Aircrete is an eco-friendly building material with uniformly distributed stable air cells and a lower density that makes it lightweight for comfortable working. On the other hand, concrete, which contains coarse and dense traditional aggregates, is robust, making it ideal for load-bearing structures. So, which is better?
Both Aircrete and concrete have compelling advantages over the other. The appeal of aircrete over concrete is its lightness, affordability, and high insulation. Concrete on the other hand, is excellent for heavy construction. It features stone aggregates for strength and can withstand heavy weights.
This guide will compare and contrast different features that give concrete and aircrete versatile properties as building materials. In this case, the user has to decide which one works best for them. Read on and find out.
Aircrete vs. Concrete
Aircrete, also known as aerated concrete, belongs to a family of lightweight cement masonry products known as form concrete. It’s a popular building material in Europe and Asia and accounts for one-third of all concrete blocks used in the United Kingdom.
The aerated concrete is the lightest in the family of concrete blocks. Aircrete blocks consist of sand, cement, lime, pulverized fuel ash (PFA), and water. A small amount of aluminum sulfate is added to the slurry and reacts with the lime to form hydrogen bubbles. The mixture expands into a “cake,” and the hydrogen diffuses when replaced by air.
The correct water-to-cement ratio for aircrete slurry is 1 to 2 and may vary according to specific project requirements. When the mixture partially sets, it’s cut into block size and transferred to an autoclave for curing with high-pressure steam to harden and give it strength.
Mostly little or no coarse aggregate features in the manufacturing of aircrete. Replacing admixtures entirely or partially variates the density of aerated concrete varies from 400kg/m3 to 1600kg/m3.
On the contrary, concrete is a composite material that includes fine and coarse aggregates combined with a fluid cement that hardens over time. The slurry is mixed with dry Portland cement and water to make a mixture that forms into shapes when poured or molded.
Curing is a necessary process that ensures the concrete achieves its final comprehensive strength. The method enables hydration to occur and allows calcium-silicate hydrate to form. Over four weeks, the concrete mix attains more than 90 percent of its concentration.
During the first three days, hydration and hardening of concrete are crucial. Fast drying and shrinkage can occur when water evaporates, leading to increased tensile stresses when it has not gained sufficient strength.
Concrete curing helps maintain an adequate amount of moisture, which aids in cement hydration. If curing is done at the right temperature, it’ll support the hardening of concrete. Curing plays a vital role in maintaining the strength of concrete, which makes it suitable for heavy construction.
However, since concrete is weak in tensile strength, reinforcing materials such as steel can offer tensile strength for load-bearing structures. Conversely, since proper curing of concrete leads to increased strength, it also lowers permeability and reduces cracking where the surface dries out prematurely.
The workability of concrete means its ability to fill the mold appropriately without plummeting the quality and producing the desired work. Workability depends on the amount of water, size, and shape of the aggregate.
Additionally, the cementitious content can define the workability of concrete. When more water and chemical admixtures combine in the amalgam, it increases concrete’s workability.
A Contrast and Comparison of Aircrete vs. Concrete Properties
Aircrete and concrete compare and differ in their properties. Each of these building materials has different applications in construction. Let’s have a look at these properties.
Aircrete includes any type of Portland cement and Fly Ash mixture. A 90lb bag of cement produces 40-50 gals of aerated concrete. Aerated concrete has a low density and a relatively lower comprehensive strength compared to standard concrete.
The typical density range from 20-60 lbs/cu ft corresponds to a comprehensive strength range of 50 psi – 930 psi. Fine foam, which has a high density, can be added to increase aerated concrete’s strength, which results in a stronger aircrete.
Low-density aircrete is less than 300kg/m3. However, specialized foam generating, mixing, and pumping equipment have improved the product making it possible to manufacture 75 kg/m3 density blocks. Dry densities of 25 lb/ft3 to 100lb/ft3 make aerated concrete. However, it varies depending on the application from 12.5 lb/ft3 to 100 lb/ft3.
In contrast, concrete varies in density and is about 150 lb/cu ft to offer relatively higher comprehensive strength than aerated concrete. Besides, low strength concrete includes 14MPa (2000psi) while concrete for routine use includes 20Mpa (2900psi).
Typical high-strength concrete blocks have a strength of 40Mpa (5800psi) to 410Mpa (59,00psi). Also, commercial structures that are very rigid include concrete with 130Mpa (18900psi).
Aerated concrete features excellent insulating properties during summer and winter. Aircrete consists of millions of tiny closed air cells that give it different applications than conventional concrete.
