Calcium aluminate cement, sometimes referred to as aluminous cement, is a special kind of cement that is distinguished by its high early strength and resilience to harsh chemicals and temperatures. Because of this, it’s the best option for a range of specialty construction projects where regular Portland cement might not work as well.
When quick strength development is essential, this kind of cement comes in handy. For instance, because it enables the structures to be reopened for use considerably sooner than if conventional cement were used, it is frequently used to repair roads and airport runways. When building refractory linings for furnaces and kilns—where the materials must endure high temperatures—aluminous cement is also preferred.
The resilience of aluminous cement in harsh chemical environments is one of its main characteristics. For projects involving industrial floors, wastewater treatment plants, and structures exposed to sea water, this makes it a great option. Because of its special composition, it lasts longer and is more durable under these tough circumstances.
It will be easier for you to select the appropriate material for your project if you are aware of the various varieties and qualities of aluminous cement. The different varieties of aluminous cement, their unique qualities, and the technical attributes that suit them for various applications will all be covered in the sections that follow.
| Type of Aluminous Cement | Properties and Uses |
| High Alumina Cement | Quick setting, high strength, resistant to high temperatures, used in refractory concretes, furnaces, and industrial construction |
| Calcium Aluminate Cement | High early strength, resistant to sulfates and chemicals, used in sewage systems, marine structures, and chemical plants |
| Low Cement Castable | Low water content, high density, excellent mechanical strength, used in kilns, incinerators, and other high-temperature environments |
Application area
Prior to delving deeper into the characteristics, uses, and context of aluminous cement, it is imperative to comprehend its relevance. Though purchasing such expensive raw materials due to its ability to accelerate hardening is irrelevant, this type of mixture is more in demand in the industrial sector because fire resistance at thousands of degrees is not needed in daily life.
Use of aluminous cement in the manufacturing sector:
- Repair and reconstruction of bridges
- Accelerated construction of structures with a high level of stability – all work takes up to 3 days
- Cases when it is important to ensure the monolith"s resistance to sulfates
- Fixing and fastening anchor bolts
- Creation of containers for use with aggressive substances
- Arrangement of oil wells
- Aluminous cement GC40 can be used as an accelerator for concrete setting, a component for a refractory mixture
- Repair of sea vessels
- Construction of reinforced concrete structures subject to particularly serious loads
- Construction of sea and underground structures
- The introduction of adhesive solutions intended for operation in the field of construction chemistry
- Hz 40 cement is the main component in the preparation of expanding and waterproof solutions
- The production of waterproofing plaster can also be carried out using clay -earth cement – the material is used in the decoration of water lines, metro, in the joints of the pipelines, and t.D.
The application of clay-earth cement in custom building
- Arrangement of floor screed (in some cases where there are special requirements for concrete)
- Preparatory stage of work with window sills
- Construction of basements, basements of buildings (rarely)
- Repair/reconstruction of ventilation systems, chimneys in private houses.
- Often, when constructing fireplaces and furnaces in houses, and other types of heating devices, it is GC 40 cement that is used, the characteristics of which make it possible to ensure the desired structural properties
Manufacturing Features
Pure bauxite or limestone is used to make aluminous cement, which has very specific properties. Other ingredients are added to the mixture to give it the desired qualities. Melting and sintering are the two primary processes used to produce cement. The quality of the coke, the volumetric content of iron oxides in it, the composition of the bauxite, and the addition of silicic acid all influence the method of choice.
Melting
Premium bauxite is combined with coke and limestone for the melting process. After being heated to the correct temperature in recuperators, this mixture is sent to water-cooled water-jacket furnaces where it is melted by feeding air through tuyeres. After that, the mass is sent to a crusher for grinding after passing through a taphole and cooling in furnace molds. The crushers have multichamber mills installed in them. Particulated fuel is what drives the furnaces.
The mixture is occasionally purified of silicic acid through the use of electric smelting, which melts ferrosilicon. The arc smelting process, which uses unique alternating current furnaces, is occasionally employed to create exceptionally high-quality aluminous cement. The raw materials are first processed into granules or briquettes by crushing, mixing, and shaping them. Although bauxite is calcined and a batch containing coke is used, limestone is calcined beforehand.
The silica in the batch is reduced to silicon due to the extraordinarily high temperatures that can be reached in modern electric arc furnaces; silicon then combines with iron to form ferrosilicon.
Aluminous cement can also be made in blast furnaces, although the product loses strength quickly after hardening.
Sintering
Conventional ovens are used with relatively low temperatures in this production method. Initially, the mixture is cooled gradually to cause the gehlenite to crystallize and become glassy. Here, it’s critical that the temperature during the sintering process stays above the ideal level to prevent calcium aluminates from crystallizing. In order to prevent the formation of gehlenite crystals, very quick cooling systems are designed to ensure that glass does not appear in the finished composition.
When the mixture leaves the furnace, steam-air currents turn it into granules. Comparing the aluminous cement made using this method to a substance that cooled more slowly, the former exhibits superior strength indicators.
Composition and properties
It is important to think about the composition of alumina cement in order to comprehend it better. Low-base monocalcium aluminate, also known as CaO-A12O3, is the primary ingredient in the mixture. During the hardening process, it changes into dicalcium hydroaluminate. This kind of cement comes in two varieties: low-lime (CaO < 40%) and high-lime (CaO > 40%).
