progress report: using thermal modification technology to ...the split resistance strength was...

N

RR

I T

echn

ical R

epo

rt –

Marc

h 2

01

9

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 2019

Report Number: NRRI/TR-2019/18

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 .................................................................................... 2 Outcomes, Accomplishments, Results ............................................................................................ 3

Outcomes .......................................................................................................................... 3 Accomplishments .............................................................................................................. 3 Results ............................................................................................................................... 4 Electron Spin Resonance (ESR) ............................................................................... 4 Split Resistance ....................................................................................................... 6 Screw Withdrawal Strength .................................................................................... 7 Impact Penetration ................................................................................................. 8 Bending Properties ................................................................................................. 9

Coating Performance ............................................................................................ 12 Coating Adhesion ...................................................................................... 12 Weather Resistance .................................................................................. 13

Durability .............................................................................................................. 15 Field-testing: L-joint Test ......................................................................... 15

Field-testing: Lap Joint Test ..................................................................... 17 Field-testing: Ground Proximity Test ....................................................... 19

Appendix A Firmolin Report ..................................................................................................... 23 Appendix B MTU – Inspection Report, L-joint Test .................................................................. 33 Appendix C MTU – Inspection Report, Lap Joint Test .............................................................. 64 Appendix D MTU – Inspection Report, Ground Proximity Test ............................................... 86

Date: 3/31/2019

Report Period: 01/01/2018-12/31/2018 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 Achieve in Accomplishing Project Goals and Objectives

Overarching Goals and Objectives 1. Define product performance benchmarks by identifying mechanical, physical, and

biological durability performance targets for the selected thermally-modifiedmaterials.

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 buildingmarkets.

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). This will identify the change in free radical levels in the wood, which has been shown to correlate with degree of modification

Actual: Dr. Wim Willems of Firmolin Technologies (The Netherlands) executed ESR analysis and provided additional elemental analysis (at no additional cost). This data provides a basis for the development of a quality assurance method.

Problem(s): None.

Goal/Objective 3.1 Planned: Moduli of rupture (MOR) and elasticity (MOE), hardness, shear strength, nail holding strength, compression and impact penetration, 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: All testing is completed. However, we determined that screw holding strength is a more important property than nail holding strength for thermally modified wood and its intended applications, so we replaced the nail holding strength test with a screw holding strength test.

Problem(s): None.

1

Goal/Objective 3.2 Planned: Biological durability will be determined by Michigan Technological University (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: The second-year long-term ground proximity, above-ground lap joint, and L-joint testing field inspections for all species except Eastern hemlock have been completed. The first-year long-term ground proximity, above-ground lap joint, and L-joint testing field inspections for Eastern hemlock have been completed.

Problem(s): The Eastern hemlock has undergone one year of testing. MTU has expressed interesting in completing three years of testing on the Eastern hemlock, but this would exceed the funded project period. No resolution has been achieved yet.

Goal/Objective 4.1 Planned: Develop a structured plan targeting technical and non-technical reporting formats.

Actual: • NRRI Technical Report was written: Aro, M., Geerts, S. M., French, S., and Cai, M. 2018.

Differences in Particulate Matter (Dust) Between Non-modified and Light-modified(170°C) Wood Species. NRRI Report no. NRRI/TR-2018/46.

• One peer-reviewed publication: Aro, M.D., Geerts, S.M., French, S. et al. Eur. J. WoodProd. (2019) Particle size analysis of airborne wood dust produced from sawingthermally modified wood, 77: 211. https://doi.org/10.1007/s00107-019-01385-z.

• Invited to write one industry blog article:http://thermallymodifiedwood.com/blog/thermal-modification-which-is-an-emerging-chemical-free-technology-in-the-u-s-can-add-substantial-value-twood/?utm_source=novawood+Ash+Decking+Newsletter&utm_campaign=ae85b2bdb2-RSS_EMAIL_CAMPAIGN&utm_medium=email&utm_term=0_297d8685cd-ae85b2bdb2-135393393

Problem(s): None.

Activity Anticipated Next Reporting Period Goal/Objective: We expect the third-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. The PI will establish a LinkedIn group to report activity and build the technology dissemination platform and has been invited to speak at an upcoming Northeast Lumber Manufacturers Association meeting (NELMA). We also intend to publish the ESR results (4.1).

2

Outcomes, Accomplishments, Results

Outcomes: The majority of technical tasks have been completed except for the remaining field durability inspections. Thermally modified wood technology continues to gain traction across the U.S. as a chemical-free method to increase the durability and dimensional stability of traditionally low-durability wood species.

The NRRI continues to lead the efforts in the U.S. toward the introduction of test standards for thermally modified wood. Such standards are necessary to characterize and specify this material for appropriate use in various applications, such as cladding, decking, and window frames. Results of the project were also shared with selected companies that expressed interest in vetting potential thermal modification production capacity – these discussions are ongoing.

NRRI leadership has augmented the continued development of thermally modified wood technologies by funding an exhaustive voice-of-customer and customer discovery project. The results of these industrial development tasks have provided a road map for research endeavors to fill the gaps that still seem to be present in the fledgling thermally modified wood sector. The NRRI’s thermally modified wood research has led to one new National Science Foundation-funded research project in the mass timber sector in collaboration with Washington State University (NSF project no. 1827434). In addition, the NRRI has executed a Joint Venture project with the USDA Forest Products Laboratory to evaluate the leachates of thermally modified Southern yellow pine, lodgepole pine, and black locust to better understand their potential to be utilized in areas with high biodeterioration potential (FS Agreement no. 18-JV-11111136-048).

Accomplishments: The now completed physical and mechanical testing 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. Most importantly, we believe the split resistance data developed in this project will be critical to potential end-users; we also believe this is the most exhaustive thermally modified wood split resistance data made publicly available in the U.S. Further, we believe the impact penetration data developed in this project is the most exhaustive data of this type made publicly available.

Two years of field durability performance data for U.S. species are now in the public domain. Even though the field inspections after the second year of exposure are not conclusive, they do show that thermal modification does improve durability when subjected to harsh environments. Further, there will be one more inspection to complement the current findings. The expectation is that we will be able to more clearly delineate the differences between treatment intensities and durability between species.

3

Results:

Electron Spin Resonance (ESR). Thermally modified aspen, balsam fir, red maple, white ash, and yellow poplar were subjected to electron spin resonance (ESR) analysis and correlated with the results from the soil-block fungal decay tests to assess the suitability of ESR signal intensity as a marker for the quality control of thermally modified wood. The results of this study show that ESR signal intensity appears to correlate well with the soil-block fungal decay of the wood species (Figure 1).

Figure 1: Plot of ESR signal intensity and soil-block fungal decay mass loss.

The ESR signal intensity also appears to be well-correlated with elemental composition, namely the oxygen-to-carbon (O/C) and hydrogen-to-carbon (H/C) ratios. Fig. 2 shows the relationship between the soil-block fungal decay results and O/C ratio , while Figure 3 shows the relationship between O/C ratio and ESR signal intensity.

