Article on 'Indian Precast Concrete Building Industry' by Chaitanya Raj Goyal
Tuesday, 16 April 2013
Monday, 15 April 2013
Sunday, 14 April 2013
Improving Demolition and Waste handling practices in India: The Equipment prespective
-
Nikita P. Kumar, Architect, Mumbai
It is clear that while
demolishing a building, effective equipment need to be utilized; not only to
bring down the structure safely, but to also ensure proper and profitable
handling of debris. This brings us to the mammoth and sometimes even diminutive,
but highly efficient tools and equipment that have changed the way demolition
industry functions, from tearing down structures and handling scrap, to
recycling it for good!
When
coupled with hydraulic excavators, loader backhoes, compact excavators and skid
steers, the right attachments can increase a demolition contractor's
productivity on site and make the recycling of those materials that much
easier. Some attachments gradually gaining popularity in the Indian market include
hydraulic breakers, demolition processors, shears and demolition grapples.
Hydraulics are especially popular when working with concrete, because they enable
a contractor to process more in a given time frame, while reducing carrier wear.
However, it is imperative that all contractors and agencies (especially small
scale) are educated about these equipment and their usage, which can yield
major benefits for them and the environment.
The Inside Job: Mini Excavators and Steer Skids
7.
Demolition Robots: Demolition robots add a new dimension
to interior demolition. These robots have a more narrow application focus and
can cost significantly more than a mini-excavator, but there are advantages
that make them the most effective choice in certain applications. Unlike
mini-excavators, demolition robots are unmanned and allow the operator freedom
to move around the job site because they are operated by a remote control
feature with Bluetooth technology.
Their dexterity and
ability to handle large volumes of bulky, inconsistently sized material gives grapples
an advantage over standard buckets on the demolition site. There is normally
quite a bit of material sorting done of C&D, and the sorting requirement is
almost certainly increasing in importance. The mechanical grapple is much
better suited for the sorting task than a bucket.
3.
Materials Sorting Screens & Steel Separation Magnets: Typically,
mixed C&D debris is tipped at a central facility, and the materials with a
high market value, such as large pieces of sawn lumber, are removed. The
remaining mixed C&D materials are then processed using one of two primary
methods. The mechanized size reduction method uses a crusher, a dozer, or a
compactor.
As construction methods and materials have grown increasingly complex over the years, the process of creating accurate demolition plans to safely and successfully bring down structures has also become more complex. Without a way to accurately and efficiently analyze demolition plans, most of the learning curve has taken place during live building demolitions. Unfortunately, this learning can come at a ghastly cost to adjacent structures, infrastructure, and even human life. However, such lessons combined with technological breakthroughs in past decades, have gifted the global demolition industry with some amazing tools, equipment and methodologies, to enable them wreck effectively and efficiently.
Another massive
challenge during the demolition process is the handling, disposal and recycling
of debris that is generated. According to the report of JNNURM (Jawaharlal Nehru National Urban Renewal
Mission), it is estimated that the C&D industry in India generates
about 10-12 million tons of waste annually. While some of the items like
bricks, tiles, wood, metal are re-used and recycled to an extent, concrete and
masonry – which constitute about 50 per cent of the this waste are not
currently recycled in India. The presence of C&D waste and other inert
matters is significant (almost one third of total MSW on an average), but so
far, no notable development has taken place for utilizing this in an organized
manner. At present, private contractors remove this waste to privately owned
low-lying land for a price, or more commonly, dump it in an unauthorized manner
along roads or other public land.
Pulling
the Gear: Grasping the Current Situation
With
growing urban density, contractors in India are now distancing themselves from
dangerous demolition tools like the Wrecking Ball, and are increasingly
adopting long-reach excavators, with which one has better ability to control
the demolition process, which is especially critical in urban areas. As this
technique of controlled demolition, i.e., using high-reach hydraulic handlers
or skid-steer loaders, fitted with variety of attachments to carefully
deconstruct a building, gains popularity, so does the importance of having the
appropriate battery of attachments to perform a variety of tasks common to many
demolition sites.
