The city of Dammam (Saudi Arabia) builds 24 new circular tanks

Faster formworks in Arabia

The destiny of a country and probably of the whole world changed at the drilling point no. 7, near the small Saudi-Arabian fishing village of Dammam on the Arabian Gulf, on 4 March 1938, the day when oil was found. A lot of oil indeed! The province around Dammam is alleged to own 25% of all the world’s oil reserves!
A small settlement soon gave way to a cosmopolitan city which merged with the surrounding towns and is now home to over 2 million inhabitants and the biggest oil company in the world, making a dramatic contribution to the country’s welfare.
The existing wastewater treatment plant with its 24 circular tanks now requires extensive expansion.

Dammam (Saudi Arabia)

The go-ahead for the extensive expansion of the existing wastewater treatment plant was the reaction of the Ministry of Water and Electricity to the increasing number of inhabitants in Dammam. The contractor entrusted with this task, SysTech (Riyadh branch), began the shell construction works in December 2010.
The new structures will be hosted on three construction sites. Each of these will include two big aeration tanks (98.50 x 56.70 metres) with 6 coils across a width of 9 metres into which the water masses are conveyed. Beside these, there are four circular tanks (external diameter 39.90 metres with 40 cm wall thickness), two smaller circular tanks (external diameter 33.60 metres) as well as conventional technical rooms. 8 circular, in-situ-casted concrete structures will stand on a construction ground of approximately 400 x 500 metres; the final project will include the same facility on three construction grounds of about 60 hectares (85 football fields) for a total number of 24 circular structures.
The structural works will be completed in phases. Approximately 200 men will work on the construction site starting from 2013. 
The project was realised in collaboration between PASCHAL team, SysTech and Eifics in Dammam, the PASCHAL distributer for Saudi Arabia.

Formwork and concrete works

PASCHAL adjustable-radius TRAPEZOIDAL GIRDER formwork (TTR) will be installed in Saudi Arabia for the first time.
As the formwork enters the service on the construction site, all foundations have already been laid and many straight walls are currently being raised.

A German supervisor has instructed the teams how the formwork can be installed on the corresponding circular footprint on site and has shown them
many tricks to facilitate their work. The circumference was exactly determined to the centimetre by means of the equipment provided on site.
For the 4.95 metres concrete height, segment heights of 3.00, 1.50 and 0.75 metres were used, i.e. a framework height of 5.25 metres. These segments remain in height and keep on being used. Assembly, installation and realisation proved to be surprisingly easy. The quantity of tie points is very low when compared with other systems and the formwork thus needs no adjustment and no final matching of the finished construction profiles. Even though the circular formwork is a completely new technology for the team, a whole work cycle can be completed in just two days, representing an unexpectedly fast construction/site time.

TTR is an amazing technology in terms of handling, strengths as well as advantages for construction managers.
The aeration tanks have an inner radius of either 18.45, 9.15 or 4.50 m. The external circular walls are conical with a wall thickness of 60 cm at the base and 30 cm on top. For this reason, some steel filler pieces were manufactured in the main plant in Steinach. These are compatible with TTR and can be locked in using bolts. This is a fast, easy and system-integrated solution to a challenging task.
Each of the 24 structures shall be erected using the TTR. The increased efficiency obtained by means of this circular formwork will lead to the construction of further units.

TTR – adjustable-radius trapezoidal girder formwork

The adjustable-radius TRAPEZOIDAL GIRDER formwork (TTR) was developed with this kind of construction work in mind.
The TTR is made of a 21 mm strong, 15 layers nail-on Finnish birch plywood – this is the only system which can be flexibly bent up to a radius of 2.5 metres, while other types of plywood with a similar thickness would break or form waves.
As a so called “double girder segment” (i.e. a segment with two longitudinal beams), this formwork can handle radiuses of up to 1.0 m with 18mm thick plywood. This makes the formwork steady, completely round and exact without any deformation even in case of reuse. The circumference can be determined to the centimetre and with no final adjustment of the construction profiles. Although there are only 0.28 tie points per square metre, one square metre of formwork can bear up to 60 kN fresh concrete pressure. It is precisely these advantages that come into play when facing challenging technical constructions in both high-quality architecture and in the case of these circular tanks. Thanks to the fast installation processes and the incredibly low number of tie points as well as no need of further rounding or additional support/belts, the entire formwork-making process was practical, safe and fast. In short: it is the best and most efficient system currently available. Moreover, the low number of tie points has increased the quality of the concrete surface.

Overview

TTR ensures safer and more efficient onsite works.

Concreting took less time when compared to other types of circular formworks. Three different radiuses were used for the construction of the aeration tanks.