Cement and Concrete History

• Cement uses have been important for chemists and engineers since lime mortars and natural cements were discovered.
• Cement's convenience, low cost, adaptability, durability, and strength have made it fundamental for applications.
• The term "cement" comes from the Romans.
• Romans used opus caementicium which describes masonry like modern concrete including crushed rock and burnt lime.
• Volcanic ash and pulverized brick additives in lime were called cementum, cimentum, cäment, then cement.
• Joseph Aspdin made cement in England in 1824.
• He made an artificial cement via calcination from argillaceous limestone.
• Aspdin named it "portland" because after being made into concrete, it resembled building stone from the Isle of Portland near England.
• Concrete is man-made stone mixing cement, water, and fine and coarse aggregate.

History

• Ancient Macedonians first used cement, then Romans used it on a big scale three centuries later.
• Romans used natural pozzolans and artificial pozzolans in concrete.
• Greeks and Romans used volcanic tuff with lime for cement.
• Egyptians used cements for the Pyramids.
• The understanding of how to make hydraulic cement and portland cement, was formalized by French and British engineers in the 18th century.
• Modern hydraulic cements came with the Industrial Revolution around 1800.
• Portland cement was expensive before 1900, limiting concrete use.
• Cement prices decreased due to machines.
• Cement is used everywhere for buildings, bridges, roads, etc.
• In 1980, the US had 142 Portland cement plants.
• 10 of the biggest plants made 48% of all cement and the 20 largest had 72%.

Classification of Cement

• Cement has different types meeting construction needs.
• Main cement classification factors involve composition, strength and how it sets.
• Natural Cement:
  • Natural cement rock of argillaceous nature, combined with clay and limestone make natural cement.
  • Quick setting, cheap, with hydraulic properties but does not have enough strength.
  • Argillaceous rocks are shales, argillites, siltstones, and mudstones.
• Pozzolana Cement/Pozzolanic:
  • This is not cementitious on its own, but it is when mixed with lime.
  • Pozzolana Cement strenght is less than Portland cement, but have equal strenth after 1 year.
  • It resists saline solutions and seawater well.
• Slag Cement:
  • Also called ground granulated blast furnace slag cement.
  • It is a supplementary cementitious material that is a byproduct of the steel industry.
  • It is made by grinding granulated blast furnace slag made when molten iron slag is quickly cooled with water during production of steal.
• Portland Cement:
  • The most common cement for construction.
  • Has hydraulic properties, meaning it hardens after being mixed with water via hydration.
  • Essential with concrete, mortar, and stucco, this making it a must for modern construction.
• Other cements:
  • High Alumina Cements: Includes bauxite and limestone and is used in high-temperature applications, furnace linings, and refractory concrete.
  • Silicate Cements: Uses alkali metal silicates such as potassium or sodium silicate and are reactive with materials having silica. Used as acid-resistant coatings and eco-friendly construction materials.
  • Sulfur Cements: Thermoplastic cement using elemental sulfur, polymers and fillers. Hardens when it cools, not when mixed with water. Used for corrosive environments and industrial applications because of its benefits, high chemical resistance, and fast setting time
  • Polymer Cements: Improve strength, durability, and flexibility. Emulsions, powders, or liquid resins are added to Portland cement, this enhancing workability, adhesion, and resistance to cracking.
  • Magnesium Oxychloride Cement: Reacts magnesium oxide with a magnesium chloride solution unlike hydraulic cement made unlike Portland. Forms a high-strength material (sets quickly) through a chemical reaction and does not require heat. It is useful in flooring, although humidity can affect it.

