Construction Materials Exam 2 Questions
with Correct Answers
wood is the earliest material used because it is... - ANSWERSeasy to use, durable,
strong, lightweight, available, inexpensive
wood is widely used for... - ANSWERSbuilding frames, bridges, floors, roofs, trusses,
piles
endogenous (intertwined growth) (palm trees) - ANSWERSstrong and lightweight, not
usually used for engineering
exogenous (outward growth) (most trees) - ANSWERSfibers grow outward by adding
concentric rings = more predictable engineering properties
deciduous (broad leaf) - ANSWERShardwood, expensive and slow growing
coniferous (cone-bearing, evergreens) - ANSWERSsoftwood
earlywood (light rings) - ANSWERSrapid spring growth of hollow thin-walled cells
latewood (dark rings) - ANSWERSdense summer growth of thick-walled cells (stronger
and harder)
pith - ANSWERScenter stem
heartwood (darker) - ANSWERSstructural support
sapwood (lighter) - ANSWERStransports sap
cambium (very thin) - ANSWERSlocation of wood growth
longitudinal - ANSWERSparallel to long axis (grain), strongest and least shrinkage
radial - ANSWERSperpendicular to growth rings (out from center)
tangential - ANSWERStangent to growth rings, weakest and most shrinkage rings
chemical composition of wood - ANSWERScellulose, hemicellulose, extractives, lignin,
ash-forming
lignin - ANSWERSglue
, moisture content of wood - ANSWERSaffects shrinkage, strength, and weight
depends on air temp and humidity
Mc = Wm-Wd / Wd
fiber saturation content - ANSWERSmoisture content when cells are completely
saturated with bound water but no free water [21-36%]
(above = affects wet weight)
(below = affects all properties)
shrinkage - ANSWERSlargest in tangential direction, smallest in longitudinal direction,
zero shrinkage above FSP [1% shrinkage per 5% MC change]
lumber production - ANSWERSharvesting, sawing, seasoning (drying), surfacing
(planning), grading, preservative treating
structural framing - ANSWERSdimensional lumber = light framing
heavy timber = heavy framing
sawing - ANSWERSlive (plain) = rapid and economic
quarter = max prime cuts
combo = most typical
flat-sawn - ANSWERSworst quality, <45 degress
rift-sawn - ANSWERS45-80 degrees
quarter-sawn - ANSWERSbest quality least shrinkage
seasoning (drying) - ANSWERSair, kiln, or combo of both
15% MC when it leaves the mill
surfacing (planing) - ANSWERStakes 1/4" or more from each side
S4S = surfaced four sides = dressed
2x4 dimensions - ANSWERS1.5x3.5
lumber grades - ANSWERSaccording to defects like knots, checks
can be visual or machine-graded
lumber defects - ANSWERScaused by growth, seasoning too fast, disease, insects,
parasites, faulty processing
knots - ANSWERSbranch base that degrades mechanical properties
shakes - ANSWERSwood separations between annual rings
with Correct Answers
wood is the earliest material used because it is... - ANSWERSeasy to use, durable,
strong, lightweight, available, inexpensive
wood is widely used for... - ANSWERSbuilding frames, bridges, floors, roofs, trusses,
piles
endogenous (intertwined growth) (palm trees) - ANSWERSstrong and lightweight, not
usually used for engineering
exogenous (outward growth) (most trees) - ANSWERSfibers grow outward by adding
concentric rings = more predictable engineering properties
deciduous (broad leaf) - ANSWERShardwood, expensive and slow growing
coniferous (cone-bearing, evergreens) - ANSWERSsoftwood
earlywood (light rings) - ANSWERSrapid spring growth of hollow thin-walled cells
latewood (dark rings) - ANSWERSdense summer growth of thick-walled cells (stronger
and harder)
pith - ANSWERScenter stem
heartwood (darker) - ANSWERSstructural support
sapwood (lighter) - ANSWERStransports sap
cambium (very thin) - ANSWERSlocation of wood growth
longitudinal - ANSWERSparallel to long axis (grain), strongest and least shrinkage
radial - ANSWERSperpendicular to growth rings (out from center)
tangential - ANSWERStangent to growth rings, weakest and most shrinkage rings
chemical composition of wood - ANSWERScellulose, hemicellulose, extractives, lignin,
ash-forming
lignin - ANSWERSglue
, moisture content of wood - ANSWERSaffects shrinkage, strength, and weight
depends on air temp and humidity
Mc = Wm-Wd / Wd
fiber saturation content - ANSWERSmoisture content when cells are completely
saturated with bound water but no free water [21-36%]
(above = affects wet weight)
(below = affects all properties)
shrinkage - ANSWERSlargest in tangential direction, smallest in longitudinal direction,
zero shrinkage above FSP [1% shrinkage per 5% MC change]
lumber production - ANSWERSharvesting, sawing, seasoning (drying), surfacing
(planning), grading, preservative treating
structural framing - ANSWERSdimensional lumber = light framing
heavy timber = heavy framing
sawing - ANSWERSlive (plain) = rapid and economic
quarter = max prime cuts
combo = most typical
flat-sawn - ANSWERSworst quality, <45 degress
rift-sawn - ANSWERS45-80 degrees
quarter-sawn - ANSWERSbest quality least shrinkage
seasoning (drying) - ANSWERSair, kiln, or combo of both
15% MC when it leaves the mill
surfacing (planing) - ANSWERStakes 1/4" or more from each side
S4S = surfaced four sides = dressed
2x4 dimensions - ANSWERS1.5x3.5
lumber grades - ANSWERSaccording to defects like knots, checks
can be visual or machine-graded
lumber defects - ANSWERScaused by growth, seasoning too fast, disease, insects,
parasites, faulty processing
knots - ANSWERSbranch base that degrades mechanical properties
shakes - ANSWERSwood separations between annual rings
