability against white-rot and brown-rot decay fungi is enhanced. Also, for the first time, field durability performance data for U.S. species are now in the public domain (note: this testing is

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http://www.dmc.mn/

being completed at MTU’s field site near Hilo, HI). Even though the field inspections after the first year of exposure are not conclusive, there will be two more inspections (at the end of years two and three); the expectation is that these inspections will demonstrate that wood thermally modified at higher modification levels performs much better in severe field exposure testing. The physical and mechanical testing completed to date clearly demonstrates that the performance of thermally-modified wood is very species-dependent. These results can be used by manufacturers to identify what specific characteristics need to be considered when designing products for various end-use applications. For example, the improved hardness imparted by thermal-modification processing (with the exception of balsam fir) would be a good attribute when designing an external cladding system. In addition, the dimensional stability of the hardwoods in the study is a significant result that can be applied to the building sector immediately. Accomplishments Public domain documentation of the field durability performance of thermally-modified wood using AWPA testing protocols is fully underway with the first-year exposure results available to the fledgling industry. The completion of the dimensional stability component of the work plan is another important task that provides important benchmarks to the building sector on the effects of equilibrium moisture content on dimensional changes while in service. Often, early adopters of thermal-modification technology have overstated the increased dimensional stability imparted by the process. This study provides evidence that the reduction in dimensional movement is significant, and demonstrates what changes will occur so that producers can properly design new products. The thermally-modified wood manufacturing sector continues to grow, with additional new production in both the Western U.S. and in the Eastern hardwood-containing region. The major wholesale lumber sector has also begun to support further development of the thermal-modification sector, with several manufacturers displaying products at the November 2017 North American Wholesale Lumber Traders Market.

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Results pH. The average pH of select thermally-modified and unmodified specimens was calculated and compared to determine how thermal-modification processing affects wood acidity (Table 1). As expected, the pH of the thermally-modified wood was lower than unmodified wood; however, the pH is still considered benign in regard to human contact.

Material Average pH

Yellow poplar (unmodified) 5.01

Yellow poplar (170°C) 3.50

Balsam fir (unmodified) 4.88

Balsam fir (170°C) 4.01

Red maple (unmodified) 4.66

Red maple (170°C) 3.39

Aspen (unmodified) 4.37

Aspen (170°C) 3.47

White ash (unmodified) 4.47

White ash (170°C) 3.51

Table 1. pH of unmodified and thermally-modified wood.

Hardness. The hardness of the thermally-modified wood was determined according to ASTM D143 (Figures 2 and 3) and compared to unmodified wood, with ten specimens per group and two hardness values per direction (i.e., radial, tangential, end). Statistical differences between test groups were determined via single-sample t-tests, with letters in each hardness direction indicating values that are not statistically different at the 95% significance level (p

As shown in Figure 4, the radial and end hardness of balsam fir dropped substantially when thermally modified, with average reductions of 45% and 27% in the radial and end directions, respectively, when thermally modified at 180°C. There was a 15% reduction in tangential direction hardness when thermally modified at 180°C. As shown in Figure 5, the radial and tangential hardness of Eastern hemlock increased 16% and 14%, respectively, when thermally modified at 170°C, with reductions in hardness when thermally modified at 180°C. The Eastern hemlock also experienced splitting/cracking as treatment temperature increased. Figure 6 shows that red maple experienced minimal changes in radial and tangential hardness when thermally modified; however, the end hardness increased 18% when thermally modified at 170°C. As shown in Figure 7, white ash experienced substantial reductions in hardness when thermally modified at 170°C; however, the hardness increased substantially when treatment temperatures increased to 180°C. The white ash also experienced some splitting as treatment temperature increased. Finally, the radial, tangential, and end hardness of yellow poplar increased 42%, 23%, and 17%, respectively, when thermally modified at 180°C (Figure 8).

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Figure 4. Balsam fir hardness.

Figure 5. Eastern hemlock hardness.

Figure 6. Red maple hardness.

Figure 7. White ash hardness.

Figure 8. Yellow poplar hardness.

Compression Strength Parallel to Grain. The compression strength parallel to the grain was determined according to ASTM D143 (Figure 9) by our project partner, the U.S. Forest Service Forest Products Laboratory (FPL). There were 20 specimens per group. Statistical differences between test groups were determined via ANOVA analysis, with letters in each row indicating values that are not statistically different at the 95% significance level (p

Figure 9. Compression strength testing. Compared to the control specimens, the balsam fir thermally modified at 170°C exhibited very little difference in compression strength; however, there was a 40% increase between the control specimens and those thermally modified at 180°C. Compared to control specimens, the red maple experienced 14% and 23% improvements in compression strength when thermally modified at 170°C and 180°C, respectively. The white ash experienced a 13% reduction in compression strength when thermally modified at 180°C, with the yellow poplar experiencing very little change at either treatment temperature.

Material Maximum Compression Strength, Parallel to Grain (psi)

Control 170°C 180°C

Balsam Fir 4,676 a 4,854 a 6,545 b

Red Maple 6,504 a 7,433 b 8,003 b,c

White Ash 9,547 a 8,639 b 8,265 b,c

Yellow Poplar 6,356 a 6,540 a 6,236 a

Ponderosa Pine 4,539

Table 2. Maximum compression strength of specimens. Letters in each row indicate values that are not statistically different at the 95% significance level (p

Figure 10. Specimens in the environmental chamber.

Figure 11. Measuring length changes. Compared to control specimens, all thermally-modified wood species exhibited substantially lower moisture content after four weeks of exposure, as shown in Table 3.

Material Moisture Content


Red Maple 16.3% 7.7% 7.3%

Eastern Hemlock 17.4% 12.3% 6.8%

Yellow Poplar 16.7% 8.3% 6.6%

Balsam Fir 18.4% 10.5% 8.3%

White Ash 15.6% 8.0% 7.1%

Table 3. Moisture content of specimens after four weeks of exposure at 73°F and 85% relative humidity.

Dimensional Stability: Length Change. Figures 12-16 present the average length change of the specimens after four weeks of exposure at 73°F and 85% relative humidity. As expected, the change in length was minimal, with the red maple control specimens and the white ash thermally modified at 180°C both experiencing the greatest change (0.15%).

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Figure 12. Red maple length change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 13. Eastern hemlock length change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 14. Yellow poplar length change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 15. White ash length change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 16. Balsam fir length change after four weeks of exposure at 73°F and 85% relative humidity.

Dimensional Stability: Width Change. Figures 17-21 present the width change of the specimens after four weeks of exposure at 73°F and 85% relative humidity. In general, compared to the control specimens, the thermally-modified specimens experienced lower increases in width after exposure, with the greatest increases occurring during the first week. As shown in Figure 17, all red maple specimens experienced minimal width increases between Weeks 1 and 4, but the control specimens experienced greater increases (1.75%) after the first week of exposure compared to those thermally modified at 170°C (0.55%) and 180°C (0.49%). The Eastern hemlock also experienced the greatest increase in width after the first week of exposure (Figure

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18), with the control specimens and those thermally modified at 170°C experiencing 1.31% and 0.91% width increases, respectively. As shown in Figure 19, the yellow poplar specimens thermally modified at 170°C and 180°C experienced 0.67% and 0.54% increases in width, respectively, after the first week of exposure. Figure 20 shows that the white ash control specimens experienced a 2.76% increase in width after four weeks of exposure, while the specimens thermally modified at 170°C and 180°C experienced 0.83% and 0.28% width increases, respectively. Similar results were found with balsam fir (Figure 21).

Figure 17. Red maple width change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 18. Eastern hemlock width change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 19. Yellow poplar width change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 20. White ash width change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 21. Balsam fir width change after four weeks of exposure at 73°F and 85% relative humidity.

