By Benjamin Roberts
The use of precast concrete has increased – but only after overcoming a few hurdles
Precast concrete is becoming more frequently used in a greater
variety of projects throughout the Gulf region, but ideological differences are
preventing a much wider take-up of the approach, say manufacturers.
The building market today is a curious mix between what advocates
say is a cheaper, more accurate and cost-efficient method of creating concrete structures
for housing and other buildings, and the older system of casting concrete on-site
– or ‘in situ’, as it is termed.
Much of precast concrete is explained by the name: the creation
of hollow-core slabs, beams and walls in reusable molds (or ‘forms’) in a factory
that are then transported to the site and placed into the correct position. The
controlled environment allows specialists to oversee the vital curing process of
the concrete, which otherwise must be completed on-site while construction activity
continues all around the slabs.
Precast is perceived as quicker because all elements needed between
each wall are able to be assembled in the factory to create a complete wall. This
includes the steel frame, cables and insulation, which will be procured by the manufacturer.
“With a pre-cast wall, the whole thing can be created in a factory under a controlled
environment and then sent to site,” says Abdullah Abdullah, sales manager at RAK
Precast. “Otherwise, all the steel, cables insulation and MEP are put together on-site.”
Abdel Dajani, managing director at Xtramix Concrete Solutions, adds that precast
can also produce fine finishes on the concrete by the time it leaves the factory.
Precast concrete is seen to be cheaper, despite the cost of transportation,
because fewer labourers are needed to perform the pouring and curing processes.
But this is part of the reason why the uptake of this solution has been stilted
in areas of intense building work.
“The reason that precast had not been used compared with casting
in situ is because it would mean that for many contractors that their labourers
would be idle on-site,” says B.S. Pillai, executive sales manager at United Precast
Concrete. However, he adds, the speed at which the concrete can be produced – and
therefore the speed in which buildings can be finished – is a convincing consideration
“Contractors want things to be finished yesterday. Three years
ago people were rushing, and would rather someting take eight months to complete
than two years. That is the benefit of precast.”
United Precast Concrete’s recent new business is perhaps one
of the best examples of how the benefits of precast concrete are getting through
to the market. The company recently signed an AED43million deal with Carillion to
provide all the external cladding for towers 54, 55 and 56 in Business Bay
in Dubai, an area
that stalled in the last 18 months, and which has seen more activity since the start
of the year.
It has another deal with Al Futtaim Carillion for towers 58 and
59, as well as 53 (a), in the Burj Khalifa town area. “Also with Arabian Construction
Company (ACC) we will work on towers 52 and 53,” says Pillai.
The recent decline in commercial projects in Dubai and the subsequent rise in infrastructure projects in
places such as Qatar and Abu Dhabi has caused a number
of manufacturers to expand their product lines for the demands of bridge, road and
utilities construction. RAK Precast, for example, is working on its second bridge
in Abu Dhabi in quick succession an oversea link
Island near the border of the UAE and Saudi Arabia.
“It was difficult work once again, as well as a new challenge.
We finished 24 piles, erecting head beams that had been transported by a company
on barges, and then we uses special cranes.”
But precasting methods occasionally are not used if the consultant
on a project does not have experience with precast designs. B.S. Pillai adds that
the cost-saving benefits of precast reduce the construction costs to the extent
that it reduces the commission taken by the consultant.
Heath Anderson, director of building services at Ramboll Middle
East, the design engineering consultancy, contests this, saying that the clients
have estimates, and employed companies will use that as “a rule of thumb” in terms
of cost. “The market dictates what our fee is,” he says.
The option to use precast concrete is frequently on the table
at client meetings for low-rise and medium structures, Anderson explains. He adds that the accuracy of
precast concrete works particularly well with business information modelling (BIM)
– computer-generated designs that give a precise, holistic view of the future building.
“Because the BIM has detailed all the precast panels for the
structure, there was not a single penetration that was missed,” he says of a recently-completed
project in Denmark.
“On some occasions when taking something from designs, human error creeps in, and
panels might not be in the right place or right size. With BIM you have very specific
and detailed designs that link with what is being manufactured.”
Some engineering firms are attempting to shave further time off
the precasting method. JCB Engineering & Consultancy has, for the last few months,
been promoting a US
system called Platform, in which portable machinery allows the steel and bar detailing
to be worked on on-site, simultaneously with the concrete.
“You do not have to put the steel in a mould, pretension and
prepare it, then cast the concrete and cut the rebar,” explained Andre Tufenkjian,
partner at JCB, in an interview with CW in December.
“Instead, you have two lines, one for the steel and one for the
concrete; they work together. Instead of doing everything in series, we are doing
it in parallel. So you prepare the steel outside, then you put it in the mould and
cast the concrete. That makes it faster,” said Tufenkjian.
New companies have also recently come on-line to capitalise on
the growing demand for fast solutions. Xtramix Concrete Solutions launched Xtramix
International Precast last year, and is working on a number of projects in Abu Dhabi and Ras Al Khaimah,
Dajani says precast still a new concept in the market, especially
compared to European residential construction, but clients are increasingly becoming
convinced of the effective benefits.
At EPC we have been pioneering the use of structural synthetic fibres in precast concrete for many years, whereby our high tenacity fibres replace the steel mesh in many applications. Because the fibres are premixed into the concrete there is no labour required for steel fabrication, no production bottleknecks waiting for steel cages to be made and savings of around 30% can be achieved on the overall cost (materials and labour savings), as well as producing a greener product that is ligher, quicker to produce and more durable, especially where corrosion is a potential risk in water tanks etc.