AAC can bring down construction cost by up to 20percentage
AAC can bring down construction cost by up to 20percentage

AAC can bring down construction cost by up to 20percentage

Sourabh Bansal
Managing Director, Magicrete
The use of red bricks have found reference in the era of Harappan Civilization. The product has been that old and is still in use. However due to environmental degradation that takes place while manufacturing red bricks, has put a question mark on its further use. AAC blocks is a dependable alternative.
Sourabh Bansal, Managing Director, Magicrete
takes us through the changing scenario and the technological alternative.

Explain us the need for autoclaved aerated concrete (AAC) blocks.
Being a developing economy, India has been riding a growth wave, but a lot of development is still to happen. This unprecedented development has resulted in urban population growing at faster rate, and is estimated to reach 590 million by 2030. Total built-up area requirement in residential sector is expected to grow at 7 per cent CAGR between 2005 and 2030, from 2.900 billion sq.ft. to 69.8 billion sq.ft. In short, we need to develop at least 100 smart cities in the next 10 years and it is priority of the Government too. A smart city uses digital technologies to enhance quality and performance of urban services, to reduce costs and effective utilisation of various infrastructures. Sectors that have to be developed in smart cites include government services, public infrastructure like schools and hospitals, low-cost housing, transport & traffic management, energy, health care, water and waste management.

To support these, we need millions of square feet of physical infrastructure to be ready at faster pace and at affordable prices. Road networks, ring roads, rail networks, residential apartments, hospitals, government offices and other social infrastructure need to be constructed at a breakneck speed. It is important to note that around 60 per cent of construction required for 2025 is yet to be constructed. Global economies going through difficult phase makes this even more difficult. To achieve this, innovative and eco-friendly construction technologies are needed. One such technology is AAC. The use of AAC can bring down the construction cost by up to 20 per cent, increase speed up walling by up to three times and it could be deployed to bridge the demand-supply gap in the affordable housing segment and other infrastructure projects. AAC blocks have proved its worth by saving a lot of construction time in Europe and the Middle East. The best part of this is that it not only speeds up the construction work, but also enhances the quality of output. Also, it helps in creating additional carpet area up to 3 per cent, reducing requirement of unskilled labour by almost 10 times and improving safety norms.

How the replacement of red bricks with AAC is happening?
Red bricks industry (a Rs 50,000-crore industry in India) is plagued by fragmentation, highly labour dependent and are produced in energy-inefficient processes. In addition as the name suggests they are made of agricultural top soil, thereby rendering useful agricultural land infertile. In addition, red bricks are more than 2000 year old technology, and the supply of consistent quality and quantity of red bricks is next to impossible for any brick kiln.

The need for better walling construction technology has always been felt and AAC fits in the requirement exactly. AAC blocks are nine times the size of a red brick and have up to 30 per cent higher compressive strength as compared to red bricks. Also they are made in a five times energy efficient autoclaving process. In addition, AAC is 3.5 times lighter than red bricks resulting in concrete and steel savings of up to 20 per cent. Due to all these advantages, AAC has found a very high rate of acceptance in last 5-6 years in India especially in markets of west and north India.

What are the bottlenecks in the industry?
In the last couple of years, a number of new AAC blocks projects have come up across India. With increasing supply and promotion of AAC blocks, awareness about this sustainable product is also increasing. More builders are exploring AAC blocks as their preferred walling material. Although number of users in absolute terms is small, growth in relative terms has been encouraging.

This growth can reach higher levels, but there are some bottlenecks in widespread adoption of AAC in India. Most important of them is that up to 25 per cent of cost of AAC is logistics. As a result any plant of AAC can supply economically in a radius of 250 km. Because of this, areas like central India, extreme north and north eastern states have seen comparatively less conversion of AAC as compared to west and north India.

In addition there are certain misconceptions and issues related to usage AAC blocks. Some of these include: AAC blocks have higher water absorption compared to clay bricks, AAC blocks are not suited for external walls in areas with high rainfall, AAC blocks lead to higher project cost in high-rise buildings, AAC blocks are not as strong as clay bricks, a wall made of AAC blocks can´t hold nails, it is hard to carve conduit ´jari´ in AAC blocks wall, plaster does not stick well to AAC blocks, and cracks appear in walls 2-3 months after plaster is applied.

