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Sat 25 Jul 2009 04:00 AM

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Cheaper, greener, faster, stronger

Can you build a villa superstructure in 24 hours? Apparently it's not that difficult. This week CW looks at some of the innovative wall construction systems being touted as cheaper, greener, stronger and faster than conventional techniques.

Cheaper, greener, faster, stronger
Cheaper, greener, faster, stronger
Green Precast CEO Salvatore Saker.
Cheaper, greener, faster, stronger
Head of marketing and sales for Jehan Green Walls Cedric Pinto.
Cheaper, greener, faster, stronger
Managing director Walid Taha.

Can you build a villa superstructure in 24 hours? Apparently it's not that difficult. This week CW looks at some of the innovative wall construction systems being touted as cheaper, greener, stronger and faster than conventional techniques.A positive spin-off of any recession is that innovation is often brought to the fore, and this is already starting to show in the Gulf's construction industry.

Consultants are now searching for cheaper and more efficient methods of construction, which might otherwise have been overlooked in the boom times.

As such, some of the most innovative companies in wall construction say fresh contracts and inquires are growing at unprecedented rates despite the downturn.

Green Precast

After starting operations in the UAE six months ago, Australian company Green Precast has already secured a number of sizeable projects including a US $109 million (AED 400 million) contract to build villas in Abu Dhabi.

CEO Salvatore Saker says the firm has also received more than 50 invitations to work in Saudi Arabia, Qatar and Kuwait, a staggering figure considering the lack of new contracts being signed at the moment.

The secret to the company's success is its precast concrete building system, which uses computerized hydraulic moulds to produce 3D monolithic structures at the site of the project.

The system operates like an onsite production line and as such is ideally suited to large scale villa projects that require a fair amount of repetition.

Saker explains the production process: "First is the fabrication of the steel element. Steel cages are produced every six hours and then go inside a mould. You then fit all the MEP, which also goes inside the mould. Then you pour the concrete.

After nine-twelve hours you can lift the module out of the mould. Installation takes between 2-2½ hours to put together a 500m² villa by dropping the modules into place.

"So basically in 24 hours you have a cycle that produces anything from one to ten villas depending on the number of moulds committed to the project."

Apart from speed, Saker also promises that the Green Precast method will be greener, stronger and cheaper than regular block-work construction.

First of all, there is much less transportation of materials required and almost zero wastage on-site, which not only reduces costs but also the carbon footprint, he says.

Secondly, Green Precast has developed its own thin wall technology which uses around 1/3 less steel and concrete while maintaining strength and insulation.

"Basically our internal 9cm thin wall is equal to a regular 30cm thick wall," says Saker.

"Our external walls are 20cm to achieve the thermal rating that the GCC requires. We have two insulations, sandwich panel insulation and an external UV paint coating which can give us a U-value between 0.28 - 0.38 W/m²°K.

"This is significantly better than a standard wall and helps to keep the running cost of the building cheaper by 50%."

In terms of strength, Saker says all walls are load bearing, fire-proof and earthquake- proof. The system also incorporates controlled joints, 2cm of mastic filler, between each module which acts as a shock absorber preventing up to 90% of on-going maintenance for cracks in the walls, he says.

Overall, Saker says the Green Precast system will save developers between 5%-50% on construction costs. The cost saving is mainly dependent on how quickly the developer wants to build, he says.

Jehan Green Walls

Another firm promising significant savings and quick, green construction is Jehan Green Walls.

The company began operations at its Sharjah-based factory in the UAE only two months ago but has already picked up six contracts and is getting "inquires left, right and centre", according to head of marketing Cedric Pinto.

The factory produces 3D panels, which are composed of a fire-retardant polystyrene core and 3mm of galvanized steel mesh covering either side which is connected through the core by diagonal truss wires.

Pinto says the panels are used to create a reinforced insulated wall and form the basis of three different walls solutions. The first is Jehan's own "shotcrete" construction system where the 3D panels are erected as walls and slabs in the shape of the desired building before being sprayed with concrete.

Case studies at a glanceGreen PrecastProject brief:To build 4500 family homes near Riyad in Saudi Arabia using their onsite precast system to produce and install both modular and flat panel elements. The client also requires that all external surfaces are sand blast finished for longevity. A total of 60 moulds will be operational onsite to produce 3D monolithic modules.

Project size:4500 family villas

Timeframe:Three years a rate of six villas per day for 280 days a year Construction cost:confidential

Workforce:980 people (720 for fabrication) Thermal rating of walls/U-value:external 200mm wall achieves a U-value of 0.495 W/m²°K which can be lowered to 0.38 W/m²°K with 20mm added insulation

Other advantages:

• Speed of construction up to 70% quicker than traditional methods

• Construction costs are around 50% less than traditional concrete frame and block work construction

• Material wastage is minimized down to 1-3%

• Longevity of the villas is significantly increased due to strength of the precast 3D module

• Integrating a UV-IR reflective paint solution will ensure saving of up to 50% on ongoing cooling costs Jehan Green Walls

Project brief:The firm is bidding as turnkey contractors for a project in Fujairah UAE. The project consists of 35 ground floor villas, three G+3 labour accommodations and two G+3 apartment blocks.

Type of wall:Reinforced concrete using Jehan's 3D panels and shotcreteing method.

