Effects of Cedar Oil and Silica Gel Treatment on Dimensional Stability and Mechanical Properties of Southern Yellow Pine Boards

Transcription

1 United Sttes Deprtment of Agriculture Effects of Cedr Oil nd Silic Gel Tretment on Dimensionl Stbility nd Mechnicl Properties of Southern Yellow Pine Bords Xiping Wng Christopher A. Senlik Robert Ross Nel Bennett Deborh Conner Forest Service Forest Products Lbortory Reserch Note FPL RN 0339 September 2016

2 Abstrct A lbortory study ws conducted to investigte the effects of cedr oil nd silic gel tretment on dimensionl stbility nd mechnicl performnce of southern yellow pine (SYP) bords. Two hundred pieces of SYP nd 100 pieces of red ok bords with nominl dimension of 1 by 6 by 48 in. (25 by 152 by 1,219 mm) were selected for this study. The red ok bords were included s stndrd mmunition pllet stock for comprison. The experimentl procedure involved stress wve E-rting, grouping, defect mpping, preservtive tretment, high-temperture kiln (simulting hot nd dry service condition), nd fltwise sttic bending test. Cedr oil nd silic gel tretment hd positive effect on dimensionl stbility of the No. 2 SYP bords, s indicted by reduced visible end-splits nd bord wrp. Our results lso indicted tht cedr oil nd silic gel tretment hd detrimentl effect on stiffness nd strength of the No. 2 SYP bords. Both modulus of elsticity nd modulus of rupture decresed significntly in treted SYP compred with those of untreted SYP. Keywords: End split, pllet deck bords, stiffness, strength, wrp, work to mximum lod Contents Introduction... 1 Mterils nd Methods... 1 Results nd Discussions... 2 Conclusions... 4 Literture Cited... 5 September 2016 Wng, X.; Senlik, C.A.; Ross, R.; Bennett, N.; Conner, D Effects of cedr oil nd silic gel tretment on dimensionl stbility nd mechnicl properties of southern yellow pine bords. FPL-RN Mdison, WI: U.S. Deprtment of Agriculture, Forest Service, Forest Products Lbortory. 5 p. A limited number of free copies of this publiction re vilble to the public from the Forest Products Lbortory, One Gifford Pinchot Drive, Mdison, WI This publiction is lso vilble online t Lbortory publictions re sent to hundreds of librries in the United Sttes nd elsewhere. The Forest Products Lbortory is mintined in coopertion with the University of Wisconsin. The use of trde or firm nmes in this publiction is for reder informtion nd does not imply endorsement by the United Sttes Deprtment of Agriculture (USDA) of ny product or service. In ccordnce with Federl civil rights lw nd U.S. Deprtment of Agriculture (USDA) civil rights regultions nd policies, the USDA, its Agencies, offices, nd employees, nd institutions prticipting in or dministering USDA progrms re prohibited from discriminting bsed on rce, color, ntionl origin, religion, sex, gender identity (including gender expression), sexul orienttion, disbility, ge, mritl sttus, fmily/prentl sttus, income derived from public ssistnce progrm, politicl beliefs, or reprisl or retlition for prior civil rights ctivity, in ny progrm or ctivity conducted or funded by USDA (not ll bses pply to ll progrms). Remedies nd complint filing dedlines vry by progrm or incident. Persons with disbilities who require lterntive mens of communiction for progrm informtion (e.g., Brille, lrge print, udiotpe, Americn Sign Lnguge, etc.) should contct the responsible Agency or USDA s TARGET Center t (202) (voice nd TTY) or contct USDA through the Federl Rely Service t (800) Additionlly, progrm informtion my be mde vilble in lnguges other thn English. To file progrm discrimintion complint, complete the USDA Progrm Discrimintion Complint Form, AD-3027, found online t nd t ny USDA office or write letter ddressed to USDA nd provide in the letter ll of the informtion requested in the form. To request copy of the complint form, cll (866) Submit your completed form or letter to USDA by: (1) mil: U.S. Deprtment of Agriculture, Office of the Assistnt Secretry for Civil Rights, 1400 Independence Avenue, SW, Wshington, D.C ; (2) fx: (202) ; or (3) emil: progrm.intke@usd.gov. USDA is n equl opportunity provider, employer, nd lender.