Figure 2: Plot of O/C ratio and soil-block fungal decay mass loss.

4

Figure 3: Plot of ESR signal intensity and O/C ratio.

The changes in the elemental composition of wood with increasing heat treatment severity appear to be independent of the wood species and independent of the heating process variables; thus, O/C ratio may be a potentially robust quality control method for thermally modified wood.

See the entire report in Appendix A.

5

Split Resistance. The split resistance strength was determined according to a modified ASTM D143 test method. Results are presented in Figures 4-8.

Figure 4: Eastern hemlock split resistance strength.

Figure 5. Red maple split resistance strength.

Figure 6: White ash split resistance strength.

Figure 7: Balsam fir split resistance strength.

Figure 8: Yellow poplar split resistance strength.

As shown, the split resistance strength for all species, except Eastern hemlock, generally declined with increasing treatment temperatures, with the most substantial decreases found in red maple, white ash, and yellow poplar. The red maple, white ash, and yellow poplar specimens thermally modified at 180°C experienced 79%, 76%, and 77% reductions in split resistance strength, respectively, compared to the non-modified control specimens. Statistical differences within species groups were determined with a Tukey Honest Significant Difference multiple comparison analysis at the 95% significance level (p

Screw Withdrawal Strength. Screw withdrawal strength was determined according to a modified ASTM D1761 test method. Results are presented in Figures 9-13.

Figure 9: Eastern hemlock screw withdrawal strength.

Figure 10. Balsam fir screw withdrawal strength.

Figure 11: Red maple screw withdrawal strength.

Figure 12: White ash screw withdrawal strength.

Figure 13: Yellow poplar screw withdrawal strength.

As shown, for all species the screw withdrawal strength generally decreased at the 170°C treatment level, with minimal further reductions at the 180°C treatment level. The red maple and white ash experienced the greatest reductions in screw withdrawal strength, with reductions of 69% and 55%, respectively, at the 170°C treatment level. Statistical differences within species groups were determined with a Tukey Honest Significant Difference multiple comparison analysis at the 95% significance level (p

Impact Penetration. The impact penetration was determined according to a modified National Electrical Manufacturers Association LD 3-2005, Section 3.8 Ball Impact Resistance method. Impact penetrations were measured with 6-in, 12-in, and 18-in drop heights. Results are presented in Figures 14-18.

Figure 14: Eastern hemlock impact penetration.

Figure 15. Red maple impact penetration.

Figure 16: White ash impact penetration.

Figure 17: Balsam fir impact penetration.

Figure 18: Yellow poplar impact penetration.

As shown, the impact penetration depth for all species generally increased as both treatment temperature and drop height increased. The red maple and white ash experienced the least increase in penetration depth with increasing treatment temperature. Statistical differences within species groups were determined with a Tukey Honest Significant Difference multiple comparison analysis at the 95% significance level (p

Bending Properties. Modulus of rupture (MOR) and modulus of elasticity (MOE) were determined according to the ASTM D143 test method (secondary bending method). Results are presented in Figures 19-23.

Figure 19. Balsam fir modulus of rupture (MOR) and modulus of elasticity.

Figure 20. Red maple modulus of rupture (MOR) and modulus of elasticity.

9

Figure 21. Eastern hemlock modulus of rupture (MOR) and modulus of elasticity.

Figure 22. White ash modulus of rupture (MOR) and modulus of elasticity.

Figure 23. Yellow poplar modulus of rupture (MOR) and modulus of elasticity.

10

As shown, the MOR generally decreased with increasing treatment temperatures. The red maple and white ash generally experienced the largest decreases in MOR, with 35% and 32% reductions at the 170°C treatment level, respectively, compared to the control specimens. The balsam fir specimens thermally modified at 170°C experienced an 18% reduction in MOR compared to the control specimens; however, this difference was not statistically significant when analyzed with a Tukey Honest Significant Difference multiple comparison analysis at the 95% significance level (p

Coating Performance: The adhesion of a coating to the thermally modified wood and coating color change when subjected to an accelerated weathering test was examined. The samples were coated by U-C Coatings, LLC, (Buffalo, NY). The NRRI shipped samples to U-C Coatings where they were coated with SEAL-ONCE NANO GUARD PLUS POLY Premium Wood Sealer with a brown semi-transparent tint. The coating was applied to five species of thermally modified wood and an untreated pine control. The NRRI provided U-C Coatings with 138 sample boards for this study: 27 white ash (WA), 27 yellow poplar (YP), 27 Eastern hemlock fir (HF), 27 balsam fir (BF), 27 red maple (RM), and 3 ponderosa pine. The samples were shipped back the NRRI for further preparation and evaluation.

Coating Adhesion: The NRRI used Work Instruction NRRI-WP-WI-35, Adhesion by Tape to assess the propensity of the coating to adhere to the wood. This performance measure is determined by cutting a lattice pattern with either six or seven cuts in each direction through the coating film layer into the substrate, applying a pressure-sensitive tape over the lattice pattern, removing the tape, and assessing the adhesion qualitatively on a six-point scale, as noted below.

The results are presented in Figure 24.. Results are weighted where a lower adhesion score means the coating adhered better to the specimens. The results demonstrated that all thermally modified species had reduced coating adhesion over the unmodified control specimens. In the case of Eastern hemlock, there was a significant loss in coating adhesion. There was only one case, 170°C modified balsam fir, where the coating adhesion was improved. In the hardwood species, the reduction in coating adhesion was less prominent than in the softwoods.

Figure 24. Coating adhesion results.

0

20

40

60

Eastern hemlock Balsam fir Red maple Yellow poplar White ashWei

ghte

d Ad

hesio

n Sc

ore

Cross-hatch Adhesion

Control 170C 180C

12

Weather Resistance (measured as resistance to color change): Coated samples were installed in the NRRI QUV test chamber, a device that uses cycles of UV light, water spray, and condensation to simulate exterior weathering. The QUV was operated using a standard procedure from the EN-927 test method. Exposures are not intended to simulate the deterioration caused by localized weather phenomena, such as atmospheric pollution, biological attack and saltwater exposure. The procedure lasted for a 12-week period with continuous cyclic operation.

The effects of the accelerated exposure are measured by color change using a Konica Minolta CR-400 colorimeter. Color difference is defined as the numerical comparison of a sample's color to the standard. It indicates the differences in absolute color coordinates and is referred to as Total Color Difference (ΔE). The color differences between the sample and standard are calculated using the resulting colorimetric values with the CIE L*a*b* color space. Generally speaking, if ΔE

Figure 26. Color change of all specimens after 12 weeks of QUV exposure.

14

Durability field testing, L-joint (AWPA E9): The NRRI prepared L-joint specimens from four deciduous and four conifer species. The deciduous species were yellow poplar, red maple, white ash, and aspen. Each of these species was thermally modified at 170°C and 180°C. Balsam fir and Eastern hemlock were also subjected to the thermal treatments. Ponderosa pine and Southern pin were prepared without thermal treatment as controls. All specimens were shipped to MTU for additional processing.

