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STRCTENG 201 > Timber > Flashcards

Timber Flashcards

1
Q

volume of wood used is

A

less that volume of wood grown

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2
Q

what percent of wood is carbon

A

50%

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3
Q

CO2 + H2O ->

A

C6H12O6 + O2

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4
Q

softwood forests are

A

coniferous/evergreen

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5
Q

hardwoods forests are

A

deciduous/broad-leaved

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6
Q

which wood grows faster

A

softwoods generally grow faster than hardwoods

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7
Q

what species of timber does the timber industry rely on worldwide to build in construction

A

softwood species provide the bulk of timber used in timber construction

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8
Q

when are hardwoods used

A

in limited cases

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9
Q

which wood is cheaper

A

softwoods

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10
Q

what is the part of wood on the outside layer called

A

outer bark (dead)

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11
Q

what is the part of wood inside the outside layer called

A

inner layer (living)

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12
Q

what is the part of wood inside the inner layer called

A

cambium

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13
Q

what is the part of wood called spanning the outer layer inside the cambium

A

sapwood

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14
Q

what is the part of wood spanning the inside of sapwood

A

heartwood

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15
Q

what is the middle of the wood called

A

pith

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16
Q

what are the directions of wood called

A

wood rays

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17
Q

what part of wood participates in sap conduction

A

sapwood, not heartwood

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18
Q

what wood is lighter and not resistant to fungi

A

sapwood

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19
Q

what wood is more resistant to fungi and difficult to treat and more stable in changing moisture conditions

A

heartwood

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20
Q

are there differences in structural properties between sapwood and heartwood

A

no

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21
Q

light bands are

A

earlywood

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22
Q

dark hands are

A

latewood

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23
Q

summerwood cell properties

A

densely packed, thicker cell walls, higher density

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24
Q

radial and tangential are called

A

traverse

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25
Q

what are the longitudinal direction of wood grains called

A

parallel to grain

25
Q

why is flatsawn used more than quartersawn

A

because you get a lot more material produced from each log

25
Q

EL: ER: ET ≈

A

20 : 1.6 : 1

26
Q

why is quartersawn used less then flatsawn

A

because its expensive to buy and theres risk of less material

27
Q

what are the positives of quartersawn

A

better moisture fluctuation resistance and stability

28
Q

what are the negatives of flatsawn

A

risk of deformation

29
Q

what is the single most important indicator of strength in wood

A

density

30
Q

what is density related to

A

hardness, ease of machining and nailing resistance

31
Q

what is specific gravity of timber

A

ratio of density of wood to the density of water using oven-dry weight and current volume

32
Q

what is a defect in wood

A

any feature that alters the natural grain of the wood

33
Q

what are different defects in wood

A

knots, slope of grain, resin pocket, check, split, compression wood, and wane

34
Q

what occurs as a result of changes in moisture

A

check and split

35
Q

when are defects critical

A

when there are knots in tension zones or split/check in connection area

36
Q

what are knots

A

remnants of the branch connections on the trunk, can be “tight” (packed in) or ‘loose’ (pop out) and can be very dense

37
Q

how to increase the quality of wood and its value

A

branches are cut regularly to minimise knots

38
Q

90% of all problems with wood involve

A

moisture

39
Q

why are wood in trees very wet

A

because the cell structure contains excessive water (sap) and is fully swollen

40
Q

when wood is used the water will

A

dry out and partially shrink

41
Q

what will be reached eventually for wood moisture

A

the moisture balance between the dryness of the wood and the humidity of its environment will bereached

42
Q

what determines the moisture content of the wood

A

atmospheric humidity

43
Q

wat determines the dimensions of the wood

A

moisture content of the wood

44
Q

how to calculate moisture content %

A

weight of water/weight of oven dry wood x 100/1

45
Q

what is humidity referred to

A

water or moisture in vapour form in the atmosphere

46
Q

what is relative humity

A

the ratio of the amount of moisture in the air at a certain temperature to the amount it would be able to hold at that temperature

47
Q

how does wood remain

A

hygroscopic

48
Q

what does hydroscopic mean

A

responds to changes in atmospheric humidity and loses bound water as the relative humidity drops and regains bound water as relative humidity increases

49
Q

when wood is no longer gaining or losing moisture, wood is said to have reached its

A

equilibrium moisture content

50
Q

what is air-dry wood

A

wood which moisture content is in equilibrium with the ambient air relative humidity

51
Q

what is kiln-dried wood

A

wood which moisture content has been reduced to about 15-19% (it can still gain moisture)

52
Q

whats bow shrinkage letter

A

w

53
Q

whats spring shrinkage letter

A

x

54
Q

whats twist shrinkage letter

A

y

55
Q

wats cup shrinkage letter

A

z

56
Q

in protected areas, the moisture content varies from ? in unheated areas

A

14-18%

57
Q

in protected areas, the moisture content varies from ? in heated areas

A

8-12%

58
Q

change in dimension due to moisture content is calculated from

A

(% shrinkage)/100 x (change in moisture content)/(fibre saturation point -12) x (initial dimension)

59
Q
A

STRCTENG 201 (3 decks)

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