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Dimensional Stability: Thickness Change. Figures 22-26 present the thickness change of the specimens after four weeks of exposure at 73°F and 85% relative humidity. In general, the thermally-modified specimens experienced lower thickness increases compared to the control specimens, with the greatest increases occurring during the first week. As shown in Figure 22, the thermally-modified red maple specimens experienced minimal thickness increases after four weeks of exposure, with the 170°C and 180°C groups experiencing 0.50% and 0.42% increases in thickness, respectively. The thermally-modified Eastern hemlock (Figure 23) experienced similar thickness increases after four weeks of exposure, with the 170°C and 180°C groups exhibiting 0.68% and 0.55% increases, respectively. Similar results were found with yellow poplar (Figure 24). While the white ash control specimens experienced a 1.45% increase in thickness after four weeks of exposure (Figure 25), the specimens thermally modified at 170°C experienced a 0.71% thickness increase. The specimens thermally modified at 180°C experienced nearly 0% thickness increase. As shown in Figure 26, the balsam fir control specimens experienced a 1.37% increase in thickness during the first week of exposure, while the specimens thermally modified at 170°C and 180°C experienced 0.58% and 0.48% increases in thickness, respectively, during the same period.

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Figure 22. Red maple thickness change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 23. Eastern hemlock thickness change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 24. Yellow poplar thickness change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 25. White ash thickness change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 26. Balsam fir thickness change after four weeks of exposure at 73°F and 85% relative humidity.

Dimensional Stability: Volume Change. Figures 27-31 present the volume change of the specimens after four weeks of exposure at 73°F and 85% relative humidity. As expected, the largest volume increases for all specimens occurred during the first week of exposure. The volume changes for the red maple (Figure 27), yellow poplar (Figure 29), and white ash (Figure 30), whether thermally modified at 170°C or 180°C, varied little.

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Figure 27. Red maple volume change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 28. Eastern hemlock volume change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 29. Yellow poplar volume change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 30. White ash volume change after four weeks of exposure at 73°F and 85% relative humidity.

Figure 31. Balsam fir volume change after four weeks of exposure at 73°F and 85% relative humidity.

The average volume of the specimens across the entire four-week exposure period is presented in Table 4. Statistical differences between test groups were determined via a repeated measures ANOVA analysis, with letters in each row indicating values that are not statistically different at the 95% significance level (p

volume of all white ash specimens, regardless of treatment, were different, while the average volume of the Eastern hemlock specimens thermally modified at 180°C was statistically different than those thermally modified at 170°C.

Material Average Volume (in3)


Balsam Fir 27.76 a 27.38 b 27.84 a,c

Red Maple 28.00 a 27.27 b 27.28 b,c

White Ash 28.07 a 27.30 b 27.53 c

Yellow Poplar 28.13 a 27.33 b 27.29 b,c

Eastern Hemlock 27.55 a,b 27.75 a 27.44 b

Table 4. Average volume of specimens during a four-week exposure at 73°F and 85% relative humidity.

Durability: Soil-Block. While laboratory soil-block testing was already completed by MTU, unexpectedly promising results led us to complete further testing to generate more valuable test data for the thermally-modified balsam fir and Eastern hemlock. This testing was completed by the U.S. Forest Service Forest Products Laboratory (FPL) according to the American Wood Protection Association (AWPA) E10 test standard with two brown-rot (G. trabeum, P. placenta) and two white-rot (I. lacteus, T. versicolor) fungi. Figures 32 and 33 show test specimens colonized by fungi.

Figures 32-33. Specimens colonized by fungi during AWPA E10 soil-block durability testing.

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Figures 34-37 present a summary of the soil-block durability results.

Figure 34. Soil-block durability of wood specimens subjected to G. trabeum (BF = balsam fir, EH = Eastern hemlock), with standard deviation noted by bars.

Figure 35. Soil-block durability of wood specimens subjected to P. placenta (BF = balsam fir, EH = Eastern hemlock), with standard deviation noted by bars.

Figure 36. Soil-block durability of wood specimens subjected to T. versicolor (BF = balsam fir, EH = Eastern hemlock), with standard deviation noted by bars.

Figure 37. Soil-block durability of wood specimens subjected to I. lacteus (BF = balsam fir, EH = Eastern hemlock), with standard deviation noted by bars.

In general, there is a near-linear trend in durability improvement when the balsam fir and Eastern hemlock were subjected to the brown-rot fungi; however, there was more variability in the decay trends when the specimens were subjected to the white-rot fungi. As can be seen, thermal-modification processing greatly improved the durability of balsam fir when subjected to all fungi, with the greatest improvements (i.e., lowest weight loss) occurring in the 180°C treatment group. Balsam fir, when thermally modified at 180°C and exposed to G. trabeum, had 9.74% weight loss, which is an 84.0% improvement over the control specimens (Figure 34). Similar results were found when balsam fir was exposed to P. placenta (Figure 35) and T. versicolor (Figure 36). The Eastern hemlock also experienced substantial durability improvements when thermally modified at 180°C. However, when it was thermally modified at 170°C and exposed to I. lacteus (Figure 37), it experienced 12.7% weight loss, compared to 6.65% weight loss in the control specimens. Durability: Field Testing, Ground-Proximity Test. White ash, aspen, and balsam fir that was thermally modified at 170°C and 180°C, in addition to untreated ponderosa pine and Southern pine controls, were subjected to ground-proximity decay testing. Yellow poplar and red maple

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specimens that were thermally modified at 170°C and matched untreated control specimens pressure treated to a target retention of 4.5 kg/m3 disodium octaborate tetrahydrate (DOT) were also subjected to decay testing. The Southern pine was pressure-treated to a target retention of 1.0 kg/m3, 2.0 kg/m3, or 4.0 kg/m3 with ACQ-C. The ponderosa pine was dip-treated for three minutes using Woodtreat Millwork® at a 4:1 aqueous dilution of the concentrate. After these treatments were completed, all decay blocks were uniquely labelled using stainless steel ID tags and fasteners. The field-ready blocks were then shipped to the test site (near Hilo, HI) and installed in an AWPA E18 decay test. The specimens were then visually evaluated for decay and insect attack after one year of exposure. Statistical analysis on the data was performed using JMP Pro 13. A summary of major findings is presented below. The full test report from MTU can be viewed in Appendix 4.

1. There was visible decay among all untreated wood control types. The most severe decay occurred among the balsam fir control specimens. Decay amongst the hardwood species control specimens was comparable to one another.

2. Preliminary results seem to indicate that thermal modification at 170°C did not significantly improve the decay resistance of yellow poplar, white ash, or aspen. It did, however, improve the decay resistance of red maple and balsam fir.

3. Preliminary results seem to indicate that thermal modification at 180°C significantly improved the decay resistance of all species. Higher treatment temperatures did not improve the decay resistance of aspen or balsam fir.

4. There appeared to be no significant improvement in protection against decay among the yellow poplar with DOT treatments. There was a marked improvement in decay resistance among the red maple treated with DOT, but no apparent synergy between the DOT and thermal (170°C) treatment existed.

5. There was minor, non-termite insect attack among the decay specimens. Durability: Field Testing, Lap Joint Test. Yellow poplar, red maple, white ash, aspen, and balsam fir that was thermally modified at 170°C and 180°C, in addition to untreated ponderosa pine and Southern pine controls, were subjected to lap joint decay testing. Yellow poplar and red maple specimens that were thermally modified at 170°C and matched untreated control specimens pressure treated to a target retention of 4.5 kg/m3 DOT were also subjected to decay testing. The Southern pine was pressure-treated to a target retention of 1.0 kg/m3, 2.0 kg/m3, or 4.0 kg/m3 with ACQ-C. The ponderosa pine was dip-treated for three minutes using Woodtreat Millwork® at a 4:1 aqueous dilution of the concentrate. After these treatments were completed, all decay blocks were uniquely labelled using stainless steel ID tags and fasteners. The field-ready blocks were then shipped to the test site (near Hilo, HI) and installed in an AWPA E16 decay test. The specimens were then visually evaluated for decay and insect attack after one year of exposure. Statistical analysis on the data was performed using JMP Pro 13.

