High Alumina cement including lime, they are ground into cement clinkers in a process called fusing or sintering.
The term “calcium aluminium cement” is another name for this material.
In this article you’ll learn:
So, if you’re ready to go with High Alumina cement, this article is for you.
Let’s dive right in.
Introduction to High Alumina Cement:
In 1925, a cement manufacturer by the name of Lafarge created the first High Alumina Cement in the United Kingdom.
It was largely employed for naval building because it was discovered to be resistant to chemical attacks.
This Cement has several features including quick strength gain and ease of fabrication, were discovered and used for precast concreting because of its popularity increased.
This kind of cement is made by grinding clinkers that are created during the calcination of bauxite and lime. Bauxite is an ore of aluminium.
The ratio of alumina to lime is measured in terms of weight which must be between 0.85 and 1.30, the total alumina content must not be less than 32%.
Composition of High Alumina Cement:
Characteristics of High Alumina Cement:
- This cement is excellent resistance to chemical attacks.
- There is a pH problem.
- It is used to construct water and sewage pipes, factory drains, coastal constructions, and manufacturing chimneys due to its strong resistance to chemical corrosion.
- There is a high refractive index in the cement issue.
- It is highly resistant to sulfuric acid.
- This cement’s rapid cementing property.
- Due to its ability to establish a ceramic bond at high temperatures, it serves as a bonding agent when added to refractory castable.
Manufacturing of High Alumina Cement:
- The primary components utilized are limestone or chalk and bauxite.
- Bauxite is a by-product of the weathering of aluminium-containing rocks in tropical environments.
- It is made up of hydrated alumina, iron oxide, titanium oxide, and trace amounts of silica.
- Lime and bauxite are broken down into lumps no larger than 100 mm.
- Dust would dampen the furnace, and dust and tiny bits of bauxite created during crushing are bonded into smaller briquettes.
- At the required ratios, the crushed materials are fed into an open-hearth furnace that is a hybrid of a cupola (vertical stack) and reverberatory (horizontal type) furnace.
- For burning, pulverized coal is utilized.
- About 22% of the weight of the cement that is produced is coal.
- The materials are heated by the hot gases of the furnace to a temperature of approximately 1600°C, which is their fusion point, driving off moisture and carbon dioxide in the process.
- The fusion occurs at the bottom of the stack, where the molten material flows into the reverberatory furnace, and then into steel pans via a spout.
- Pig-shaped solidified molten material forms in steel pans.
- In a tube mill, it is ground after being broken up in a rotating chiller, all iron particles are separated during grinding by magnetic separators.
- This cement has a kepi fineness of between 2500 and 3200 cm2/gram, but under no circumstances may its specific surface area must be less than 2250 cm2/gram.
- High alumina cement clinker has a very high degree of hardness; hence the grinding mill uses more energy and wears out faster than regular Portland cement.
- Therefore, the cost of this cement is very expensive (approximately three times that of regular Portland cement) in comparison to that of conventional Portland cement due to high costs of power for grinding and bauxite high costs of fuel for fire materials up to high temperatures.
- In the kiln, the ingredients necessary to make this cement are fused.
- The characteristics of regular Portland cement and high alumina cement are very dissimilar.
- In a discussion on regular Portland cement, it was noted that whereas regular Portland cement’s alumina compounds are mostly to blame for sulphate solution attack, high alumina cement that contains 40% alumina is immune to this assault.
- It happens because it is fused and no free lime is present, however, this is not the case with regular Portland cement; instead, free lime is present in regular Portland cement.
Advantages of High Alumina Cement:
Some advantages of high alumina cement include the following:
- More mixing and putting time are required because of the longer setting time.
- The chemical activity is well-resisting.
- Able to endure extreme temperatures.
- Due to increased heat evolution during setting, frosted action is minimal.
- In addition to having a very high compressive strength, it is also quite reactive.
- Strong resistance to flames.
Disadvantages of High Alumina Cement:
Some disadvantages of high alumina cement are as follows:
- The cost of producing this cement is considerable since more heat is needed during the manufacturing process.
- Since the fineness is maintained at or above 2250 cm2/gram, it is extremely fine.
- It must be avoided coming into touch with the mouth or eyes of people.
- It cannot be employed in large-scale concreting projects because of the significant heat evolution during the setting.
Applications for High Aluminous Cement:
- It is frequently utilized in sewer infrastructure and maritime building because of its quick hardening and strength properties.
- Refractory concretes that need higher strength at very high temperatures, also use this cement.
Also read: Soil Cement | Types of Cement | Portland Slag Cement (PSC)
It should never be combined or stored with ordinary Portland cement or high alumina cement since the mixture will cause the regular cement to flash set.
This substance generates fissures in the concrete as it expands.
Different countries have different names for this cement-like Fondu in France, Lightening in the United Kingdom, and Limonite in the United States.