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Solid lightweight Bricks

Bricks have evolved from the time when they were just hand packed blocks of mud. With “green’ becoming the norm, bricks have now evolved into material that are lightweight but surprisingly very durable and strong.

Brick is the most extensively used building material all over the World. To most of the people, brick symbolizes the basic unit of construction – one, which seems to have been present since time immemorial. But in spite of its long history the bricks suffer from many shortcomings like:

 

  • Top soil erosion: Bricks are produced with the use of good quality agricultural topsoil.
  • Power & Fuel Hungry: Manufacturing of one lakh bricks requires 25.77Mt of coal
  • Smallness of size: Smaller size of brick warrants higher mortar and labour inputs for masonry and plastering work.
  • Inadequate & Seasonal Supply: Supply of bricks is mostly not able to keep pace with the demand. Moreover production is restricted to six months in a year.
  • One size, Different Quality: To top it all, even the bricks produced are not of a uniformlygood quality.

The need for an alternative building material was, therefore, being keenly felt in the construction industry.

Since the early twentieth century, two ideas were developed to produce lightweight concrete – Aerated Autoclave Concrete (AAC) and Cellular Lightweight Concrete (CLC). Each is based on the idea that adding air bubbles to mortar would lower its weight while at the same time improving the product.

AEROCON ACC block is a revolutionary product which is light weight and fire resistant making it ideal for building in earthquake and other disaster-prone areas. In addition, its energy efficiency helps to maintain a moderate temperature within a building and gives you an enormous saving on energy bills.

Cellular Lightweight Concrete (CLC)

Cellular Lightweight Concrete (CLC) is conventional concrete, where natural aggregate (gravel) is exchanged for the best insulation medium available, namely air, embedded in organic and bio-degradable foam that offers no chemical reaction but solely serves as wrapping material for the air. Consequently CLC behaves, like conventional concrete, in particular concerning curing, hardening and most important “ageing “. CLC infinitely increases its strength by hydration (forming of crystals in cement) as long as exposed to humidity in the atmosphere.

It may be cast in-situ into a complete structure or the walling and /or roofing elements of a structure or it can be made into pre-cast elements – whether reinforced or un-reinforced.

Among the Light weight bricks Cellular Lightweight Concrete (CLC) bricks are extensively used in majority of projects as they can be casted in project site where as AAC bricks need large scale machineries set up in factories.

Durability of Light weight Bricks:

The uniform size and space with even finished exposure to the atmosphere, the compressive strength of the brick increase 25% after one year, the intensity remaines stable after 10 years, most of the strength of aerated concrete block increase a little after natural carbonation, which shows aerated concrete block and cellular lightweight blocks posses’ good durability and gains strength with age.

Strength

Generally overall strength of each light weight block is generally equivalent to 10 pieces of clay bricks, so the utilization of high strength masonry strength utilization factor is 0.7 to 0.8, while Clay’s strength utilization factor is only 0.2 ~ 0.3. The general compressive strength of a block is 2.0 to 7.0 N/mm2.

Advantages of Light Weight Bricks:

  • Light Weight: Blocks are lightweight having density range from 650 Kg/m3 to 1250 Kg/m3 as compared to 1800 Kg/m3 to 2400 Kg/m3 for conventional brick and concrete respectively. Despite millions of tiny air filled cells. Products are strong and durable. The lightweight advantage for the structure design leading to savings in supporting structures and foundation.
  • Comprehensive Strength: Blocks are available in wide range of density from 650 Kg/m3 to 1250 Kg/m3 of average compressive strength of 2.0 to 7.0 N/mm2.
  • Excellent Acoustic Performance: Blocks has excellent acoustic performance and can be used as effective sound barrier and for acoustic solutions. Hence, highly suitable for partition walls, floor screens / roofing and panel material in auditoriums.
  • Earthquake Resistant: Blocks are lighter than concrete & brick respectively. The lightness of the material increases resistance against earthquake as well as less chances of loss / damage to human lives.
  • Insulation: Blocks provide superior thermal insulation properties compared to that of conventional brick and concrete. This property of CLC blocks reduces the heating and cooling expenses.
  • Workability: Blocks products are produced in a rectangular shape for internal and partition walls or in shapes as required. The products are lightweight, making them easy to [place and secure using less skilled labour. The bricks can be drilled and shaped like wood using standard hand tools, regular screws and nails. It is simpler than brick or concrete.
  • Lifespan: Blocks products are weather proof, pest resistant and fire proof and increase durability along with age.
  • Savings in Material: Blocks products reduce dead weight of filler walls in framed structures by more than 50% as compared to brickwork resulting in substantial savings. Due to the bigger and uniform shape of blocks, there is a saving in bed mortar and plaster thickness.
  • Water Absorption: Blocks products are closed cellular structures and hence have lower water absorption.
  • Skim Coating: Blocks products do not require plaster and water repellent paint suffices. Wallpapers and plasters can also be applied directly to the surface.
  • Environment Friendly: Blocks products are manufactured with fly ash 100% recycled resource. As a building material, Cellular Lightweight Concrete products conserve fertile agricultural soil. It has a dramatic impact on emission of Green House Gases created during cement manufacturing.
Houses built for Metro workers

Light material is most ideal and cost effective where time and financial budget is a constraint. This material saves time of construction due to light weight, handling is easier, needs less labour and sizes are large than conventional blocks and which needs less mortar as well.

“Time is money” bigger blocks, Light weight panels help in faster construction and also helps on reducing on site work time as the bricks can imported from the factory or can be prepared in the suitable surroundings.

One example, I would like to showcase is, A housing project for 300 metro workers at Jakkur which was completed in a short period of two months. A period of 1 month was taken for construction of foundation, plinth and flooring on site, the second period of month was taken for eructation of the Light weight blocks, Panels and Pre fabricated roof structure.

We professionals like to adopt innovative materials which are durable and reliable and are better performers, time savers and cost saving products with ease of construction. Light weight brick is such a material of the day and days to come which substitute the conventional and environmentally unsustainable materials like clay bricks etc.

Buildotech talks to N.K. Jayakrishnan,

General Manager – Aerocon Blocks, Hyderabad Industries Ltd (HIL)

Aerocon has become synonymous with AAC blocks…

Being pioneers in AAC blocks in India and with considerable focus given by us in propagating the light weight design concept using AAC blocks and positioning Aerocon as a brand in the market, stake holders started viewing the product as Aerocon rather than AAC. We had an early mover advantage, primarily because we propagated Aerocon Blocks as a superior replacement for conventional walling material like red clay bricks.

Factors like light weight properties, faster construction, energy savings due to superior insulation properties, easy workability, high fire resistance and eco-friendly nature propels AAC blocks as the most superior walling material. Dimensional accuracy, strict adherence to consistent quality parameters and superior service levels are hall marks of Aerocon AAC blocks.

What is the level of understanding and awareness in the markets you operate?

Though AAC blocks concept was known to specifiers in India, they were not aware of its availability in India. However the efforts put in by Aerocon over a period of time has had very positive impact. Today more and more stake holders are specifying Aerocon AAC Blocks in their projects. Green building rating agencies like IGBC and GRIHA are also actively involved in propagating such products which are eco-friendly.

The acceptability for the product has also witnessed substantial improvement with more and more end users willing to specify Aerocon AAC blocks and consider this as a USP for positioning their projects.

This trend is expected to continue with increasing awareness of light weight structures, green material and the considerable impetus being given by the statutory authorities to restrict mining of clay.

What are your challenges?

The main challenge is in design of structures based on light weight property of AAC Blocks. However with availability of AAC blocks on the rise, our TG are increasingly willing to go in for designing structures with Aerocon blocks.

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