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A summary of major findings is presented below. The full test report from MTU can be viewed in Appendix 5.

1. There was visible decay among all untreated control types. The most decayoccurred among the red maple control specimens, and the least among the whiteash. Decay amongst the yellow poplar, aspen, and balsam fir specimens wascomparable to one another.

2. Preliminary results seem to indicate that thermal modification at 170°C did notsignificantly improve the decay resistance of the hardwood species. It did, however,improve the decay resistance of balsam fir.

3. Preliminary results seem to indicate that thermal modification at 180°C significantlyimproved the decay resistance of the hardwood species, except white ash. Therewas no further benefit to decay resistance of balsam fir with increased treatmenttemperature.

4. There appeared to be no significant protection against decay among the yellowpoplar DOT control lap joints; however, there was a marked improvement in decayresistance among the red maple DOT control lap joints compared to the untreatedcontrol specimens. Secondary DOT treatment of both yellow poplar and red maplelap joints thermally modified at 170°C appeared to provide more decay resistancethan either DOT or thermal modification at 170°C, separately. These lap joint typesperformed comparably to the yellow poplar and red maple lap joints thermallymodified at 180°C.

5. There was minor, non-termite insect attack among the yellow poplar lap joints, andminor to moderate insect attack among the aspen and balsam fir lap joints.

Durability: Field Testing, L-Joint Test. Yellow poplar, red maple, white ash, aspen, and balsam fir that was thermally modified at 170°C and 180°C, in addition to untreated ponderosa pine and Southern pine controls, were subjected L-joint decay testing. Yellow poplar and red maple specimens that were thermally modified at 170°C and matched untreated control specimens pressure treated to a target retention of 4.5 kg/m3 DOT were also subjected to decay testing. The Southern pine was pressure-treated to a target retention of 1.0 kg/m3, 2.0 kg/m3, or 4.0 kg/m3 with ACQ-C. The ponderosa pine was dip-treated for three minutes using Woodtreat Millwork® at a 4:1 aqueous dilution of the concentrate. After these treatments were completed, all L-joints were painted with white exterior latex paint (Sherwin Williams A100®) (Cleveland, OH) and the outside ends were sealed with Epoxy King SC110® UV-resistant, marine-grade epoxy (ResTech Environmental Products, LLC; Addison, TX). After drying, the painted L-joints were assembled and uniquely labelled using stainless steel ID tags and fasteners.

The field-ready specimens were then shipped to the test site (near Hilo, HI) and installed in an AWPA E9 decay test. The specimens were then visually evaluated for decay and insect attack after one year of exposure. Evaluations were performed and reported separately for the mortise and tenon. Statistical analysis on the data was performed using JMP Pro 13. Figure 38 shows the L-joint test specimens at the test site near Hilo, HI.

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Figure 38. L-joint test specimens near Hilo, HI. A summary of major findings is presented below. The full test report from MTU can be viewed in Appendix 6.

1. There was visible decay among all untreated wood control types. The most severe decay was seen among the yellow poplar, red maple, and aspen control specimens, which had comparable decay. The white ash and balsam fir control specimens had less visible decay that was comparable to each other.

2. Preliminary results seem to indicate that thermal modification at 170°C and 180°C significantly improved the decay resistance of all species. There was no further benefit to the decay resistance with increased treatment temperature.

3. Synergies between DOT and thermal treatment at 170°C were tested using yellow poplar and red maple. L-joints that were either unmodified (DOT control) or thermally modified at 170°C were treated with DOT at the recommended above-ground retention for Southern pine. All combinations of thermal modification and/or DOT improved the decay resistance of both yellow poplar and red maple. The treatments were equivalent to one another for each species.

4. L-joints thermally modified at 170°C or 180°C had decay resistance comparable to Southern pine L-joints treated with ACQ-C and with ponderosa pine treated with Woodtreat Millwork®.

5. There was minor, non-termite insect attack among the red maple L-joints.

21

Appendix 1 American Wood Protection Association (AWPA), Annual Meeting

Presentation and Abstract April 9-11, 2017 Las Vegas, NV

22

Biological Durability of Hygrothermally Modified Hardwoods and Softwoods

AWPA Annual MeetingApril 9-11, 2017

Matthew Aro, Dana Richter, Glenn Larkin, Suzanne French, Erik Keranen, Peter Laks

23

What do we know now?

24

Reduce the ability of wood to absorb water, and you reduce water’s effects

when in contact with wood.

25

The Good News

• We know that water likes to bond tohemicellulose

• We also know that hemicellulose is a majorfood source for fungi and bacteria

So, is there a way to remove some of the hemicellulose??

26

Thermal Modification (TM)

• Chemical-free process that chemically modifieswood cell walls

– Heat wood to ~160 – 220°C in an O2-deprivedenvironment

• Destroys some hemicellulose

• Removes H2O-absorbing OH- groups

• Works with hardwoods and softwoods

27

• ~40 – 60% decrease in equilibrium moisture content (EMC)

• ~30 – 50% increase in dimensional stability (less swelling/shrinkage)

Benefits

Sources: Ohlin Thermo Tech 2010, Welzbacher et al. 2007, Jämsä and Viitaniemi 2001, Paul et al. 2006, Syrjanen and Kangas 2000, Donahue et al. 2011.

• Increase in fungal decay resistance

• 5 – 15% reduction in thermal conductivity (due to lower density)

• Consistent darkening of wood

28

• Decreased bending strength

• Reduced hardness (usually)

• Reduced density

• Reduced splitting strength

Tradeoffs

• Increased brittleness

29

NRRI’s Thermal Modification Pilot Plant

30

Wood thermally

modified at 170C

and 180C 31

Black Ash

Source: Dr. Mat Leitch, Lakehead University

32

Materials• Yellow poplar

– Untreated control, TM 170C, 180C, 170C + disodium octaborate tetrahydrate (DOT)*, DOT*

• Red maple– Untreated control, 170C, 180C, 170C + DOT*, DOT*

• White ash, aspen, balsam fir– Untreated control, 170C, 180C

• Ponderosa pine– Untreated control, IPBC/TEB/PPZ-SB-1** dip

• Southern pine– Untreated control, ACQ-1, ACQ-2, ACQ-4***

• Birch– Untreated control

*DOT target retention = 4.5 kg/m3; **mineral spirits formulation of IPBC, tebuconazole, and propiconazole in a 1/1/1 ratio at a

total active ingredient concentration of 0.63%; ***1 kg/m3, 2 kg/m3, 4 kg/m3 target retention33

AWPA E10 (soil block)

• Brown rot

– Gloeophyllum trabeum (tolerant to creosote and other phenolics)

– Postia placenta (copper tolerant)

• White rot

– Trametes versicolor (resistant to borates)

– Irpex lacteus (very aggressive)

34


Soil block decay testing is conducted under sterile conditions using pure cultures of standard wood decay fungi. 35

Fungus Culture

36


Decay is based on mass loss in 19mm cubes

1. Dry blocks at 40°C for 24 hours

2. Weigh blocks (approx. 3-5 grams)

3. Inoculate with fungus

4. Incubate for 12 weeks

5. Remove, dry, and weigh. Calculate weightloss (typically 0-70%).

38

Results

• Controls and preservative benchmarks

– Untreated Controls: Weight losses demonstrategood fungal vigor

– Benchmarks: Demonstrate efficacy against testedfungi

Ponderosa pine (IPBC/TEB/PPZ-SB-1)

