Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CIVI 321 > Supplementary Cementing Materials (SCM's) > Flashcards

Supplementary Cementing Materials (SCM's) Flashcards

1
Q

What is SCM’s?

A

Material when used with portland cement contributes to the properties of the hardened concrete through:
Hydraulic Activity
or
Pozzolanic Activity
or
BOTH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 2 types of SCM’s?

A

Pozzolans and natural Pozzolans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is a pozzolanic reaction?

A

When SCM’s is added, it provide a reactive amorphous silica (S) in the hydration products in order to have more Calcium Silica Hydroxyde (CH–>CSH). (this addition of S leads to a pozzolanic reaction)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 benefits of adding SCM’s?

A

Pozzolanic reaction –> higher strength
Physicall filler effect –> Less voids, higher strenght
Densification of agg.- Cement Paste transition Zone (BOTH)–> Denser transition zone (more impermeable)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the interfacial transition zone (ITZ)?

A

It is a thin layer between the agg. and cement of concrete caused by the wall effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Where is the weakest component in the concrete?

A

ITZ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is the most permeable area in the concrete?

A

ITZ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is silica fume?

A

A SCM
Smoke by product from the production of ferrosilicon and silicon metals
Very fine non-crystalline silica
Amorphous Silica

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is an amorphous silica?

A

High Silica content
Unstable
Surface can react

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is a crystal silica?

A

Like glass
No reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 3 silica fume product forms?

A

As produced powder
Silica Fume slurry
Densified Silica Fume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is particle size of SF?

A

<1micrometre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the strength activity index?

A

= (A/B)*100
A: average compressive strength of blended cement mixture cubes
B: average compressive strength of pure cement mixture cubes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is responsible in the strength of cement (hydration product)

A

CSH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How can SF enhance durability to corrosion?

A

SF reduces permeability of concrete and diffusion of chlorides, which enhance durability to corrosion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does adding SF will result in the cement?

A

higher strength
less permeability (enhance durability)
less segregation (Increase concrete cohesiveness)

17
Q

How much days for moist curing to prevent water evaporation of SF concrete (Shrinkage cracks)?

A

7

18
Q

What is FA?

A

By product of coal burned power plants
Spherical particles

19
Q

What are the 2 type of FA?

A

Type C (high calcium oxyde)
Type F (low calcium oxyde)

20
Q

Does FA have a filler effect?

A

Yes, less effective than SF

21
Q

What is the particle size of FA?

A

Between 1micro meter to 100 micro meters

22
Q

SA of FA?

A

200 to 700 m^2/kg

23
Q

SA of SF?

A

13000 to 30000 m2/kg

24
Q

Does SF has a higher pozzolanic activity than FA? (NOT SURE)

A

No, FA has higher pozzolanic activity (NOT SURE)

25
Q

What does FA brings to concrete?

A

Increases late strength (S+CH=CSH)
Reduces permeability (enhance durability)
Increase workability
Reduce heat of hydration
Increase concrete Alkali-Silica reaction resistance
Increate concrete sulfate resistance

26
Q

What influences the setting time of FA?

A

FA hydrates slowly (setting time extended)
Finer fly ash –> shorter setting time
high CaO content –> shorter setting time

27
Q

FA concrete tends to gain strength at quicker rate or slower rate then concrete without FA?

A

Slower (long term gains are higher with FA)

28
Q

When will the long term strength of OPC+FA be higher than OPC

A

90 days and after

29
Q

which type of FA reduces sulfate attacks?

A

Type F (low calcium)

30
Q

What is slag?

A

by product of metallurgical industry
Crystalline (used as agg.)
Can be used hydraulic binders (GBFS; Granulated Blast Furnace Slag)
React slowly with water (low heat of hydration)

31
Q

What are the properties of slag?

A

Smoother than cement particles
density is lower than cement
Replacement by weight leads to a higher paste volume and better workability
At low T, setting time is increased
Low heat of hydration

32
Q

How does the strength of concrete’s affected with slag?

A

Low early strength, High later strength (significant after 1 year)
Comparable strength to OPC after 28 days

33
Q

What does slag bring to concrete?

A

Increases later strength
Reduces permeability (enhance durability/less corrosion)
Increases workability
Reduce Heat of hydration
Increase ASR resistance (less expansion)
Fire resistance

34
Q

What are the 2 types of natural pozzolans?

A

Raw (ash from volcanic) and calcined natural pozzolans (calcined clays)

35
Q

Which SCM’ could be used for ASR resistance?

A

FA
Slag
SF
Nat pozzolans

36
Q

Which SCM’s could be used to reduce permeability?

A

FA
Slag
SF
Nat pozzolans
(ALL OF THEM)

37
Q

Which SCM’s could be used to increase workability?

A

FA
Slag
Nat pozzolans

38
Q

Which SCM’s could be used to reduce heat of hydration?

A

FA
Slag
Nat pozzolans
SF VARIES

39
Q

Why does SF has high water requirements?

A

Because water evaporates and results in drying shrinkage

CIVI 321 (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions