The best way to restore concrete slab road surfaces is to use the geopolymer injection method Slab Lifting. It allows to raise settled concrete slabs, and to level the surface of the entire section of a road or car park. The Slab Lifting method also allows to repair inoperable sections of roads adjacent to bridges, railways, port docks, loading platforms, etc.
An extensive sewage network was built in 2016 as commissioned by the city of Jurmala. In the course of the works, sewage collection wells of up to eight meters in depth were also installed. During the installation work, one of the sewage collection wells had been badly damaged, as a result of which groundwater penetrated through the well´s wall, constantly filling the collection well with water. Consequently, the sewage collection wells had to be emptied much more frequently than originally envisioned by the City. This, in turn, caused the sewage collection wells´ maintenance costs to be considerably higher than planned. Furthermore, relevant examinations revealed that the load bearing capacity of the soil was not correctly assessed during installation work, and by that time the collection well´s load bearing plate had begun to sink askew. This situation put the long-term use of the sewage collection well under a serious doubt. During a consultation, URETEK Baltic’s team immediately proposed to the heads of the City of Jurmala a viable solution in the form of URETEK technology, and the work was completed quickly within a few days. Relevant sewage collection wells served the residents of several multi-story buildings on account of which these buildings could not be switched over to another sewage route. URETEK Baltic’s team set very clear goals - the work must be performed quickly and professionally, while failure is not an option.
First, the sewage collection well was emptied and washed in order to carry out a more detailed inspection. URETEK Baltic's technicians then stabilized the subsoil under the well’s load bearing plate to stop further setting. Until the leakage stopped, the surface behind the leaks was injected through the collection well´s wall.
The same procedure was replicated for all leaks until the desired result was obtained. The work was carried out on two separate days in four-hour work cycles so as to ensure uninterrupted sewage use for the multi-story buildings.
The waterway accident in the center of Tallinn, at the intersection of Mere puiestee and Ahtri Street, resulted in stopping tram traffic. A 200-mm-diameter water pipe broke. Asphalt sank next to the tramway at the accident site and the sinkhole opened. As the load-bearing structural layers under the tramway were washedout, tram traffic was stopped. One of the trams that derailed from its path was also affected. According to City Transport Company, the water accident was very extensive, resulting waterflow approximately 800 cubic meters per hour.
This was a rather rare and unique case, in which the time factor played a particularly important role. The intersection, where the work needed to be performed, is one of the busiest in the city The water accidend caused stoppage of several tramway lines. As a first phase, the void was filled with as much sand as possible. In this operation, the filling process was made from the side and the sand was pressed into the voids under the concrete tramway slabs. In the second phase, URETEK filled the cavities under the tramway slabs with an expandable geopolymer. The injections were started from a depth of three meters to ensure the largest possible reinforcement of the soil and to press the sand fill against the tramway structure. As the third phase, after filling the gaps, URETEK started lifting the tramway slabs and re-leveling them to their original position. This work was performed using a tram specially ordered from the fleet, which was used as a weight in the injection area. The same tram was used several times to check for possible slab descents. The final result - accuracy of the work was measured up to 1 mm, taking into account the initial height and the final height after the job.
At 8:00 in the morning, it was discovered that there was an accident. At 9.00 URETEK made a call to the appropriate authorities about the problem At 10.30 URETEK visited the site and discussed possible problem solutionsThe appropriate paperwork and the preparation time took from 12.00 to 21.00. The execution of the works started from 00.00 During the works, the initial position of the tramway was restored and, in agreement with the customer, it was decided to increase it by another 2 mm in order to prevent any subsidence due to soil compaction. The first tram made a test drive on the lane at 4.50 The second tram made a test drive on the at 7.05 The last height adjustments of 2 mm to level the tramway to the starting position were performed by URETEK at 8.00 am All tramway-related work was considered to be completed at 9.15 am and the tramway line was open to its normal operations.
According to the specialists, the duration of the restoring works using traditional methods was estimated to be approximately two weeks, during which time tram traffic on the line would have been completely closed. Therefore a number of different technologies were considered, which could be used to restore both the tramway and normal traffic in the shortest possible time. City engineers came to the conclusion that the best and fastest solution was the URETEK injection method, which could not only stabilize the surface under the tramway, but also return the sunken tramway slabs to their original level.
Riga authorities decided that during renovation of the tramway tracks the heating system pipeline that was running under the tracks had to be replaced as well. As location of the pipeline changed after construction of the technical line, it was decided that the pipeline was to be installed by way of boring. Unfortunately, boring operations resulted in decreased density and settlement of the ground, which in turn led to uneven settlement of slabs under the tracks. After long discussions Riga authorities and engineers decided to use services of URETEK in order to resolve the problem without disturbing the tram traffic.