Also,
in addition to demolishing structures, contractors face a variety of
recycling-related tasks, including the primary sizing and separation of
materials, but the prevailing lack of awareness among many medium and small
scale Indian contractors and agencies about the global technological
advancements in demolition and recycling methods, and equipment, continues to
hamper the growth of scrap recycling in India.
When
coupled with hydraulic excavators, loader backhoes, compact excavators and skid
steers, the right attachments can increase a demolition contractor's
productivity on site and make the recycling of those materials that much
easier. Some attachments gradually gaining popularity in the Indian market include
hydraulic breakers, demolition processors, shears and demolition grapples.
Hydraulics are especially popular when working with concrete, because they enable
a contractor to process more in a given time frame, while reducing carrier wear.
However, it is imperative that all contractors and agencies (especially small
scale) are educated about these equipment and their usage, which can yield
major benefits for them and the environment.The Inside Job: Mini Excavators and Steer Skids
In controlled
demolition the contractor will normally remove any material with salvage value,
such as wires, conduits, pipes and electrical equipment, using small shears and
grapples on skid-steer loaders or mini/ standard-size excavators. A
mini-excavator is really the best carrier for a hydraulic attachment. It is
better suited than a skid steer because it allows positioning the tool in many
different angles and can complete jobs on walls and structures, but due to the
compact size, low weight and speed, and great selection of work tools available
for the skid-steer loader, they are also widely used in selective demolition
jobs, like refurbishment of residential and office buildings. A skid steer
equipped with a bucket is also ideal for picking up material and loading it
out.
Apart from the above, there
is a whole new range of remote controlled robots for interior demolition. These
automatic, unmanned machines are posing a tough challenge to the modified steer
skids and mini excavators in the first world nations, but are still struggling to
find their way in ‘cheap-labor’ nations like India due to the associated capital
requirement.
Wrecking
for Progress: Demolition Machines and Work Tools
There are few jobs more demanding, on human or machine, than demolition and scrap recycling. Demolition today has become a dynamic and increasingly complex business. Contract periods are becoming shorter, legislation is stricter, environmental pressure is increasing and skilled labor is harder to find. As a consequence, demolition contractors are looking for the most efficient, cost effective and safe equipment for deconstructing buildings and structures.
1.
Hydraulic concrete splitters: This equipment is
mainly applied to partial or integral demolition of concrete facilities (walls,
cement road, machinery base, bridge building parts etc). About the size of a
jackhammer, the tool utilizes a shaft known as a plug-and-feather assembly
which, when inserted into a drilled hole and forced downward by the tool’s
piston, creates the lateral forces that break the concrete. No heavy impact is
utilized to form the crack, which spreads quickly and without any noise between
the pre-drilled holes until the concrete is split into manageable pieces.
Hydraulic splitting
eliminates both shocks and vibrations associated with large impact tools. It can
split the rock or concrete in seconds, and the direction of breaks can be
controlled as required. It is suited for a place where there are strict
limitations on noise, dust, flying debris, vibrations and exhaust gas. It is thus
widely use in conditions where the demolition has to be non-explosive and blasts
are forbidden.
2.
Hydraulic Concrete Crushers: These are excavator
mounted mechanical tools for demolition works. The action of HCC is by the
opening and closing of its jaws to crush concrete, powered by the hydraulic fluid
supplied by the excavator. The main noise source from HCC is from the excavator
itself.
Interchangeable jaws in
some crushers, including cracking jaws, shear jaws and pulverizing jaws are
often used to work along with various types and configurations of jaw teeth in
order to better fit the crusher to a particular job.
Secondary concrete
crushers usually have some type of pulverizing jaws and are used on jobs where
primary demolition is accomplished by hammers, crushers, blasting, ball and
crane, or sawing. In this instance, the primary demolition work creates large
quantities of concrete rubble which the secondary crusher further reduces,
separating concrete from reinforcement.