Chemical components that make up aluminous cement are as follows:
- Iron oxide – from 5% to 15%
- Silicon oxide – from 5% to 15%
- Calcium oxide – from 35% to 45%
- Aluminum oxide – from 30% to 50%
Aluminates, dicalcium silicate (which slows down hardening), and gehlenite as a ballast admixture are also added to the mixture.
1) The cement has outstanding binding qualities and a high strength after it has fully hardened because calcium aluminates are present in the mixture. However, although aluminous cement behaves similarly to Portland cement, its hardening process involves the release of heat; on the first day, approximately 70% of the heat is released, which is dangerous. The concrete will exhibit resistance that is two to three times less than the standard if the air temperature is higher than +30 degrees.
2) Alumina cement exhibits superior strength and resistance to harsh environments, resulting in a denser artificial stone when compared to Portland cement. However, an alkaline environment causes such a monolith to quickly deform, so mixing it with gypsum, Portland cement, or lime is not allowed.
3) This kind of concrete solution has a rapid rate of hardening; the mixture starts to solidify in 30 minutes and takes 12 hours to finish. Similar to Portland cement, alumina cement sets, but it reaches its standard strength in 72 hours as opposed to 28 days.
Qualities of cement made of alumina:
- Resistance to gaseous environments, aggressive liquids
- Ability to carry out work at minus
- Rapid strength gain
- High density of the created monolith
- High level of thermal stability, which allows you to get refractory solutions
Structure and types
This kind of cement is separated into two primary categories: normal composition and high-alumina, based on the quantity of impurities present in the material. After seventy-two hours, the cement grade is established. The composition is typically imported in small quantities into Moscow and the surrounding areas, where it is sold in containers weighing 40–50 kg or in special bags. Aluminous cement can have colors ranging from green to yellow to brown to black, depending on the amount of iron present in the mixture as well as the rate at which the constituents oxidize.
The three primary grades of aluminous cement—GC-40, GC-50, and GC-60—variate in their capacity to tolerate compressive loads. The GC-40 mixture becomes stronger from 22.5 (MPa after 24 hours) to 40 MPa after 72 hours of pouring. This is the most well-known brand, appropriate for a range of building projects. The cement used in the fuel and energy sector has a strength index of GC-50, which reaches 50 MPa. GC-60 is a mixture with a strength of up to 60 MPa that is utilized in the metallurgical and defense sectors.
An ingredient that needs to be used properly is aluminous cement. It is best to leave work involving the mixture to experts. When mixing cement (as opposed to regular Portland cement, for example), it is more difficult and takes longer due to its high viscosity; however, proper mixing is essential to the consistency and longevity of concrete.
Since it is nearly impossible to use large volumes of concrete quickly and it is impossible to slow down the hardening process, the mixture is typically prepared in small portions. It is very difficult to work with compositions that start to set right away after preparation, and this can have an impact on the final structure’s quality.
Aluminous cement is frequently used to create a variety of expanding mixtures and compositions that harden quickly. The composition and component ratios are computed independently for each such solution. Usually, the mixture self-compacts and expands in volume as it hardens, compensating for shrinkage. These mixtures are created by combining aluminous cement with different additives.
- Expanding cement with gypsum and crushed slag – sets quickly, expands in water.
- A waterproof mixture with minimal shrinkage – gypsum hemihydrate and slaked lime are added to the cement, which makes it possible to obtain a material suitable for use in waterproofing work.
- Expanding waterproof cement – quickly gains strength, used for waterproofing shipping locks, tunnels, pipelines, swimming pools, etc.d.
Aluminous cement, sometimes referred to as high-alumina cement, is a versatile and quick-setting material that finds application in construction due to its special qualities, which include resistance to chemical attacks, rapid hardening, and high early strength. It is frequently utilized in places that need to be repaired quickly, like industrial floors and roads, as well as in places that are subjected to extreme heat or strong chemicals. The many varieties of aluminous cement, their unique qualities, and the technical features that enable them to be utilized for a range of specialized applications will all be covered in this article.
Specifications
- Rapid hardening – begins after 30-45 minutes, ends after three days.
- The release of large volumes of heat during the hardening process, due to which aluminous cement can be used at temperatures down to -10C.
- Increased resistance characteristics to both low, as well as to high temperatures.
- Fire resistance – up to +1300-1700 C.
- High density (few pores in the structure).
- Very high strength.
- Resistance to gaseous and liquid media, corrosion, sulfur compounds of magnesium and calcium, alkali metal chlorides.
With its distinct properties and unique qualities, aluminous cement is a material that can be used for a variety of specialized applications. Its quick setting time and high early strength development make it especially useful for quick turnaround construction projects like emergency repairs and winter construction.
Aluminous cement not only sets and hardens quickly, but it also has exceptional resistance to harsh chemicals and high temperatures. Because of this, it’s the perfect option for refractory concretes, which are utilized in kilns, furnaces, and other high-temperature industrial environments. Because of its chemical resistance, concrete can be used in environments where acidic or sulfate conditions may be present.
Aluminous cement has many benefits, but it must be used properly to prevent problems like conversion, which over time can cause strength to diminish. For aluminous cement structures to perform and last over time, proper mix design and application methods are crucial.
All things considered, aluminous cement is a useful instrument for the building sector, providing answers for difficult situations in which regular Portland cement might not work as well. Professionals can fully utilize this specialized material to achieve successful and long-lasting construction outcomes by being aware of its properties and applications.