Southern yellow pine (ACQ)

• 3-minute dip• Weight loss = 3.6 to 14.7%

• Pressure-treated (1.0, 2.0, 4.0kg/m3)

• Weight loss for 4.0 kg/m3 = 3.7to 5.3%

• Dose response most evident forPostia placenta (Cu tolerant)

39

Thermal modification reduced weight loss

• Trametes versicolor – 170°C TM: 30-60% weight loss reduction

– 180°C TM: 50% weight loss reduction (except

white ash)

– 180°C TM:

Synergy of TM + borate (DOT) not demonstrated

• Trametes versicolor

– Borate reduced weight loss

– Yellow poplar: TM + DOT weight loss < DOT

– Red maple: TM + DOT weight loss > DOT

• Irpex lacteus

– Borate reduced weight loss

– Yellow poplar: TM + DOT weight loss > DOT

– Red maple: TM + DOT weight loss > DOT

Results: White Rot Fungi

41

Thermal modification reduced weight loss

• Gloeophyllum trabeum – 170°C TM: large weight loss reduction (except yellow

poplar)

– 180°C TM: 50% weight loss reduction (except white

ash)

– 180°C TM:

Conclusions

• Soil block decay tests were successful based on high untreated control weight losses

• Wood modified at higher temperatures (generally) experienced less decay

• TM at 180C (generally) as effective as benchmark preservative systems for reducing weight loss from fungal decay

49

Thank you.

This work was financially supported by the U.S. Department of Agriculture, Wood Education and Resource Center under grant no. 15-DG-11420004-082.

50

Biological Durability of Hygrothermally Modified Hardwoods and Softwoods

Matthew Aro

Suzanne French University of Minnesota-Duluth

Duluth, Minnesota

Dana Richter Glenn Larkin Erik Keranen

Peter Laks Michigan Technological University

Houghton, Michigan

ABSTRACT Yellow poplar, red maple, white ash, aspen, and balsam fir were hygrothermally modified at 170 and 180 degrees Celsius

(C) prior to undergoing soil block decay tests to determine durability. The yellow poplar and red maple were also co-treated with a borate preservative to examine the effects of a hygrothermal modification-borate co-treatment. Ponderosa pine treated with IPBC/TEB/PPZ-SB-1 preservative and Southern yellow pine treated with ACQ preservative were used as performance benchmarks.

When subjected to T. versicolor (white rot), all species thermally modified at 170C experienced a 30-60% weight loss reduction, while all species thermally modified at 180C experienced less than 10% weight loss. When subjected to I. lacteus (white rot), all species (except white ash) thermally modified at 170C experienced greater than 50% weight loss reduction. All species (except aspen) thermally modified at 180C experienced less than 15% weight loss. When the thermally modified yellow poplar and red maple was co-treated with a borate preservative, there was no improvement in weight loss when subjected to both T. versicolor and I. lacteus.

When subjected to G. trabeum (brown rot), all species (except yellow poplar) thermally modified at 170C experienced large weight loss reductions, while all species (except aspen) thermally modified at 180C experienced less than 10% weight loss. When subjected to P. placenta (brown rot), all species (except white ash) thermally modified at 170C experienced greater than 50% weight loss reduction, while all species (except red maple) thermally modified at 180C experienced less than 20% weight loss.

Overall, the wood treated at 180C generally resisted decay better than the wood treated at 170C, with some in-species variation in durability performance depending on the treatment temperature and presence of borate preservative.

52

Appendix 2 Window and Door Manufacturers Association, Technical & Manufacturing Conference

Presentation June 6-8, 2017

Minneapolis, MN

51

Airborne Dust from Thermally Modified WoodThe Latest Research

Matthew AroStephen Monson Geerts

Suzanne FrenchMeijun Cai

2017 WDMA Technical & Manufacturing Conference 53

Agenda

• Introduction to the Natural Resources Research Institute (NRRI)

• What is thermal modification?

• Applications of thermally modified wood

• Analysis of thermally modified wood dust

• Results and discussion

54

NRRI Mission

To deliver research solutions to balance our economy, resources and environment for resilient communities

55

Agenda






57

Why is wood a goodbuilding material?

• Renewable/sustainable

• Carbon-neutral (hot topic!)

• Relatively lightweight (easy to move/transport)

• High strength/weight ratio

• “Easy” to repair/maintain

• Looks good!

58

Some Problems with Wood

• Hygroscopic (absorbs water)

–Leads to swelling and shrinking

• Subject to biological decay (rot) if notprotected from the weather/moisture

–Mold and decay fungi

–Bacteria, insects (termites!)

• Flammable

59

Composition of Wood

~A brief review~

60

Wood Structure

Source: C. Staalner.

61

Wood Structure

The bound water is the water that makes wood rot and decay!

Source: C. Staalner.

62

Thermal Modification

• Chemical-free process that chemically modifies wood cell walls

–Heat wood to ~150 – 220°C in an O2-deprived environment

• Destroys some hemicellulose

• Removes H2O-absorbing OH- groups

• Works with hardwoods and softwoods

63

What is really happening when you heat wood?

64

160 – 220°CHemicellulose decomposition(results in relative increase in lignin content)

Crystalline cellulosedecomposition

~300-340°C

Cellulose crystallization (perhaps some decomposition)

>160°C

Lignin decomposition>280°C

65

These changes reduce H2O penetration, help prevent swelling and shrinking, reduce EMC,

and increase biological durability.

66

Change in performance properties is determined by treatment intensity!

Treatment intensity is a function of:

• Time in the kiln

• Temperature

• Atmospheric conditions/air compositioninside kiln

• Species

• Moisture content of wood

67

• ~40 – 60% decrease in equilibriummoisture content

• ~30 – 50% increase in dimensionalstability

Benefits

Sources: Ohlin Thermo Tech 2010, Welzbacher et al. 2007, Jämsä and Viitaniemi 2001, Paul et al. 2006, Syrjanen and Kangas 2000, Donahue et al. 2011.

• Increase in decay resistance

• 5 – 15% reduction in thermalconductivity (due to lower density)

• Consistent darkening of wood

68

• Decreased bending strength

• Reduced hardness (usually)

• Reduced density

• Reduced splitting strength

Concerns

• Increased brittleness

69

Agenda






70

Applications

71

Applications

Source: www.m-sora.si

Thermally-Modified Spruce72

Source: www.tmt.ihd-dresden.de

73

Source: Masonite.com

74

Agenda

• Introduction to the Natural ResourcesResearch Institute (NRRI)





75

The Potential Problem

• Thermally modified wood is more brittlethan unmodified wood

• Anecdotal reports suggest that dustproduced when sawing/sandingthermally modified wood is finer thanunmodified wood

• Is the airborne dust really different?

• If it is different, would it requireupgrades to dust extraction systems? 76

The Fundamental Question

Is the airborne dust particle size of thermally modified wood

really different?