3.
Diamond Wire Saw: A loop of diamond wire mounted on a
flywheel is driven by a hydraulic or electric motor. Using diamond beads strung
on special aircraft cable separated by springs or plastic, the wire can be
wrapped around any length, depth, or configuration of reinforced concrete.
These lightweight,
portable saws have changed the character of building modification. Cutting
openings in concrete walls with diamond tools causes no structural damage and
requires little patching. Diamond wire saws are more efficient than circular
saws, able to cut concrete of almost any thickness.
This makes them very
useful for the kind of heavy demolition found in bridges, damns and thick
concrete structures. In addition, they create little dust, noise and vibration,
making them ideal for demolition work within inhabited structures. If time is
money, this tool is superior to all.
4.
Mounted Hydraulic breakers: The
demolition industry forever changed in 1968 when the first hydraulic breaker
was mounted on a backhoe. These demolition hammers vary greatly in size to
accommodate almost any carrier application available, from the smallest
skid-steer loader to the largest class of excavators.
But the tool that is
right for you is dependent on the size of your job and your budget. Attaching a
hammer to a lightweight carrier not only decreases the boom’s reach, it also
can potentially be the cause of an overturning accident. Breakers that weigh 60
pounds or more can handle heavy reinforced concrete jobs such as demolishing
roads, pavements and thick concrete.
Due to their unmatched
versatility when compared to other demolition equipment, their speed of
processing without the footprint and safety zone requirements of explosion and
wrecking ball demolition, these breakers turn out to be an excellent option.
5.
Expansive Demolition Agents: The expansive
demolition agent is a cementitious powder. Using a drill with a mixing
attachment, the powder is mixed in a bucket and poured or tamped into drilled
holes. As the mix hardens and expands, the concrete cracks between the drilled
holes. As the hairline cracks develop over the slab, they run outward into each
other and grow wider, until the slab literally falls apart under an expansive
force that can exceed 83,000 kpa.
Used correctly,
expansive demolition agents produce little dust or debris. The only labor
involved is in drilling the holes, mixing and applying the agent, and then
hauling the broken up pieces of concrete away.
6.
Pneumatic Hammer: They only account for a small portion
of total hammers in use today. There are still a number of advantages in using
pneumatic hammers, however. They can be mounted on lighter carriers, since
their external air compressor negates the extra hydraulic demands of a
hydraulic hammer. Moreover, pneumatic hammers work better in confined spaces
than hydraulic hammers due to their high weight-to-power ratio and are more
conducive to underwater use.
7.
Demolition Robots: Demolition robots add a new dimension
to interior demolition. These robots have a more narrow application focus and
can cost significantly more than a mini-excavator, but there are advantages
that make them the most effective choice in certain applications. Unlike
mini-excavators, demolition robots are unmanned and allow the operator freedom
to move around the job site because they are operated by a remote control
feature with Bluetooth technology.
These robots are able
to climb stairs, and the outriggers, on various models, allow them to fit in
tight spaces while still ensuring stability. The ability to mount a camera on
the unit opens up even more possibilities.
Rethinking
Debris: Scrap Handling & Recycling
Apart from those valuable metals such as steel rebars and aluminum window frames, which have high scrape value, rubble and demolished concrete can be processed into recycled rock fill or aggregates for use in construction.
As landfill costs for construction, demolition, and land-clearing debris continue to rise and the landfills become more heavily regulated, it makes economic sense to seek alternative means of disposal of concrete from construction and demolition operations. Many equipment like track loaders, wheel loaders & steer skids can be used to collect & deposit scrap at the recycle plant, which can be on or off the site depending on its portability.
