Dear Reader ,
Shriram is doing his civil engineering degree and was at Dubai recently to study the special aspects of construction there. On our request , he has quickly written down this running commentary about his perceptions about Dubai projects as a guest author for the blog .
We all are always curious about Skyscrapers. How are they built ? Which technologies they use ? What materials are required ? These questions comes in mind. And one more thing which comes in mind when it comes to skyscrapers is Dubai. Fortunately, I was one lucky guy to get a chance to visit construction site of one of the upcoming megaproject in Dubai.
Dubai & sky scrappers :
Dubai is the city of Skyscrapers. It has 911 high rise buildings and over 88 buildings taller than 180m.
Most modern techniques are usually implemented in Dubai first. They have big plans , ideas and a vision to make each skyscraper distinct from other. They have best architects, Contractors and skilled labors.
Getting a construction contract :
To grab any contract, companies have to try hard. Along with quality and speed one more important aspect is safety. As the projects are very big, chances of mishaps are more. So companies are tested for their safety implementation. They are given with huge safety instruction list and are checked whether the company is following it or not. Their reputation is checked. Company should have experience of some mega-projects and should be capable enough to handle it.
Lost Time in Injury ( LTI ) :
One term which is very important when it comes to safety is ‘Lost Time in Injury’ that is ‘LTI’. Every company have to keep record of the time spent on recovery time of Labor’s injury. Companies should have least LTI. Sometimes companies have Zero LTI in a million hours which is the best thing possible. Less is the ‘LTI’, more is the chances of winning the contract. After completion of each project, companies are certified with their LTI hours and total construction hours. LTI is major factor in giving the contract. Preferences are given to the companies having least LTI and those who have expertise in big projects.
Whiles other three aspects are common everywhere which are quality, speed and time. They have a unique solution to achieve these three things. Contractors are generally tied with all the extra agencies or material provider. Either contractors are the owner of such agencies or they have joint venture with them. From the supply of steel, concrete and all material departments like plumbing, electrification, interiors all are under one roof. Interior designs and materials to be required for it are also manufactured by company or is the sub-branch of the company. Everything is done with co-ordination. Due to this , there is no separate bidding for agencies like plumbing, electrification and interiors. Also all the materials supply and quality is under the contractor then it doesn’t have to look upon the bargaining in their rates. Now this is really big advantage if you think deeply. Companies get better co-ordination when it comes to work. Everything is done on time. Quality is no doubt very good. Due to this, companies generally don’t get much in trouble as they already know their capabilities and their expertise. Due to this, generally they get tender to complete fully furnished building. Thus they grab bigger money and money is spread with respective shares holders . This saves time , provides better quality and achieves better economy.
A mega project ( Under construction ) :
Now, coming to the construction of the Mega project. It is hotel project owned by a private company. It is going to be the biggest hotel in Dubai overcoming Burj al Arab and JW Marriott of Dubai. It is 2.5 billion dollars project and it has two Skyscrapers. The project is so big that it has a water stage theater of 1100 capacity and a Dubai canal is going to pass from the property. It has over 1 million sq ft of construction. It has 3000 workers working on one shift. Well these are enough facts to prove that it is a mega-project.
Construction sequence :
Let’s start from the base. Every project in Dubai has two basic things and those are Pile foundation and Secant pile wall. As there is loose soil and no rock solid base these things are must.
What is a Secant pile wall ?
So first thing that I saw was a secant pile wall. Secant pile wall is nothing but closely spaced or in fact jointed piles constructed at the periphery of area. It was 25-30 meter deep. It is constructed before the pile foundation. Secant pile foundation doesn’t allow the ground water to enter the foundation area and it creates a barrier for soil to enter in the construction area. As the soil is loose and it tends to move easily and it creates pressure on the Secant wall. Secant wall was constructed till the ground level. After the Secant wall is constructed, piles foundation work is started. Now, the project which I had been had two towers construction going on. One had reached level 28 while the other was at foundation level. Secant pile wall was already been constructed. So I got to see the piles and it was spread across the whole area. Piles were constructed at some respective distances and were almost uniform in diameter. Piles were 30 m deep and diameter of around 1 meter. Piles are constructed from concrete reinforced with steel bars. After filling the concrete in bore holes, it is allowed to settle and it is covered with sand to keep temperature cool.