77

Our Study

• Materials

–Aspen, red maple, white ash, yellow poplar, balsam fir

• Thermal modification method

– Thermally modified at 170°C in a pressurized (“closed”) IWT/Moldrup hygrothermal modification kiln (75-110 min)

78

Our Study

• Sawing method– Delta®/Rockwell Unisaw (model no. 126-600P)

equipped with a 12-in Freud Diablo D1244x 44-tooth carbide-tip saw blade (maximum RPM 3000)

– Grizzly® dust collector (model no. 8718046) with a maximum 2,300 CFM air flow on during entire sawing operation

– 1-inch-thick boards (random widths and lengths) were rip-cut for 30 minutes

81

Our Study

• Aerosol (airborne dust) sampling method– Dust sampled using 10-stage Micro-Orifice

Uniform Deposit Impactor (MOUDI)

– Vacuum pump draws air (30 L/min) through MOUDI, impacting dust onto foil substrates in particle cut sizes from 18 to 0.056 μm

– Wood dust particles then separated into common fractions (PM10, PM2.5, PM1)

83





• Results and conclusions

Agenda

91

Results

• Particle size differences statistically compared via two-sample, non-parametric Kolmogorov-Smirnov (K-S)

• NO statistically significant difference (p

Discussion

• Focused on what airborne sizefractions might exist in a zone adjacentto an equipment operator

• PM10 particles can get deep into lungsand possibly the bloodstream

• Consistent association between PM2.5exposure and cardiopulmonary and lung cancer mortality

• Study not meant to assess health risks 100

Discussion

• Results suggest that enhanced dustextraction equipment/efficiency maynot be necessary to effectively collectairborne dust produced when sawingthe studied wood species whenthermally modified at 170°C

• More research needed to assess risk ofwood thermally modified at othertemperatures

101

Thank you.

This work was financially supported by the U.S. Department of Agriculture, Wood Education and Resource Center under grant no.

15-DG-11420004-082. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the

authors and do not necessarily reflect the views of the U.S. Department of Agriculture.

102

Appendix 3 Minnesota Department of Natural Resources, Marketplace Newsletter

Spring 2017

103

Appendix 4 Michigan Technological University

AWPA E18, Standard Field Test for Evaluation of Wood Preservatives to be Used Above Ground (UC3B); Ground Proximity Decay Test

Year 1 Inspection Report

107

Matt Aro Natural Resources Research Institute 5013 Miller Trunk Highway Duluth, MN 55811

February 28, 2018

Dear Matt,

This letter serves as the first report for Project E48057B, Adding Value to Small-Diameter Hazardous Fuels Through Thermal Modification (E18). The data reporting for Project E48057 had been separated into three parts: Project E48057B constitutes the ground proximity decay test, Project E48057C constitutes the L-Joint decay test, and Project E48057A constitutes the lap joint decay test. The decay blocks were evaluated on February 2, 2018 at the Michigan Tech Wood Protection Group (WPG) Kipuka Field Test Site near Hilo, HI. Kipuka site characteristics, climate data during the exposure period, and the test exposure history are included in Appendix A. Test data is summarized in Figures 1 and 2 and tabulated data is attached as Appendix B.

Decay Blocks (12 Months, Evaluation 1 of 3 for Current Contract)

The Natural Resources Research Institute at the University of Minnesota at Duluth (NRRI) prepared ground proximity decay blocks from four deciduous and three conifer species. The hardwoods are yellow poplar (Liriodendron tulipifera), red maple (Acer rubrum), white ash (Fraxinus americana), and aspen (Populus tremuloides). Each of these species was modified by thermal treatment at 170°C or 180°C. Balsam fir (Abies balsamea) was also subjected to the thermal treatments. Ponderosa (Pinus ponderosa) and southern (Pinus spp.) were prepared, without thermal treatment as controls. The decay blocks were shipped to the WPG in Houghton, MI for additional processing.

Yellow poplar and red maple blocks that were thermally treated at 170°C and matched untreated controls were pressure treated to a target retention of 4.5 kg/m3 disodium octaborate tetrahydrate, DOT. The southern pine was pressure-treated to a target retention of 1.0 kg/m3, 2.0 kg/m3, or 4.0 kg/m3 with ACQ-C.1 The ponderosa pine was dip-treated for three minutes using Woodtreat Millwork®2 at a 4:1 aqueous dilution of the concentrate. After these treatments were completed, all decay blocks were uniquely labelled using stainless steel ID tags and fasteners.

1 Current Version: AWPA Standard P28-14, Standard for Alkaline Copper Quat Type C (ACQ-C), American Wood Protection Association (2017) Birmingham, AL USA. 2 Woodtreat Millwork is a registered trademark of Kop-Coat (Pittsburgh, PA). The active biocides are 3-Iodoprop-2-yn-1-yl butylcarbamate (IPBC), tebuconazole, and propiconazole.

108

The field-ready blocks were shipped to the test site near Hilo, HI, and installed in an AWPA E183 decay test during February 2017. Sue French (NRRI) was present and assisted. They were visually evaluated for decay and insect attack as shown in Table A2 (Appendix A). Statistical analysis on the data was performed using JMP Pro 13.4 At 12 months of field exposure:

A. There was visible decay among all the untreated wood control types (Figure 1). The most severe decay occurred among the balsam fir controls. Decay amongst the hardwood species controls were comparable to one another.

B. Preliminary results (Figure 1) seem to indicate that thermal modification at 170°C did not significantly improve the decay resistance of yellow poplar, white ash, or aspen. It did, however improve the decay resistance of red maple and balsam fir.

C. Preliminary results (Figure 1) seem to indicate that thermal modification at 180°C significantly improved the decay resistance of all species in this test. Higher treatment temperature did not improve the decay resistance of aspen and balsam fir.

Figure 1. Box plot showing the effect of thermal modification at 170°C (TM 170) or 180°C (TM 180) on the decay resistance of wood after it has been exposed in an AWPA E18 decay test at the WPG Kipuka Field Test Site near Hilo, HI, for a period of 12 months. The dots indicate outliers. When the minimum or maximum value are not part of the box or an outlier, they are indicated by the whiskers. Lines dividing the inside of the boxes are medians. In this instance some medians are equal to the first or third quantiles that define the lower and upper box borders. 3 Current Version: AWPA Standard E18-15, Standard Field Test for Evaluation of Wood Preservatives to Be Used Above Ground (UC3B); Ground Proximity Decay Test, American Wood Protection Association (2017) Birmingham, AL USA. 4 JMP Pro 13 (2016) SAS Institute Inc., Cary NC, USA

Visua

l Dec

ay Ra

ting

0

2

4

6

8

10

Control TM 170 TM 180Treatment

Yellow Poplar

Red MapleWhite AshAspenBalsam Fir

109

Figure 2. Box plot showing the effect of DOT and/or thermal modification at 170°C (TM 170 + DOT) on the decay resistance of yellow poplar and red maple exposed in an AWPA E16 decay test at the WPG Kipuka Field Test Site near Hilo, HI, for a period of 12 months. The dots indicate outliers. When the minimum or maximum value are not part of the box or an outlier, they are indicated by the whiskers. Lines dividing the inside of the boxes are medians. In this instance the medians are equal to the first or third quantiles that define the lower and upper box borders.

D. Synergies between DOT and thermal treatment were tested using yellow poplar and red maple (Figure 2). Decay blocks that were either unmodified by thermal treatment (DOT control) or modified by treatment at 170°C were treated with DOT at the recommended above ground retention for southern pine. There appeared to be no significant improvement in protection against decay among the yellow poplar blocks with DOT treatments. There was a marked improvement in decay resistance among the red maple blocks treated with DOT, but no apparent synergy between the DOT and thermal (170°C) treatments. Thermal treatment at 180°C appeared to be more effective for improving decay resistance during the ground proximity exposure than the DOT treatments.

E. Decay blocks modified by thermal treatment at 170°C had lower apparent decay resistance than southern pine blocks treated at the lowest retention of ACQ-C. Blocks modified by thermal treatment at 180°C had decay resistance comparable to southern pine treated at all retentions of ACQ-C and ponderosa pine treated with Woodlife 111 (Table B1, Appendix B).

F. There was minor, non-termite, insect attack among the decay blocks.

The next evaluation (2 of 3) is scheduled during February 2019 at 24 months of field exposure.