Yellow poplar and red maple L-joints that were thermally modified 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. The ponderosa pine was dip-treated for three minutes using Woodtreat Millwork® at a 4-to-1 aqueous dilution of the concentrate. After these treatments were completed, all L-joints were painted with white exterior latex paint (Sherwin Williams A100) and the outside ends were sealed with Epoxy King SC110 UV-resistant marine grade epoxy. After drying, the painted L-joints were assembled and uniquely labelled using stainless steel ID tags and fasteners.

A summary of the major findings is presented below. The full reports from MTU can be viewed in Appendix B.

L-joint results after 24 Months (yellow poplar, red maple, white ash, aspen, balsam fir)1. There was visible decay among all the untreated wood control types (Figure 27). Thewhite ash and balsam fir controls had less visible decay and were comparable to eachother.

Figure 27. Box plot showing the effect of thermal modification at 170°C and 180°C on the decay resistance of wood after 24 months.

2. Current results (Figure 27) show that thermal modification at 170°C or 180°Csignificantly improved the decay resistance for yellow poplar and red maple, and theremay be improved decay resistance with thermal modification at 180°C for the otherspecies compared to the controls.

15

3. Synergies between DOT and thermal treatment at 170°C were tested using yellowpoplar and red maple (Figure 28). L-joints that were either unmodified (DOT control) ormodified by thermal treatment at 170°C were treated with DOT at the recommendedabove-ground retention for Southern pine. All combinations of thermal treatmentand/or DOT in this study improved the decay resistance of both yellow poplar and redmaple.

Figure 28 Box plot showing the effect of DOT and/or thermal modification at 170°C and DOT after 24 months.

4. L-joints modified by thermal treatment at 180°C had decay resistance comparable toSouthern pine L-joints treated with ACQ-C at retentions of 2.0 kg/m3 or higher andponderosa pine treated with Woodtreat Millwork®.5. There was variable, non-termite insect attack among the L-joints.

L-joint results after 12 months (Eastern hemlock)1. There was minor to moderate visible decay among all the untreated control Easternhemlock and Southern pine L-joints. The mean decay ratings were 8.9 (Eastern hemlock)and 9.0 (Southern pine).2. Preliminary results seem to indicate that thermal modification at 180°C may improvethe decay resistance of Eastern hemlock compared to the controls. Figure 29 shows anL-joint sample and the test rack in Hilo, HI.

Figure 29. L-joint sample (left) and L-joint rack in Hilo, HI (right).

16

Durability field testing, Lap Joint (AWPA E-16): The NRRI prepared longitudinal lap joints for four deciduous and four conifer species. The deciduous species were yellow poplar, red maple, white ash, and aspen. Each of these species was thermally modified at 170°C and 180°C. Balsam fir and Eastern hemlock were also subjected to the thermal treatments. Ponderosa pine and Southern pine were prepared without thermal treatment as controls. The lap joints were shipped to MTU 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 of DOT. The ponderosa pine was treated with Woodtreat Millwork® using a three-minute dip at a 4-to-1 dilution of the concentrate. Assuming 1% active biocides, the resulting mean preservative uptake was approximately 0.2 kg/m3 (or 3.0 kg/m2 surface coverage). 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. After these treatments were completed, all lap joints were assembled and uniquely labelled using stainless steel ID tags and fasteners.

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

Lap Joints results after 24 Months (yellow poplar, red maple, white ash, aspen, balsam fir) 1. There was visible decay among all the untreated wood control types for the speciesthat were thermally modified (Figure 30). The most decay occurred among the aspenand balsam fir controls, and the least among the white ash. Decay amongst the yellowpoplar, red maple and white ash were comparable to one another.

Figure 30. Box plot showing the effect of thermal modification at 170°C and 180°C after 24 months.

2. Current results (Figure 30) seem to indicate that thermal modification at 170°C mayimprove the decay resistance of the balsam fir and the hardwood species, except aspen,compared to the controls.3. Current results (Figure 30) seem to indicate that thermal modification at 180°Cimproved the decay resistance of all species in this test compared to the controls. There

17

was no further benefit to the decay resistance of balsam fir with increasing treatment temperature. 4. Synergies between DOT and thermal treatment were tested using yellow poplar andred maple (Figure 31). Lap joints that were either unmodified (i.e., no thermaltreatment) (DOT control) or modified by treatment at 170°C were treated with DOT atthe recommended above-ground retention for Southern pine. There appeared to be nosignificant protection against decay among the DOT control lap joints, compared to theuntreated controls. Secondary DOT treatment of both yellow poplar and red maple lapjoints thermally modified at 170°C may provide more decay resistance than either DOTor thermal modification at 170°C, separately.

Figure 31. Box plot showing the effect of DOT and/or thermal modification at 170°C and DOT on the decay resistance after 24 months.

5. Lap joints modified by thermal treatment at 170°C had decay resistance comparableto Southern pine lap joints treated at the lowest retention of ACQ-C. Lap joints modifiedby thermal treatment at 180°C had decay resistance comparable to Southern pine lapjoints treated at higher retentions of ACQ-C and ponderosa pine treated with Woodlife111®.6. There was variable, non-termite insect attack among the lap joints during thisevaluation.

Lap joints results after 12 months (Eastern hemlock) 1. There was variable visible decay among all untreated control Eastern hemlock andSouthern pine lap joints. The mean decay ratings were 9.3 (Eastern hemlock) and 9.2(Southern pine).2. Preliminary results seem to indicate that thermal modification at 170°C or 180°C mayimprove the decay resistance of Eastern hemlock compared to the controls. Figure 32shows a lap joint sample and the test rack in Hilo, HI.

18

Figure 32. Lap joint sample (left) and sample rack in Hilo, HI (right).

Durability field testing; Ground Proximity Decay Blocks (AWPA -E18): The NRRI prepared ground proximity decay blocks from four deciduous and four conifer species. The deciduous species were yellow poplar, red maple, white ash, and aspen. Each of these species was thermally modified at 170°C and 180°C. Balsam fir and Eastern hemlock were also subjected to the thermal treatments. Ponderosa pine and Southern pine were prepared without thermal treatment as controls.

The decay blocks were shipped to MTU for additional processing. Yellow poplar and red maple blocks that were thermally modified at 170°C and matched untreated controls were pressure treated to a target retention of 4.5 kg/m3 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. The ponderosa pine was dip-treated for three minutes using Woodtreat Millwork® at a 4-to-1 dilution of the concentrate with water. After these treatments were completed, all decay blocks were uniquely labelled using stainless steel ID tags and fasteners.

A summary of major findings are presented below. The full reports from MTU can be viewed in Appendix D.

Results after 24 months results (yellow poplar, red maple, white ash, aspen, balsam fir) 1. There was visible decay among all untreated control specimens for all species thatwere thermally modified (Figure 33). Decay was universally severe.

Figure 33. Box plot showing the effect of thermal modification at 170°C and 180°C after 24 months.