Later they cut the piles for about 2-3 meters to make a uniform base for the raft foundation. Building had a 4 storey basement parking so excavation was done for around 14-15 m deep. So raft foundation is constructed around 12m below ground level. Interesting thing about excavation is that building owner gets paid from the excavators. All the machines are brought by the excavating agencies and they excavate and fill all the soil in their trucks and sale the soil. Soil is important thing there. As we all know about reclamation projects in Dubai, these soil is usually sold to the developers of such projects. They sell it about 4-5 times more than the excavation cost. After excavation and cutting of piles, raft foundation work was started. Raft foundation was 2.5 meter thick filled with rich concrete. So now, foundation work is completed and superstructure starts.
What I saw there was that there are two types of designs for building frame. One is column based and other is beam based. Either they make columns very heavy or beams very heavy. Luckily I saw both designs. In column based design, columns are usually 1 m wide. They make sure that maximum load is transferred through columns. In this design slabs are directly connected to columns and beam is not present. After interval of 7 to 8 floors heavy beams are constructed and they carry load of above floors and transfer it to column. One new thing which I noticed was columns were surrounded by brickwork. They use variety of steel bars with maximum diameter of steel being 40mm. Labors are trained specially to deal with so heavy bars. To make reinforcement is a real big task there. Another thing , which is new is that there is a gun to join the binding wires. First binding wire roll is rolled in the gun then it cuts the binding wire automatically and binds the bars with binding wire. This indeed saves a lot of time, cost and simplifies the work.
Formwork for column is created on a hydraulic platform. Then they fill in the concrete in the form work it is allowed to settle. In Dubai, concreting work is done during nights as there is very high temperature during the day. After the concrete is settled, same formwork is lifted up with help of hydraulic jacks. Then they make formwork for slabs and beams. After making formwork, concreting work is done. Concreting is done with help of high pressure concrete pipe. High pressure is created by the motors and it allows to lift the concrete till 100 floors also. Pump has so much pressure that no air gaps are created. All concrete is continuously supplied through the pump. After settling down of beams and slabs, columns are filled and same procedure continues.
The other design I saw was beam based design. In this, heavy beam is constructed at interval of 10-12 floor levels. Beam is so huge that is almost equivalent to floor to floor height. Beam is so long that it requires connectors to join the bars. 40 mm bars are used with combination of other sized bars. This beam is so heavy that it carries the load transferred by the 10-12 storey’s. Then this load is transferred to columns. Heavy instruments or materials are carried by crane at higher levels. Each tower has hydraulic lifts which lifts all the material, machines and labors. This way frame of building is constructed.
After the beams and columns are constructed, exterior columns and beams are painted with special black colored paint which resists germs and insects to attack on it. It also protect it from chemical reactions. After it is painted, this building had some special RX Gypsum coating from exterior. This coating was to improve appearance. This RX Gypsum is a precast element and it is directly fitted on the site with accuracy. This improves the appearance of building and gives bigger look to the columns.
For interior design, they use the best quality materials. Hotel project had imported marbles from Italy. Everything is lavish and compromise is made on nothing. Dado walls of bathroom are made from Italian marbles. One more thing which they take care of is landscaping. For hotel like this, landscaping decides the beauty of the building. They start planning about it from day one. The landscaping of this project lies above the 4 storey basement parking. Landscaping had started before the construction of the superstructure. Plantation of date trees is a common thing which you will find in Dubai. They had created fountains in the entrance area. One who will enter these premises will feel royal .
Safety First :
One thing which is given highest preference is safety. Special committee is nominated to check for safety daily. Each site is pasted with safety instructions. Labors are trained specially to follow safety tips. Everyone is given safety instruments like helmets, jackets and special shoes. Without these things, you can’t enter the construction site. If any labor is injured then his injury time is calculated and submitted in LTI records. If any incidence happens then safety committee checks it thoroughly. They look for the cause of incident and check for the solution so it doesn’t repeat again. Photographs of such incidents are taken and along with it a special note is made which is about the cause of the incident. Then this thing is pasted on all the other ongoing projects of company. Labors are provided with homes at residential camps. Their transport and food is taken care of by the company. Every labor’s work is observed and it is noted on worksheet of each labor. They are given suitable wages depending upon the work.
So this was all about the things which I observed on my site visit. It was a great experience for me. Of course I got to know about the new technologies which they are using and about working of the company. I would like to mention that all the information above is true and personally experienced and nothing is taken from internet. All photographs are taken by me.
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