Ch.10 Flashcards
__________ is the hardened form of cement produced from Portland cement, coarse and fine aggregates and water ?
Concrete
____________ make up a large percentage of the total volume of concrete?
Aggregates
__________ can help tailor a batch of concrete for specific functions ?
Admixtures
Admixture that reduces the density of the concrete?
Shake or clinker
Admixture that produces a mixture that flows more freely , makes concrete workable , pliable and soft while using relatively little water?
Superplasticizers
Like masonry , concrete is strong in compression but weaker in tension , the ultimate compressive strength can range from ______. To ______psi?
2500 to 6000 psi
_______________ includes components added to the concrete before it hardens to resist tensile forces?
Reinforced concrete
_____________ uses steel bars placed in the framework , and wet concrete is placed in the framework around the bars?
Ordinary reinforcing
The most commonly used size of rebar is _____?
5 (0.625inches)
Vertical reinforcing bars are known as _________ and are provided to resist the diagonal tension ?
Stirrups
The technique of ___________ is a more efficient use of concrete than ordinary reinforcing?
Prestressing
Two common methods of prestressing concrete are ?
Pretensioning
Post tensioning
____________________ uses steel strands (cables) stretched between anchors producing a tensile force in the steel?
Pretensioned reinforced concrete
________________ uses reinforcing steel cables that are not tensioned until after the concrete has hardened to a certain strength?
Post tensioned reinforcement concrete
_________ is placed in forms and cured at a plant away from the job site?
Precast concrete
_____________ is placed into forms at the building site as a wet mass and hardens in prepared forms ?
Cast in place concrete
The systems use reinforcing cable and rods made of high strength steels that can yield at temperatures as low as _____ ?
752 degrees F
Reinforcing strands are placed in a form work and covered with ________ or __________ to prevent binding with the concrete?
Grease or plastic tubing
Theoretically ,properly cured concrete continues to harden indefinitely at a gradual rate , normal design strength is reached after _____ days?
28 days
The single most important factor in determining the ultimate strength of concrete is the ______________?
Water to cement ratio
Hardening of concrete involves a chemical process known as _____________ , in which water combines with the particles of cement to form a microscopic gel?
Hydration
During the hardening of concrete , heat is given off by the chemical process?
Heat of hydration
The _______ curing of concrete produces a stronger concrete?
Moist
Concrete in the process of curing must be maintained at the correct temperature, ideally between ___ and ___ degrees ?
50 to 70 degrees F
The _________ uses a standard sized cone shaped mold and sample of wet concrete?
Slump test
__________ testing is a separate test that uses a small test cylinders of a concrete batch to determine the compression strength of that batch?
Compression
Concrete structural systems can have fire resistance rating from __ to __ hours ?
1-4 hours
________________ concrete has a lower density than ordinary concrete and has a lower thermal conductivity, and therefor acts as a better insulator against the heat of a fire than ordinary concrete of comparable thickness?
Structural lightweight
Construction technique using concrete slabs supported by concrete columns ?
Flat slab concrete frame
Plain floor slab about 8 inches thick that rests on columns spaced up to 22 feet apart and depends on diagonal and orthogonal patterns of reinforcing bars for structural support because the slab lacks beams?
Flat plate
Because concrete has relatively good insulating properties, it tends to retain the heat of an exposing fire and release it slowly , in an effect referred to as the ?
Heat sink effect
The ____________ is a simple system that consists of a concrete slab with concrete columns for support , the slab of concrete ranges in thickness from 6 to 12 inches ?
Flat slab concrete frame
In a building that will support heavy live loads , the area around the columns is reinforced with additional concrete in the form of ____________ or __________?
Drop panels or mushroom capitols
If the building will support light loads , this additional reinforcing is not necessary, the system is then known as a _____________?
Flat plate
A _____________ consists of a concrete slab supported by concrete beams, this framing system is extremely lightweight and is best suited for buildings with light floor loads ?
Slab and beam frame
Slabs in slab and beam framing construction can be as thin as __ inches ?
2 inches
Slab and beam framing is sometimes referred to as _________________ construction?
Concrete joist construction
________________ construction is known as waffle construction because of the waffle like pattern of the bottom of the concrete slab?
Two way slab
This design provides a thicker slab while eliminating the weight of unnecessary concrete in the bottom half of the slab?
Waffle construction
Waffle construction is used where spans are _____ and floor loadings are _____?
Short and high
Precasting concrete became a common practice after ________?
World War II
A major disadvantage to using __________ is the need to transport the finished components to the job site?
Pre cast concrete
Pre cast concrete solid slabs are used for short spans up to approximately ____ feet while the Tee slabs can be used for spans up to ____ feet?
30 feet
120 feet
___________ is a common form of construction used with precast concrete ?
Tilt up construction
________ walls can be several stories in height?
Tilt up
A variety of techniques, such as ________,________ and ______________ can be used to connect precast structural components to each other?
Bolting
Welding
Posttensioning
Supports for precast beams may include __________ cast into the columns ?
Corbels (brackets)
