Materials:Cement and Concrete-based Materials Flashcards
What is concrete made up of ?
Concrete is made up of cement, water, sand and aggregates
What is the most common cement?
Portland Cement
What are the raw components of cement?
Limestone, clay, shale or mudstone
What is the process of making cement?
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
Why do we preheat cement?
We preheat cement because it dry’s and decarbonates he limestone
What does heating in the kiln do?
Heating in the kiln partially melts and fuses to make clinker
What is clinker?
Clinker is a material produced during the manufacturing of cement
What is C3S (Alite) and what does it add?
Tricalcium Silicate/Alite. Fast rate of hydration and high contribution to strength
What is C2S (Belite) and what does it add?
Dicalcium silicate. Slow rate of hydration and high contribution to strength
What is C3A and what does it add?
Tricalcium aliminate. Fast rate of hydration and low contribution to strength
What is C4AF
Tetracalcium Aluminate. low rate of hydration and low contribution to strength
What does increasing the temperature do to clinker?
Increasing the temperature means more production of alite which leads to more strength early on
What are SCMs and why are they used?
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
What is cement paste made up of?
Cement + water
What is mortar made up of?
Cement +water + sand (no coarse aggregate)
What is the cement recipe?
w/c = 0.5, aggregate:cement = 3:1, 160x40x40mm, 28 days (0.5:3:1)
What is the different strength classes?
32.5N, 42.5N, 52.5N
What tests do we conduct to find the strength of concrete?
We conduct a tensile strength test and then you use one of the half’s and compress it to get the compressive strength
What can you combine with Portland cement?
Granulated blast-furnace slag (GGBS), fly ash (PFA) and silica fume (SF)
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?
You could use industrial waste materials such as GGBS, fly ashes and silica fumes
What are pozzolans?
Pozzolans are finely divided material which don’t have cementitious properties but react with lime in the presence of water
What are some benefits of SCMs?
-They use industrial by-products
-Preservation of virgin materials
-Waster disposal
-Often leads to increase strength
What is GGBS?
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
What are the benefits of GGBS?
GGBS improves workability, strength and durability and is also chloride resistant. Good for bridges on top of water etc.
What is PFA?
Pulverised fly ashes is derived from coal fired power stations.
What are the benefits of PFA?
PFA can be used to improve the workability and there is no need to grind it but it is less effective on strength
What is CSF?
Condensed silica fume is a by product of the glass making process.
What are the benefits of CSF?
CSF improves workability and fills capillary pores and increases strength
