Defects in timber
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Defects in timber

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presentation try to cover as many defects as possible in an interactive manner

presentation try to cover as many defects as possible in an interactive manner

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Defects in timber Defects in timber Presentation Transcript

  • SUBMITTED BY-JAYVANT CHOUDHARYC.E , 4TH SEM
  • DEFINITIONCLASSIFICATION OF DEFECTSDEFECTS DUE TO NATURAL FORCESDEFECTS DUE TO FUNGIDEFECTS DUE INSECTSDEFECTS DUE TO CONVERSIONDEFECTS DUE TO SEASONING
  • • A DEFECT IS AN IRREGULARITY OR ABNORMALITY OCCURING IN OR ON WOOD WHICH IS RESPONSIBLE FOR ITS1. STRENGTH REDUCTION2. LOWERING OF DURABLITY3. LOWERING OF UTILITY4. POOR APPERANCE5. DECAY
  • (CAUSED DUE TO)NATURAL FORCES INSECTS SEASONING FUNGI CONVERSION
  • CHEMICAL STAIN KNOTS SHAKES TWISTED FIBRES RIND GALLS UPSETS BURLS
  • CHEMICAL STAIN:-THE WOOD ISSOMETIMES DISCOLOURED BY THECHEMICAL ACTION CAUSED WITHIT BY SOME EXTERNAL AGENCY.THISIS KNOWN AS CHEMICAL STAIN. RIND GALLS:-THE RIND MEANS BARK AND GALL INDICATES ABNORMAL GROWTH.HENCE PECULIAR CURVED SWELLING FOUND ON THE BODY OF TREE ARE KNOWN AS RIND GALL.THEY DEVELOP AT POINTS FROM WHERE BRANCHES ARE IMPROPERLY CUT OFF OR REMOVED.THEY ARE RARELY FOUND IN A TREE AND THE TIMBER IN THIS PART IS VERY WEAK AND NOT DURABLE.
  • COARSE GRAIN:-IF THE TREE GROWS RAPIDLY,THE ANNUALRINGS ARE WIDENED.IT IS KNOWN AS THE COARSEDGRAIN TIMBER AND SUCH TIMBER POSSESSES LESSSTRENGTH KNOTS:-THESE ARE THE BASES OF BRANCHES OR LIMBS WHICH ARE BROKEN OR CUT OFF FROM THE TREE.THE PORTION FROM WHICH THE BRANCH IS REMOVED RECIEVES NOURISHMENT FROM THE STEM FOR A PRETTY LONG TIME AND IT ULTIMATELY RESULTS IN FORMATION OF DARK HARD RINGS WHICH ARE KNOWN AS KNOTS.AS CONTINUITY OF WOOD FIBRES ARE BROKEN BY KNOTS,THEY FORM A SOURCE OF WEAKNESS
  • PIN KNOT:-DIAMETRE UPTO 6.50MMSMALL KNOT:-DIAMETRE UPTO 6.5 AND 20MMMEDIUM KNOT:-DIAMETER BETWEEN 20 AND 40MMLARGE KNOT:-DIAMETER GREATER THAN 40MMDEAD KNOT:-KNOT WHICH IS SEPERATED FROM BODY OF WOOD.IT IS NOTSAFE TO USE WOOD WITH SUCH A KNOT FOR ENGINEERING PURPOSES.DECAYED KNOT:-POPULARLY KNOWN AS UNSOUND KNOTAND FORM BYACTION OF FUNGI ON WOOD.LIVE KNOT:-IT IS THOROUGHLY FIXED IN WOOD AND CANNOT SEPERATED OUTFROM BODY OF WOOD.IT IS FREE FROM CRACKS AND DECAY.WOODCONTAINING THIS KNOT CAN BE USED FOR ENGINEERING PURPOSES.LOOSE KNOT:-IT IS PRELIMINARY STAGE OF DEAD KNOT.ROUND KNOT:-THE CROSS-SECTION OF THIS TYPE OF KNOT IS EITHER ROUNDOR OVALTIGHT KNOT:-IT IS PRELIMINARY STAGE OF LIVE KNOT.THE FIBRES OF KNOT AREFIRMLY HELD IN SORROUNDING WOOD.
