top of page
  • Writer's pictureEr S G Ashok Kumar PMP, IGBC-AP

AREATED AUTOCLAVED CONCRETE BLOCKS:-

Updated: Aug 2, 2021

· INTRODUCTION:-

The Autoclave aerated concrete blocks are also known as Auto clavedlight weight concrete(ALC).It is an ultra-light concrete masonry product. The Autoclaved Aerated Concrete (AAC) is one of the eco – friendly and certified green building materials . AAC was perfected in the mid of 1920s by the Swedish architect.

It has become one of the most used building materials in Europe and is rapidly growing in many other countries around the world .Basically,AAC is a mixture of cement, fly ash , sand , water, and aluminium powder. When the materials are proportionally weighed. AAC is using no aggregate larger than sand.

Here, Aluminium powder reacts with calcium hydroxide and water to form hydrogen.AAC is one of the materials which can cope up with the shortage of building raw materials and can produce a light weight, energy efficient and environmentally friendly concrete.

· DEFINITION:-

The Autoclaved aerated concrete (AAC) is a lightweight, precast, foam concrete building material suitable for producing concrete masonry unit (CMU) like blocks is known as autoclaved aerated block. It Composed of quartz sand, calcined gypsum, lime, cement, water and aluminum powder. The AAC products are cured under heat and pressure in an autoclave.

· MATERIALS USED IN AAC BLOCKS:-

The following are the materials used in AAC blocks production are listed below:-

1- Cement

2- Fly ash

3- Sand

4- Lime stone

5- Aluminum powder and

6- Gypsum.

1- CEMENT:-

The Cement is known as the binder material , it is a substance used in the construction process that sets and hardens and is capable of binding other materials together. 14% present in AAC block this substance is available in different colours and grades.

The following are the properties of OPC used in the AAC block are listed below


FIG -1 CEMENT

1- Colour- white

2- Density of cement – 1440kg/m3

3- Type of cement – OPC 53 grade

4- Compressive strength – 53 MPA

5- Codal provision- IS-269-1989 and IS-383-1970

6- Chemical composition of cement

2- FLY ASH:-

The Fly ash is waste industrial product used for reduction of construction cost. The density of fly ash ranges from 400-1800kg/m3 . It provides thermal insulation, fire resistance and sound absorption.

The type of fly ash used is of Class C with contains 20% lime (Cao) and loss of ignition not be more than 6%. Majorly the fly ash used in autoclaved aerated blocks is 68%. fly ash is a by product of burning pulverized coal in an electric generation power plant.

These are mixed with water to form a fly ash slurry which is then mixed with other ingredients to form blocks.


FIG-2 CLASS C FLYASH

3- FINE AGGREGATE :-

The Fine aggregate are basically sand consists of crushed stone with maximum particles passing through a 4.75mm sieve, . As per codal provision IS 383:1970,the silica content shall not be less than80%.


FIG -3 FINE AGGREGATE

4- LIME STONE:-

Limestone is a common type of carbonate sedimentary rock. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO).

Limestone forms when these minerals precipitate out of water containing dissolved calcium. Limestone is obtained either by crushing to fine powder at AAC factory or by directly purchasing it in powder form from a merchant .


FIG -4 LIME STONE

5- ALUMINIUM POWDER:-

Aluminum is an expansion agent. When the raw material reacts with aluminum powder, air bubble introduced due to reaction between calcium hydroxide, aluminum and water and hydrogen gas is released. Aluminum Powder is used in the production of many types of explosives and fire works.


FIG -5 ALUMINIUM POWDER

6- GYPSUM:-

The Gypsum powder is a natural product found in deposits throughout the United States. It begins as a soft, white mineral rock and is processed to make a dry powder. In ACC blocks the gypsum is used reducing setting time, increasing strength, maintain light weight etc..


FIG -6 GYPSUM

MANUFACTURING PROCESS OF AAC BLOCKS


AAC BLOCK FOR SALE

· MERITS OF AAC BLOCKS:-

The following are the merits of autoclaved aerated blocks are listed below:-

1- Autoclaved aerated concrete combines insulation and structural capability in one material for walls, floors, and roofs.

2- Durability and dimensional stability. A cement-based material, AAC resists water, rot, mould, mildew, and insects. Units are precisely shaped and conform to tight tolerances.

3- Fire resistance is excellent, with eight inch thick AAC achieving a four-hour rating (actual performance exceeds that and meets test requirements for up to eight hours). And because it is non-combustible, it will not burn or give off toxic fumes.

4- The light weight also gives a high sound reduction for privacy, both from outside noises and from other rooms when used as interior partition walls.

· DEMERITS OF AAC BLOCKS:-

The following are the demerits of AAC blocks are listed below:-

1- It is not as widely available as most concrete products, though it can be shipped anywhere.

2- It is lower strength than most concrete products or systems, in load-bearing applications.

3- It also requires a protective finish since the material is porous and would deteriorate if left exposed.

· COMPOSITION OF AAC BLOCKS :-



Mainly the most constituent material in ACC block is fly ash. The percentage of fly ash is used in ACC block is 68%. The other materials used in ACC block are cement, gypsum, lime, fine aggregate and other miscellaneous materials.

AAC BLOCK SPECIFICATIONS



· REFERENCES: -

1- IS 2185,PART 3 1984,specification for concrete masonry units, Autoclaved cellular(aerated) Concrete blocks.

2- P.S.Bhandari, Dr. K.M.Tajne, Cellular Lightweight Concrete Using Fly Ash, International Journal of Innovative Research in Science, Engineering and Technology, Vol. 3, Issue 11, November 2014.

3- Ashish S. Moon, Dr. Valsson Varghese , S. S. Waghmare, Foam Concrete as A Green Building Material, INTERNATIONAL JOURNAL FOR RESEARCH IN EMERGING SCIENCE AND TECHNOLOGY, VOLUME-2, ISSUE-9, SEP-2015.

4- S. Nandi, ArnabChatterjee, PrantikSamanta, TanushreeHansda, Cellular Concrete & its facets of application in Civil Engineering, International Journal of Engineering Research ISSN:2319-6890(online),2347- 5013(print),Volume No.5, Issue Special 1 pp : 37-43 8 & 9 Jan 2016.

5- FunsoFalade, EfeIkponmwosa, Bright Ukponu, The Potential of Laterite as Fine Aggregate in Foamed Concrete Production, Civil and Environmental Research ISSN 2224-5790 (Paper) ISSN 2225-0514 (Online)Vol.3, No.10, 2013

BLOG AUTHOR DETAILS:-

BABA AFRID .S

CMTI Campus Ambassador

GRADUATED – Mother Theresa Institute of Engineering and Technology

PALAMNER ,CHITTOR DISTRICT [2021]

7 views

Commentaires


bottom of page