As landfill costs for construction, demolition, and land-clearing debris continue to rise and the landfills become more heavily regulated, it makes economic sense to seek alternative means of disposal of concrete from construction and demolition operations. Many equipment like track loaders, wheel loaders & steer skids can be used to collect & deposit scrap at the recycle plant, which can be on or off the site depending on its portability.
1. Grapples and Bucket attachments: The
versatility of grapples on a demolition site is often understated. Many
grapples are built to do a lot of actual demolition in terms of ripping and
tearing a structure apart. It can act almost as a shear to an extent if the
steel is in the realm of the excavator's break-out force. The grapple then can
be used to pick and sort through the resulting rubble.
Their dexterity and
ability to handle large volumes of bulky, inconsistently sized material gives grapples
an advantage over standard buckets on the demolition site. There is normally
quite a bit of material sorting done of C&D, and the sorting requirement is
almost certainly increasing in importance. The mechanical grapple is much
better suited for the sorting task than a bucket.
2.
Portable Concrete crushers: This impressive piece of
demolition equipment crushes concrete into reusable coarse/ fine aggregate,
which can then be recycled onsite. With the help of such concrete crusher, you
can recycle thousands of tons of concrete every year.
After tearing down a building, the concrete slab is pulled up and cut into 2-foot squares to run through the crusher. The machine then grinds it into gravel-sized chunks, which can be used for road compaction, structural fill, pipe bedding and other applications.
3.
Materials Sorting Screens & Steel Separation Magnets: Typically,
mixed C&D debris is tipped at a central facility, and the materials with a
high market value, such as large pieces of sawn lumber, are removed. The
remaining mixed C&D materials are then processed using one of two primary
methods. The mechanized size reduction method uses a crusher, a dozer, or a
compactor.
The materials are then
passed through a series of screens, magnets, and other separation equipment.
The manual labor method relies on human sorters to pick out materials and place
them in specific containers. Screens and magnets may also be employed with the
human labor method, but the materials are left in their original form rather
than crushed so that they can be easily distinguished and sorted. The most
common approach is a blend of the mechanized size reduction and the human
sorter methods.
Conclusion
A primary success for a debris recycling operation hinges on the degree of contamination of the valued materials by other types of waste such as nails, paint, foil, oil or plastic. Some processing facilities that aggressively handle a mixed waste stream may cause contamination of the C&D materials, thereby limiting their potential to be recycled. Educating contractors and owner-agencies about latest demolition/ scrap recycling methods, tools and equipment through a cost benefit approach will help improve the existing scenario in the industry.
So far in India there has been very little effort to manage and utilize construction and demolition waste. Each city needs to have its own mechanism for collection and disposal of waste from bulk waste producers and major/ minor construction & demolition sites. It is necessary to evolve a system in which the generator of such waste, whether small or large, pays for appropriate disposal. Not much effort has been made in this sector and data on generation and characteristics is scarcely available.
The awareness level and availability of technology for Demolition waste re-use and recycling needs to be improved to make a sustainable change in India. Quality standards for the recycled or re-used products need to be developed and monitored by Bureau of Indian Standards. Separation of C&D waste at source through Public-Private-Partnership schemes should be promoted to be a possible mechanism of implementation of waste management in India.
References:
1. Diven, R., & Taylor, M.R. (2006). Demolition Planning. Supplemental Architectural Services, The American Institute of Architects
2. Hemalatha, B.R, Prasad, N., & Subramanya, B.V. (2008). Construction and demolition waste recycling for sustainable growth and development. Journal of Environmental Research and Development, Vol. 2 No. 4
3. Atlas Copco Construction Tools. (2010). Selective and powerful demolition: Sink your teeth into this. Stockholm, Sweden
4. DeAnne Toto. (2004). Demolition Tools. Construction & Demolition Recycling
5. Bhavani Balakrishna. (2013). Concrete Recycling: Need of the Hour. The Masterbuilder Construction Magazine
6. Ghosh, S., & Ghosh, S. (2011). Rebuilding C&D waste recycling efforts in India. Waste management World Press
7. Volvo Construction Equipment. (2009). Volvo Excavators: Demolition. Sweden
So far in India there has been very little effort to manage and utilize construction and demolition waste. Each city needs to have its own mechanism for collection and disposal of waste from bulk waste producers and major/ minor construction & demolition sites. It is necessary to evolve a system in which the generator of such waste, whether small or large, pays for appropriate disposal. Not much effort has been made in this sector and data on generation and characteristics is scarcely available.