19

2. Current results (Figure 33) show that thermal modification at 170°C did notsignificantly improve the decay resistance of any wood species.3. Current results (Figure 33) seem to indicate that thermal modification at 180°C mayimprove decay resistance of white ash and balsam fir, compared to the controls.4. Synergies between DOT and thermal treatment were tested using yellow poplar andred maple (Figure34). There appeared to be no significant improvement in protectionagainst decay among the yellow poplar and red maple blocks with DOT treatments.There was no apparent synergy between the DOT and thermal (170°C) treatment.Thermal treatment at 180°C does not appear to be more effective than the DOTtreatments for improving decay resistance during the ground proximity exposure.

Figure 34. Box plot showing the effect of DOT and/or thermal modification at 170°C on decay resistance after 24 months.

5. Decay blocks thermally modified at 170°C had lower apparent decay resistance thanSouthern pine blocks treated at the lowest retention of ACQ-C. Yellow poplar, redmaple, and aspen blocks thermally modified at 180°C had decay resistance comparableto Southern pine treated at the lowest retention of ACQ-C and ponderosa pine treatedwith Woodlife 111®. White ash blocks thermally modified at 180°C had decay resistancecomparable to Southern pine treated at the highest retention of ACQ-C.6. There was variable, non-termite insect attack among the decay blocks.

Results after 12 months (Eastern hemlock) 1. There was variable visible decay among all the untreated control Eastern

hemlock and Southern pine lap joints. The mean decay ratings were 8.9 (Eastern hemlock) and 8.0 (Southern pine). 2. Preliminary results seem to indicate that thermal modification at 170°C or 180°C mayimprove the decay resistance of Eastern hemlock compared to the controls.3. There was variable, non-termite insect attack among the decay blocks. Figure 35shows the ground proximity sample plot in Hilo, HI.

20

Figure 35. Ground proximity sample plot in Hilo, HI.

21

Appendix A: Firmolin Report Appendix B: MTU – E9 Report (L-Joint) Appendix C: MTU – E16 Report (Lap-joint) Appendix D: MTU – E18 Report (Ground Proximity Decay Block)

22

Appendix A: Firmolin Report

23

Company Reg. Nr. 12063696 | IBAN NL 58 ABNA 0605 592 438 | VAT Nr. NL 817 051 958 B01

Electron spin resonance (ESR) characterization ofthermally modified wood

Date: August 23, 2018Author: Dr. W.P.M. WillemsFirmoLin Technologies BVGrote Bottel 7b5753 PE Deurne, The NetherlandsTel. +31 - 493 - 242142Mobile: +31 – 6 [email protected] by:Mr. Matt Aro,National Resource Research Institute (NRRI)5013 Miller Trunk HighwayDuluth, MN 55811, United States of AmericaProject reference:U.S. Department of Agriculture, Wood Education and Resource Center,grant no.15-DG-11420004-082

24

1. IntroductionThe Natural Resource Research Institute (NNRI) in Duluth MN, leads the efforts in the USAtowards the introduction of test standards for thermally modified timber (TMT). Suchstandards are necessary to characterize and specify this material for appropriate use in variousapplications (Willems et al. 2015). Among the applications of interest are cladding, decking andwindow frames, requiring a verified durability performance.As required by the AWPA regulations, the durability performance must be assured throughverification in long-term field tests in combination with a production quality control system.One of the key elements of the production quality control system is a method providing aquantitative marker that can be directly correlated to the critical performance parameter(s) ofthe product.NNRI produced wood samples in two batches of their pressurized hydrothermal woodmodification reactor, operated at 170°C and 180°C respectively, each loaded with aspen,balsam fir, red maple, white ash and yellow poplar boards. The treated material has beendurability tested at the mycology lab of the Michigan Technological University in standardizedfungal decay tests with 16 weeks incubation time, using the Irpex lacteus, Poria placenta,Trametes versicolor and Gloeophyllum trabeum test fungi (Appendix A.1.). The largest of themass decay values obtained by these separately tested fungi was taken as the measure ofdurability of the heat-treated wood species to correlate with the strength of the specific ESRsignal (arb. units per mg wood).2. ESR methodThe provided as-produced blocks (25 x 25 x 25 mm3) were cut perpendicular to the grain into 5mm slices using a miniature bandsaw with a thin and narrow blade and fine teeth, producingminimal heat. The outer two slices of the block (caps) were discarded. Cylinders of 2 mmdiameter and 5 mm length were carefully taken from the remaining slices using a hole punch,cutting along the grain. The samples were conditioned at a temperature of 25°C and 40%RH.The used electron spin resonance (ESR) spectrometer is a table-top continuous wave X-band(10 GHz) type MS100 (Magnettech, Germany). The stable radical singlet electron spin signals atg ≈ 2.0030 in thermally modified wood (Sivonen et al. 2002) were measured with the samplesin 3 mm internal diameter quartz ESR tubes in the centre of the microwave cavity. Instrumentsettings: central field strength of 336.1 mT, sweep range 9.7 mT, modulation amplitude 0.3 mT,RF-power 0.5 mW (23dB), gain 200, sweep time 20s, 3 passes. The unfiltered signal isquantified by the product of the amplitude and the squared distance of 1st-derivative ESRsignal peaks collected in 4096 channels, calculated per mg of wood sample. Each block wastested in quadruplicate.

25

3. Elemental composition methodIn addition to the ESR measurements (outside the original scope of the project), FirmoLin hadone analysis per wood species and treatment variant tested externally. The elementalcomposition of as-produced samples was determined by flash combustion analysis (Euro EA-CHNS, Hekatech GmbH, Germany). The detector was calibrated to weight-% C, H, N and Scontent, with sulfanilamide (C6H8N2O2S) and BBOT (2,5-bis(5-tert-Butyl-2-benzoxazolyl)thiophene, C26H26N2O2S) standards. Approximately 2 mg of oven-dried (105°C)wood samples were quickly weighed with an analytical balance (1 μg readability), wrapped intin foil, re-dried at 105°C, transferred to the instrument and kept in a He flow to avoid moistureuptake before the actual CHNS composition measurement was executed. The relevant mole-ratios O/C=0.75*%O/%C and H/C=12*%H/%C are calculated using the molar masses of theelements. The %O content is not directly measured, but calculated from:O%=100%-C%-H%-N%-S%This calculation neglects the (generally small) inorganic ash content. The repeatability of theO/C and H/C measurements was determined at 0.01 (standard deviation) in earlierinvestigations using this procedure.4. ResultsThe ESR experiments were conducted in five consecutive series, wherein all different species,aspen (AS), balsam fir (BF), red maple (RM), white ash (WA) and yellow poplar (YP), in eithertreatment variant (170/180°C) where represented by one block each. The first testing day 10thJuly 2018 comprised one full series (10 blocks, 40 spectra). The second testing day 11th Julycomprised three full series (30 blocks, 120 spectra) and the third day the last series of theremaining 10 blocks, 40 spectra. The parameters of each single specific ESR signal strengthresult are listed in the data file (Appendix A.2.).The relative differences between the ESR signals of the 10 blocks within each series appearconsistent among the five series. The absolute values of the signals for each wood species andtreatment variant from different series were significantly deviating for the three testing days,but not between the three series on the second testing day. While the microwave tuning andcoupling in the spectrometer was recalibrated before the acquisition of each individual ESRspectrum, this did not remove the day-to-day difference. The exact reason for the day-to-daynon-repeatability of the signal levels could not be identified, although there is a strongsuspicion towards an influence of abnormally changing weather conditions over the testingperiod. This has either changed the moisture content of the samples and/or the Q-factor of themicrowave resonator of the ESR-spectrometer. In both ways, the signal level is changed bysome factor, which does not affect the relative differences between the samples in a series –wherein the factor does not vary much over a testing day.

