b'PageNo.3 Let\'stakealookatwhatthisextrememidwesttemperature candotoabuilt-uproof.UnitedStatesGovernmentreportsshown lastyearatthisconventiontoldusthattheseroofscansuffer atemperaturedifferentialofsome180,someti~eswithinafew hours.Thisiswhatweknowinthetradeasthermalshock.Illustration#3isalaboratorytestofagypsumdeckthathadabuiltincrack,overwhichwasapplie dinsulationandaspecification built-uproof : zsorT[t,,IP["ATUftECHANG,[T(ST CIN )Ot,mt) 2001\'.o~~\'~\'sr:T~?~~RTIcuc,c.oP(JlIIN(; _ . TM"""m 1H~Arl,.~,.sON; - /JR\'I" ,cc ON 1t00,I[ \'HCAr l,U,,PSoo, 1)0;\'L(I\':\' -""""\'-1fa\'-\'"I11\';ic";;,r,::\'\'~~~ 100 ,,"\' :___.- \',qiDUK~= ~I\'- ;,Oto T~~\',, \'!!! ) - ,~,::1e ~0- I- tl\'J~J ~i ~ $0- 1 ~ rr. ;; IOO- Ir.J~ LOAO 1)00- ~ Tli.ttHII.S-l,.O,ID-tC:,_DCCK Asshownbythisgraph,thetemperaturereadingsareontheleft, vertically.Acrossthebottomistime,movingfromOto8hours. Tensionisnotedontherightsideofthegraph.AtOhours,the heatlampswereturnedon.FromOtothefirsthour,thetemperature ofthebuilt-uproofrosetoapproximately150.Atonehoura slightloadwasappliedtothebuilt-uproofwhilemechanically pullingthedeckapartatthecrack.Aloadofapproximately1lb. perinchofwidthwasappliedandat2hoursthelampswereturned offandtheroofdeckwasloadedwithsome400lbs.ofdryice. Immediatelythetemperatureofthebuilt-uproofdroppedtoapproximatelyminus100.Asthebuilt-uprooftemperaturedropped,the loadingrosetoapproximately16lbs.perinch.Astimeprogressed tothethirdandthefourthhour,thebuilt-uprooftemperatureheld constantataboutminus100;thetensiononthebuilt-uproofdropped from16lbs.toapproximately12lbs.Thisdropintensionwasdue toelongationoftheroofingmaterials.Thisisnottobeconfused withelasticity.Wewillgetintothedifferencebetweenelasticity andelongationinafewmoments.At4hoursthetensiononthe built-uproofwasholdingratherconstantandanelectricmotor drivingascrewmachinewassetintomotiontopullthedeckapart atthebuilt-insplit.Thisdeckmovedatapproximately3/16ofan inchperhour.Thisisaveryslowmovement.Atthefifthhour andthesixthhour,thetensiononthebuilt-uproofrosetoabout SOlbs.perinchatwhichtimetheinsulationshearedfromthedeck. Theresultsofthistestandthetests likeitareofgreatvalueto roofingcontractors,forthistest,coupledwiththeresultsofthe'