The awareness level and availability of technology for Demolition waste re-use and recycling needs to be improved to make a sustainable change in India. Quality standards for the recycled or re-used products need to be developed and monitored by Bureau of Indian Standards. Separation of C&D waste at source through Public-Private-Partnership schemes should be promoted to be a possible mechanism of implementation of waste management in India.
References:
1. Diven, R., & Taylor, M.R. (2006). Demolition Planning. Supplemental Architectural Services, The American Institute of Architects
2. Hemalatha, B.R, Prasad, N., & Subramanya, B.V. (2008). Construction and demolition waste recycling for sustainable growth and development. Journal of Environmental Research and Development, Vol. 2 No. 4
3. Atlas Copco Construction Tools. (2010). Selective and powerful demolition: Sink your teeth into this. Stockholm, Sweden
4. DeAnne Toto. (2004). Demolition Tools. Construction & Demolition Recycling
5. Bhavani Balakrishna. (2013). Concrete Recycling: Need of the Hour. The Masterbuilder Construction Magazine
6. Ghosh, S., & Ghosh, S. (2011). Rebuilding C&D waste recycling efforts in India. Waste management World Press
7. Volvo Construction Equipment. (2009). Volvo Excavators: Demolition. Sweden
Saturday, 13 April 2013
For Wind lovers: Recent updates on Wind Energy Research :D
1) Tunisian green energy start up Saphon Energy has created a new blade-less wind turbine which draws inspiration from the design of a ship’s sails, and promises to convert the kinetic energy of the wind into electricity at up to double the efficiency – and half the cost – of a typical wind turbine.
http://www.gizmag.com/saphonian-bladeless-wind-turbine/24890/
http://www.gizmag.com/saphonian-bladeless-wind-turbine/24890/
2) Hail the blade-less wind turbine which produces energy using Charged Water Droplets: A TU Delft innovation.
Source: Gizmag
Friday, 12 April 2013
Thursday, 11 April 2013
Wednesday, 10 April 2013
Civil Engineers: Switch to ASCE Facebook Timeline Covers
Show your love for the civil engineering profession through your Facebook Timeline! ASCE has developed new Facebook covers showcasing civil engineering achievements and landmarks across the country.
Here are the links:
Group 1
Group 2
Enjoy!!! :D
Tuesday, 9 April 2013
"Home Sweet Home": Castles in the Sky
Like millions of middle-class Indians, I woke up at 6 am today and dragged myself through the living room of my rented studio apartment to reach out for the newspaper. Suddenly my eyes light up as I read the front page advertisement, “Budget Luxury Apartments all Set to Inspire Your Senses” as my eyes crawl down to the bottom of the page desperately searching for some ‘really affordable' pre-launch offer; reality hits me yet again as the bottom of the page reads, “price starting from as low as Rs. 70 Lakhs”!. I decide to move on to the sports page with a disheartened sigh and by-then an empty cup of tea.
I am just another of those random Indian ‘Aam Aadmi’’ whose morning newspaper comes wrapped in a familiar dream, sold in countless real estate ads spread across billboards, magazines and newspapers. The Indian realty sector has seen property prices skyrocket in recent years, so much that majority of the builders are managing to stay afloat by purely selling in the international market these days. NRI investments have now become the major source of income for the industry which is struggling to find buyers in the domestic market. The ‘still denied’ Indian property bubble is purported to be in existence since March 2005, when the current UPA government decided to liberalize foreign direct investment norms in real estate in Feb, 2005, introduced the SEZ Act in 2005, and allowed private equity funds into real estate.
