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materials > Wood > Flashcards

Wood Flashcards

1
Q

how much % of world’s wood comes from North America?

A

1/3

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2
Q

t or f wood takes less energy to produce than that of steel, cement, copper and aluminum

A

true

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3
Q

what is the most economical choice for building materials

A

wood

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4
Q

what is wood technically?

A
  • dead or dying cells below the cambium layer

- made of small fibres that are long and narrow

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5
Q

what strength is wood strong in?

A

tension

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6
Q

what bonds the cells (cellulose) together in wood?

A

lignin

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7
Q

what % makes up wood?

A
  • 60% cellulose ; small long narrow cells
  • 28% lignin; glue that holds all together
  • 12% sugars and extracts
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8
Q

what are characteristics of hardwoods?

A
  • dicotelydons
  • oak, maples, birch ect
  • cells thicker, denser and stronger
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9
Q

what are characteristics of softwoods?

A
  • conifers/ evergreen
  • spruce pine fir and cedar
  • cells are thin, less dense and weaker
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10
Q

what is the pith of the tree

A
  • centre, where earliest growth occurs
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11
Q

what is the heartwood?

A

dead portion of the tree located towards the centre

-provides structural support, more resistant to rot

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12
Q

what is the sapwood?

A

-contains the living portion of the tree: sap

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13
Q

what is the cambium ?

A

growth area of the tree

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14
Q

what is the springwood ?

A

rapid growth, thin walled cells

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15
Q

what is the summerwood?

A

slow growth, thick walled cells

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16
Q

when does the growth year start/ stop of a tree?

A

-stops when tree drops leaves and goes dormant, starts when new leaf development

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17
Q

t or f, all trees have growth rings

A

-false; only occurs when climate limits growth part of the year

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18
Q

characteristics of cedar

A

-tannins, resists rot, easy to work with, food look, colour and aroma

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19
Q

uses of spruce ?

A
  • farming, must have preservatives for outdoor use

- good availability

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20
Q

uses of pine?

A
  • good availability

- needs preservatives for outdoor uses

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21
Q

what is the hardest softwood?

A

fir

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22
Q

characteristics of hemlock

A

-good rot resistance, poor availability, hard to work with

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23
Q

characteristics of fir?

A

-even grain, needs preservatives for outdoor use

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24
Q

redwood characteristics

A

-good for structure, rot resistant, poor availability= expensive

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25
Q

characteristics of hardwoods?

A

-good for furniture, expensive, will rot and doesnt receive preservatives well

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26
Q

what are 4 natural destructive agents to wood?

A
  • decay/ rot
  • fire
  • insects
  • UV rays
27
Q

what 4 things need to be present for decay ?

A
  • food supply
  • moisture
  • oxygen
  • warm temperatures
28
Q

what is green wood?

A
  • term for freshly cut or ‘live’ wood

- moisture content over 32%, could be as high as 100%

29
Q

what is seasoning of wood?

A
  • process of removing moisture from wood

- reduces moisture content to make stronger

30
Q

what is the fibre saturation point

A
  • as moisture content of wood is reduced from seasoning process, water removed from cell cavities and voids
  • any remaining moisture is contained within cells = fibre saturation point
31
Q

what is the moisture content at the fibre saturation point?

A

25%- 32%

-point where cell shrinkage and reduction of wood column begins

32
Q

what direction does wood shrink? by what % at the end of the seasoning process?

A
  • width

- 2.6%

33
Q

what varies as moisture content varies?

A
  • strength
  • weight
  • shrinking
  • ability to resist and decay
34
Q

when is wood considered ‘seasoned wood’

A

-19%

35
Q

describe natural method of seasoning wood?

A
  • undercover/ out of direct sunlight and weather
  • open sides to env’t
  • properly / neatly stacked off the ground with spaces b/ween layers –> air flow
  • takes min 1 year
36
Q

what is kiln dried?

