AAC blocks Introduction
November 26, 2020

AAC blocks Introduction

The AAC blocks   (Autoclaved Aerated Concrete) material was developed in 1924 in Sweden. It has become one of the most used building materials in Europe and is rapidly growing in many other countries around the world. Aerated block machine/arc machinery/automatic block machine is available in the whole world.
Autoclaved Aerated Concrete (AAC Blocks), is a lightweight, load-bearing, high-insulating, durable building product, which is produced in a wide range of sizes and strengths.
Autoclaved aerated concrete (AAC Blocks) offers incredible opportunities to increase building quality and at the same time reduce costs at the construction site. AAC is produced out of a mix of quartz sand and/or pulverized fly ash brick plant (PFA), lime, cement, gypsum/anhydrite, water and Aluminum and is hardened by steam-curing in autoclaves. As a result of its excellent properties, AAC is used in many building constructions, for example in residential homes, commercial and industrial buildings, schools, hospitals, hotels and many other applications.
Autoclaved aerated concrete (AAC Blocks) is actually hydrated calcium silicate. The calcium is obtained from quick lime, hydrated lime and cement. The gypsum is used as a catalyst and for optimizing the properties of AAC.
The silica is obtained from silica sand, fly ash (PFA), crushed silica rock and/or stone. It is possible to obtain silica as a by-product from other processes, e.g. foundry sand or burgee from glass grinding, provided the levels of alkalis or other impurities are not too high.
This product is key equipment which has a widely application in building material factory to autoclaved cure different kinds of building materials. It is also used in areas of chemical, textile, wood, metallurgy, military industry. Convenient operation, security and reliable are its advantage.

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November 26, 2020

AAC Blocks Applications

In the manufacture of clay bricks, the top soil is depleted and natural resources are eroded, resulting in ecological imbalances. But by utilizing fly ash which is the waste material generated by thermal power stations, we will be saving the natural resources on one hand and putting the industrial waste into productive use. This makes #AACBlocks one of the best examples of a truly “green product”, in every sense of the term. Sand is another alternative to fly ash for manufacturing AAC blocks. However, sand cannot be recycled like fly ash and therefore manufacturing #AACBlocks using sand cannot be considered a green process and the resultant product a green product. Using sand will only erode the natural river bed, thereby changing its course and result in ecological imbalances.As every structural engineer knows, that adequate care needs to be given to masonry wall members, since it gives full shape and structure to the building. I have realized that everyone neglecting the wall member in the structure will mean that importance of the masonry wall will have been neglected by all parties’ concerned – structural consultants, builders, promoters, contractors, etc. This will mean not following the specifications laid down in BIS 6041 of 1985 and BIS 1905 of 1987, which will lead to problems like, shear crack, horizontal crack and settlement crack etc., in the wall at a later date. I therefore appeal to all friends, contractors, constructors, builders, etc, to follow certain important guidelines given below before and during construction of AAC masonry wall for better achievement.

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November 26, 2020

AAC Blocks VS Clay | Red Bricks

No. Parameter AAC Block(Fusion Blocks)  Clay | Red Bricks 1 Size (mm) 600 * 200 * 100 – 300 230 * 115 * 75 2 Precision in size Variation (+ /-) 1 mm Variation 5 – 15 mm(+/-) 3 Compressive Strength 3.5–5N/mm2(As per IS.:2185), Part-3, Grade-|| 2.5-3.5 N/mm2 4 Dry Density 550-650 kg/m3 (Oven dry)

No. Parameter AAC Block(Fusion Blocks)  Clay | Red Bricks
1 Size (mm) 600 * 200 * 100 – 300 230 * 115 * 75
2 Precision in size Variation (+ /-) 1 mm Variation 5 – 15 mm(+/-)
3 Compressive Strength 3.5–5N/mm2(As per IS.:2185),
Part-3, Grade-||
2.5-3.5 N/mm2
4 Dry Density 550-650 kg/m3 (Oven dry) 1950 Kg/m3
5 Wet Density App. 800 Kg./m3 App. 2400 Kg./m3
6 Fire Resistance 2 to 6 Hour depending on thickness 2 Hours
7 Sound Reduction Index (dB) 45 for 200 mm thick wall 50db for 230 mm thick wall
8 Thermal Conductivity.
0.16 0.81
9 Quality Uniform  &  Consistent Normally Varies
10 Quantity of Cement Consumption per M3 wall with 1:6 0.5 bag of Cement 1.4 bag of Cement
11 Construction Time
per mason
Very  High due to bigger in  Size , light weight , less no of Joints Comparatively lower
12 Chemical Composition Fly ash used app. 60 % which reacts with binders (Lime & Cement) to form AAC which is an inert material Soil is used which contains many inorganic Impurities like sulfates etc. which results in Efflorescence
13 Energy Saving ~25% Reduction in Power consumption of A/C No  Saving
14 Contribution to carpet area 3 – 5 % No saving
15 Cost benefit Factor Depending upon project design, savings up to 20% in structural cost due to reduction of dead load No saving
16 Availability Anytime Shortage in Monsoon
17 Breakage Less than 3% Average 12 to 15%
18 Fitting & Chasing All kind of fittings and Chasing Possible All kind of fittings and Chasing Possible
19 Structural Cost  Steel Saving  Up to 15% No  Savings

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Fusion Jointing Mortar
November 26, 2020

AAC Blocks Manufacturing Flow Process Chart

AAC also known as Autoclaved Aerated concrete.  It is a lightweight concrete. AAC Blocks has been widely using across the world. AAC Blocks are made by mixing Portland cement, lime, fly ash, water, and aluminum powder the final mixture is poured into a moulds. The reaction between aluminum and lime causes microscopic hydrogen bubbles to form lower density concrete by expanding it. After evaporation of the hydrogen and initial setting, aerated concrete is cut into required sizes and cured by steam-curing in a pressurized chamber (an autoclave) or low pressurized steam chambers. The result is a nontoxic, high strength, light weight, airtight material that can be used for all walling applications. AAC Blocks are green building material that generates no pollutants or hazardous waste during the manufacturing process.

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