Visua

l Dec

ay Ra

ting

0

2

4

6

8

10

Control DOT DOT + TM 170 TM 170 TM 180Treatment

Yellow Poplar

Red Maple

110

I welcome your questions or comments and may be reached by telephone at (906) 487-3316 or e-mail at [email protected]. Dr. Xinfeng Xie, WPG Group Leader, may be reached at (906) 487-2294 or [email protected].

Yours truly,

Glenn M. Larkin Sr. Research Scientist Wood Protection Group

Cc: File: E48057B

111

Appendix A: Test Site Information and Project Exposure History

112

TestSite Location ClimateStation StationNumber SchefferIndexKipuka Kea'au,HI(USA) HiloInt'lAirport 511492 3220mm 127" 23⁰C 74⁰F 330 SiltyClayLoam HiloSeries Alternaria spp. Mold/SoftRot Xylocopa spp. CarpenterBee

Antrodiavaillantii BrownRot

Antrodiaxantha BrownRot

Cladosporium spp. Mold/SoftRot

Coniophora spp. BrownRot

Curvularia spp. Mold/SoftRot

Dacrymyces spp. BrownRot

Epicoccum spp. Mold/SoftRot

Fusarium spp. Mold/SoftRot

Hyphoderma spp. WhiteRot

Neolentinuslepideus BrownRot

Paecilomyces spp. Mold/SoftRot

Penicillium spp. Mold/SoftRot

Perenniporiatephropora WhiteRot

Phanaerochaete spp. WhiteRot

Pleurotusostreatus WhiteRot

Pycnoporuscinnabarinus WhiteRot

Sistotrema spp. BrownRotTrichoderma spp. Mold/SoftRot

FigureA1.Measured(blue)andmeanhistorical(red)monthlyprecipitationattheWPGKipukaFieldTestSite(red)duringthefieldexposure. FigureA2.Measuredmean(blue)andmeanhistorical(red)monthlytemperatureattheWPGKipukaFieldTestSite(red)duringthefieldexposure.

TestSite Project# TestMethod WPGSOP SpecimenType Installation/RenewalDate InspectionDateKipuka E48057B AWPAE18 565 DecayBlocks February2017 ---

--- Feb'2018

ProjectNameAddingValuetoSmall-DiameterHazardousFuelsThroughThermalModification(AWPAE18)

TableA2.ExposureandInspectionHistoryofSpecimensExposedinanAWPAE18TestattheWPGKipukaFieldTestSitenearHilo,HI

TableA1.SummaryofWPGKipukaFieldTestSiteCharacteristicsMeanAnnualPrecipitation MeanAnnualTemperature SoilType KnownFungi* KnownInsects*

*IsolatedorobservedbyWPG

0.0

100.0

200.0

300.0

400.0

500.0

600.0

February March April May June July August September October November December January

2017 2018

Prec

ipita

tion

(mm

)

Month/Year

Recorded

Historical

20.0

21.0

22.0

23.0

24.0

25.0

26.0

27.0

28.0

29.0

30.0


2017 2018

Tem

pera

ture

(oC)

Month/Year

Recorded

Historical

113

Appendix B: Ground Proximity Decay Test Data

114

Type Species 170 180 DOTb ACQ-Cc WoodtreatMillworkd Decay Insect1 --- + --- --- --- 10 102 + --- --- --- --- 8.1 103 + --- 4.5 --- --- 9.0 104 --- --- 4.5 --- --- 8.6 9.65 --- --- --- --- --- 8.5 9.66 --- + --- --- --- 9.9 107 + --- --- --- --- 8.9 108 + --- 4.5 --- --- 9.7 109 --- --- 4.5 --- --- 9.6 1010 --- --- --- --- --- 7.2 1011 --- + --- --- --- 10 1012 + --- --- --- --- 9.0 9.913 --- --- --- --- --- 8.7 9.922 --- + --- --- --- 9.9 1023 + --- --- --- --- 9.5 9.924 --- --- --- --- --- 8.1 9.714 --- + --- --- --- 9.6 1015 + --- --- --- --- 10 1016 --- --- --- --- --- 7.5 9.917 PonderosaPine --- --- --- --- N/A 9.7 1018 --- --- --- 1.0 --- 9.5 1019 --- --- --- 2.0 --- 10 1020 --- --- --- 4.0 --- 10 1021 --- --- --- --- --- 9.4 10

Aspen

dWoodtreatMilworkisaregisteredtrademarkofKop-Coat(Pittsburgh,PA)

Feb'18(12Mos.)TableB1.MeanVisualRatingsforThermallyModifiedWoodExposedinanAWPAE18TestnearHilo,HI.(Project48057B)a

cACQ-C=AmmoniacalCopperQuatTypeC

DecayBlock ThermalModification(oC) PreservativeTargetRetention(kg/m3)

aExposureisattheWPGKipukaFieldTestSitebDOT=disodiumoctaboratetetrahydrate

YellowPoplar

Redmaple

WhiteAsh

BalsamFir

SouthernPine

115

Type Species 170 180 DOTb ACQ-Cc WoodtreatMillworkd "P"Series Decay Insect7041 10 107042 10 107043 10 107044 10 107045 10 107046 10 107047 10 107048 10 107049 10 107050 10 10Mean 10 10STDEV 0.0 0.0

STDERR 0.0 0.07051 10 107052 10 107053 9 107054 7 107055 0 107056 10 107057 8 107058 8 107059 10 107060 9 10Mean 8.1 10STDEV 3.0 0.0


STDERR 0.2 0.07071 9 107072 8 97073 9 107074 8 107075 8 97076 9 107077 8 97078 9 107079 8 97080 10 10Mean 8.6 9.6STDEV 0.7 0.5

STDERR 0.2 0.27081 10 107082 8 97083 8 107084 9.5 107085 9 107086 7 87087 8 107088 7 97089 9 107090 9 10Mean 8.5 9.6STDEV 1.0 0.7

STDERR 0.3 0.2

--- ---

--- ---

--- ---

5 YellowPoplar --- --- --- --- ---

+ --- 4.5

2 YellowPoplar + --- ---

3 YellowPoplar

1 YellowPoplar --- + ---

Feb'18(12Mos.)ThermalModification(oC) PreservativeTargetRetention(kg/m3)TableB2.MeanVisualRatingsforThermallyModifiedWoodExposedinanAWPAE18TestnearHilo,HI.(Project48057B)a

LapJoint

--- ---

4 YellowPoplar --- --- 4.5

116

Type Species 170 180 DOT ACQ-C WoodtreatMilwork "P"Series Decay Insect7091 10 107092 9 107093 10 107094 10 107095 10 107096 10 107097 10 107098 10 107099 10 107100 10 10Mean 9.9 10STDEV 0.3 0.0





STDERR 0.2 0.0

4.5 --- ---

10

8 RedMaple + --- 4.5

--- ---

--- ---

9 RedMaple --- ---

RedMaple --- --- --- --- ---

+ ---

--- ---

6 RedMaple ---

TableB2.MeanVisualRatingsforThermallyModifiedWoodExposedinanAWPAE18TestnearHilo,HI.(Project48057B)-ContinuedLapJoint ThermalModification(oC) PreservativeTargetRetention(kg/m3) Feb'18(12Mos.)