Types of Portland Cement

• Composed of 5 types categorized based on composition, setting time, strength, and durability (ASTM C150 standard).
  • Type I (Regular):
    • Is the most popular cement type, and it's used for most projects.
    • Moderate strength, with a setting time that is fast.
    • Common for bridges, pavements, precast concrete, and some buildings.
    • No suitable for hot environments and where is a lot of sulfide.
  • Type II (Moderate-Heat-of-Hardening and Sulfate-Resisting):
    • Resists sulfate and moderates heat during hardening.
    • Generates less heat reducing thermal cracking.
    • Used in structures and structures, exposed to soils and soil.
    • It is not used for aggressive sulfate conditions.
  • Type III (High-Early-Strength or HES):
    • This cement type has high strength because its faster than Type 1:
    • Used for emergency and fast-track construction, fixes to roads, and high-rise structures.
    • Cracking because of heat makes it not recommended.
  • Type IV (Low-Heat):
    • Generates the least amount of heat and reduce thermal stresses.
    • Ideal for long-term endurance.
    • mostly employed for dams, bridges, or building foundations.
    • Slow strength advancement versus the rest.
  • Type V (Sulfate-Resisting):
    • Highly resists sulfate assaults and stops disintegration of concrete in aggressive settings.
    • Used in sulfate-rich oil, marine structures and chemical/ sewage plants.
    • Lower initial strength relative to Type 1 and Ⅲ.

Grades of Portland Cement

 - 33 grade: Good for plastering and regular masonry work since high strength isn't needed.
 - 43 grade: 43 Grade Cement has  minimum strength of 43 megapascals (MPa) after curing for 28 days. It is good for structural work.
 - 53 grade: Used for buildings, taller frameworks, precast pre-stressed components and builds, plus bridges. It quickly strengths and it speeds builds.

Types of Cement

Raw Materials

• Cement industry creates clinker (main component) using raw materials.

• These have oxides like calcium oxide (CaO), silica (SiO2), alumina (Al2O3) and iron oxide (Fe2O3). Calcareous Materials (Contain Calcium as CaCO3):

  • Are the main way of forming calcium oxide (CaO).
  • Limestone: Consists mostly calcium carbonate(CaCO3).
  • Cement Rock: Mixes limestone and silica.
  • Chalk: Fine-grained, limestone.
  • Marl: Includes clay and calcium carbonate which is used for cement.
  • Marine Shells: Has deposits for calcium carbonate.
  • Alkali Waste: Has CaCO3 during production of caustic soda. Argillaceous Materials (Contain Silica - SiO2)
  • Source for alumina, silica, and iron oxide which is important for clinker.

• Clay: Contains hydrated aluminum silicates and is naturally gotten.

• Shale: Contains clay minerals while being sedimentary, and fine-grained.

• Slate: Has silica and alumina as building blocks like a metamorphic rock.

• Blast Furnace Slag: It supplies silica and alumina plus, it is rich of iron from iron production.

• Ashes: Posses a high silica of volcanic deposits.

• Cement Rock: Consists of calcium carbonate and silica. Gypsum (CaSO4 2H2O)

  • Cement mix, with 4%-5% of gypsum which works like set regulator.
  • Regulates setting time, forms C₃A·3CaSO₄·31H₂O during hydration, prevents flash setting. Silica (SiO2) or Sand
  • To change the cement, silica makes sure it has a balance for creation of clinker.
  • Originates from industrial silica by-product

• Cement relies on balance of key materials to ensure properties and chemical.

• High-quality resources are available for cement production which requires methods for extraction.

• Proper extraction help optimize production and sustainability and understand raw materials.

Cement Industry Manufacturing Process

• Cement production involves several stages and this requires machines to keep up efficiency.
• Major operations include material, grinding, reactions, and the control of those.
• Specialized Machines enhances efficiency.

Technical Manufacturing Process

It all starts with a bang!

• First stage: gathering of raw materials

  • Blasting mines limestone and Marl in the quarry.
  • To start creating the cement, rock is drilled with holes and hauled to machines.
  • Blasting methods are modern to minimize shock waves.
  • Crushers break the rock into smaller fist size.
  • Landscape architects and communities extract materials in an environmentally safe way.

