__________ reinforcing steel bars not only have a differing chemical composition, but
are considered weldable. - ANSWER-A706
.28-Day acceptance of strength is the average of: - ANSWER-(3) 4 x 8 cylinders or (2) 6
x 12 cylinders
.A ____ is a horizontal member that transfers loads laterally. - ANSWER-Beam
.A beam is primarily subject to _____ while a column is primarily subject to ______. -
ANSWER-Flexure, compression
.A concrete mix design specifies a water/cement ratio of 0.45 maximum. When batched,
a particular load has a water/cement ratio of 0.38. Which of the following statements is
true? - ANSWER-The compressive strength will likely be higher than normal.
.A grade 60 bar has - ANSWER-A minimum yield strength of 60,000 psi
.A low-alloy steel bar conforms to - ANSWER-ASTM A706
.A mechanical splice must achieve - ANSWER-125% of the grade strength of the bar
.Adding water to a concrete mix will: - ANSWER-Decrease the compressive strength
.Additional revolutions of a drum mixer filled with concrete __________ the slump and
__________ the entrained air. - ANSWER-decrease, decrease
.After initial curing is complete, sample cylinders should be maintained at a temperature
between: - ANSWER-73.5 +/- 3.5 degrees
.Air content required for a 5,000 psi, 3/8 inch aggregate mix of concrete exposed to very
severe cycles of freezing and thawing is: - ANSWER-7.5%
.Air-entraining admixtures must conform to: - ANSWER-ASTM C260
.Aluminum embedments in structural concrete are: - ANSWER-Permitted only if coated
or covered to prevent an aluminum-concrete reaction
.An acceptable reinforcing steel support mechanism for a 24-inch deep footing includes:
- ANSWER-precast dobie blocks
.An ASTM A615 #7 bar has the diameter of - ANSWER-7/8 of an inch (#22)
.As a general rule, lap splicing bars larger than No. 11 is - ANSWER-not permitted
, .Bars must be tied in place to avoid displacement during concrete placement. The
following is not acceptable for securing rebar intersections: - ANSWER-welding
.Before new concrete is placed, construction joints must be: - ANSWER-wetted, and
standing water removed
.Bundled bars can have a maximum of ____ bars bundled together. - ANSWER-4
.Concrete can be placed into its intended structure unless: - ANSWER-It has
segregated
.Concrete exposed to moisture but not external sources of chloride: - ANSWER-Is
considered moderate exposure, a class C1
.Concrete is a mixture of - ANSWER-Aggregate, sand, cement and water
.Concrete must be dispensed from the truck: - ANSWER-Before 300 drum revolutions
take place
.Concrete placed in an 11-foot high column should not: - ANSWER-be dropped from the
top of the form
.Concrete sampling must be done at a minimum of: - ANSWER-- Once for every 5,000
sq. feet of surface area for slabs or walls
- Once for every 150 cu. yards placed
- Once every 50 cu. yards placed per day
.Concrete with the most severe sulfate exposure will be in contact with a percentage of
soil containing water-soluble sulfate: - ANSWER-Greater than 2.00
.Construction joints have the following recommendations except: - ANSWER-Beams
supported by a column or wall should not be cast until concrete in the vertical
supporting member has reached full compressive strength
.Core samples can be considered acceptable so long as: - ANSWER-They are
transported in watertight containers and cure at least 48 hours prior to breaking
.During the first 24 hours of initial curing for a set of concrete cylinders with the design
strength 5,000 psi, the curing temperatures must remain at: - ANSWER-60 - 80 degrees
F
.Epoxy-coated bars must conform to ASTM __________. - ANSWER-A775
.For 5,000 f'c concrete, cylinder breaks can be acceptable if: - ANSWER-No single
strength test falls below 4,500 psi