Today, if one looks at the real estate market in terms of pricing alone, it would seem that demand is growing. But on the ground, the demand in six major real estate markets - Delhi, Mumbai, Kolkata, Chennai, Pune and Bengaluru has declined by around 40% in the past one year. New project launches have seen a drop of nearly 50 %. We have a situation where on one hand there are 11% vacant houses while on the other we have a shortage of 18.5 million houses. Vacant houses are a bubble that can burst at any time. Economists expect this time to come by November 2014.
As for the country, the problem of course is that wealth 'created' on the back of housing bubbles is largely illusionary. Buying property because its value will go up so you can then sell it for profit, or perhaps borrow against the value of the first house to buy another, sounds nice when you're reading a “Get rich-quick in real estate" book, but it is not something you want your personal finances to be built on – especially if your banking system acts as though such a situation is risk-free. Dubai is an example too famous!
The Finance Minister, in an effort to strike balance, is looking to tweak the lending policy of banks to housing projects. To mark the launch of the operations of the scheme, three major lending agencies in the retail housing market - State Bank of India, Central Bank of India and HDFC entered into agreement with the National Housing Bank (NHB). Another fact is that real-estate market does not always work according to demand and supply, because many builders — who have taken loans to purchase land — continue to sell it at a high price. So, there is no threat to investors. Nonetheless the previous pace of progress no longer seems possible unless one believes in miracles!
Low cost housing projects are expected to bring out the true potential of the market in future and might as well turn out to be the very miracle we need!
Excellent Tips for Basic Earthquake Engineering by IIT Kanpur
IITK-BMTPC Earthquake Tips:: Learning Seismic Design and Construction
The Republic Day earthquake of 26 January 2001 in Gujarat clearly demonstrated the earthquake
vulnerability profile of our country. It created a considerable interest amongst the professionals associated with construction activities in any form, as well as the non-professionals regarding the earthquake safety issues. While the subject of earthquake engineering has its own sophistication and a lot of new research is being conducted in this very important subject, it is also important to widely disseminate the basic concepts of earthquake resistant constructions through simple language. With this objective, the Indian Institute of Technology Kanpur (IITK) and the Building Materials and Technology Promotion Council (BMTPC), a constituent of the Ministry of Urban Development & Poverty Alleviation, Government of India, launched the IITK-BMTPC Series on Earthquake Tips in early 2002. Professor C. V. R. Murty was requested to take up the daunting task of expressing difficult concepts in very simple language, which he has very ably done.
In all 24 Tips has been released and is targeted at persons interested in building construction. The Tips cover topics such as basic introduction to earthquakes and terminology such as magnitude and intensity, concepts of earthquake resistant design, and aspects of a seismic design and construction of buildings. Utmost care is taken to ensure that despite complexity of the concepts, the Tips are simple and unambiguous. To ensure the highest quality of technical contents, every Tip is carefully reviewed by two or more experts, both within and outside India and their feedback is used before finalizing the Tips.
The Tips are released for publication to all interested journals, magazines, and newspapers. The Tips are also placed at the web site of Building Materials & Technology Promotion Council (BMTPC) (www.bmtpc.org). The project has succeeded way beyond our own expectations: a large number of journals of architecture, construction and structural engineering, and many prestigious newspapers have published some or all the Tips.
Development of the Tips was financially supported by the BMTPC New Delhi. Financial support for this reprint and dissemination was provided by the National Programme on Earthquake Engineering Education (www.nicee.org/npeee) and the Joan and Haresh Shah family funds, respectively, which is gratefully acknowledged.
We hope that the readers will find the Tips useful when constructing buildings in earthquake prone areas and will consult the expert for finalising their design and construction details. Earthquake Tips are now available in Hindi and Marathi also.We welcome comments and suggestions; please email to nicee@iitk.ac.in.
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