26

While the data file contains the ESR signals of all five series, this report will only use the threeseries that were tested on the second day for correlation with the durability data, to avoidunnecessary inaccuracy by the systematic day-to-day signal drift. This study shows the need fora reliable calibration procedure of the ESR signals, based on the use of reference samples thatare stored and measured under the same conditions as the test samples.ESR signals were determined on samples of nearly constant volume (φ 2 mm, L=5mm). Foreach wood species, the ESR levels were markedly higher for the samples treated at 180°C (Fig.1). Signal levels of the hardwood samples are systematically larger than of the softwoodsamples.

Fig. 1: constant volume samples effect of treatment temperature on ESR signal intensitySince the samples differ in density (cell wall mass), the signal level per unit mass is a bettermeasure of the treatment level. A higher treatment severity would lower the dry mass as wellas the equilibrium moisture content. However, for the samples from the NRRI hydrothermalprocess, the masses of the 180°C samples were rather high compared to their 170°Ccounterparts. Remarkably, the balsam fir and red maple sample masses even increased from170 to 180°C, indicating an abnormally high content of cell wall degradation products in the180°C samples.A high content of degradation products in the 180°C samples implies that their specific ESRsignals are underestimated. The accuracy of the ESR method may be increased by adopting aquite elaborate extraction procedure for the degradation products, as in Altgen and Militz(2016), which would also serve as a relaxation treatment, giving more consistent results.Fortunately, the changes in ESR signal outweigh the anomalies of the sample masses, giving auseful correlation between the specific ESR signal and the TMT durability (Fig. 2) for qualitycontrol. Note, that the untreated NRRI samples were not measured with ESR. One point,belonging to pine sapwood sample heat treated in a hygrothermal process at 180°C, was addedfor reference. The 16 weeks decay mass loss value of this point was measured in an EN113standard setup at the Freiburg University in Germany (Tausch 2011).27

Fig. 2: Correlation between 16-week fungal decay mass losses and the specific ESR signal, containing greenpoints (untreated), blue points (170°C), orange points (180°C) and one purple point (180°C pine sapwoodreference sample).The fungal mass losses after 16 weeks of fungal exposure appear correlated with amonotonously decreasing function of the measured specific ESR signal, confirming earlierstudies (Willems et al. 2010). The correlation is inaccurate in the lower treatment intensityrange by the very large statistical error in the fungal mass losses. However, the durability maystill be assured by setting a minimum threshold value for the specific ESR signal, where theperformance is consistently good with little statistical error. A reference sample with a certifieddurability at the threshold signal level may be used for this purpose (for instance the pinesapwood reference in Fig. 2).In addition to the ESR data, elemental compositions were determined on one block per woodspecies and treatment temperature (single measurement each). The oxygen to carbon ratio O/Cis an interesting metric for the treatment severity (Chaouch et al. 2010). It has the advantage tobe an analytical technique, providing absolute quantitative data. The calibration andverification are assured with the use of analytical grade chemical reference substances. It wasestablished in a recent study by the author (not published) that the O/C value of heat treatedbeech only slightly changed by leaching of the thermal degradation products in the cell wall.The O/C ratio can therefore be measured without special pre-treatment other than oven-dryingof very small samples (milligram range) and interpreted without knowing the thermal processdetails. The CHNS flash combustion elemental analyser provides results in a few minutes oftime.To illustrate the generality of the change of O/C by heat treatment the elemental compositionratios O/C and H/C of the ten NRRI samples is plotted in a van Krevelen diagram (Willems et al.2013).

28

This correlation (Fig. 3) is shared by all other heat-treated wood species that were recentlytested by the author (including European beech, oak, ash, pine, spruce, fir and African obeche,iroko, okoumé in closed reactors) and by many other species heat-treated in open as well asclosed reactors (blue line H/C=0.5+1.5*O/C in Fig. 3). Note that this correlation can be used todetect systematic errors in the elemental composition data (e.g. the outlier at O/C≈0.48).Untreated wood has an O/C ratio of nearly 0.70, which is progressively reduced by heattreatment.

Fig. 3: Correlation between O/C and H/C for five wood species of this study in two treatment intensities(blue 170°C, yellow 180°C) and pine sapwood reference 180°C (purple). The blue line is an accuratecorrelation obtained from data from other studies.Correlating O/C of the NRRI samples with the durability data, one obtains Fig. 4. Since the datapoints are drawn from single measurements of O/C, the inaccuracy of measurement wasroughly indicated with a standard error bar of 0.02. Like the ESR correlation, it seems possibleto assign a threshold value of O/C to assure the performance in a targeted risk class ofapplication. Unlike ESR, this threshold is a maximum threshold value and it can be definedwithout the need for reference samples.Having specific ESR signals and O/C data from each type of sample (wood species andtreatment temperature), it is interesting to investigate a correlation between the two. This isgraphically represented by Fig. 5. Besides a few outliers the correlation is surprisingly good,given the problematic mass normalization in the specific ESR signal with the samplescontaining extractable degradation products and a moisture dependence of the ESR signal. Thelatter is due to dissipative microwave absorption by moisture in the sample, which varies withthe degree of thermal modification. The RH of 40% helped to keep the moisture levelsreasonably low.

29

Fig. 4: Correlation between 16-week fungal decay mass loss and the O/C ratio of TMT, symbols as in Fig. 2.