7 RedMaple +

--- ---

117

Type Species 170 180 DOT ACQ-C WoodtreatMilwork "P"Series Decay Insect7141 10 107142 10 107143 10 107144 10 107145 10 107146 10 107147 10 107148 10 107149 10 107150 10 10Mean 10 10STDEV 0.0 0.0



STDERR 0.3 0.1

WhiteAsh + --- ---

11 WhiteAsh --- + --- --- ---

--- ---

13 WhiteAsh --- --- ---


--- ---

12

118




STDERR 0.2 0.2


22 Aspen --- + --- --- ---

23 Aspen + --- --- --- ---

24 Aspen --- --- --- --- ---

119


STDERR 0.2 0.07181 10 107182 10 107183 10 107184 10 107185 10 107186 10 107187 10 107188 10 107189 10 107190 10 10Mean 10 10STDEV 0.0 0.0


STDERR 0.6 0.1

14 BalsamFir --- + --- --- ---

---

BalsamFir --- --- ---

LapJoint ThermalModification(oC) PreservativeTargetRetention(kg/m3)

---

--- ---

15 BalsamFir + --- ---

16

Feb'18(12Mos.)TableB2.MeanVisualRatingsforThermallyModifiedWoodExposedinanAWPAE18TestnearHilo,HI.(Project48057B)-Continued

120






STDERR 0.2 0.0

dWoodtreatMilworkisaregisteredtrademarkofKop-Coat(Pittsburgh,PA)

aExposureisattheWPGKipukaFieldTestSitebDOT=disodiumoctaboratetetrahydratecACQ-C=AmmoniacalCopperQuatTypeC

--- --- --- 4.0 ---

18 SouthernPine --- --- --- 1.0

--- N/A

2.0 ---

--- ---


---

20 SouthernPine

21 SouthernPine --- --- ---

19 SouthernPine --- --- ---

17 PonderosaPine --- --- ---

121

Appendix 5 Michigan Technological University

AWPA E16, Standard Field Test for Evaluation of Wood Preservatives to be used Above Ground (UC3B); Horizontal Lap-Joint Test

Year 1 Inspection Report

122

Matt Aro Natural Resources Research Institute 5013 Miller Trunk Highway Duluth, MN 55811

February 28, 2018

Dear Matt,

This letter serves as the first report for Project E48057A, Adding Value to Small-Diameter Hazardous Fuels Through Thermal Modification (E16). The data reporting for Project E48057 had been separated into three parts: Project E48057A constitutes the lap joint decay test, Project E48057B constitutes the ground proximity decay test, and Project E48057C constitutes the L-Joint decay test. The lap joints were evaluated on January 30, 2018 at the Michigan Tech Wood Protection Group (WPG) Kipuka Field Test Site near Hilo, HI. Kipuka site characteristics, climate data during the exposure period, and the test exposure history are included in Appendix A. Test data is summarized in Figures 1 and 2 and tabulated data is attached as Appendix B.

Lap Joints (12 Months, Evaluation 1 of 3 for Current Contract)

The Natural Resources Research Institute at the University of Minnesota at Duluth (NRRI) prepared longitudinal lap joints for four deciduous and three conifer species. The hardwoods are yellow poplar (Liriodendron tulipifera), red maple (Acer rubrum), white ash (Fraxinus americana), and aspen (Populus tremuloides). Each of these species was modified by thermal treatment at 170°C or 180°C. Balsam fir (Abies balsamea) was also subjected to the thermal treatments. Ponderosa (Pinus ponderosa) and southern (Pinus spp.) were prepared, without thermal treatment as controls. The lap joints were shipped to the WPG in Houghton, MI for additional processing.

Yellow poplar and red maple lap joints that were thermally treated at 170°C and matched untreated controls were pressure treated to a target retention of 4.5 kg/m3 disodium octaborate tetrahydrate, DOT. The southern pine was pressure-treated to a target retention of 1.0 kg/m3, 2.0 kg/m3, or 4.0 kg/m3 with ACQ-C.1 The ponderosa pine was dip-treated for three minutes using Woodtreat Millwork®2 at a 4:1 aqueous dilution of the concentrate. After these treatments were completed, all lap joints were assembled and uniquely labelled using stainless steel ID tags and fasteners.

1 Current Version: AWPA Standard P28-14, Standard for Alkaline Copper Quat Type C (ACQ-C), American Wood Protection Association (2017) Birmingham, AL USA. 2 Woodtreat Millwork is a registered trademark of Kop-Coat (Pittsburgh, PA). The active biocides are 3-Iodoprop-2-yn-1-yl butylcarbamate (IPBC), tebuconazole, and propiconazole.

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The field-ready lap joints were shipped to the test site near Hilo, HI, and installed in an AWPA E163 decay test during February 2017. Sue French (NRRI) was present and assisted. They were visually evaluated for decay and insect attack as shown in Table A2 (Appendix A). Statistical analysis on the data was performed using JMP Pro 13.4 At 12 months of field exposure:

A. There was visible decay among all the untreated wood control types (Figure 1). The most decay occurred among the red maple controls, and the least among the white ash. Decay amongst the yellow poplar, aspen, and balsam fir were comparable to one another.

B. Preliminary results (Figure 1) seem to indicate that thermal modification at 170°C did not significantly improve the decay resistance of the hardwood species in this test. It did, however improve the decay resistance of balsam fir.

C. Preliminary results (Figure 1) seem to indicate that thermal modification at 180°C significantly improved the decay resistance of the hardwood species in this test, except white ash. There was no further benefit to the decay resistance of balsam fir with increased treatment temperature.

Figure 1. Box plot showing the effect of thermal modification at 170°C (TM 170) or 180°C (TM 180) on the decay resistance of wood after it has been exposed in an AWPA E16 decay test at the WPG Kipuka Field Test Site near Hilo, HI, for a period of 12 months. The dots indicate outliers. When the minimum or maximum value are not part of the box or an outlier, they are indicated by the whiskers. Lines dividing the inside of the boxes are medians. In this instance some medians are equal to the first or third quantiles that define the lower and upper box borders. 3 Current Version: AWPA Standard E16-16 Standard Field Test for Evaluation of Wood Preservatives to be Used Above Ground (UC3B); Horizontal Lap Joint Test, American Wood Protection Association (2017) Birmingham, AL USA. 4 JMP Pro 13 (2016) SAS Institute Inc., Cary NC, USA

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Figure 2. Box plot showing the effect of DOT and/or thermal modification at 170°C (TM 170 + DOT) on the decay resistance of yellow poplar and red maple exposed in an AWPA E16 decay test at the WPG Kipuka Field Test Site near Hilo, HI, for a period of 12 months. The dots indicate outliers. When the minimum or maximum value are not part of the box or an outlier, they are indicated by the whiskers. Lines dividing the inside of the boxes are medians. In this instance the medians are equal to the first or third quantiles that define the lower and upper box borders.

D. Synergies between DOT and thermal treatment were tested using yellow poplar and red maple (Figure 2). Lap joints that were either unmodified by thermal treatment (DOT control) or modified by treatment at 170°C were treated with DOT at the recommended above ground retention for southern pine. There appeared to be no significant protection against decay among the yellow poplar DOT control lap joints, however, there was a marked improvement in decay resistance among the red maple DOT control lap joints compared to the untreated controls. Secondary DOT treatment of both yellow poplar and red maple lap joints modified at 170°C appeared to provide more decay resistance than either DOT or thermal modification at 170°C, separately. These lap joint types performed comparably to the yellow poplar and red maple lap joints thermally modified at 180°C.

E. Lap joints modified by thermal treatment at 170°C had decay resistance comparable to southern pine lap joints treated at the lowest retention of ACQ-C. Lap joints modified by thermal treatment at 180°C had decay resistance comparable to southern pine lap joints treated at higher retentions of ACQ-C and ponderosa pine treated with Woodlife 111 (Table B1, Appendix B).

F. There was minor, non-termite, insect attack among the yellow poplar lap joints, and minor to moderate insect attack among the aspen and balsam fir lap joints.

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The next evaluation (2 of 3) is scheduled during February 2019 at 24 months of field exposure.