In conventional concrete structures, 40 to 50 percent of the energy loss is around the thermal bridges where floors and roofs meet the wall. Aircrete provides a seamless integration on floors, walls, and ceilings eliminating the thermal bridge, making it easier to heat and cool a dome house.
A Contrast and Comparison of the Benefits of Aircrete vs. Concrete
There are many benefits of using aerated concrete, and so is standard concrete. Here is how these two products compare and contrast.
Aircrete is a high-quality, low-cost material that eliminates the need for aggregates such as gravel, sand, and rock. Conversely, concrete is a composite material that employs coarse aggregates for strength, making it more expensive than aerated concrete.
Besides, mixing standard concrete is not nearly as a straightforward process as it seems. Combining concrete aggregates is a complicated process that takes up space on the job site and requires a lot of room to deal with the materials. Prefabricated aircrete products are taken to the worksite and assembled to form the desired structure.
Aerated concrete offers a smooth finishing that saves plastering and labor costs involved in painting. On the other hand, concrete surfaces tend to be porous and have a relatively uninteresting appearance.
Therefore, different finishes can be applied to improve the appearance and prevent the surface against staining, water penetration, and freezing. For instance, decorative stones such as quartzite, small river stones, or crushed glass on concrete’s surface make a decorative finish.
Other finishes achieved through chiseling, painting, or conventional techniques make excellent finishes for concrete. Thus, concrete structures are more expensive to build and finish than aircrete homes.
Although the use of insulating materials is not widespread despite their long-term financial benefit, Aircrete offers excellent thermal insulation effect and saves energy. Aerated concrete helps a homeowner save a considerable amount of money on bills throughout the year.
Concrete, which is the most popular building material in the world, is not a good insulator because of its resistance to heat flow. Thus a concrete structure will not reduce electricity consumption because of the air-conditioning system; hence it’s not economical. However, it requires little energy to combine and produce raw materials.
While insulation minimizes energy loss through the building envelope as with aircrete, thermal mass uses walls to store and release energy in concrete. However, concrete features high thermal mass properties that make it ideal for making electrical night storage heaters.
Also, well designed and concrete pavements and roads are more fuel-efficient to drive on and last longer than other surfaces.
Easy to Work and Handle
Aircrete includes lightweight prefabricated structures like blocks, walls, roofs, floorings, lintels, and cladding panels. The ready-made products are easy to transport and assemble to desired structures. Besides, you can make aerated concrete yourself with a small Aircrete machine called – the little dragon.
On the other hand, concrete needs a wealth of preparation before using it on the site. The mix design, quality of concrete, placement processes, form removal on the and curing need consideration beforehand.
Besides, concrete may seem easy to handle, but it needs ground leveling for best results, which requires land clearing and topsoil removal. Additionally, ground leveling is crucial for adequate support and shaping of the structure.
The other thing to keep in mind is the narrow window of time of working with concrete. Therefore, the failure of proper tools can result in subpar installation and a waste of time, money, and effort. It also dries out quickly, leaving no time to make adjustments.
Today, we are all the more committed to protecting our environment. Aircrete has a lower environmental impact compared to concrete as it consists of eco-friendly materials. These include: fly ash, lime, cement, gypsum, aluminum powder, and water.
When making aerated concrete, cement is expanded six times its original volume with air reducing the carbon footprint. Additionally, as adhesives with fewer carbon footprints become widely available, it will be possible to make aircrete more environmentally friendly. Besides, the disposal of aerated concrete does not bring any harm to the environment.
The primary component in concrete is the cement, which exerts a significant greenhouse gas – CO2 into the atmosphere. Portland cement contributes to eight percent of global carbon dioxide emission due to the sintering of limestone and clay at 2700 F.
Conversely, grinding of concrete can produce hazardous dust, and exposure to cement for long periods can lead to kidney disease, silicosis, skin irritation, and other repercussions.
National Institute for Occupational Safety and Health recommends attaching local exhaust ventilation shrouds to electric concrete grinders to control dust. Besides, handling wet concrete must always be done with proper protective equipment.
Concrete recycling is a standard method of disposing of concrete structures.
The U.S. military firearm training utilizes aerated concrete in high intensity. The capacity of energy absorption in aircrete varies from 4 to 15 M.J./m3, depending on its density. Additionally, aerated concrete panels have continuous pore structures providing an opportunity for acoustic absorption in offices, next to roads, HVACs etc.
Besides, aircrete can float, making it suitable for marine floatation, although it should be in a protective membrane.
