The company GEOMEHANIČKI TIM d.o.o. from Belgrade is one of the few companies that uses SDA technology in its work, ie reinforced concrete piles with Solid Displacement Auger (SDA) technology. SDA technology is used in unstable terrains and is very effective in loose and unconsolidated materials. The execution technology itself is efficient and fast because all operations are performed continuously, without interruption, just like with CFA technology. SDA pile technologies with the use of special tools press the ground from the side, thus increasing the bearing capacity of the pile. SDA technology is a combination of broken and CFA piles and is an excellent replacement for broken piles because it does not create large vibrations on the ground during construction, it allows it to be applied in urban areas.

The application of SDA technology requires the engagement of special mechanization such as MAIT HR 180 with special tools. As we could hear from our interlocutors, the method of making SDA piles has three operations: drilling, concreting from the bottom up, through the machine system connected directly to the auto-pump through which concrete is injected through the machine system, reinforcement and lowering the reinforced basket to the projected depth.

Considering the specific weight of the mechanization, as well as the manufacturing technology itself, the working plateau must be adequately prepared, well-planned wild material and rolled. On a substrate prepared in this way, make a curtain of gravel or gravel with good compaction from 30 MPa to 35 MPa. The prepared terrain should enable drainage from atmospheric precipitation and as such enables movement and proper operation of engaged machinery, equipment, correct centering, leveling and better performance. Before the start of work, the machine system itself is connected to the autopump. After connecting the system, it is necessary to pump cement milk through the auto-pump systems and the machine system.

SDA drilling technology:

Before the start of drilling, it is necessary to mark the exact position and center of the piles with steel anchors 30 cm long. After that, the mechanization is brought to the correct position of the pile, the tower is leveled, a specific drill is lowered to zero, after which the computer in the machine for adjusting the depth and monitoring the making of the pile is adjusted. It starts with drilling. The better side of SDA pile technology is that it does not remove earth from the pile hole when making the piles themselves, which automatically reduces the need to engage an excavator as well as a landfill truck. Before concreting, a sample is taken from the auto-mixer, and it is poured using the Abrams cone. The required pouring of concrete should be from 56cm to 60cm.