Fig 5: Correlation between ESR and O/C. Broken line is guide to the eye. Symbols as in Fig. 2.The correlation of Fig. 5 contains an outlier that corresponds to the outlier at O/C=0.48 in Fig.3, belonging to balsam fir (180°C). The reason for the ESR-O/C correlation is thought to beconnected to the universal correlation in the van Krevelen diagram (blue line in Fig. 3). Thisline implies a relative increase of hydrogen to oxygen ratio with increasing treatment severity,i.e. an increase of the ratio of valence electron donors vs. acceptors. This necessarily increasesthe average electron charge density in the carbon chains of the wood polymers (Willems et al.2013). This may in turn be speculated to cause an associated increase of the electron chargedensity of the conjugated lignin structure, increasing the number of unpaired electrons asdetected by ESR.30

5. ConclusionsFive hydrothermally treated wood North-American wood species (aspen, balsam fir, red maple,white ash, yellow poplar) were subjected to an ESR test and correlated with standardizedlaboratory fungal decay data, to assess their suitability as a marker for the quality control ofTMT. Although the ESR method is sensitive for various factors, requiring a proper samplemoisture pre-conditioning and leaching (if necessary), standardized laboratory environmentalconditions and calibration with reference samples, the method is shown to be suitable forquality control of the tested wood species in this study. The results confirm similar findings onsix European wood species tested according to EN113 standard.After calibration, minimum threshold values for the specific ESR-signal strength can beestablished for a pass/fail test of the sample for suitability in each service risk class. The largestinaccuracy defining proper threshold values are due the statistical errors in the fungal decaytest data. When the durability threshold values are chosen too conservatively, the TMT materialwill suffer from large strength losses.ESR appears to be well-correlated to another method of treatment level measurement, basedon the elemental composition of the samples. The CHNS elemental composition can be directlydetermined using well-established analytical procedures and automated desk-top equipment.The changes in the elemental composition of wood with increasing heat treatment severityappear to be independent of the wood species and independent of the heating processvariables. In this study, the fungal decay mass loss seems to be a single function of the oxygento carbon atomic ratio of the hydrothermally modified wood sample, independent of the woodspecies. A similar conclusion was reached in a European study (Chaouch et al. 2010) using aheat treatment process conducted in atmospheric nitrogen at various temperatures anddurations, using five European wood species (ash, beech, poplar, fir and pine).Since the specific ESR signals are correlated to the O/C ratio, one may hypothesize that thedurability prediction is likewise wood-species and process independent, as was concluded bythe author in previous studies with hygrothermally treated European wood species.

31

References

M. Altgen and H. Militz (2016). Influence of process conditions on hygroscopicity and mechanicalproperties of European beech thermally modified in a high-pressure reactor system. Holzforschung,70(10), 971-979.M. Chaouch, M. Pétrissans, A. Pétrissans and P. Gérardin (2010). Use of wood elemental composition topredict heat treatment intensity and decay resistance of different softwood and hardwood species.Polymer Degradation and Stability, 95(12), 2255-2259.H. Sivonen, S.L. Maunu, F. Sundholm, S. Jämsä and P. Viitaniemi (2002). Magnetic resonance studies ofthermally modified wood. Holzforschung, 56(6), 648-654.A. Tausch (2011). Fungal resistance of thermally modified wood - gravimetric and microscopicinvestigations. PhD thesis, University of Freiburg.W. Willems, A. Tausch, H. Militz (2010). Direct estimation of the durability of high-pressure steammodified wood by ESR-spectroscopy. In: 41st Annual Meeting of the International Research Group onWood Protection, Biarritz, France, 9-13 May 2010.W. Willems, C. Mai and H. Militz (2013). Thermal wood modification chemistry analysed using vanKrevelen's representation. International Wood Products Journal, 4(3), 166-171.W. Willems, Lykidis, M. Altgen and L. Clauder (2015). Quality control methods for thermally modifiedwood. Holzforschung, 69(7), 875-884.

Appendices

A.1. Durability results from the MTU mycology lab (used values are marked green).A.2. ESR data file (.xlsx)

32

Appendix B: MTU – E9 Report (L-Joint)

33

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

March 16, 2019

Dear Matt,

This letter serves as the second report for Project E48057C, Adding Value to Small-Diameter Hazardous Fuels Through Thermal Modification (E9). The L-joints were evaluated on February 17, 2019 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. Above ground decay test data is summarized in Figures 1 and 2 and tabulated data is attached as Appendix B.

L-Joints (24 Months, Evaluation 2 of 3 for Current Contract)

The Natural Resources Research Institute at the University of Minnesota at Duluth (NRRI) prepared L-joints using 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 L-joints were shipped to the WPG in Houghton, MI for additional processing.

Yellow poplar and red maple L-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 to 1 aqueous dilution of the concentrate. After these treatments were completed, all L-joints were painted with white exterior latex (Sherwin Williams A100) 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.

1 Current Version: AWPA Standard P28-14, Standard for Alkaline Copper Quat Type C (ACQ-C), American Wood Protection Association (2018) 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.

34

The field-ready L-joints were shipped to the test site near Hilo, HI, and installed in an AWPA E93 decay test during February 2017. They were visually evaluated for decay and insect attack as shown in Table A2 (Appendix A). Evaluations were performed and reported separately for the mortise and tenon. A combined rating, the lower value of the mortise or tenon, is also reported (Table B1, Appendix B). There was strong agreement between the L-Joint decay ratings for the mortises and tenons (r = 0.99), therefore the discussion is based on the combined ratings. Statistical analysis on the data was performed using JMP Pro 14.4 At 24 months of field exposure:

A. There was visible decay among all the untreated wood control types (Figure 1). The most severedecay was seen among the yellow poplar, red maple, and aspen controls, which had comparabledecay. The white ash and balsam fir controls had less visible decay that was comparable to eachother.

B. Current results (Figure 1) show that thermal modification at 170°C or 180°C significantly improvedthe decay resistance for yellow poplar and red maple in this test, and there may be improved decayresistance with thermal modification at 180oC for the other species in this test when compared tothe controls. There may also be further benefit with increased thermal modification 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 E9 decay test at the WPG Kipuka Field Test Site near Hilo, HI, for a period of 24 months. 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. Results are shown for the combined mortise and tenon ratings.

3 Current Version: AWPA Standard E9-15 Standard Field Test for Evaluation of Wood Preservatives to be Used Above Ground (UC3A & UC3B); L-Joint Test, American Wood Protection Association (2018) Birmingham, AL USA.4 JMP Pro 14.3 (2018) SAS Institute Inc., Cary NC, USA

TreatmentControl TM 170 TM 180

Mean

Deca

y Rati

ng

0

2

4

6

8

10

Yellow PoplarRed MapleWhite AshAspenBalsam Fir

35

C. Synergies between DOT and thermal treatment at 170°C were tested using yellow poplar and redmaple (Figure 2). L-joints that were either unmodified (DOT control) or modified by thermaltreatment at 170°C were treated with DOT at the recommended above ground retention forsouthern pine. All combinations of thermal treatment and/or DOT in this study improved the decayresistance of both yellow poplar and red maple. The treatments were equivalent to one anotherwithin each species.

D. L-joints modified by thermal treatment at 180°C had decay resistance comparable to southern pineL-joints treated with ACQ-C at retentions of 2.0 kg/m3 or higher and with ponderosa pine treatedwith Woodtreat Millwork (Table B1, Appendix B).

E. There was variable, non-termite, insect attack among the L-joints.

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 E9 decay test at the WPG Kipuka Field Test Site near Hilo, HI, for a period of 24 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. Results are shown for the combined mortise and tenon ratings.

The next evaluation (3 of 3) is scheduled during February 2020 at 36 months of field exposure.

