ACI 318
Governs structural concrete design, construction, inspection and acceptance
Load Path
A continuous system of structural elements that
... [Show More] transfer an applied load to the supporting soil.
Which of the following publications are most useful for a Special Inspector?
ACI 318
A_____ is a horizontal member that transfers loads laterally.
Beam
Plain concrete refers to:
Concrete with less than minimum amount of reinforcement
A beam is primarily subject to ____ whole a column is primarily subject to _______.
A. Shear, Flexure B. Compression, flexure C. Flexure, compression D. Compression, shear
Answer C. Flexure, Compression
A beam is primarily subject to compression while a column is primarily subject to shear. True or False
False.
Beam is subject to Flexure, column is subject to compression.
The best place to look up definitions in ACI 318-14 is:
Chapter 2
Foundations cast at the same elevation as the soil grade are known as:
Shallow
What causes concrete to set and become hardened?
Hydration
Cement forming chemical bonds with water molecules, which sets things in motion to become an extremely hardened material.
Hydration Process
In general, how long does it take for concrete to move from a plastic state to a hardened state, depending on weather and admixtures?
30 minutes to 5 hours
Many project specifications consider concrete rejectable after it has bee what?
Batched for 90 minutes
Hydration is "exothermic", meaning what?
It produces heat.
What are pozzolans?
siliceous or siliceous/aluminous materials which have little to no cementitious value alone; react with lime and water to form a product similar to C-S-H.
Aggregates not conforming to ASTM C33 or C330 must be what?
Shown by test or actual service to produce concrete of adequate strength and durability and approved by the building official.
Aggregates make up what percent of concrete?
60-80%
Pumice and tuff are considered what kind of aggregate?
Lightweight
When pouring a structural concrete slab over a metal deck, what kind of concrete is necessary?
Lightweight
ASTM C33 pertains to what?
A: Water B: Steel Fiber Reinforcement C: Calcium Chloride D: Normalweight Aggregate E: None of the Above
Answer D: Normalweight Aggregate
ASTM C33 is divided into 2 Categories. What are they?
Coarse & Fine
What is honeycomb?
Visible voids in the concrete
What are the parameters for maximum coarse aggregate size permitted in concrete mix?
1/5 the narrowest dimension between sides of forms, 1/3 the depth of a slab, 3/4 the minimum clear spacing between individual reinforcing bars, tendons, or ducts
Water for concrete mixing must conform to what ASTM standard?
C1602
Non-potable water can be used in concrete without any kind of testing. True or False?
False.
Potable water can be used without testing.
When is concrete considered batched?
When water is added
The amount of water in pounds divided by the amount of cement in pounds.
Water/cement ratio
How much does water weigh per gallon, approximately?
8.34 pounds
What is the equation for water/cement ratio
Weight of water divided by total weight of cement mixture
Most commercial mix designs for structural concrete specify a ratio between what two numbers?
.40 & .50
According to section 19.2.1.1, no structural concrete shall be less than _______ psi in strength.
2,500
What is the maximum compressive strength requirement of concrete?
No maximum, unless specified in special seismic cases
Concrete is a mixture of:
Aggregate, Sand, Cement, and Water
Portland cement must conform to _____ and normal-weight aggregate must conform to _____ in all concrete.
A: ASTM C150, ASTM C33 B: ASTM C1602, ASTM C33 C: ASTM C1602, ASTM C150 D: ASTM C33, ASTM C1602
Answer: A ASTM C150, ASTM C33
Structural normal weight concrete MUST contain/produce
Potable or non-potable water, cementitious material and aggregate conforming to ASTM C33
Hydration
Is an exothermic (heat producing) chemical reaction that begins when water and cement are combined
The maximum allowable nominal aggregate size for a 6-inch slab is:
2 inches: 1/3 the thickness of the slab
What must air entrainment admixtures conform to?
A: ASTM C260 B: ASTM C1582 C: ASTM C94 D: ASTM C39
Answer: A: ASTM C260
Adding water to a concrete mix will:
Decrease the compressive strength
Why is reinforcing steel (rebar) used in concrete?
To improve tensile and flexural strength
What is reinforced concrete?
Structural concrete that contains the minimum amount of reinforcing steel required by ACI 318, to give additional strength properties that it doesn't have on its own, which increases its structural capacity
True or False: the minimum amount of reinforcement is determined by the special inspection agency.
False. Determine by the engineer based on ACI 318
Describe the difference between tensile, flexural, and shear forces
Tensile: being pulled apart
Flexural: Flexing
Shear: being bent
Why is fiber used in concrete?
To help control cracks
Why do many bridges or piers use epoxy-coated rebar?
They are in high corrosion areas
Standard hook
a 90º or 180º bend made at the end of a reinforcing bar according to standards
Stirrups
U, L, or rectangular shaped bars that are wrapped around longitudinal bars and used to resist shear forces in flexural members like beams. They usually terminate with 135 degree or 90 degree bend
Ties
Refer to a loop of reinforcing bars that enclose longitudinal vertical bars, typically used to resist shear and lateral forces in compression members, terminating with a 135 degree or 90 degree bend
Spiral
Continuously wrapped around longitudinal bars
Deep Foundation Caisson
Round concrete columns extending deep into the ground
What is the most common type of reinforcement?
CAPTION Rebar
What type of bar has protrusions that significantly improve their bond with concrete?
Deformed Bar
What type of reinforcement helps anchor the metal decking and structural steel to the concrete?
Headed Studs
What type of bar are meant to slip while creating a connection between two adjacent members that aren't intended to bond with concrete?
Plain Bar
What does WWR stand for?
Welded Wire Reinforcement
What does ASTM A615 pertain to?
Carbon Steel Rebar
Nonprestressed bars and wires shall be deformed, except when?
Plain bars or wires are permitted for use in spirals
Rebar comes in a variety of sizes, ranging from what?
3/8" (#3) to 2 1/4" (#18)
What nominal size is #9 bar?
9/8" (1 1/8" when converted)
An ASTM A615 #7 bar has the diameter of?
A: 7/8 of an inch (#22) B: 3/4 of an inch (#19) C: 1/2 of an inch (#13) D: 1 1/8 of an inch (#29)
Answer: A
A low-alloy steel bar conforms to?
ASTM A706
Ref: ACI 318, 20.2.1.3
What type of reinforcement is only acceptable for structural use in spiral reinforcing?
Plain Reinforcement
A grade 60 bar has a minimum what?
Minimum YIELD strength of 60,000 psi
Which bar has the largest nominal diameter?
#9 bar
Standard hooks for deformed bars in tension are either ______ or ______.
90 degrees or 180 degrees
How many bars can be bundled together maximum?
4
True or False: #14 rebar is the largest diameter allowed in bundled bars in beams.
False:
#11 Bar is largest allowed
What type of rebar has the highest tensile strength?
Grade 80
Why is most rebar deformed?
Better adherence to concrete
The minimum bend diameter of a number 9 standard hook in tension is:
9 inches [Show Less]