Other challenges in the AAC blocks industry include under-utilisation of assets and unrelenting fixed costs, which continue to eat into margins of the players. Players are also been grappling with the problem of higher input costs such as rising cement prices.

Roughly, how big is the size of the market? How many players are in the race?
While around for a long time, AAC blocks are a relatively new phenomenon in Indian construction industry. Although first AAC blocks plant in India was set up in early 1970s in Pune, it is only recently that manufacturing and usage of AAC blocks have reached a sizable number. In spite of huge growth in manufacturing of AAC products, the current the market share of AAC products is small as compared to the red clay bricks, which presents a great opportunity for manufacturers. There are around 75 plants operating in this space, including some big names such as UltraTech and JK Lakshmi Cement. AAC blocks have seen tremendous acceptance amongst developers, such as L&T, Lodha, Shapoorji Pallonji, DLF, Rustomjee, Raheja, Mantri Developers, Embassy Group, etc. Palava by Lodha Group, being dubbed as India´s first smart city, uses AAC blocks as its walling product. AAC was a meager Rs 50 crore industry in 2008 and now the market for AAC blocks is estimated at Rs 2,000 crore in India, and is expected to be a Rs 5,000 crore industry in the next five years or so.

Kindly provide an overview of the technology used to produce AAC blocks, and also some details on the typical investment and the size of the plant, etc. AAC blocks are manufactured using 70 per cent fly ash, cement up to 22 per cent, lime 7-8 per cent and aluminium powder. All these products are mixed in form of a slurry in a computer-controlled batching process. This slurry mixtures are cast into huge moulds where a reaction between lime and cement takes place and hydrogen gas is evolved, it inflates the material to 200 per cent, making it lightweight. This gives AAC its porous and robust honeycomb structure. Further these moulds are wire cut into blocks of desired thickness. Then AAC blocks are cured in a high pressure steam chamber called autoclaves at a temperature of 190 Degree Celsius and a pressure of 12 kg/cm2 for 12 hours. This results in high strength to weight ratio of AAC. The whole process of production is computer controlled and stringent quality control measures are enforced, thereby resulting in a very high quality product with virtually no wastage in the production process.

An AAC plant of annual capacity 400,000 CBM requires an investment of up to Rs 50 crore including land, machinery and civil construction cost. An approximate land area of 10 acre is required for such a greenfield AAC plant. These machinery is generally imported from China. However these investments would more than double if the complete plant and machinery are imported from Germany.

How is the product marketed?
AAC is a direct competitor to red bricks and is technically superior to red bricks in every aspect. More importantly it has fly ash as a raw material, which is a bye-product of thermal power plants and is a national waste. Hence AAC is environmentally green in nature. In addition to all these advantages, AAC is more economical to be used than red bricks and supply of quality and quantity of AAC is consistent. AAC blocks have a very high sound insulation properties and has an sound transmission class (STC) Rating of 44 decibels, which result in virtually sound-proof interiors. These multiple reasons serve as USPs for AAC and there resulting in widespread adoption of AAC in India.

Magicrete undertakes rigorous market creation and awareness activities in order to propagate the use of AAC in India. Magicrete [till date] has trained more than 3,000 masons through its masonry trainings at its constriction sites. It conducts meets for builders, retailers architects and contractors across its markets to increase AAC awareness and penetration among the stakeholders. Magicrete AAC blocks are available at more than 2,000 building material stores across west and north India.

Explain the properties of AAC bricks v/s red bricks. Also give us some commercial comparison.
The conventional normal burnt clay bricks are detrimental to environment because they not only use the fertile agricultural top soil, but also a lot of carbon dioxide is released in environment in the process of making of the red brick. The brick industry is estimated to be the third most coal-consuming industry after power and steel. The Supreme Court has given directives for phasing out of the red clay bricks. Not only the bricks work out to be costlier as walling cost account for 10 per cent of project cost, but are extremely energy-consuming, labour and land-intensive. AAC blocks are technically superior in every aspect compared to red bricks. The main advantages are.