• Second stage: Mechanical Process

  • Primary Crushing is rocks fed into the jaw or gyratory crusher, this reduced them into small pieces
    • The trucks transport raw materials to the crusher with 60 tons of capacity..
    • Crushers are either jaw crushers or gyratory crushers. Gyratory crusher
    • High capacities which often exceeds 600 tons per hr.
    • it has a head in a conical surface. Jaw Crusher
    • Rock is crushed.
    • used mostly for cement production.
    • Mobile crushers process on the job in rock pits.
  • The rock is gathered and turned for 1/4 inch rocks and saved in halls before going to the factory.
  • Ground limestone or crude will make rough limestone products as the first process.
  • Thrid Stage: Preparation of the raw mixture and mixing
    • Dry Process:
    • Mix limestone, clay, shale, and slate for this process
    • Minimal usage fuel consumption to up the kiln's capacity.
    • Minimizes air pollution and creates no mud rings.
    • Cement rocks are crushed and then stored,
    • Dry Separate powders are dosed for kilns that turn quickly.
    • Wet process:
    • Mixes materials plus blending the sides and reduces blending the sides.
    • Move product easily although uses additional energy to dry product.
    • Eliminates residue or dirt using materials during wash
    • Blend in quantities, powdered mixtures to formulate a slurry
    • Examine compound formulation right and adjust slurry. Secondary crushing of raw materials

• It gets grinding of the raw materials as next step

• Trains are used for transportation depending on the location of the plant.

• Each Train carries over 2200 tons.

• On arrival, ingredients automatically go to plant hoppers and go to the premixing halls.

• Halls help with material allocation.

• There is a circle with a diameter of 81 m and a height of 28 m.

• the hall is a space that can carry over 25000 tons of mixture.

• Substances were taken through scraper to ensure accurate compounds by composition.

• The combination is made of clay,limestone, shale, or minerals

• Limestone is mostly used to produce cement while shales are used to make alumina ingredients

• Send taken rock to the batching unit which ensures formula monitoring.

• If proportions aren't right, Department adds small of materials.

• It makes the limestone shells blend efficiently.

Chemical Composition Monitoring Requirements

• Limestone is carefully checked to monitor key elements:
  • Key ingredients for cement are limestone, calcium oxide with strength, and silicon dioxide
  • Other compounds includes the color and iron which influences and aluminum.

Corrective Materials And Additives

• Department corrects mix by a ratio if it does not satisfy the ratio.
• Essential Additives include iron and gypsum.

Importance of Quality Control

• Consistent Cement Properties:
  • Standardized products needs to be assured.
• Reliable Performance:
  • The performance has to be ensured.
• Minimizing Variability:
  • Material composition helps with the adjustment and final adjustments.

Grinding

• Then take carefully measurement and make vertical rollers which is called as meal mixture
• Allows stronger composition, and finer chemicals that produce reactions.
• The saving happens through total traditional electrical consumption mills.
• The result comes from a fine meal powder that comes through the exit.
• Continuously checked for the quality that shows homogeneous result that tests.
• Contain materials that are stored from liquid containing 30% to 40& in storage tank.
• In that time it is then put into a tank that is called homogeneous tanks.

Heating Process

(Pre Heating, Partial Calcination)

• Raw meal is then added at the upper level of tower used to heat it.
• Raw is also from of hot gases like current from 300 degrees
• At 900C at tower, the fuel is decontaminating at 2000c with hot burner.
  • The short time increases productivity of kiln, plus boosting saving energy.
  • Preheating evaporates removes raw meal, helps carbon dioxide.

Calcination process

• Decarbonation takes place in the precalciner as the first stage.
  • Carbon dioxide releases calcium that reduces lime and carbonates from limestone.