A

kiln dried 80- 100C for 24-48 hours

37
Q

what is dressed lumber ?

A

-process of planing down the lumber to its finished dimension leaving it with smooth / dressed surfaces

38
Q

when is the best time to dress wood?

A
  • after the seasoning process so that most of the woods shrinking would already occurred
  • accurate dimension–> wood done shrinking
39
Q

what would a piece of lumber be stamped with if it was dressed after seasoning?

A

KD- HT

40
Q

what would a piece of lumber be called if it was dressed on green wood?

A

S-GRN

41
Q

what is the most effective way to prevent rot and decay

A

add preservative –> Pressure treating

42
Q

describe pressure treating process

A
  • heat up wood to allow for better penetration than inject/ spray chemical on wood at high pressure
43
Q

name 2 common chemicals used in pressure treatments?

A
  • CA (copper azole) and ACQ (sodium borate)
44
Q

which chemicals should you avoid pressure treating with?

A
  • creosote (railroad ties)
  • pentachlorophenol (hudro poles)
  • both petroleum based
45
Q

what is the difference between wood preservatives and coatings?

A
  • coating provide protection but don’t preserve
46
Q

give 3 ex of wood coatings

A

stain, paint, water coating

47
Q

what other benefits are there for coating wood?

A
  1. reduce effects of UV
  2. retard moisture fluctuations
  3. provide increased resistance to abrasion
48
Q

what is grading lumber

A
  • gov’t agencies that control grades of lumber

- measurement of amount of ‘clear wood’ in a piece

49
Q

what is ‘select wood’

A
  • no large or loose knots and no less than 85% clear wood
50
Q

name 4 common grades of lumber

A
  1. select
  2. structural
  3. light framing
  4. stud
51
Q

who reinforces the grading of lumber?

A
  • National Lumber Grades Authority (NLGA)
52
Q

differences between western red cedar vs eastern white cedar

A

red: stronger psi
- straight grain
- higher shipping cost
- high ability to hold fasteners

White: -smaller, lots of knots

  • weaker
  • cheaper to ship
  • better posts
53
Q

what are common sizes of lumber ?

A

1x2, 2x2, 2x4, 2x8, 2x10, 2x12

8, 10, 12, 14, and 16 lengths

54
Q

what lengths do 1x 6 fence boards come in?

A

4, 5, 6, 8

55
Q

describe how EcoVantage wood is produced?

A

no chemicals, wood treated with heat and steam

  • processed over 400F
  • eliminates sugars and starches
56
Q

what are pros of ecovantage wood

A
  • natural wood product
  • free toxins and chemicals
  • fully recyclable
  • bio- degradable
  • no resin, sugars, low moisture
  • 30 year warranty
57
Q

key properties to EcoVantage wood

A
  • permeability
  • warp. twist, expansion substantially reduced
  • hardness improved
  • strength reduced
  • density increased
  • biological durability improved
58
Q

what is pervious concrete?

A
  • ‘No fines concrete’
  • concrete with interconnected voids to allow water to pass through
  • near 0 slump
  • course aggregate, cement, admixtures and water
59
Q

what date was pervious concrete invented?

A

1852, became popular after WW2

60
Q

what are pros of pervious concrete?

A
  • reduced upfront infrastructure cost
  • reduce burden on again infrastructure
  • controls flooding and erosion
  • reduces glare
  • reduced ice pavement build up
61
Q

how does pervious concrete improve water quality?

A
  • removes 80% suspended solids from rainwater
    -contains hydrocarbon within system
    , then broken down over tiem by micro organisms
62
Q

what is hydromedia technology ?

A
  • 2nd generation High Performance Pervious concrete
  • uses sufficient paste to coat and bind the aggregate particles together to create a system of highly permeable, interconnected voids that drains quickly
  • doesn’t require heavy compaction
63
Q

name 3 types of hydromedia finishes

A
  1. cost effective
  2. coloured/ intergral
  3. polished

materials (5 decks)

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