  • High strength: Autoclaving (high pressure steam curing) process and hexagonal porous structure gives Magicrete AAC blocks strength to weight ratio, higher than that of M150 concrete. Magicrete is India´s only manufacturer making ISI Grade 1 blocks which have 33 per cent more strength than others.
  • Faster construction: AAC blocks are nine times larger than regular red brick. This results in six times lesser joints and three times faster construction.
  • Light weight: AAC blocks have three times lesser density than red bricks. Thus overall dead weight of the building is reduced and it translates into structural steel and concrete saving of up to 20 per cent.
  • Thermal resistance: AAC blocks are six times more thermally insulating as compared to red bricks. This results in HVAC cost savings of up to 30 per cent.
  • Water barrier: Discontinuous porous microscopic structure does not allow capillary action in AAC blocks there by reducing water penetration by up to five times.
  • Sound absorption: AAC blocks have a sound transmission rating of 44 DB.
  • Carpet area increase: Owing to very water barrier, high thermal and sound insulation a 9ö external brick wall can be replaced by a 6´ AAC blocks. AAC blocks have excellent dimensional accuracy (tolerance of 1 per cent) and thereby reduce plaster thickness. Coupling all these factors usage of AAC blocks results in carpet area increase of up to 2 per cent.
  • Economical: Faster construction, increase in carpet area and structural steel and concrete saving, leads to up to 20 per cent economical construction and makes walling almost free of cost.
  • Earthquake resistance: Earthquake forces are directly proportional to the dead weight of a building. Reduced dead weight of a building by using AAC blocks there by increases earth quake resistance of a building
  • Green building material: AAC blocks have 70 per cent of fly ash, which is a national waste. Also AAC blocks are five times energy efficient. As a result, AAC blocks are completely green in nature and when used give maximum points in LEED certification.
  • Ease of working: AAC blocks can be machined, chiseled, nailed and sawed making it very MEP friendly.
  • Pest resistant: Being made of inorganic material AAC doesn´t promote growth of moulds.

What kind of mortar is used to join the blocks ? Also provide its properties.
Dry mix mortar is an innovative technology that offers an extremely thin-joint (approx 3 mm) alternative to the conventional mortar. More than 90 per cent of AAC blocks worldwide are joined using thin bed mortar. Magicrete´s Magicbond Dry Mix is a thin-joint polymer modified adhesive A factory-mixed mortar manufactured in a computerised batching process, it is constituted by cement, graded sand and blended with polymers.

Various properties of Magicrete Thin Bed Mortar-Magicbond are:

  • High bond strength: MagicBond is prepared with proprietary technology and the polymeric additives and binders ensure that the high bond strength (>3.4 mpa) is achieved leading to superior masonry strength and excellent load-bearing capacity

  • No shrinkage cracks: Water is retained in mortar, thus prevents shrinkage cracks.
  • High thermal insulation: Thin joints prevent heat transfer through walls.
  • Zero wastage: It is easy to apply and avoids wastage of material
  • No curing required: Due to water retention polymers, curing is not essential after application.
  • High coverage: Due to lower density & higher volume, a 40 kg bag of Magicbond covers 200-225 sq.ft. with a thickness 3 mm (for 4ö thick AAC blocks)
  • Economical: Quantity of Magicbond required for laying blocks is three times less than conventional mortar. This saves money as well as time.
  • Premixed: No job site blending of powder is required, only water is to be added.

Magicrete Building Solutions is India´s frontline manufacturer of AAC blocks, a technology that has turned over a new leaf in the construction industry. A pioneer in green building materials, with the vision of introducing prefabricated construction technologies to the Indian construction and infrastructure industry and over the years, they have been regarded as a frontline producer of these blocks with two manufacturing units in Gujarat and Haryana covering the strategic markets of west and north India respectively. Magicrete is a part of a conglomerate that has an aggregate turnover of over Rs 5 billion and is into sectors like chemicals, real estate and textiles.

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