  • DEAD WOOD:-THE TIMBER WHICH IS OBTAINEDFROMDEAD STANDING TREES CONTAINS DEADWOOD.IT IS INDICATED BY LIGHT WEIGHT ANDREDDISH COLOUR.DRUXINESS:-THIS DEFECT IS INDICATED BY WHITE DECAYED SPOTSWHICH ARE CONCEALED BY HEALTHY WOOD THEY ARE PROBABLYFORMED BY ACCESS OF FUNGI. SHAKES:-THESE ARE LONGITUDINAL SEPERATIONS IN WOOD BETWEEN THE ANNUAL RINGS.THESE ARE CRACKS WHICH PARTLY OR COMPLETELY SEPARATE FIBRES OF WOOD.THE SEPERATIONS MAKE THE WOOD UNDESIRABLE WHEN APPERANCE IS IMPORTENT
  • STAR SHAKES:-THESE ARE CRACKS WHICH EXTEND FROM BARK TOWARDS THE SAP WOOD.THESE ARE USUALLY CONFINED UPTO THE PLANE OF SAP WOOD.THESE ARE WIDER ON OUTSIDE ENDS AND NARROWER ON INSIDE ENDS.THEY ARE USUALLYFORMED DUE TO EXTREME HEAT OR SEVERE FROST DURING THE GROWTH OF TREECUP SHAKES:-IT APPEARS AS CURVED SPLITWHICH PARTLY OR WHOLLY SEPERATESANNUAL RINGS FROM ONE ANOTHER.IT ISCAUSED DUE TO EXCESSIVE FROST ACTION ONSAP PRESENT IN THE TREE ESPECIALLY WHENTHE TREE IS YOUNG
  • HEART SHAKES:-THESE CRACKS OCCUR IN CENTREOF CROSS-SECTION OF TREE AND THEY EXTENDFROM PITH TO SAP WOOD IN DIRECTION OFMEDULLARY RAYS.THESE CRACKS OCCUR DUE TOSHRINKAGE OF INTERIOR PART OF TREE WHICH ISAPPROACHING MATURITY.THE HEART SHAKEDIVIDE THE TREE CROSS-SECTION INTO TWO ORFOUR PARTS. RING SHAKES:-WHEN CUP SHAKES COVER THE ENTIRE ,THEY ARE KNOWN AS RING SHAKES
  • TWISTED FIBRES:-THESE ARE KNOWN AS WANDERINGHEARTS AND CAUSED BY TWISTING OF YOUNG TREES BYFAST BLOWING WIND.THE TIMBERS WITH TWISTEDFIBRES IS UNSUITABLE FOR SAWING UPSETS:-THESE INDICATE WOOD FIBRES WHICH ARE INJURED BY CRUSHING OR COMPRESSION.THE UPSETS ARE MAINLY DUE TO IMPROPER FELLING OF TREE AND EXPOSURE OF TREE IN ITS YOUNG AGE TO FAST BLOWING WIND BURLS:-THEY ARE PARTICULARLY FORMED WHEN A TREE RECIEVES SHOCK OR INJURY IN ITS YOUNG AGE.DUE TO ITS INJURY,THE GROWTH OF TREE IS COMPLETELY UPSET AND IRREGULAR PROJECTIONS APPEAR ON THE BODY OF TIMBER
  • BLUE STAIN BROWN ROT DRY ROT HEART ROT WET ROT WHITE ROT
  • BLUE STAIN :-THE SAP OF WOOD IS STAINED TOBLUISH COLOUR BY THE ACTION OF CERTAIN TYPEOF FUNGI BROWN ROT :-THE TERM ROT IS USED TO INDICATE DECAY OR DISEASE OF TIMBER,THE FUNGI OF CERTAIN TYPE REMOVES CELLULOSE COMPOUNDS FROM WOOD AND HENCE WOOD ASSUMES THE BROWN COLOURWHITE ROT:-IT IS JUST OPPOSITE OF BROWNROT.IN THIS CERTAIN TYPE OF FUNGI ATTACKLIGNIN OF WOOD AND WOOD ASSUMES THEAPPEARANCE OF A WHITE MASS CONSISTINGOF CELLULOSE COMPOUNDS
  • HEART ROT:-THIS IS FORMED WHEN BRANCH HAS COME OUT OF THE TREE.IN SUCH CASE,THE HEART WOOD IS EXPOSED TO ATTACK OF ATMOSPHERIC AGENTS.ULTIMATELY THE TREE BECOMES WEAK AND IT GIVES HOLLOW SOUND WHEN STRUK WITH HAMMER WET ROT:-SOME KIND OF FUNGI CAUSEDCHEMICAL DECOMPOSITION OF WOOD OF TIMBER AND IN DOING SO CONVERT TIMBER INTO GREYISH BROWN POWDER.IT IS KNOWN AS WET ROT. SOME IMPORTANT POINTS TO BE REMEMBERED ABOUT WET ROT ARE.THE ALTERNATE WET AND DRY CONDITIONS FAVOURS THE DEVELOPMENTOF WET ROTIF UNSEASONED OR IMPROPERLY SEASONED TIMBER ARE EXPOSED TO RAINAND WIND,THEY BECOME EASILY LIABLE FOR ATTACK OF WET ROT.TO PREVENT WET ROT,THE WELL SEASONED TIMBER SHOULD BE USED FOREXTERIOR WORK OR FOR UNDERGROUND WORK AND IT SHOULD BE COVEREDBY TAR OR PAINT FOR PROTECTION AGAINST MOISTURE
  • DRY ROT :- SOME TYPES OF FUNGI FEED ONWOODS AND DURING FEEDING THEY ATTACK ONWOOD AND CONVERT IT INTO DRY POWDERFORM.THIS IS KNOWN AS DRY ROT.THEFOLLOWING FACTS TO BE NOTED.DRY ROT OCCURS AT THE PLACES WHERE THERE IS NO FREE CIRCULATION OF AIRSUCH AS IMPROPERLY VENTILATED BASEMENTS,ROOMS ETC AND DAMPED SITUATIONLIKE KITCHEN TOILET ETC.THE UNSESONED SAP WOOD ARE EASILY ATTACKED BY DRY ROT.THE FAVOURABLE CONDITIONS FOR GROWTH OF FUNGUS CAUSING DRY ROT AREABSENCE OF SUNLIGHT,DAMPNESS,PRESENCE OF SAP,STAGNANT AIR AND WARMTH.IT IS ALSO CAUSED BY CHARRING,PAINTING AND TARRING THE UNSEASONEDTIMBER.THE DRY ROT MAY BE PREVENTED BY USING WELL SEASONED TIMBER FREE FROMSAP.WHEN A PART OF TREE IS SERIOUSLY AFFECTED BY DRY ROT,THE DAMAGED PORTIONMAY BE COMPLETELY REMOVED AND REMAINING UNAFFECTED PORTION SHOULD BEPAINTED WITH A SOLUTION OF COPPER SULPHATE.