3 Effects of Cedr Oil nd Silic Gel Tretment on Dimensionl Stbility nd Mechnicl Properties of Southern Yellow Pine Bords Xiping Wng, Reserch Forest Products Technologist Christopher A. Senlik, Reserch Generl Engineer Robert Ross, Project Leder Forest Products Lbortory, Mdison, Wisconsin Nel Bennett, Generl Engineer Deborh Conner, Biologicl Technicin Forest Products Lbortory, Princeton, West Virgini Introduction Use of wood in the mnufcture of shipping continers, specificlly pllets, is well documented nd bsed on strong theoreticl nd experimentl reserch bse. Wood pllets re now in use worldwide to ship wide rnge of products, from griculturl food stuffs to mmunition used in militry opertions. The USDA Forest Products Lbortory (FPL) ws recently contcted by technicl representtives from the U.S. Deprtment of Defense (DoD) nd sked to provide ssistnce in evluting the performnce of new wood preservtive tretment tht is being considered for potentil use in the mnufcture of wood pllets used to trnsport smllrms mmunition. The hypothesis tested in this project ws if cedr oil nd silic gel, commercilly vilble nd environmentlly friendly preservtive product, cn cuse softwood four-wy entry mmo pllets to perform s well s hrdwood pllets yet without experiencing dimensionl stbility problems. The foundtion for the preservtive tretment utilizes nturl wood oils extrcted from Juniperus species. Reserch hs been conducted to determine the termiticidl nd fungl ctivities of hertwood, brk/spwood, nd leves from dominnt juniper species in the United Sttes s prt of n evlution of the commercil potentil of plnts tht re now considered to be noxious tree species in rngelnds (Adms nd others 1988; Adms 1991; Clrk nd McChesney 1990). Bsed on results from these studies, commercil cedr oil nd silic gel product ws developed nd is now mnufctured nd mrketed s n environmentlly friendly wood preservtive. The gol of this project ws to investigte the effects of the cedr oil nd silic gel tretment on the dimensionl stbility nd mechnicl performnce of southern yellow pine (SYP) bords. Red ok bords were included s stndrd mmunition pllet stock for comprison. The project involved stress wve E-rting, grouping, defect mpping, preservtive tretment, high-temperture kiln (simulting hot nd dry service condition), nd fltwise sttic bending. Specific objectives were to (1) develop technicl dt on the effect of high-temperture kiln on end splits nd wrp in preservtive-treted nd untreted deck bords; (2) determine the effect of cedr oil nd silic gel tretment on dimensionl stbility of SYP bords; nd (3) determine the effect of cedr oil nd silic gel tretment on mechnicl properties of SYP bords. Mterils nd Methods Mterils In lte November 2014, 150 pieces of red ok nd 300 pieces of SYP bords were obtined by the Deprtment of Ammunition Center (DAC) nd shipped to the wood lbortory in Princeton, West Virgini. All bords were in nominl dimension of 1 by 6 by 48 in. (25 by 152 by 1,219 mm). The red ok group ppered to be cler nd high-qulity wood; ll the SYP bords were No. 2 kiln dried nd het treted (Fig. 1). Through initil stress wve E-rting procedure, we selected 100 pieces of red ok nd 200 pieces of SYP bords s test specimens: Group ok bords, stndrd pllet mterils Group SYP bords (kiln dried nd het treted), no preservtive tretment nd used s control group Group SYP bords (kiln dried nd het treted), to be treted with cedr oil nd silic gel In mid-februry 2015, Group 3 ws shipped to McAlester Army Ammunition Plnt (MAAP) to receive preservtive tretment. At MAAP, ll bords of Group 3 were treted with cedr oil nd silic gel through immersion method for