Firing/Burning

• Preheated and also pre-caicined meal enters kiln which is 54 meters lined.
• Can rotate based on the speed and the material will burn over to called clinker .
  • There starts the temperature transformation into mineral and clinker.
• Clinker production and also the temp is regulated.

Clinkerization Process

• It then travels with the heat that results in high temp that has calcinication .
• Decarbonation where lime is released where carbon dioxide.
• The clinker which will forms a liquid phase and a binding.
• This provides final reaction of silicate and gives off heat when produced.
• Keep temperature low or has molten mass.
• All these makes for clinker form

Clinker Mineral Formation

• Lime reacts with alumina to cause minerals

• Alite silicate produces its responsible for hardening

• Alite releases heat quickly to initial starting.

• Belite dicalcium release dicalcium helps with long term.

• Hydrates creates strength to cement

• Also has aluminate plus the heat when starts for strength the form.

• Hydrate with water.

• Control with starting heat generation to prevent breaks

• These qualities form strong for the cement type.

• the composition of the processes ensures that the final specifications.

Summary of Heating Process

• Contains water by evaporation.
  • Combined with clay and water
  • Crystallization causes dehydration produces causes a 900C reaction.
  • Initial liquid happens between 1250C and the clinker cooled using quenching from 100-200C.
  • The exit creates artificial stone called clinker .
  • Clinker makes forms silicates aluminates
  • When water is discharged, clinker is then cooled in cooler grate where air from cooler helps lower degrees.
  • Helps save from crystal forms.
  • Reduces power consumption through the waste.
  • Facilities have exhaust emissions where strict limits has highest degrees of high technology.
  • The heat that occurs uses it for the sludge and the district system.
  • Plant uses shells and the mineral composition where they are in good condition.
  • Also burns to become energy that contributes to dioxide.

The cooling stiffens in a process that becomes in a clinker

• Then placed in silo containing 55k stones.
• To finally have cement that must go through grinding.
• Must be finner for strength to be shown.
• Cement Production:
  • Finner the grinding means faster the strength.
  • Roller will go grind even more to have a clinker product.
  • Mixture of cement from by cement mills.
  • Cement mills uses grinded clinker together.
  • Also to customize it to a specific one that it needs.
  • Tube: the tubes makes has inlet and outlets, the process depends on the fineness of outcoming products.
  • the material has passed for mills:
    • circuit is there and after grind it comes up with classifier, that parts has 2 sections such as separator with fine and corse.
    • then turns into quality based to size and particle. material grinds continually for wanted size, it then goes in to next without recirculation.
    • With this final form there is operation that may ground more but be used when the sizes is needed to critical.
  • Additives - With dosages extend a high limestone by high grade. It reduces the carbon printing with those products also adding gypsums set that sets, to control quicker that allows to control set to have good time to mix water. - Calcium creates with dissolution , form process that help control heat. - agents are present is help with lump with particles, and it effects with work to flow and those are the composition of products that come out.

Distrubution

• Production, and place through into different conveyors and send .
• Plants contain silos that allow weeks for capacity of all demands.
• Portion comes at 50, that helps pack on the pallets that cover weather conditon.
• This allow dispatch.
• Majority come reach in bulk from rail or sea.
• Plant that's use creates crucial steps that helps examine for product with industry.
• Data Center:
• Helps production that ensures to standards is met and with well guided .
• All test that are consistent performs to world class.
• process of crushing that customer will get to what needed , and in addition can become a type of cement that friendlier.

Characteristics of Cement

• With sand and cement mixed with water combines hydration and becomes one surface.
• Size will decide the form cement will turns too.
• Cement needs to be balanced .
• Cement advantage is in strong form comes with shape that is mass.
• They are subjection, it can be hard to cure

Setting and Hardening

• Cement causes reaction water
• It starts a specific hours, but then is a compressive.
• There has be well water.
• Cement process requires well grinding
• Requires equipment with final product.
• Hydration needs cement with range with certain lvl called is set and setting plus it starts hardening.