Concrete part 1

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  • Created by: Bobb21
  • Created on: 12-05-24 12:10
What is concrete made from?
Concrete is made from mixing cement with aggregates, water and some admixtures
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List some types of special cements
Geopolymer, high-alumina (CAC), Magnesium-based cement
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What you can do with cement?
- High strenght (around 28 days)
- Setting, how long can I work with the cement before it hardens
- Durability
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What is the specification of Portland cement?
EN 197: CEM 1
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What are the raw materials used in cement?
- Limestone
- Clay, shale, mudstone
- Minor constituents
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What is the process to making cement?
1st - Mill and blend the components such as limestone and clay using correct chemical composition
2nd - Preheat the material which is where you dry and decarbonate the material. Then Kiln process, where partially melted in a kiln and then fused which prod
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Which two process can be used for pre-kiln?
- Dry process - where Clay and limestone is milled and then put into a preheat tower where it will decarbonate the rawmix (basically the limestone).
- Wet process - Much easier than dry process but uses significantly more energy. Chalk and clay are washed
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What is a kiln?
A kiln is a hot chamber which rotates at 10rpm and is basically like a oven which can be used to heat or dry such as the composition of limestone and clay to produce clinker. The kiln is fed with coal to produce the high temperatures of 1450 degrees. Note
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How does the process of kiln work?
The rawmix or composition from the pre-heat enters the kiln where it firstly the water from the composotion will evaporate as it continues to move down the kiln the temperature of the kiln increases and this will cause the materials to chemically react wh
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Explain the process of grinding
The clinker is grinded to a fine powder which can be around 2 to 80 micrometers. There can be stuff added to the clinker such as calcium sulphate which aid in improving production and efficiency and also makes it so less energy is needed to grind which he
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Why is it important to add ferrous sulphate to the clinker?
It reduces the amount of Cr (VI) which can be an irritant to the skin which is a impact on the health and safety of workers and also it has the additional benefit on increasing the shelf life on the grinded clinker.
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How is the final cement product distributed?
75 percent of the cement is distribute in bulk which can be in rail or in tankers. They are used for large scale projects with ready-mix produces.
The other 25 percent is distributed to DIY markets where it bags of cement are sold. An example is such as S
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What are the four components that can make up the clinker?
Alite - which compromises most of the clinker and can be around 50 percent of the clinker
Belite - Around 10 to 25 percent of the clinker
Tricalcium aluminate - 10 to 15 percent
Tetracalcium aluminoferrite - 10 to 15 percent
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What is the compound number of each compound?
Alite - Ca3SiO5 or C3S
Belite - Ca2Sio4 or C2S
Aluminate - Ca3Al2O6 or C3A
Aluminoferrite - Ca2Al2Fe2O5 or C4AF
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What is the rate of hydration for the compounds mean and what are they for each compound?
How fast each compounds reacts with water.
Alite - Fast
Belite - Slow
Aluminate - Fast
Aluminoferrite - Slow
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What are the effects of temperatures to the rawmix as it increases?
As temperatures increases, more alite produced which then means more early age strenght
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Explain why the formation of 1 tonne of Portland cement clinker releases
considerable quantities of CO2
into the atmosphere?
The reason is because when the clinker is being produce it has to go through the process of decarbonising which is dry process of pre-kiln. The limestone is decarbonised which releases CO2 as a by-product, this is then released to the environment which co
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What are SCMs and why are they used?
SCMs (Supplementary Cementous Material) are materials which can partially replace portland cement in concrete mixtures. The reason they are used since they are cost-effective due to being cheap and also it reduces the impact on the environement since less
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Write the following components in Portland cement using conventional
cement chemistry notation.
- Alite
- CaCO3
- C3S
- Limestone
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what can be in an EN197-1 compliant cement?
• PC clinker: some modifications covered
• Granulated blast-furnace **** (GGBS)
• Fly ashes (PFA)
• Silica fume (SF)
• Burnt Shale
• Pozzolanic (natural) materials
• Limestone (filler)
• Minor additional constitu
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Name a Supplementary Cementious Material and talk about what it is and its properties.
Pozzolan is a material which reacts with the limestone in the present material which can produce additional Cementous compounds to the concrete along with Portland cement.
You can also extra CSH (Calcium Silica Hydrate) however compared to the of OPC it i
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Benefits of SCM
Cost-effective
Increases strenght
Replaces ordinary portland concrete
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What is GGBS and how is it made?
Ground granulated blast furnance ****
- Molten **** is cooled down quickly and then granulated.
- Grounded to cement fineness
- Used for large scale project such as dams
- Higher strenght and durability
- chroride resistance
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What is - PFA?
Pulverised fuel ash are aluminosilicates which come from coal-fired power stations. The calcium content in it depends on the type of coal burnt.
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What are the stats of PFA?
- Spherical glassy particles which means no need to grind
- Particle size are less than 600msquared/kg
- No effect on strenght
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What are microsilica / CSF.
Condensed silica fume are a by-product of silicon purification. Very small particles which means improved workability. Higher strenght
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What are Metakaolin MK
- Calcined china clay
- Expensive
- Excellent chloride resistance
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How much clinker are there in portland cement in %
Around 95
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What is RHPC, modified PC
Rapid Hardening Portland Cement - Higher strenghts earlier
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What is LHPC, modified PC
Low heat Portland cement - Environementally friednly since less energy needed. Useful for large pours such as dams, tunnels.
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Other cards in this set

Card 2

Front

List some types of special cements

Back

Geopolymer, high-alumina (CAC), Magnesium-based cement

Card 3

Front

What you can do with cement?

Back

Preview of the front of card 3

Card 4

Front

What is the specification of Portland cement?

Back

Preview of the front of card 4

Card 5

Front

What are the raw materials used in cement?

Back

Preview of the front of card 5
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