AAC, also known as autoclaved aerated concrete, was developed in 1924 as an alternative building material to wood. It has several advantages over other cement materials, including improved thermal efficiency, workability, resource efficiency, lighter weight, and earthquake resistance. AAC products include blocks and panels that are available in various sizes. It is produced through a process that results in a lightweight, noncombustible material with compressive strength and thermal resistance properties suitable for construction uses.

1. What is AAC:
Autoclaved aerated concrete (AAC), also known as autoclaved cellular
concrete (ACC), autoclaved lightweight concrete (ALC), autoclaved
concrete, cellular concrete, porous concrete, Ytong, Hebel Block,
Aircrete, Thermalite.
When was AAC first developed:
AAC was developed in 1924 by a Swedish architect, who was looking
for an alternate building material with properties similar to that of wood –
good thermal insulation, solid structure and easy to work with – but
without the disadvantage of combustibility, decay and termite damage.
It has been refined into a highly thermally insulating concrete-based
material used for both internal and external construction.
AAC products include blocks, wall panels, floor and roof panels, and
lintels.
AAC Blocks Manufacturers

3. Advantages
AAC has been produced for more than 70 years, and it offers several
significant advantages over other cement construction materials, one of
the most important being its lower environmental impact.
* Improved thermal efficiency reduces the heating and cooling load in
buildings.
* Workability allows accurate cutting, which minimizes the generation of
solid waste during use.
* Resource efficiency gives it lower environmental impact in all phases
of its life cycle, from processing of raw materials to the disposal of
waste.
* Light weight saves cost & energy in transportation.
* Light weight saves labor expenses.
* Light weight increases chances of survival during seismic activity.

5. * Larger size leads to faster masonry work.
* Termite/Pest Resistant
* Cost Effective
* Precision
* Earthquake Resistant
* Easy Workability and Design Flexibility
* Thermally Insulated & Energy Efficient
* Fire Resistant
* Eco-friendly

7. Sizes:
Both blocks and panels are available. Blocks are stacked similarly to conventional
masonry, but with a thin-bed mortar, and panels are stood vertically, spanning full-story
heights.
* Panels extend from floor to top of the wall:
Height: up to 20 ft
Width: 24 in.
Thickness: 6, 8, 10, or 12 in. (4 in. thick interior partition panels are available)
* Blocks are larger and lighter than traditional concrete masonry:
Height: 8 in. typical
Width: 24 in. long
Thickness: 4, 6, 8, 10, and 12 in.
A standard 8 x 8 x 24 in. unit weighs about 33 lbs.
* Specialty shapes:
U-shaped bond beam or lintel blocks are available in thicknesses of 8, 10, and 12 in.
Tongue and groove blocks are available from some manufacturers, and these
connect to adjacent units without mortar at vertical edges
Cored blocks available for creating vertical reinforced grouted cells

8. AAC Blocks Manufacturers

9. Manufacturing and Physical Properties
This manufacturing process produces a lightweight, noncombustible
material with the following properties:
Density: 20 to 50 pcf (lb per cu ft)—this is light enough to float in water
Compressive strength: 300 to 900 psi
Allowable shear stress: 8 to 22 psi
Thermal resistance: 0.8 to 1.25 per in. of thickness
Sound transmission class (STC): 40 for 4 in. thickness; 45 for 8 in.
thickness

11. Installation, Connections and Finishes
Due to the similarity to traditional concrete masonry, AAC units (block)
can be easily installed by concrete masons. Depending on the type of
finish selected, they can be directly adhered or mechanically attached to
the face of AAC.
* Block:
First course is laid and leveled. Blocks are stacked together with thin-bed
mortar in a running bond with a minimum of 6-in. overlap.
Walls are plumbed, leveled, and squared with a rubber mallet.
Openings and odd angles are cut with a handsaw or bandsaw.
Reinforcement locations are determined, rebar placed, and grouting
occurs. Grout must be mechanically vibrated to consolidate it.
Bond beams are placed at the top of the wall and can be used for heavy-
duty fixture attachment.

13. * Panels:
~ Panels are placed one at a time, starting from the corner. Panels are set
into a layer of thin-bed mortar and vertical rebar is attached to dowels
extending up from the floor before the adjacent panel is placed.
~ A continuous bond beam is created at the top, either with plywood and
AAC material or with bond beam block.
~ Openings can be precut or field cut.
* Connections:
~ Roof frame/framing is connected to a conventional top plate or
hurricane straps embedded in the bond beam.
~ Floor framing is attached with standard ledgers anchored to the side of
the AAC assembly adjacent to a bond beam.
~ AAC floor systems bear directly on top of AAC walls.
~ Larger structural steel members are set on weld plates or bolt plates set
into the bond beam.

15. Finishes:
Stucco-type finishes are made specifically for AAC. These polymer-
modified plasters seal against water intrusion yet allow moisture vapor
for breathability.
Conventional siding materials are mechanically attached to the wall
face. Furring strips should be employed if back ventilation of the siding
material is desirable.
Masonry veneers can be directly adhered to the wall face or can be built
as cavity walls. Direct-applied veneers are typically lightweight materials
like manufactured stone.
AAC Blocks Manufacturers

20. AAC Blocks Manufacturers