Materials:Cement and Concrete-based Materials

Question 1

What is concrete made up of ?

Answer 1

Concrete is made up of cement, water, sand and aggregates

Question 2

What is the most common cement?

Answer 2

Portland Cement

Question 3

What are the raw components of cement?

Answer 3

Limestone, clay, shale or mudstone

Question 4

What is the process of making cement?

Answer 4

You mill and blend the components then you pre-heat then heat in a kiln to make clinker which is grinded to make powder which is then packaged and distributed

Question 5

Why do we preheat cement?

Answer 5

We preheat cement because it dry’s and decarbonates he limestone

Question 6

What does heating in the kiln do?

Answer 6

Heating in the kiln partially melts and fuses to make clinker

Question 7

What is clinker?

Answer 7

Clinker is a material produced during the manufacturing of cement

Question 8

What is C3S (Alite) and what does it add?

Answer 8

Tricalcium Silicate/Alite. Fast rate of hydration and high contribution to strength

Question 9

What is C2S (Belite) and what does it add?

Answer 9

Dicalcium silicate. Slow rate of hydration and high contribution to strength

Question 9

What is C3A and what does it add?

Answer 9

Tricalcium aliminate. Fast rate of hydration and low contribution to strength

Question 9

What is C4AF

Answer 9

Tetracalcium Aluminate. low rate of hydration and low contribution to strength

Question 10

What does increasing the temperature do to clinker?

Answer 10

Increasing the temperature means more production of alite which leads to more strength early on

Question 11

What are SCMs and why are they used?

Answer 11

Supplementary cementitious materials are used to reduce the amount of Portland cement as to make Portland cement, it uses a lot of energy and produces a lot of CO2 emissions. They are used to reduce the clinker factor

Question 12

What is cement paste made up of?

Answer 12

Cement + water

Question 13

What is mortar made up of?

Answer 13

Cement +water + sand (no coarse aggregate)

Question 14

What is the cement recipe?

Answer 14

w/c = 0.5, aggregate:cement = 3:1, 160x40x40mm, 28 days (0.5:3:1)

Question 15

What is the different strength classes?

Answer 15

32.5N, 42.5N, 52.5N

Question 16

What tests do we conduct to find the strength of concrete?

Answer 16

We conduct a tensile strength test and then you use one of the half’s and compress it to get the compressive strength

Question 17

What can you combine with Portland cement?

Answer 17

Granulated blast-furnace slag (GGBS), fly ash (PFA) and silica fume (SF)

Question 18

What are some industrial waste materials you can use as Portland cement takes a lot of energy to make and produces a lot of waste?

Answer 18

You could use industrial waste materials such as GGBS, fly ashes and silica fumes

Question 19

What are pozzolans?

Answer 19

Pozzolans are finely divided material which don’t have cementitious properties but react with lime in the presence of water

Question 20

What are some benefits of SCMs?

Answer 20

-They use industrial by-products
-Preservation of virgin materials
-Waster disposal
-Often leads to increase strength

Question 21

What is GGBS?

Answer 21

Granulated ground blast-furnace slag is a by-product of manufacturing iron and it is made by molten slag being cooled very quickly and granulated

Question 22

What are the benefits of GGBS?

Answer 22

GGBS improves workability, strength and durability and is also chloride resistant. Good for bridges on top of water etc.

Question 23

What is PFA?

Answer 23

Pulverised fly ashes is derived from coal fired power stations.

Question 24

What are the benefits of PFA?

Answer 24

PFA can be used to improve the workability and there is no need to grind it but it is less effective on strength

Question 25

What is CSF?

Answer 25

Condensed silica fume is a by product of the glass making process.

Question 26

What are the benefits of CSF?

Answer 26

CSF improves workability and fills capillary pores and increases strength