4 Reserch Note FPL RN 0339 Figure 1 Red ok nd southern yellow pine bords s received: (top) red ok bords (nominl 1 by 6 by 48 in.); (bottom) southern yellow pine bords (nominl 1 by 6 by 48 in.). Figure 2 Bord smples entered into the dry kiln to be heted to 160 F for 30-dy. over 12 h. In mid-june 2015, the treted SYP bords (Group 3) were shipped bck to Princeton, West Virgini, for physicl mesurements. Testing Procedures Bord smples were mesured for bsic physicl properties t the time received, before entering the kiln, nd fter 30 dys of high-temperture in the kiln. A kiln of 160 F dry-bulb temperture with low reltive humidity in 1,000-bord-foot Irvington Moore Dry Kiln (Jcksonville, Florid) ws used to simulte hot nd dry environmentl condition tht the mmo pllets could experience during service. Figure 2 shows ll the smple bords wheeled into the dry kiln to be heted for 30-dy hightemperture. The physicl mesurements on the bord smples t ech stge included the following: Mesure wrp (crook, bow, twist) of ech bord using luminum wedges nd mesurement tble Mrk end splits with color pen (defect mpping) Mesure stress wve velocity on ech bord (E-rting) Weigh ech bord Mesure moisture content on subsmple of bords Following the 30-dy kiln nd finl physicl mesurements in Princeton, bords of ll three groups were shipped to the Forest Products Lbortory in Mdison, Wisconsin, nd stickered in conditioning room of 75 F nd 65% reltive humidity. Upon reching equilibrium moisture content, the bords were subjected to fltwise sttic bending testing with center point lod ccording to ASTM stndrd D 198 (ASTM 2014). Lod-deflection dt for ech bord were recorded to determine mechnicl properties: modulus of elsticity (MOE), modulus of rupture (MOR), nd work to mximum lod (WML). During the sttic bending test process, subsmple of 20 bords were rndomly selected from ech group nd moisture block ws cut from ech of these bords for determintion of moisture content (MC) using oven dry method ASTM D (ASTM 2015). Results nd Discussions Dimensionl Stbility As service conditions chnge during service, wood pllets tend to chnge dimension nd develop defects such s checks, crcks, nd splits. These defects could cuse wood pllets to be downgrded or rejected if they re not within specifictions. The quntittive prmeters we exmined concerning the dimensionl stbility of the pllet bords were end splits nd bord wrp (bow, crook, nd twist). Figure 3 shows the distribution of end splits for three groups of pllet deck bords mesured before nd fter the high-temperture kiln. Tble 1 summrizes the cumultive length of the end splits for ech group. 2

5 Effects of Cedr Oil nd Silic Gel Tretment on Dimensionl Stbility nd Mechnicl Properties of Southern Yellow Pine Bords Figure 3 Distribution of end splits mesured on red ok nd southern yellow pine bords (1 in. = 25.4 mm). 3

6 Reserch Note FPL RN 0339 Tble 1 Cumultive length of end splits visully mpped on the bords t the time received, before kiln, nd fter kiln Cumultive length of ll end splits (in.) Pllet deck bord No. of bords No discernible differences in end splits for both red ok (Group 1) nd untreted SYP (Group 2) were found before nd fter the kiln. However, overll end splits in treted SYP (Group 3) were reduced 11% fter kiln. The cedr oil nd silic gel tretment my hve contributed to relief of drying stress during kiln nd subsequently yielding very few new short end splits while reducing the length of some visible splits bsed on our visul observtion. Tble 2 shows cumultive wrp for ech bord group. Overll, the red ok group hd much less wrp thn the SYP groups. This is not surprising, becuse the ok bords we received were high-qulity wood with few defects (Fig. 1). The SYP bords, on the other hnd, were No. 2 grde nd hd vrious defects such s big knots, slope of grin, wne, nd blue stin (Fig. 1b). For SYP bords, cumultive wrp for the untreted group incresed with mgnitude higher thn tht for the treted group. The cedr oil nd silic gel tretment seemed to help stbilize wood nd reduce the tendency of wrping in SYP bords. Mechnicl Properties Received Before kiln After kiln Group 1: Red ok Group 2: Untreted SYP Group 3: Treted SYP in. = 25.4 mm. Tble 3 shows bsic properties of the pllet bords mesured t the time they were received. Both density nd dynmic MOE of the ok group were significntly higher thn those of two SYP groups (p = ) t 95% confidence level. These mesured properties re consistent with property vlues given in the Wood Hndbook (FPL 2010) for the species. For SYP bords, no sttisticl differences in density (p = ) nd dynmic MOE (p = ) between Group 2 (Untreted SYP) nd Group 3 (SYP to be treted) were found t 95% confidence level, indicting tht the SYP bords in these two groups cn be deemed s hving the sme qulity. Tble 4 shows the moisture conditions of the red ok, untreted SYP, nd treted SYP bords before nd fter the kiln nd t the time of sttic bending tests. The MC dropped to 2.2% for red ok nd bout 7% for SYP fter the 30-dy kiln. After conditioning in the environmentl room t 75 F nd 65% RH for 2 months, the MC ws up to 7.9% for red ok, 10.6% for untreted SYP, nd 10.4% for treted SYP. Tble 5 tbultes sttic bending properties (MOE, MOR, nd WML) of the pllet bords fter the 30-dy kiln. All sttic bending properties of the ok group re significntly higher thn those of the two SYP groups t 95% confidence level (p = ). There re sttisticl differences in MOE (p = ) nd MOR (p = ) between Group 2 (SYP with no preservtive tretment) nd Group 3 (SYP with preservtive tretment) t the 95% confidence level. Both MOE nd MOR decresed significntly in the treted SYP group compred to tht in untreted SYP group, indicting possible detrimentl effect of the preservtive on mechnicl performnce. There is no sttisticl difference in WML (p = ) between the two SYP groups t 95% confidence level. Conclusions The red ok bords received were high-qulity bords with very few defects. The 30-dy dry kiln time did not hve much effect on existing end splits nd wrp of the bords. Mechnicl properties of the red ok group obtined through destructive bending tests were significntly higher thn those of untreted SYP nd preservtive-treted SYP. The cedr oil nd silic gel tretment hd positive effect on dimensionl stbility of the No. 2 SYP bords. Cumultive length of the end splits in treted SYP ws reduced by 11% fter kiln, compred to tht before kiln, wheres cumultive length of end splits in untreted SYP remined the sme fter kiln. The cedr oil nd silic gel tretment likely contributed to relief of drying stress during high-temperture nd subsequently reduced the length of visible splits, though techniclly end Tble 2 Cumultive bord wrp (crook, bow, twist) physiclly mesured t time received, before kiln, nd fter kiln Cumultive wrp (in.) Received Before kiln After kiln Pllet deck bord Crook Bow Twist Crook Bow Twist Crook Bow Twist Group 1: Red ok Group 2: Untreted SYP Group 3: Treted SYP in. = 25.4 mm. 4

