Uta Construction Management, Module 6.1

Front 1

Name the 3 components of concrete.
Tell about the process of becoming concrete.

Back 1

Aggregates (sand, gravel)
Portland cement
Water
Chemical process to bond. It hydrates, cures and hardens.

Front 2

What are the 2 main types of concrete for construction use that are most commonly used?

Back 2

Type I: Normal, used in most construction.

Type III: High early strength, to cure quicker (cold weather, or speed required)

Front 3

What are the other 3 main types of concrete?

Back 3

Type II: Mod resistance to sulfate attack (water contains mod levels of sulfates)
Type IV: Low heat of hydration (massive structures that will generate enough heat to damage)
Type V: High resistance to sulfate attack (water contains highlevels of sulfates)

Front 4

How much volume of the concrete is the aggregate?

How can perlite be used in concrete?

Back 4

75%

Perlite is a light weight aggregate for making non-structural concrete (low strength)

Front 5

What the rule of thumb for the basic mixture of concrete?

Back 5

10% cement
20% water and air
30% sand
40% gravel

Front 6

Describe 3 tests performed on concrete.

Back 6

1. Compressive strength - apply stress til it breaks, using a cylinder
2. Air entrainment - find out how much air content
3. Slump test - measure wetness and workability before poured

Front 7

Admixtures can be added to concrete to accomplish what?

Back 7

To improve or alter the concrete propoerties by:
Increase strength
Improve workability - flow easier, better
Change curing time
Add color

Front 8

What are 3 reasons to entrain air into concrete?

Back 8

1. Improve workability - flow easier, better
2. Reduce permeability, block channels for bleed water to escape
3. Reduce damage from freeze/thaw; creates room for water to expand when freezing.

Front 9

When the surface of concrete cracks and flakes off due to, for example, freeze/thaw cycle, it is called ______________.

Back 9

Spalling

Front 10

Describe 3 attributes of formwork.

Back 10

1. Like building a hollow wood building to shape/form concrete.
2. Forms support concrete and rebar.
3. Use (oil) coating to remove form so it can be reused.

Front 11

Describe 4 ways to place concrete.

Back 11

1. Shotcrete - no forms needed.
2. Chute from mixing truck
3. Placing via pump
4. Crane and bucket - place on upper levels.

Front 12

1. How is concrete consolidated?
2. Why?
3. What happens if too much consolidation?

Back 12

1. Mechanical vibrator
2. To get rid of rock pockets and large air pockets, and blend consecutive lifts or batches. To completely fill form and produce a tight bond between cement and aggregates.
3. Segregation

Front 13

1. The first pass made towards leveling the surface of a newly poured concrete slab is called _____________________.

2. What is the purpose of floating?
3. What is the purpose of finishing?

Back 13

1. Screeding
2. Create a level surface, fill voids and remove ridges, embed large aggregates below surface. Done after bleed water evaporates and can walk on it.
3. For dense, smooth finish. (Timing is critical.)

Front 14

How can the surface of concrete be textured?
Why?

Back 14

Broom finish or wire broom.
To improve slip-resistance

Front 15

Why is it important to keep concrete moist after its poured? For how long?

Back 15

Water is required for complete hydration and curing to develop strength. If it drys out, the design strength will not be achieved.
7 days of moisture => 100% design strength eventually (1/2 year?)
28 days of moisture => 100% of design strength at 28 days

Front 16

Names 3 ways to keep moisture on concrete while curing.

Back 16

Burlap blankets
Plastic sheets
Spray-on curing compound

Front 17

1. What is the purpose of rebar in a concrete beam?
2. Why does rebar have a deformed surface?

Back 17

1. Rebar at btm of beam adds tensile strength.
Rebar at top of beam near columns and stirrups reinforce concrete near columns for handling shear forces.
2. So concrete can grab it and transfer load efficiently.

Front 18

1. What are 2 purposes of reinforcing bars in concrete columns?
2. What function do ties perform?
3. What kind of tie is good in earthquake areas?

Back 18

1. Resist lateral loads (improve tensile strength).
Share compression load.
2. Resist outward buckling (concrete stops inward buckling)
3. Spiral

Front 19

Putting a steel tendon inside a sleeve into a concrete beam to create tension is called ____________________.

What is the purpose?

Back 19

Post-tensioning, a specific type of prestressing.

Put the bottom of the beam in tension to resist stress cracking at the bottom of the beam, and so beam can be lighter and/or stronger.

Front 20

High early strength concrete is known as "Type ____".

Back 20

III

Front 21

The on-site test to test for a concrete mix's wetness and workability is called a "___________ test".

Back 21

slump

Front 22

When placing concrete using a crane and bucket, formwork is NOT required.

Back 22

FALSE

Front 23

In order to ensure that concrete reaches its design strength, it needs to be kept moist for AT LEAST _____ days.

Back 23

7

Front 24

Given concrete's zero design strength in terms of tension and shear, _____________ are required to be installed near the points of support to handle the shear stresses.

Back 24

stirrups