I welcome your questions or comments and may be reached by telephone at (906) 487-3316 or e-mail at [email protected]. Dr. Xinfeng Xie, WPG Group Leader, may be reached at (906) 487-2294 or [email protected].

Yours truly,

Glenn M. Larkin Sr. Research Scientist Wood Protection Group

Cc: File: E48057A

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AppendixA:TestSiteInformationandProjectExposureHistory

127

TestSite Location ClimateStation StationNumber SchefferIndex

Kipuka Kea'au,HI(USA) HiloInt'lAirport 511492 3220mm 127" 23⁰C 74⁰F 330 SiltyClayLoam HiloSeries Alternaria spp. Mold/SoftRot Xylocopa spp. CarpenterBee

Antrodiavaillantii BrownRot

Antrodiaxantha BrownRot

Cladosporium spp. Mold/SoftRot

Coniophora spp. BrownRot

Curvularia spp. Mold/SoftRot

Dacrymyces spp. BrownRot

Epicoccum spp. Mold/SoftRot

Fusarium spp. Mold/SoftRot

Hyphoderma spp. WhiteRot

Neolentinuslepideus BrownRot

Paecilomyces spp. Mold/SoftRot

Penicillium spp. Mold/SoftRot

Perenniporiatephropora WhiteRot

Phanaerochaete spp. WhiteRot

Pleurotusostreatus WhiteRot

Pycnoporuscinnabarinus WhiteRot

Sistotrema spp. BrownRot

Trichoderma spp. Mold/SoftRot

FigureA1.Measured(blue)andmeanhistorical(red)monthlyprecipitationattheWPGKipukaFieldTestSite(red)duringthefieldexposure. FigureA2.Measuredmean(blue)andmeanhistorical(red)monthlytemperatureattheWPGKipukaFieldTestSite(red)duringthefieldexposure.

TestSite Project# TestMethod WPGSOP SpecimenType Installation/RenewalDate InspectionDateKipuka E48057A AWPAE16 530 LapJoints January2018 ---

--- Feb'2018

ProjectNameAddingValuetoSmall-DiameterHazardousFuelsThroughThermalModification(AWPAE16)

TableA2.ExposureandInspectionHistoryofSpecimensExposedinanAWPAE16TestattheWPGKipukaFieldTestSitenearHilo,HI

TableA1.SummaryofWPGKipukaFieldTestSiteCharacteristics

MeanAnnualPrecipitation MeanAnnualTemperature SoilType KnownFungi* KnownInsects*

*IsolatedorobservedbyWPG

0.0

100.0

200.0

300.0

400.0

500.0

600.0


2017 2018

Precipita

tion(m

m)

Month/Year

Recorded

Historical

20.0

21.0

22.0

23.0

24.0

25.0

26.0

27.0

28.0

29.0

30.0


2017 2018

Tempe

rature(o

C)

Month/Year

Recorded

Historical

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AppendixB:AboveGroundDecayTestData

129

Type Species 170 180 DOTb ACQ-Cc WoodtreatMillworkd Decay Insect1 --- + --- --- --- 10 9.92 + --- --- --- --- 9.3 103 + --- 4.5 --- --- 9.8 104 --- --- 4.5 --- --- 8.9 105 --- --- --- --- --- 8.3 9.96 --- + --- --- --- 10 107 + --- --- --- --- 9.0 108 + --- 4.5 --- --- 9.9 109 --- --- 4.5 --- --- 9.5 1010 --- --- --- --- --- 7.4 1011 --- + --- --- --- 10 1012 + --- --- --- --- 9.5 1013 --- --- --- --- --- 9.6 1022 --- + --- --- --- 9.9 1023 + --- --- --- --- 9.1 1024 --- --- --- --- --- 8.2 9.714 --- + --- --- --- 9.7 1015 + --- --- --- --- 9.6 9.916 --- --- --- --- --- 8.1 9.517 PonderosaPine --- --- --- --- N/A 9.9 1018 --- --- --- 1.0 --- 9.3 1019 --- --- --- 2.0 --- 10 1020 --- --- --- 4.0 --- 10 1021 --- --- --- --- --- 9.7 10

WhiteAsh

BalsamFir

SouthernPine

Aspen

dWoodtreatMillworkisaregisteredtrademarkofKop-Coat(Pittsburgh,PA).Theactivebiocidesare3-Iodoprop-2-yn-1-ylbutylcarbamate(IPBC),tebuconazole,andpropiconazole.

TableB1.MeanVisualRatingsforThermallyModifiedWoodExposedinanAWPAE16TestnearHilo,HI.(Project48057A)a

Feb'18(12Mos.)

cACQ-C=AmmoniacalCopperQuatTypeC


aExposureisattheWPGKipukaFieldTestSitebDOT=disodiumoctaboratetetrahydrate

YellowPoplar

Redmaple

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Type Species 170 180 DOTa ACQ-Cb WoodtreatMillworkd "P"Series Decay Insect6801 10 106802 10 106803 10 106804 10 106805 10 106806 10 106807 10 106808 10 96809 10 106810 10 10Mean 10 9.9STDEV 0.0 0.3





STDERR 0.3 0.1

TableB2.VisualRatingsforThermallyModifiedWoodExposedinanAWPAE16TestnearHilo,HI.(Project48057A)a

5 YellowPoplar --- --- ---

YellowPoplar --- + ---

--- ---

1

+

Feb'18(12Mos.)ThermalModification(oC) PreservativeTargetRetention(kg/m3)LapJoint

--- ---

--- ---

--- ------ 4.5

--- ---

3 YellowPoplar

2 YellowPoplar +

4 YellowPoplar --- --- 4.5 --- ---

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Type Species 170 180 DOT ACQ-C WoodtreatMillwork "P"Series Decay Insect6851 10 106852 10 106853 10 106854 10 106855 10 106856 10 106857 10 106858 10 106859 10 106860 10 10Mean 10 10STDEV 0.0 0.0





STDERR 0.3 0.0

TableB2.VisualRatingsforThermallyModifiedWoodExposedinanAWPAE16TestnearHilo,HI.(Project48057A)-Continued

8 RedMaple + ---

Feb'18(12Mos.)

--- --- --- ---

RedMaple +


--- ---

--- ---

--- ---

9 RedMaple --- --- 4.5 --- ---

10 RedMaple ---

4.5

6 RedMaple ---

7

+ ---

--- ---

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Type Species 170 180 DOT ACQ-C WoodtreatMillwork "P"Series Decay Insect6901 10 106902 10 106903 10 106904 10 106905 10 106906 10 106907 10 106908 10 106909 10 106910 10 10Mean 10 10STDEV 0.0 0.0



STDERR 0.2 0.0


--- ---

--- ---12 WhiteAsh + --- ---

11 WhiteAsh ---

LapJoint ThermalModification(oC) PreservativeTargetRetention(kg/m3) Feb'18(12Mos.)

---

+ ---

WhiteAsh --- --- --- ---13

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Type Species 170 180 DOT ACQ-C WoodtreatMillwork "P"Series Decay Insect7011 10 107012 10 107013 9 107014 10 107015 10 107016 10 107017 10 107018 10 107019 10 107020 10 10Mean 9.9 10STDEV 0.3 0.0



STDERR 0.3 0.2

LapJoint ThermalModification(oC) PreservativeTargetRetention(kg/m3) Feb'18(12Mos.)

22 Aspen --- +


--- --- ---

23 Aspen + --- --- --- ---

24 Aspen --- --- --- --- ---

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Type Species 170 180 DOT ACQ-C WoodtreatMillwork "P"Series Decay Insect6931 9 106932 10 106933 10 106934 8 106935 10 106936 10 106937 10 106938 10 106939 10 106940 10 10Mean 9.7 10STDEV 0.7 0.0



STDERR 0.3 0.3


--- ---

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