7 Effects of Cedr Oil nd Silic Gel Tretment on Dimensionl Stbility nd Mechnicl Properties of Southern Yellow Pine Bords Tble 3 Bsic properties of the pllet deck bords mesured t the time received Pllet deck bords No. of bords Men Density (lb/ft 3 ) dev. Dynmic MOE ( 10 6 lb/in 2 ) Men dev. Group 1: Red ok Group 2: Untreted SYP Group 3: SYP to be treted lb/ft 3 = kg/m 3 ; 1 lb/in 2 = kp. Tble 4 Moisture content of pllet deck bords during the course of the project Moisture content (MC) (%) Pllet deck bords Before kiln After kiln At time of sttic testing Group 1: Red ok Group 2: Untreted SYP Group 3: Treted SYP splits did not hel nd just visully closed. Treted SYP lso hd less wrp thn the untreted SYP group. The tretment seemed to help stbilize the wood nd reduce the tendency of wrping in SYP bords. The cedr oil nd silic gel tretment hd detrimentl effect on stiffness nd strength of the No. 2 SYP bords. Both MOE nd MOR decresed significntly in the treted SYP group compred to tht of untreted SYP group. However, the preservtive tretment hd no significnt effect on WML. Literture Cited Adms, R.P.; McDniel, C.A.; Crter, F.L Termiticidl ctivities in the hertwood, brk/spwood nd leves of Juniperus species from the United Sttes. Biochemicl Systemtics nd Ecology. 16(5): Adms, R.P Cedr wood oils nlysis nd properties. In: Modern methods of plnt nlysis. New Series, Volume 12. Essentil oils nd wxes. Linskens, H.F.; Jckson, J.F., eds. Berlin: Springer-Verlg. pp ASTM D test methods for sttic tests of lumber in structurl sizes. West Conshohocken, PA: Americn Society for Testing nd Mterils. ASTM D test methods for direct moisture content mesurement of wood nd wood-bse mterils. West Conshohocken, PA: Americn Society for Testing nd Mterils. Clrk, A.M.; McChesney, J.D Antimicrobil properties of hertwood, brk/spwood nd leves of Juniperus species. Phytotherpy Reserch. 4(1): Forest Products Lbortory Wood hndbook wood s n engineering mteril. Generl Technicl Report FPL- GTR-190. Mdison, WI: USDA Forest Service, Forest Products Lbortory. 510 p. Tble 5 Sttic bending properties of pllet bords fter 30-dy hightemperture Pllet deck bords No. of bords Men MOE ( 10 6 lb/in 2 ) b dev. MOR (lb/in 2 ) b Men dev. WML (in-lbf/in 3 ) c Men dev. Group 1: Red ok ,021 2, Group 2: Untreted SYP ,191 2, Group 3: Treted SYP ,417 2, Averge moisture content (MC) of bords ws 7.9% for red ok, 10.6% for untreted SYP, nd 10.5% for treted SYP. Wood Hndbook property vlues t 12% MC: northern red ok, MOE = lb/in 2, MOR = 14,300 lb/in 2, WML = 14.5 in-lbf in 3 ; loblolly pine, MOE = lb/in 2, MOR = 9,400 lb/in 2, WML = 10.4 in-lbf in 3. b 1 lb/in 2 = kp. c 1 in-lbf/in 3 = kj/m 3. 5