Amber Book Concrete Flashcards
What is the drying (curing) time of concrete?
28 days
What is type 1a cement?
normal concrete that is air entrained with bubbles that help with durability/workability. can be exposed in cold and mixed climates
What is type 2 cement?
moderate resistance to sulfate that can attach concrete and weaken it. USE BELOW GRADE
What is type 2a cement?
sulfates and air entrained
What is type 3 cement?
high early strength cement used for PRECAST, TILT UP to save time. also cold weather
What is type 3a cement?
high early strength with air entrained
What is type 4 cement?
low heat of hydration. used in MASSIVE INFRASTRUCTURES.
What is type 5 cement?
high resistance to sulfate
What is white portland cement?
used for countertops
What is aggregate size?
no greater than 3/4 between rebar and 1/3 depth of slab
How do you make pervious concrete?
use aggregates of the same size
What do lightweight aggregates do?
they make concrete lighter and more thermally resistant, but also weaker. POPCORN expanded shale
What is vermiculite?
expanded mica that is a lightweight aggregate
What is perlite?
expanded volcanic rock that is a lightweight aggregate
What does adding water to concrete do?
more workable but less strong
What is ultra high strength concrete made of?
silica, quartz, steel microfibers (NO REBAR)
What do shrinkage reducing admixtures do?
reduce cracking
What are corrosion inhibitors?
they reduce rusting of rebar on pavers like on parking garages or salt on the road
What does extended set control do?
delays curing for up to several days. stabilizer added when mixing which puts off until activator is added
What is self consolidating concrete?
doesn’t need vibrators. used for when rebar is croweded in the formwork. Has crisp edges. more pourable but also more pressure on formwork
How do you protect rebar from saltwater?
coat with epoxy, galvanize, stainless steel, or zinc polymers
Where do you put welded wire reinforcing? What is the spacing?
in the bottom of slabs. WWR. 2” min to 12” max grid
What length do you overlap/splice rebar?
30 x diameter
What is a reinforcing bar coupler?
a rebar combiner that puts the rebar end to end
What is shrinkage temperature steel?
steel perpendicular to rebar in a slab to prevent shrinkage in slabs
What do concrete ties do?
in columns, they prevent outward buckling. Can be rectilinear or spiral. Spiral is better for earthquakes.
What do micro and macrofibers do?
they help with shrinkage and less cracking; may replace shrinkage temperature steel
What is creep?
the squishing of concrete over time.
How thick is slab on grade?
3” to 8”
What diameter crushed stone to place under slab on grade?
1 1/2” diameter crushed stone for capilary break
What is screeding?
push and pull excess concrete over the formwork for leveling
What is floating?
with bull float or darby to make concrete flat
What is troweling?
using a tool to make concrete surface smooth
How often and how deep is a control joint?
1/4th the depth of slab. every 15’
What are isolation joints for?
fully separating two concretes for expansion and contraction.
Do thinner or thicker slabs require closer spacing of control joints?
thinner
How do you have less control joints?
make concrete stronger via dryer mix, fly ash, post tensioning, admixtures or microfibers
When do you need masonry expansion joints?
change in height, openings, wall thickness transitions, change directions, columns or pilasters
How do you make non slip finish on concrete?
stiff bristle broom perpendicular to path of travel, drag burlap, sprinkle powder, or abrasive strips
What are whalers?
formwork that holds the ties of the formwork. Horizontal members
What is the formwork for a column called?
a pile cap
What is a chamfer strip?
cast at 45 degrees for beveling corners
What are shores?
adjustable height columns used to support the beams of a slab that is not being poured on grade
What is the depth of a concrete beam?
Width x 3 = depth
What type of concrete slab system is best for rectangles? for squares?
one way for rectangle, two way for squares
What do drop panels do?
They help resist shear forces near the columns
What type of concrete slab system is best for less than 25’ spans?
two way flat plate or one way flat slab
What type of concrete slab is best used for greater than 30’ spans?
one way joist systems
What are lifting rings?
rings cast into concrete for tilt up construction that connects to a rope crane
How do you increase span?
pretensioning, taper, vault, arches, folded plates
What is board formed concrete?
a type of architectural concrete where aggregate is exposed.
What type of cement is used in precast concrete?
type 3
How do you connect things to concrete?
precast bolts, drill expansion anchors, glue steel plates, oversize a hole and put grout, concrete/masonry nails, steel tendons.
What do superplasticizers do?
they are water reducing admixtures, organic. they increase work ability so it is easier to flow into convoluted forms. it allows reduced water but maintains workable.
What is grade 75 steel used for?
making columns thinner
What are bolsters?
longer chairs to hold the rebar, often if slab on grade it is made of plastic