TreatmentControl DOT TM 170 TM 180 TM 170 +DOT

Mean

Deca

y Rati

ng

0

2

4

6

8

10

Yellow PoplarRed Maple

36

We welcome your questions or comments and I 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: E48057C

37

Appendix A: Test Site Information and Project Exposure History

38

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

TestSite Project# TestMethod WPGSOP SpecimenType Installation/RenewalDate InspectionDateKipuka E48057C AWPAE9 535 L-Joints February2017

24 Feb'201912 Feb'2018

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

ProjectNameAddingValuetoSmall-DiameterHazardousFuelsThroughThermalModification(AWPAE9)

TableA2.ExposureandInspectionHistoryofSpecimensExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI

TableA1.SummaryofWPGKipukaFieldTestSiteCharacteristicsMeanAnnualPrecipitation MeanAnnualTemperature SoilType KnownFungi* KnownInsects*

*IsolatedorobservedbyWPG

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

1400.0

Febr

uary

Mar

ch

April

May

June July

Augu

st

Sept

embe

r

Octo

ber

Nove

mbe

r

Dece

mbe

r

Janu

ary

Febr

uary

Mar

ch

April

May

June July

Augu

st

Sept

embe

r

Octo

ber

Nove

mbe

r

Dece

mbe

r

Janu

ary

Febr

uary

2017 2018 2019

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

Febr

uary

Mar

ch

April

May

June July

Augu

st

Sept

embe

r

Octo

ber

Nove

mbe

r

Dece

mbe

r

Janu

ary

Febr

uary

Mar

ch

April

May

June July

Augu

st

Sept

embe

r

Octo

ber

Nove

mbe

r

Dece

mbe

r

Janu

ary

Febr

uary

2017 2018 2019

Tem

pera

ture

(oC)

Month/Year

Recorded

Historical

39

Appendix B: Above Ground Decay Test Data

40

Type 1 2 3 4 5 6 7 8 9 10 11 12 13Species

ThermalModification(oC) 180 170 170 N/A N/A 180 170 170 N/A N/A 180 170 N/APreservativeSystem DOTb DOT DOT DOT

TargetRetention(kg/m3) 4.5 4.5 4.5 4.5February Exposure(Months)2017 02018 12 9.7 9.6 10 9.8 8.5 10 9.6 10 9.8 8.1 10 10 9.32019 24 9.1 8.9 9.8 8.1 2.6 9.9 8.3 9.5 8.4 4.2 10 9.7 8.5

February Exposure(Months)2017 02018 12 10 10 10 10 10 10 10 10 10 9.7 10 10 102019 24 9.9 9.8 9.9 9.5 7.9 10 9.8 9.9 9.9 8.5 10 10 9.8

Type 14 15 16 18 19 20 21 22 23 24Species

ThermalModification(oC) 180 170 180 170 N/APreservativeSystem

TargetRetention(kg/m3) 1.0 2.0 4.0February Exposure(Months)2017 02018 12 10 10 9.5 10 10 10 9.9 9.7 9.7 8.32019 24 9.9 9.6 8.3 7 10 10 8.4 9.8 7.8 3.4

February Exposure(Months)2017 02018 12 10 10 10 10 10 10 10 10 10 102019 24 10 10 9.9 10 10 10 9.4 10 9.8 8.7

L-JointsYellowPoplar YellowPoplar WhiteAsh

TableB1.MeanCombinedVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)a

Installed

Installed

N/A N/A N/A

MeanCombinedDecayRating

L-Joints

TableB1.MeanCombinedVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-Continued17

N/A

MeanCombinedInsectRating

0.21

SouthernPine Aspen

N/A

N/AACQ-Cd

dACQ-C=AmmoniacalCopperQuatTypeC

aValuesshownarethelowerofthemeandecayorinsectratingsforthemortiseandtenon,whichwereevaluatedseparately.bDOT=disodiumoctaboratetetrahydratecWoodtreatMillworkisaregisteredtrademarkofKop-Coat(Pittsburgh,PA)

MeanCombinedDecayRatingInstalled

MeanCombinedInsectRatingInstalled

1010

1010

BalsamFir PonderosaPine

WoodTreatMillworkc

41

Type 1 2 3 4 5 6 7 8 9 10 11 12 13Species

ThermalModification(oC) 180 170 170 N/A N/A 180 170 170 N/A N/A 180 170 N/APreservativeSystem DOTa DOT DOT DOT

TargetRetention(kg/m3) 4.5 4.5 4.5 4.5February Exposure(Months)2017 02018 12 9.7 9.7 10 9.8 8.7 10 9.6 10 9.9 8.1 10 10 9.32019 24 9.6 8.9 9.8 8.1 2.6 9.9 8.3 9.5 8.4 4.2 10 9.7 8.5

February Exposure(Months)2017 02018 12 10 10 10 10 10 10 10 10 10 9.7 10 10 102019 24 10 9.9 9.9 9.5 7.9 10 9.9 9.9 9.9 8.9 10 10 9.8

Type 14 15 16 18 19 20 21 22 23 24Species


TargetRetention(kg/m3) 1.0 2.0 4.0February Exposure(Months)2017 02018 12 10 10 9.5 10 10 10 9.9 9.7 9.7 8.32019 24 9.9 9.6 8.3 7.0 10 10 8.4 9.8 7.8 3.4


TableB2.MeanMortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)

MortisesYellowPoplar YellowPoplar WhiteAsh

N/A N/A N/A



TableB2.MeanMortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-Continued

Mortises

17BalsamFir PonderosaPine SouthernPine Aspen

N/A

N/A WoodTreatMillworkb ACQ-Cc N/A0.21MeanCombinedDecayRating

Installed10

aDOT=disodiumoctaboratetetrahydratebWoodtreatMillworkisaregisteredtrademarkofKop-Coat(Pittsburgh,PA)cACQ-C=AmmoniacalCopperQuatTypeC

10MeanCombinedInsectRating

Installed1010

42

Type 1 2 3 4 5 6 7 8 9 10 11 12 13Species

ThermalModification(oC) 180 170 170 N/A N/A 180 170 170 N/A N/A 180 170 N/APreservativeSystem DOTa DOT DOT DOT

TargetRetention(kg/m3) 4.5 4.5 4.5 4.5February Exposure(Months)2017 02018 12 9.7 9.6 10 9.8 8.5 10 9.6 10 9.8 8.2 10 10 9.42019 24 9.1 8.9 9.9 8.2 2.6 10 8.3 9.6 8.4 4.3 10 9.8 8.6

February Exposure(Months)2017 02018 12 10 10 10 10 10 10 10 10 10 10 10 10 102019 24 9.9 9.8 9.9 9.5 8.2 10 9.8 9.9 10 8.5 10 10 10

Type 14 15 16 18 19 20 21 22 23 24Species


TargetRetention(kg/m3) 1.0 2.0 4.0February Exposure(Months)2017 02018 12 10 10 9.5 10 10 10 9.9 9.8 9.8 8.52019 24 10 9.8 8.5 7.0 10 10 8.5 9.9 8.1 3.4


TableB3.MeanTenonVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)

