Construction technique: Rapidwall technology
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Rapidwall is a single panel walling system that serves as both the internal and external wall and eliminates the need for bricks, blocks, timber and steel wall frames and plasterboard linings. It is the most ecologically sound and technologically advanced building product available in the world today.
Designed and developed in Australia in the early 1990s, Rapidwall was awarded the prestigious "2009 Global Gypsum Product of the Year" award and was recognised as a "Good Practice" by the United Nations Habitat business awards for sustainable urbanization.
In a process that will change forever the way buildings are constructed, Rapidwall takes natural gypsum or by-product, chemical waste gypsum and turns it into a 12m x 3m glass-fibre gypsum plaster, single panel, load bearing walling system.
100% Recyclable and water, rot and termite resistant Rapidwall is the ideal building product for fire, cyclone and earthquake prone regions as well as for providing housing solutions for impoverished people.
Rapidwall is the lowest energy embodied building product in the world today and is eligible for Carbon Credits.
In India Rapidwall has been rigorously tested by the University IIT Madras and certified by Structural Engineering Research Centre (SERC) for use in the construction of buildings in earthquake prone areas of up to 10 storey’s.
In Australia testing has been undertaken by Adelaide University and University of South Australia.
In China testing has been undertaken by the University of Hong Kong and the University of Tianjin, School of Civil Engineering in Shandong and others.
At the School of Civil Engineering in Shandong, scientific destruction testing was undertaken on a full scale, five storey Rapidwall building where a horizontal force of 100 tonnes, simulating a force of 8 on the Richter scale, was applied. Rapidwall withstood this testing without any visible signs of cracking.
The panels, which are extremely strong yet lightweight, compared to other building methods, are ideal for a wide range of building applications from high-rise, residential, commercial and industrial building construction to low cost relocation housing. Windows and door openings and the panels themselves are pre-cut in the factory and delivered on-site, ready to erect. This reduces cost and significantly cuts down building time.
In the development of new low energy, low cost, environmentally and ecologically sound housing solutions for the 21st century, Rapidwall is the ideal product for re-housing and for new housing or industrial construction. A world class building system that is 100% recyclable, earthquake tested, is cyclone, fire, water and rot resistant, is load bearing, termite resistant and sound proof.
Simply stated it is the best building material in the world..
Manufacturing ProcessThe casting-table, in each computer-controlled plant, comprises a flat steel epoxy-coated surface with sides that are raised to contain the plaster when in the fluid state.
Prior to the commencement of the manufacturing process the casting table is first lightly greased. Commencing from the start position the crab assembly moves over the casting-table accurately dispensing the special plaster mix comprising water, Rapidflow gypsum-plaster, water repellents and additives, over the entire table to a depth of 15 millimetres.
This plaster layer is lightly screeded after which the travelling crab assembly automatically chops and dispenses a predetermined quantity of glass-fibre rovings over the entire liquid-plaster surface. This layer of glass-fibre is then rolled into the plaster to position it centrally within the 15 millimetre thick skin to provide reinforcement to the plaster.
In every 250 millimetre length of Rapidwall a 230 millimetre by 94 millimetre cell is formed using teflon coated removable plugs that are laid at right angles to the 12-metre panel. The core-table mechanism positions all 48 plugs over the plaster and glass-fibre layer on the casting table. The final quantity of plaster is dispensed onto the casting table filling between the plugs and forming the top skin of the panel.
The travelling crab then dispenses a further layer of chopped glass-fibre over these cores and the tamping process is undertaken.
A final quantity of chopped glass-fibre is again automatically and uniformly dispensed over the entire panel surface by the travelling crab. The crab assembly then automatically returns to its cleaning and filling station to be prepared for the production of the next Rapidwall panel.
Using a mesh roller the surface of the Rapidwall panel is then rolled to position this final layer of glass-fibre centrally within the plaster top skin. Final screeding and smoothing of the cast is completed manually by two operators. To this point the process has taken only 20 minutes. After this, the panel is left to cure until the temperature and the consistency of the plaster allows final screeding.
Once the plaster has completed its initial set, a further 20 minutes, the core-table mechanism advances and locks onto the core formers and slowly withdraws them from the set panel.
To remove the panel from the casting-table three perimeter edges of the casting table are opened and two panel-supports are extended. The table is then automatically tilted to approximately 88 degrees off vertical. The entire two-tonnes weight of the wet panel is taken by the bottom supports.
To this point, the entire process has taken 45 minutes.
Finally a multi-directional truck, fitted with a transfer frame, removes the Rapidwall panel from the tilted casting-table and places it either in air drying racks or in the Rapidcure drying oven for final curing prior to it being stored and ultimately cut to dimensions for installation on a specific building project.
The elapsed time of the complete manufacturing process, including full curing in the Rapidcure dryer, is less than two hours for each panel.
Building with Rapidwall in India
In India the projected population by 2026 will be 1,400 million.
By 2015, just six years away, it is estimated that the housing shortage will top 90 million.
In order to overcome this huge housing shortage is an urgent need for alternative building materials.
Building materials that:
Sustainable development also means we need to have an eye on environmental considerations.
Conventional walling materials such as fired clay bricks, solid and hollow concrete blocks, tilt-up concrete panels; timber frame, external steel cladding and steel frames have a detrimental effect on the environment. They are high energy users; deplete valuable agricultural land, cause environmental pollution, deplete forests and water and cause high CO2 emissions.
Even though these conventional materials will be around for a very long time there are now serious questions being asked by every government about the impact these products have on the environment and on climate change.
And it’s not a question of whether we personally believe in climate change or not; most people do agree that reducing carbon emissions will have a beneficial effect on the environment.
In India, clay brick production accounts for 27% of total national energy consumption.
For every million bricks produced 0.8 of a hectare of agricultural land is destroyed; 5.6 megawatts of energy is used and 310 tonnes of CO2 is emitted. Scarce water resources and sands and minerals are depleted and the atmosphere is polluted.
Within just a few years cement production in India has increased from 100 million tonnes per year to the current level of 160 million tonnes and steel production from 30 million to 60 million tonnes.
Presently 200 billion bricks are produced annually and demand is growing exponentially.
What are the alternatives?
Annual investment in housing in India will run at between US$28 and US$38 billion and the cost of building methods is increasing exponentially each year.
With traditional building materials degrading the landscape and adding significantly to CO2 emissions, building from environmentally friendly Rapidwall has become even more attractive.
India produces significant amounts of fertilizer for worldwide use but in doing so creates phospho-gypsum as a by-product in the order of millions of tonnes annually. Presently there is 31 million tonnes of excess phospho gypsum stockpiled and this is added to annually by 2.5 million tonnes.
By utilising Rapid Building Systems Rapidflow calcination plant the phospho gypsum can be turned into plaster and subsequently into Rapidwall, thereby cleaning up the environment.
Rashtriya Chemicals Fertilizer (RCF) in Mumbai and India’s oldest fertilizer company, Fertilisers and Chemicals Travancore (FACT) in Cochin, are both in the process of building new plants to turn their waste phospho gypsum into Rapidwall homes and this shows great foresight and planning.
This stockpiled Gyspum is enough to build 5 million 30m2 Rapidwall homes.
By comparison to traditional building materials, Rapidwall is a low energy user, has little CO2 emission, helps to clean up the environment, is 100% recyclable and is cheaper to produce.
( Courtesy: http://www.rapidwall.com.au/ )