b'independentofthecolorandtextureoft hesurfaceoThetempera= turesoftheambientair andofa.11specimenswereessentiallythe samewhenthespecimenswerecoveredwithsnowo Theresultsshowedthatablack.insulat edroofmembranewas subjectedtotemperaturechangesof about180Finaone-year period,andinexcessofBOFinatwo-hourperi od.Thedataregardingmembraneswithother,surfacesshowedt emperaturechangesof lesser magnitudes"Theseextremesmaybeexpectedtovaryinother locations, Todeterminethecoeffic.i.entoflinearmovementofthemembrane (acompositematerialofalternatinglayersofbitumenandfelt), theBureautestedfivesamplemembranes,Onesamplewastakenfrom anactualroof;theothe~swerepreparedinthelaboratoryoTheroof samplewasafive=plyasphalt=asphaltsaturatedorganicfeltoThe laboratorysamplesconsistedoffouralternatelayersoffeltandhot bitumenoThefeltsusedweregasphalt:=sai.turatedorganicfelt, coal=tarpitch=saturatedorganicfelt~aspha.lt=impregnatedglassmat (felt)tandasphalt-saturatedasbestosfelt . Duplicatespecimens,12by2in, 1werecutfromthesamples. Twobrassreferenceplugswer.-,insertedintoeachspecimenten inchesapartwhenmeasuredat13F,Copper~constantanthermo= coupleswereinsertedintoth2specimensandthetemperaturewas reducedto- 60F.Thedistancebetweenplugswasmeasuredtothe nearestten=thousandthofaninch,_Ameasurementwastakenat every10riseintemperaturefrom=60Fto+160F. Thetestsshowedthatthecot::-fficientoflinearexpansionwas notconstantforanyofthemembranesoverthetemperaturerange from=60Fto154F,.Thischangeinlinearmovementappearsto holdforbothasphaltandcoal-tarpitchandforbothorganicand inorganicreinforcingfeltso Thestudyrevealedthattheexpansionandcontractionofthe compositemembraneduetochangingtemperaturesisgreateratlow temperaturesthanthatoftheothercomponentsgenerallyusedina built=uproofsystemoAlso 5themovement:duetothermalchanges ismostcriticalinthelowtemperatureareas;themovementis minimalinthehightemperatureareas c- Althoughthemagnitudeof thelengthchangewasgreaterthanexpected,thechangingnature ofthecoefficientoflinearexpansioncanbeexplainedtheoretically, atleastinpart,bythevisco-elasticbehaviorofroofingbitumens-. Thechartsonthefollowingthree pagesillustratethefindingsandcon= clusionsdis.cussedaboveinMr . Cullen\'s , report,'