TenonsYellowPoplar YellowPoplar WhiteAsh

N/A N/A N/A



TableB3.MeanTenonVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-Continued

Tenons

17BalsamFir PonderosaPine SouthernPine Aspen

N/A

N/A WoodTreatMillworkb ACQ-Cc N/A0.21MeanCombinedDecayRating

Installed10

aDOT=disodiumoctaboratetetrahydratebWoodtreatMillworkisaregisteredtrademarkofKop-Coat(Pittsburgh,PA)cACQ-C=AmmoniacalCopperQuatTypeC

10MeanCombinedInsectRating

Installed1010

43

Type Species 1801 "P"Series 6561 6562 6563 6564 6565 6566 6567 6568 6569 6570

February Exposure(Months) Mean STDEV STDERR LowerCIa UpperCI2017 0 10 0.0 0.0 10 102018 12 10 9 10 10 10 10 9 10 9 10 9.7 0.5 0.2 9.4 102019 24 10 10 8 10 10 10 9 10 9 10 9.6 0.7 0.2 9.2 10

February Exposure(Months) Mean STDEV STDERR LowerCI UpperCI2017 0 10 0.0 0.0 10 102018 12 10 10 10 10 10 10 10 10 10 10 10 0.0 0.0 10 102019 24 10 10 10 10 10 10 10 10 10 10 10 0.0 0.0 10 10


February Exposure(Months) Mean STDEV STDERR LowerCI UpperCI2017 0 10 0.0 0.0 10 102018 12 9 10 9 9 10 10 10 10 10 10 9.7 0.5 0.2 9.4 102019 24 8 8 10 9 9 9 9 9 10 8 8.9 0.7 0.2 8.4 9.4

February Exposure(Months) Mean STDEV STDERR LowerCI UpperCI2017 0 10 0.0 0.0 10 102018 12 10 10 10 10 10 10 10 10 10 10 10 0.0 0.0 10 102019 24 9 10 10 10 10 10 10 10 10 10 9.9 0.3 0.1 9.7 10




Type Species N/A4 "P"Series 6591 6592 6593 6594 6595 6596 6597 6598 6599 6600

February Exposure(Months) Mean STDEV STDERR LowerCI UpperCI2017 0 10 0.0 0.0 10 102018 12 10 10 10 10 9 10 10 10 10 9 9.8 0.4 0.1 9.5 102019 24 9 10 7 8 8 8 10 8 7 6 8.1 1.3 0.4 7.3 9





TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)YellowPoplar ThermalModification(oC) PreservativeSystem N/A TargetRetention(kg/m3) N/A

SummaryStatisticsVisualDecayRating

Installed

VisualInsectRatingInstalled

TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedYellowPoplar ThermalModification(oC) PreservativeSystem N/A TargetRetention(kg/m3) N/A


Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedYellowPoplar ThermalModification(oC) PreservativeSystem DOTb TargetRetention(kg/m3) 4.5


Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedYellowPoplar ThermalModification(oC) PreservativeSystem DOT TargetRetention(kg/m3) 4.5


Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedYellowPoplar ThermalModification(oC) PreservativeSystem N/A TargetRetention(kg/m3) N/A


Installed


44








February Exposure(Months) Mean STDEV STDERR LowerCI UpperCI2017 0 10 0.0 0.0 10 102018 12 10 10 10 10 10 10 10 10 10 10 10 0.0 0.0 10 102019 24 10 9 10 9 9 10 10 10 9 9 9.5 0.5 0.2 9.2 9.8






February Exposure(Months) Mean STDEV STDERR LowerCI UpperCI2017 0 10 0.0 0.0 10 102018 12 7 8 8 7 8 9 8 9 9 8 8.1 0.7 0.2 7.6 8.62019 24 0 6 7 0 7 7 7 0 4 4 4.2 3.1 1.0 2.3 6.1


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedRedMaple ThermalModification(oC) PreservativeSystem N/A TargetRetention(kg/m3) N/A


Installed




Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedRedMaple ThermalModification(oC) PreservativeSystem DOT TargetRetention(kg/m3) 4.5


Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedRedMaple ThermalModification(oC) PreservativeSystem DOT TargetRetention(kg/m3) 4.5


Installed




Installed


45










TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedWhiteAsh ThermalModification(oC) PreservativeSystem N/A TargetRetention(kg/m3) N/A


Installed




Installed




Installed


46













TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedBalsamFir ThermalModification(oC) PreservativeSystem N/A TargetRetention(kg/m3) N/A


Installed




Installed




Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedPonderosaPine ThermalModification(oC) PreservativeSystem WoodTreatMillworkc TargetRetention(kg/m3) 0.21


Installed


47













TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedSouthernPine ThermalModification(oC) PreservativeSystem ACQ-Cb TargetRetention(kg/m3) 1.0


Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedSouthernPine ThermalModification(oC) PreservativeSystem ACQ-C TargetRetention(kg/m3) 2.0


Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedSouthernPine ThermalModification(oC) PreservativeSystem ACQ-C TargetRetention(kg/m3) 4.0


Installed


TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedSouthernPine ThermalModification(oC) PreservativeSystem N/A TargetRetention(kg/m3) N/A


Installed


48










TableB4.MortiseVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedAspen ThermalModification(oC) PreservativeSystem N/A TargetRetention(kg/m3) N/A


Installed




Installed




Installed


aLowerCi=Lowe95%ConfidenceInterval,UpperCI=Upper95%ConfidenceIntervalbDOT=disodiumoctaboratetetrahydrate,ACQ-C=AmmoniacalCopperQuatTypeCcWoodtreatMillworkisaregisteredtrademarkofKop-Coat(Pittsburgh,PA)

49


February Exposure(Months) Mean STDEV STDERR LowerCIa UpperCI2017 0 10 0.0 0.0 10 102018 12 10 9 10 10 10 10 9 10 9 10 9.7 0.5 0.2 9.4 102019 24 6 9 8 10 10 10 8 10 10 10 9.1 1.4 0.4 8.3 9.9














TableB5.TenonVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)

TableB5.TenonVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedYellowPoplar TargetRetention(kg/m3)

VisualDecayRatingInstalled


YellowPoplar


Installed


N/A

N/A

TableB5.TenonVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedYellowPoplar TargetRetention(kg/m3) 4.5

ThermalModification(oC) PreservativeSystem N/A

ThermalModification(oC) PreservativeSystem N/A

ThermalModification(oC) PreservativeSystem DOTb

TargetRetention(kg/m3)SummaryStatistics


Installed


TableB5.TenonVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedYellowPoplar TargetRetention(kg/m3) 4.5ThermalModification(oC) PreservativeSystem DOT


Installed


TableB5.TenonVisualRatingsforThermallyModifiedWoodExposedinanAWPAE9TestattheWPGKipukaFieldTestSitenearHilo,HI.(Project48057C)-ContinuedYellowPoplar TargetRetention(kg/m3) N/AThermalModification(oC) PreservativeSystem N/A


Installed


50










Type Species

progress report: using thermal modification technology to ...the split resistance strength was...

Documents