On the other hand, concrete is a poor shock absorber and is not suitable for flooring in places where physical training takes place like exercise rooms and gyms. However, it’s ideal for garages and storage areas where durable flooring is crucial.
Aerated concrete is waterproof and will not rot or decompose in water. It can make an ideal choice for a rooftop. This allows you to have vegetation and sprinkle it without any problem.
In contrast, typical concrete surfaces are not as waterproof as they become porous as they dry. As water leaks into the concrete, it begins to wear away and create larger pockets where water can collect and cause further damage.
However, there are products which, when mixed with concrete, make it less porous. Also, a surface coating that is applied during the curing process creates a waterproof finish.
The development of Aircrete was primarily intended for use in the internal skins of cavity walls instead of breeze blocks. Initially, some buildings made of aerated concrete blocks cracked a few months after construction due to unstable form bubbles.
Very low-density aircrete is not suitable for load-bearing structural applications and is prone to impact damage. The higher the volume of added air, the more brittle aerated concrete tends to be. Therefore, the air entrained in the aerated concrete must contain tiny, stable, and uniformly distributed bubbles that remain intact and isolated.
On the other hand, concrete offers superior comprehensive strength when applied to load-bearing structures. It gains strength as it matures, making it an excellent building material for use in dams, road projects, among others. Besides, reinforced concrete, which includes steel reinforcing bars, carbon fibers, glass fibers, steel fibers, or carbon fibers, can carry tensile loads.
However, when concrete is not reinforced with materials that are strong in tension (often steel), matrix cracking appears. All concrete structures crack due to shrinkage and rigidity.
Cracks in concrete may be surface – less than a few millimeters wide and deep or structural – larger than 0.25 inches. Poor construction practices cause surface cracks, freeze-thaw cycles, and alkali-aggregate reactivity.
Structural cracks which extend deeper through a wall or slab result from erosion of the fill material supporting the concrete structure. Additionally, concrete has low coefficient thermal expansion and shrinks as it matures. Therefore, concrete subjected to long-duration forces is prone to creep.
Aircrete is fireproof and can make outdoor ovens and fire pits without burning. Extensive use of aerated concrete blocks does not burn and contain the spread of fire within a building. A 100mm thick aircrete block can resist fire up to four hours. However, concrete structures have a high degree of fire resistance thanks to structural form properties.
Concrete structures have a higher degree of fire resistance than those which combine concrete and steel due to low heat conductivity. Concrete is a non-combustible substance and has a slow rate of heat transfer. It ensures that the structural integrity remains and minimizes the risk of fire.
In most cases, concrete does not require any additional fire protection as it has its inbuilt resistance. It can be used as a fire protection for steel frames or as a fire shield for a missile launchpad.
Applications Appropriate for Aircrete
Most prefabricated aerated concrete blocks come in different shapes and sizes. Aircrete products can be made into any strength to meet the application.
- Floor slabs
- Precast blocks, wall elements and panels
- Housing systems
- Underground pipe insulation
- Poured insulated roof and floor decks
- Replacement for unstable soils
- Acoustic floor underlayments and shock absorption
- Fill for abandoned tanks, mines, hollow blocks and pipelines
- Load reducing fill over an underground structure
- Bridge approach fills
Applications Appropriate for Concrete
Concrete is specific to different applications like rebuilding, mending, and construction. It can make a variety of applications which include:
- Dams, bridges, swimming pools
- Commercial and residential buildings
- Pavement blocks, roads, overpasses, and parking structures
- Lamp posts, beams, and deck
- Insulating concrete forms
- Industrial, commercial and residential floor slab construction
- Walls among other applications
In the lower density ranges, aerated concrete is more brittle and has less comprehensive strength than standard concrete. While this may be a disadvantage in load-bearing applications, it is advantageous in an aircrete construction such as domes, roofs, and floors. Besides, aircrete is eco-friendly, waterproof, easy to handle, and economical.
Concrete is perfect for heavy construction projects. It can withstand the weight and gravity.
It’s necessary to note that each form of concrete exhibits a unique family of performance and characteristics. Therefore, whether you choose to use aircrete or concrete, the application will vary depending on the project type.
- Wikipedia: Foam concrete
- Aircrete: Boggelen History of Autoclaved Aerated Concrete. (pdf)Skill-builder: Cracking up – The Trouble with Aircrete Blocks
- Domegaia: Aircrete FAQs
- Design Buzz: 8 Reasons why AirCrete needs to replace Concrete in construction
- eHow: How Absorbent Is Concrete?
- Wikipedia: Environmental impact of concrete