GOMACO World Index --- GOMACO World 39.1 - March 2011
Eren Construction Company, located in Ankara, Turkey, is at work slipforming 63 kilometers (39.1 mi) of canal. The work is the last section of a 221 kilometer (137.3 mi) long irrigation canal which will carry water from the Atatürk Reservoir into eastern Turkey to irrigate agricultural land. This final section of canal runs between the cities of Mardin and Ceylanpinar in eastern Turkey.
The irrigation project is a high priority for the Turkish government and they are pushing to complete the project quickly, but with high quality. It led Eren's officials to make major investments for the project, including the purchase of over 100 new pieces of equipment. For the concrete portion of the canal, Eren officials looked once again to the slipforming process. The company has had previous success slipforming canals in Turkey with their GOMACO four-track GP-2600 canal paver, and were prepared for the enormous length of this new canal contract. This time though, they would be introducing stringless control on their canal paver.
First, Eren Construction must excavate and remove 13 million cubic meters (17,003,358 yd3) of earth, lay down two million cubic meters (2,615,901 yd3) of fill material and then fine trim the canal. Excavation crews work during the daylight hours and the canal slipform paving crew works during the cooler night time temperatures.
Because of the government's interest in the project and their push to get the canal completed, Eren has looked at the most efficient ways of completing the project. They decided to make a major investment into stringless guidance, for their earth moving equipment and their GP-2600 paver.
The complications of paving by stringline in the darkness of night included the difficulty of setting the stringline with limited line of sight and the visibility of the stringline for workers and truck drivers delivering concrete. The conversion to the Leica Geosystems 3D system improved accuracy and eliminated any potential stringline problems.
Eren has three mobile batch plants set up along the length of the canal. They are using a standard slipformable concrete mix design, with the aggregate being produced by on-site mobile crushing plants. The concrete has a 30 MPa (4351 psi) strength, and slump averages 30 to 50 millimeters (1.2 to 2 in).
The canal is 10 meters (32.8 ft) wide at the bottom, 28 meters (91.9 ft) wide across the top, with a 10.8 meter (35.4 ft) slope run, and 1.5:1 slope walls. The canal will accommodate a six meter (19.7 ft) water depth when complete.
Before slipforming takes place, the slopes are lined with a T-Grip geotextile fabric. The fabric keeps the underlying soil from absorbing any water, which would make it swell. The GOMACO four-track GP-2600 is slipforming the slopes of the canal in 10.8 meter (35.4 ft) wide paving passes. The concrete slopes are 150 millimeters (5.9 in) thick. Paving production averages 250 to 300 meters (820 to 984 ft) per day, depending on concrete delivery.
Finishers apply a float finish to the new canal from a work bridge mounted to the back of the GP-2600 paver. Joints are cut into the new canal at three meter (9.8 ft) intervals. The fresh concrete is then covered with fabric and wet cured for four days to prevent surface cracking from the hot temperatures.
"We purchased the Leica stringless system for our paver because we wanted to remove all stringlines on the project and to make night paving easier," Yaşar Eren, Chairman of Eren Construction Company, said. "Paving at night makes it difficult to ensure that stringlines are correct or not. We did not have that worry with the stringless system. The system improved our production capacity and allowed us to work where and when we wanted. We also had cost savings from less surveying and time savings."
The Turkish government has allowed four years to complete the project, but Eren Construction estimates they will be finished in only two and one-half years. The early completion date is attributed to several factors on the project, including slipforming the concrete canal and the Leica Geosystems stringless guidance systems.
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The new canal is covered with fabric and wet cured for four days to prevent surface cracking potentially created by the country's hot daytime temperatures.
Concrete is metered down the slope by an auger. A system of baffles controls the concrete and keeps it from sliding down to the bottom of the canal.
A surveyor checks the Total Station working across the canal from Eren's GOMACO four-track GP-2600 paver on the stringless project in Turkey.
The finished canal will carry water from the Atatürk Reservoir into eastern Turkey to irrigate agricultural land.
Continue Reading GOMACO World Vol. 39, No. 1