  • (CAUSED BY)BEETLES MARINE BOARERS TERMITES
  • Flour like powder THEY FORM PIN HOLES OF SIZE ABOUT 2MM DIA IN WOOD TUNNEL FORMATION IS DONE IN SAP WOOD BY LARVAE OF BEETLE CONVERSION OF TIMBER INTO FLOUR LIKE POWDER THEY DO NOT DISTURB OUTER SHELL OR COVER
  • BOARSTHEY ARE FOUND IN SALTY WATERTHEY FORM TUNNELS OR BORES TO TAKE SHELTERSDIAMETER AND LENGTH OF HOLES ARE AS HIGH AS 25MM AND 60MM RESPECTIVELYAFFECTED WOOD LOOSES ITS COLOUR AND STRENGTHNO TIMBER IS COMPLETELY IMMUNE FROM ATTACK OF MARINEBOARERS
  • LIVES IN COLONY AND VERY FAST IN EATING AWAY THE WOODFROM CORE OF CROSS-SECTION.MAKES TUNNELS IN DIFFERENT DIRECTIONS AND USUALLYNOT DISTURB THE OUTER SHELL OR COVER.THE TIMBER PIECE ATTACKED BY TERMITES MAY LOOK SOUNDUNTILL IT COMPLETELY FAILSFEW GOOD TIMBERS LIKE TEAK,SAL,ETC CAN RESIST THEACTION OF TERMITES
  • CHIP MARK DIAGONAL GRAIN TORN GRAIN WANE
  • CHIP MARK:-THIS DEFECT ISINDICATED BY MARK OR SIGNSPLACED ON FINISHED SURFACEOF TIMBER.THEY MAY BEFORMED BY PLANING MACHINE WANE:-THIS DEFECT IS DENOTED BY PRESENCE OF ORIGINAL ROUNDED SURFACE ON MANUFACTURED PART OF TIMBER
  • DIAGONAL GRAIN:-THE DEFECT ISFORMED DUE TO IMPROPERSAWING SAWING OF TIMBER.IT ISINDICATED BY DIAGONAL MARKSON STRAIGHT GRAINED SURFACEOF TIMBER TORN GRAIN:-DEFECT CAUSED WHEN A SMALL DEPRESSION IS FORMED ON A FINISHED SURFACE OF TIMBER BY FALLING A TIMBER OR SO TORN GRAIN
  • TWIST CUP BOW SPRING SPLIT HONEY COMBING
  • BOW:-THIS DEFECT ISINDICATED BY CURVATUREFORMED IN DIRECTION OFLENGTH OF TIMBER CUP:-THIS DEFECT IS INDICATED BY CURVATURE FORMED IN TRANSVERSE DIRECTION OF TIMBER
  • CHECK:-A CRACK WHICH SEPERATES FIBRES OF WOOD.IT DOES NOT EXTEND FROM ONE END TO THE OTHER SPLIT SPLIT:-WHEN CHECKCHECK EXTENDS FROM ONE END TO OTHER,IT IS KNOWN AS A SPLIT
  • TWIST:-WHEN A PIECE OF TIMBER HAS SPIRALLY DISTORTED ALONG ITS LENGTH,IT IS KNOWN AS A TWISTHONEY-COMBING:-DUE TOSTRESS DEVOLOPED DURINGDRYING,VARIOUS RADIAL ANDCIRCULAR CRACKS DEVELOP INTHE INTERIOR PORTION OFTIMBER,WHICH RESEMBLESWITH HONEY-COMB TEXTURE HONEY-COMB STRUCTURE
  • BUILDING MATERIALS-S.K.DUGGALBUILDING MATERIALS-RANGWALABASIC CIVIL ENGINEERING-DR.B.C.PUNMIABASIC CIVIL ENGINEERING-SATHEESH GOPIGOOGLE-DEFECTS OF TIMBER