Midterm Concrete Flashcards
Which of the following techniques have proven successful in providing specified strengths in 4 hours of less? Select all that apply.
High Portland cement contents
Accelerating admixtures
Type III Portland cement
Air- en-training admixtures are primarily used to stabilize tiny air bubbles in concrete
True
Prebid and pre- construction conferences should be held to identify.
Lines of communication
Responsibilities
Discuss the contract requirements
“For all linear systems, the net response at a given place and time caused by two or more stimuli is
the sum of the responses which would have been caused by each stimulus individually”, is the:
Superposition Principle
Which deep foundation type is not suitable for installation in wet and/or loose soils?
Drilled piers
A hydraulic cement creates a chemical reaction when it comes in contact with water (hydration) but will not
cure under water.
False
(fill the blank) are the critical elements for a successful project regarding clearly delineated and
efficient office procedures for the administration of design, document control, checking of shop or
placing drawings, and processing design changes
Quality Insurance and Quality Control
Expansion joints are used at points of restraint, Expansion joints are used at points of restraint, including the junction between the elements of a structure. For example, they separate walls or columns from floors.
True
As part of jobsite preparation, before concrete is poured, it is important to be aware of any potential
increased pressure on the forms. Which of the following factors increase pressure on forms?
Increase in lift heights
Long term compressive strength of concrete using Type III Portland cement is higher than with
Type I Portland cement (general purpose).
False
Formwork accounts for 35 to 60% of the construction cost for concrete framed buildings.
True
Which of the following factors influence reinforcement development strength? I – Rebar spacing, II –
Concrete weight, III – Concrete cover, IV – Heat of hydration V – Rebar coating
I, II, III & V only
The temperature rise due to heat of hydration in concrete utilizing Type I Portland cement typically
levels off at approximately.
Between 3 and 7 days
Given the following design conditions for a Wall form system:
Concrete Mix = Type III cement without retarder, Concrete Unit Weight (w) = 150 pcf
Wall height (h) = 10 Feet high, Rate of Pour (R) = 8 Feet per hour,
Concrete Temperature (T) = 80 Degrees Fahrenheit,Wall Thickness = 12 inches
What is the maximum design pressure on the wall in pounds per square foot (psf)?
(1) (1) [150+43,400/80+2800(8/80)] =
972. 5
In regards to formwork, the lateral pressure on vertical forms is proportional to density and depth.
True
Given the following design conditions for a column form system:
Concrete Mix = Type III cement with retarder,Concrete Unit Weight (w) = 150 pcf
Column height (h) = 10, Feet highRate of Pour (R) = 8, Feet per hourConcrete Temperature (T) =
80 Degrees Fahrenheit
What is the maximum design pressure on the wall in pounds per square foot (psf)?
(1) (1.2) [ 150 + 9,000(8/80)] =
1260
Typically, the Design Professional should review and approve the concrete mixture proportions (mix
design) and submittals concerning materials, procedures, and testing data.
True
When installing concrete in extreme weather conditions, different techniques are used to help mitigate the
effect of temperature. Which of the following are typical cold weather concrete techniques? Select all that
apply.
Leave forms in place
Engineers apply factors to selected load cases to create Load Combinations used for design:
True
Contraction joints are where concrete placements stop and start.
False
Using the Strength Design Method, Design Strength must be _______ Required Strength.
Greater than or equal to
Which of the following vertical loads on horizontal forms are considered “live loads”? Select all
that apply.
A. Workers
D. Walkways / Runways
General purpose cement suitable for all uses except where special properties of the
other types are required.
Type I
Cement used where moderate sulfate resistance is required, for drainage and
environmental structures in which sulfate concentration is higher than normal, or for
concrete exposed to seawater
Type II
Cement used when high early strength is desired. Examples are early removal of
forms for cast-in-place concrete, precast concrete, and slipformed concrete. Under cold weather conditions.
Type III
Cement used when the amount of heat of hydration must be minimized; for example,
in massive structures such as gravity dams, where thermal cracking is likely to occur
Type IV
Cement used when high sulfate resistance is required, such as when concrete is
exposed to severe sulfate attack as with soils or groundwaters having a high sulfate
content
Type V
Which of the following is not a Load Case used by Engineers in foundation design?
Flexible loads
Which graphic shows the most appropriate rebar location for the load as shown in the figure
below?
B
The slope of the linear portion of the stress-strain curve is called:
Modulus of elasticity
When completing a concrete batch plant evaluation, it is important to check the “weights and
measures” seal on the scales, to make sure they are _______.
current
Which party is responsible for the design of the concrete formwork?
Field Engineer
Increasing the depth of a beam contributes significantly to _______ stress and _______ deflection.
reducing / limiting
The maximum lateral pressure of concrete in psf (lb/ft2) on forms varies by the rate of placement, ft/hr.
True
Which of the below variables has the greatest impact when calculating wind loads?
Wind speed
The Engineering Design Team is usually led by the:
Project Manager
As concrete hardens, lateral pressure on the forms decreases
True
“A pictorial device used to analyze the forces and moments acting on a body”, is a
Free-Body Diagram
Using a power buggy is a highly effective and practical method when placing a high volume of
concrete
False
Beam A-B is subject to what forces?
Moment about the z-axis, torsion about the x-axis and shear along y only.
Which of the following deep foundation types will require a specialty contractor for installation?
Driven piles
Auger-cast piles
All foundations may be classified as one of two types:
Shallow and Deep
Flexural strain at the neutral axis of a beam is
Zero
Portland cement is a type of fly ash cement.
False
Typically, review and approval of detailed formwork design is the responsibility of the Design
Professional
False
When performing a concrete batch plant evaluation it is important to obtain a sample batch ticket.
Which of the following items should be found on the batch ticket? Select all that apply.
A. Batch time and date
B. Moisture content of aggregate
C. Water/Cement (w/c)
Concrete strength development depends on which of the following? Select all that apply.
A. Curing temperature
C. Water-cement ratio
D. Chemical or mineral admixtures
When performing a concrete batch plant evaluation it is necessary to determine the batch plants rate of
production (CY/hr) and estimated delivery rate to the project site (CY/hr).
True
Which of the following best describes the costs associated with industrialized formwork?
High initial fabrication cost, but low cost per use
Define Torsion:
Bending about a longitudinal axis
All concrete that will be exposed to freezing weather during placement or in service should be air-entrained.
False
