co Flashcards
what is the most commonly used type of concrete
Type 1
what does the A after the concrete type denote?
air entrained, reduced strength but help workabilithy and or freeze thaw tolerance
what type of concrete is high early strength
Type 3
what type of concrete is resistant to sulfite degredation
Type 2
what type of concrete is used on massive infrastructure projects
Type 4, low heat of hydration
what is concrete measured in?
by volume, typically in cubic yards, 1 cubic yard = 27 cubic feet
which direction is it generally ok to pump concrete?
vertically, when pumped too far horizontally the mix starts to segregate out water causing weakness
why is concrete covered during curing?
to avoid speeding up the curing process, too hot or too windy causes problems, freezing will pause curing so admixtures are needed if below freezing
name systems for expediting formwork and reducing cost
flying formwork - truss supported forms that are dropped after casting and craned to a subsequent level
lift slab system - slabs are cast on the ground and hydraulically jacked up and welded to columns eliminating formwork
slip formwork - formwork that lifts with pours to make walls
what are lifting rings
rings used for lifting slabs in tilt up wall construction
exposed concrete is called _____
architectural concrete
what type of tensioning is done with precast
depressed pre-tensioning, cables in tension set in steel forms, cable cut after curing and released to camber member
for strength and weather resistance the grain is best laid
horizontally
the maximum amount of water that the air can hold at a certain temperature is the
relative humidity
