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Materials > Cement > Flashcards

Cement Flashcards

1
Q

What is the difference between hydraulic and non-hydraulic cements?

A

Hydraulic cemented set when mixed with water

Non-hydraulic cements harden using CO2

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2
Q

Portland cement is which type of cement?

A

Hydraulic

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3
Q

Describe the production of Portland cement

A

~75% limestone or chalk
+
~25% clay or shale

Heat to ~1450C°

Forms clinker(silicates & aluminates)

Grind to powder

Add ~4% gypsum

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4
Q

Why is sea water not good for concrete production?

A

Seawater contains high chloride concentration, which induces steel corrosion

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5
Q

Lime is produced by heating []
CaCO3 > caO + CO2

A

Calcium carbonate

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6
Q

Quicklime is mixed with [] to form []
CaO+H2O > Ca(OH)2

A

Water to form Portlandite

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7
Q

Slaked lime harden by reacting with []
Ca(OH)2 + CO2 > CaCO3 + H2O

A

CO2

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8
Q

Hydraulic or non-hydraulic?

Portland

A

Hydraulic

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9
Q

Hydraulic or non-hydraulic?

Calcium aluminate

A

Hydraulic

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10
Q

Hydraulic or non-hydraulic?

Pozzolanic

A

Hydraulic

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11
Q

Hydraulic or non-hydraulic?

Hydrophobic

A

Hydraulic

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12
Q

Hydraulic or non-hydraulic?

Natural

A

Hydraulic

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13
Q

Hydraulic or non-hydraulic?

Expanding

A

Hydraulic

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14
Q

Hydraulic or non-hydraulic?

Lime cements

A

Non-hydraulic

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15
Q

Hydraulic or non-hydraulic?

Gypsum

A

Non-hydraulic

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16
Q

Hydraulic or non-hydraulic?

Cements and plasters

A

Non-hydraulic

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17
Q

5600BC

A

Yugoslavian huts made of lime (caO)

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18
Q

Yugoslavian huts made of caO/lime

A

5600BC

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19
Q

2500BC

A

Great pyramids of Giza limestone CaCO3

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20
Q

Great pyramids of Giza limestone CaCO3

A

2500BC

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21
Q

500BC

A

Lime and sand used for weak mortars in Greece

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22
Q

Lime and sand used for weak mortars in Greece

A

500BC

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23
Q

300BC-500AD

A

Romans mistook pozollan for sand, made better concretes with lime and ash

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24
Q

Romans mistook pozollan for sand, made better concretes with lime and ash

A

300BC-500AD

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25
Q

500-1756

A

Weak, slow setting cements used

26
Q

Weak, slow setting cements used

A

500-1756

27
Q

1759

A

Eddystone lighthouse is built using hydraulic lime

28
Q

Eddystone lighthouse is built using hydraulic lime

A

1759

29
Q

1824

A

“Portland cement” made from limestone + fine clay heated to 1200°C

30
Q

“Portland cement” made from limestone + fine clay heated to 1200°C

A

1824

31
Q

Present day

A

Improved formation of calcium silicates, mainly belite (C2S) and also alite (C3S)

Increased formation of alite as standard in PC clinker

32
Q

Improved formation of calcium silicates, mainly belite (C2S) and also alite (C3S)

Increased formation of alite as standard in PC clinker

A

Present day

33
Q

What are the main calcium silicates and calcium aluminates found in cement clinker?

A

Alite C3S brown (ass-lite, brown shit)
Belite C2S (beta-two) blue
Aluminate C3A grey
Ferrite C4AF white

34
Q

What does SCM stand for?

A

Supplementary cementitious material

35
Q

What are SCMs?

A

Anything that is added to cement that is non-clinkered (at the end of production)

36
Q

Name some SCMs

A

Gypsum (main one)
Coal fly ash
Granulated blast furnace slag

Gypsies throwing coal at slags

37
Q

In the rotary kiln, what is the dominant phase in the beginning?

A

Limestone

38
Q

In the rotary kiln, what is the dominant phase in the middle?

A

Lime and belite

39
Q

In the rotary kiln, what is the dominant phase in the end?

A

Alite

40
Q

Concrete and belite continue to [] up to [] after hardening is done

A

React up to 180 days

41
Q

Hydration products are [] than clinker

A

Less dense

42
Q

What does production of hydration products do to cement?

A

Cause volume changes, as they are less dense

43
Q

1 unit vol Clinker = what unit vol of HP?
HP = hydration products

A

2-4

44
Q

PC + water gives us a

A

Plastic, workable paste before the initial set

45
Q

After the initial set we get a

A

Stiff,workable paste

46
Q

After the final set we have a

A

Rigid solid, strengthens over time

47
Q

What happens in day one of setting

A

Massive loss of fluidity, delayed increase of hydration product making and strength

48
Q

What is the purpose of gypsum?

A

Added to PC to delay initial loss of fluidity

49
Q

What happens after day 1 through to 1 year of setting?

A

Hydration product numbers increase slowly along with strength

50
Q

Cement is available in:

A

Ready mix- poured on site
Precast (OSM)
Retail - bagged for various uses

51
Q

What is a capillary pore?

A

Space not filled by hydration products

52
Q

What is the diameter of a typical capillary pore?

A

0.5-10 micrometers

53
Q

What is special about capillary pores?

A

They directly influence strength and durability of the concrete

They determine transport properties in paste

54
Q

Clay is in [], when it gets [] it expands

A

Clay is in layers
When it gets wet it expands

55
Q

C-S-H is the same as clay with how it can []

A

Expand

56
Q

C-S-H sheets have

A

High porosity
Large surface area

57
Q

SCMs are [] reactive than [] with water

A

Less reactive than clinker

58
Q

How can SCM reactivity be increased?

A

By making a more alkaline cement solution in what is called alkali activation

59
Q

What are the pros of alkali-activated materials?

A

Faster setting and strength development

Heat resistant

Better thermal expansions

60
Q

What are the cons of alkali-activated materials?

A

Prone to shrinking + cracking

Activator expensive + environ impacts

Steel corrosion chemistry differs

High pH solutions are a safety concern

Materials (13 decks)

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