URETEK’s team performed the works at night, when the trams were not operating. First and foremost the settled area was identified, following which cavities in the ground were filled by injections of geopolymer resin.
When the ground surface was stabilised and its loadbearing capacity restored, the slabs and tracks were again raised to their initial height. The entire work process took 4 hours, and this method was the most efficient way to solve the given problem.
A new reception berth for cruise ships was built in the framework of the extension works of the West Terminal of the Port of Helsinki. Already during the first tests it was recognised that there are openings between the underwater piling walls and due to the movement of water from screw propellers of ships, the filling of the berth is washed away to the sea and the concrete slabs of the berth started to sink. The survey identified extensive voids inside the berth due to the washing away of the filling soil. The engineers who consulted the construction works of the West Terminal contacted the team of URETEK to assess the possibility of cooperation. Since the given project required the involvement of specialists of different fields, URETEK was interested in this project since the very beginning. Divers had to be called in to perform the underwater survey and carry out the inspections during the works. Additionally, Finnish earth drillers had to be summoned for an extremely difficult and precise drilling works. It requires a long and well-elaborated cooperation to shape the work of all the involved parties into the perfect outcome.
Eventually, URETEK developed a solution where the openings in the piling walls were closed, the voids were filled, and the initial load-bearing capacity of the soil was restored.
The use of URETEK ’s technology helped to avoid time-consuming traditional construction works and allowed to complete the works well before the initially planned deadline.
In the course of extension works in Port of Nasva, a sheet piling was rammed in the sea, which remained unbound in one corner and east wind emptied the area behind the sheet piling. Seawater had eroded the filling material under the berth to the depth of 6 m, thus endangering the superstructure of the new berth. Therefore, it was necessary to compact the area behind sheet piling again, stabilise the soil and fix sheet piling.
URETEK team was tasked with filling the voids in the soil under the berth, closing the underwater part of berth to ensure stability of embankment, and stabilising the soil under the berth at the depth of up to 6 m. Works were performed within six hours, during which loose soil was compacted, voids filled and underwater sheet piling waterproofed.
An alternative to URETEK technology would have been concrete works, but as it is impossible to weld under water, there was no way to fix the sheet piling.
Recently built four-lane road showed signs of subsidence and voids under the pavement, which caused closing two lanes for traffic. Despite repeated attempts to solve the problem by using traditional excavation method, subsidence was not stopped.
URETEK technology was used to fill voids and prevent sand filling from entering between large-fraction crushed stone in the future. Works lasted for six hours and after asphalting, the road was open to traffic again.
Although the pavement was removed before performing injection, it would not have been necessary when using URETEK technology and in this case, it was done to find out the reason for subsidence for the purposes of expert assessment.
Pipeline was installed under a busy road in Tallinn, but the soil surrounding it was not sufficiently compacted, which caused subsidence of road surface. Subsidence has reached the point where it started to disturb traffic and after two to three attempts to fix it, the client contacted URETEK team.
Filling voids by using traditional excavation method would have caused stopping traffic for four days. Considering that it is a busy street, such a solution would have been extremely disturbing for road users. By using URETEK method, this problem was solved by closing one lane for just four hours.
In the course of this task, special geopolymer was injected directly in problem area and filled voids. After filling voids, the client replaced topmost soil layer with asphalt and street was reopened for traffic.
A subsidence occurred in recently completed road section in Jüri small town for unknown reasons, causing asphalt to collapse in 1.5 m radius. In the event of using traditional method, entire subsidence area would have been excavated and soil newly compacted. That would have taken at least two days and involved exploitation of heavy-duty machinery.
Client decided to use URETEK technology. Subsidence was filled with sand; concrete blocks were placed on top of the subsidence to achieve maximum soil compaction; and geopolymer was injected into the soil.
Gonsiori Street is one of the main arteries in Tallinn, closing of which would inevitably cause major congestions during rush hours. Unfortunately, in the course of reconstruction works carried out in Gonsiori street, there occurred subsidence under massive heating pipeline.
As the base of the road had already been completed, the client asked URETEK team to help with stabilisation of subsoil for heating pipeline. Traditional method would have involved cutting out the heating pipeline, compacting the soil and reinstalling heating system. However, that would have meant postponing the completion of works and closing roads for remarkably longer period. Client excluded that option immediately.
Geodesic specialist present at the site provided URETEK specialists with accurate data regarding the location of subsidence and URETEK team stabilised the soil and restored its load-bearing capacity. Works lasted for 2—3 hours.