Project size:33,535m2

Timeframe:10 months, inclusive of foundations, superstructure, finishes and MEP

Construction cost:Bid price - US $15 million (AED 55 million) Workforce:300 people

Thermal rating of walls/U-value:0.45W/m2°K or 0.0794Btu/hr-ft2.F

Other advantages:

• Architects delight, can form any shape

• Light weight of the walls, hence reduced size of foundations

• Monolithic structure, hence has enhanced resistance to seismic forces

• Self supporting structure and has no need for RCC framework.

• No need for lifting equipment

"Once the shotcreting is done then you have a complete self-standing monolithic structure," he says.

"The benefits of this system are many. It is lightweight, only 2.5kg per 1m², so you don't need cranes and it can be easily erected. It's also a very fast method of construction. We have done the superstructure for a 1250m² villa in just 30 working days.

"The third thing is that you only require about 30% of the manpower compared to traditional construction and the skill sets required are also much lower."

Pinto says the shotcrete method can be used up to G+5 with additional reinforcement and is ideal for low-rise buildings and large-scale villa projects.

He adds that analysis by a cost consultant showed that the method is 20% cheaper than block-work construction, including the substructure and superstructure.

In terms of green credentials, Pinto says the shotcrete method has minimal wastage, uses less materials and, most importantly, the 3D panels provide significant insulation.

"For a 20cm wall you've got a U-value of 0.45 W/m²°K which is significant when you consider that a standard wall is around 0.7," he says.

"It means you use much less energy for air-conditioning and if you want a higher U-value we can increase the thickness to 25cm."

The same thermal benefits are also achieved by Jehan's other products, precast concrete and precast gypsum walls, which also use the 3D panel as the core.

"Our precast comes at the same cost as regular precast but the difference is that it's already insulated, that's a substantial saving," says Pinto.

"The gypsum precast panels are also significantly lighter (only 60kg per m²) than block-work which can lead to a 60%-70% load off the foundations for tall buildings."

Emirates Industrial Panel

An alternative to precast concrete panels is metal faced paneling, and one company says they are leading the way in terms of product quality and technological knowhow.

Emirates Industrial Panel offers metal faced panels, which can be clad in stainless steel, aluminum or galvanized steel and either have a polyurethane or polyisocyrunate core.

The company's $27 million factory in Dubai Investment Park began operation midway through last year and has the capacity to produce four million m² of panels per year.

Managing director Walid Taha says the advantages of using such panels are well known; it enables quick construction, there is minimal wastage, they are lightweight, they have good thermal properties and they use less concrete which results in a smaller carbon footprint.

Taha adds that their state of the art production facility, which was brought over from Germany, is the only fully- automated production line in the Middle East region.

"It's a continuous production facility and only five people operate the line to produce 8000m² per eight hour shift," he says.

"In a typical discontinuous line it would require somewhere in the region of 250 people to run the line. So it's very high technology which produces a high quality product and there's limited room for human error."

Taha also says that the other upshot of having such a facility is that EIP can import the highest quality materials from Europe which gives their products durability, fire resistance and thermal qualities like no other on the Middle East market.

"We are able to offer metal facings such as hot-dipped galvanised steel with a guarantee of 40 years on the panel," he says.

"That's incredible durability brought about by the special material we import from UK and Germany. The panels also have a good thermal rating; for a 50mm wall the U-value is around 0.46 W/m²°K and for a 200mm panel is 0.12W/m²°K.

"On top of this we are the only company to offer polyisocyrunate, which is a highly fire retardant foam. Basically we have brought the high quality European panel to the Middle East."

Case studies at a glanceEmirates Industrial Panel

Project Name:Geant 3600 Hypermarket in Kuwait. Project brief:EIP's scope was to produce, supply and install panels for 36 insulated rooms along with the doors for the chiller rooms, preparation rooms and freezer rooms. The chiller and preparation rooms are constructed with 80mm thick polyurethane panels and the freezer rooms with 120mm thick polyurethane panels, floor heating cables and 150mm thick floor insulation.

Project size:3600m2 of panels used and 36 doors Timeframe:The project was completed in three months from the approval of the drawings. The time included the transportation of materials to the site in Kuwait and door installation

Construction cost:US $238,205 (AED 875,000) Workforce:A team of eight technicians and one supervisor worked under the project manager to complete the installation in 40 days

Other advantages:

• Prefabricated panels enables quick construction with reduced wastages

• Light weight but structurally strong panels reduce total weight of the construction

• Superior insulation values mean reduced energy costs

• Clean, hygienic and aesthetic appearance

• Using less concrete means less carbon emission and also thermal insulation capabilities reduce consumption of fossil fuels which again means less carbon emission.

Tiger Profiles and Insulation (TPI)

Project Name:Dubai World Trade Center Extension Project

Project brief:The extension includes a multipurpose hall with three larger exhibition halls. TPI will provide roof and wall cladding onto a steel framework. The major challenge on this project is the close coordination of various sub contractors all working hard in a very confined space to complete this very fast track project.

Project size:The roof area is 31,000m2 and wall area is 12,000m2

Type of walls:Concealed fastener wall panels with a metal face Timeframe:Six months. Construction started in March of this year and is expected to be completed sometime in September.

Construction cost:Confidential

Workforce:170 workers during the peak construction period (TPI work only)

Thermal rating of walls/U-value:The U value required for the roof and wall construction is 0.31 W/m2°K

Other advantages:

• Faster construction due to pre fabricated wall elements.

• High quality

• Concealed fastener panels provide a clean, flat, continuous appearance from foundation to eave

• Easy replacement of damaged panels

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