Pouring concrete is a complex process. One small mistake in the calculation of a large number of variables can render an entire batch of concrete unusable. And, unfortunately, not all errors can be detected immediately.
Of course, concrete pouring errors can create schedule and budget issues, but today’s advances in robotic demolition systems help correct mistakes without having to start all over again.
For large and multi-stage construction projects, water jet demolition technology offers a solution that can minimize the overall impact of concrete pouring errors and help contractors eliminate all problems and complete the project on time.
Any formwork problem, whether it be a slight shear or misalignment or a complete tear, can be a disaster in terms of loss of productivity as portable equipment may be required to fix the effects of such problems. This approach has several disadvantages.
Firstly, it is a very slow, hard work that requires enormous physical effort from the members of the brigade. In addition, as a result of strong vibration in the remaining concrete, the reinforcement is damaged and microcracks occur. And contractors have no choice but to dismantle most of the concrete structure, and sometimes even the entire structure.
In hydrojet dismantling, a jet of water is used, supplied under high pressure by injection in special water-jet devices. The outlet water pressure can reach 2758 bar. With the help of a jet of water, layers of concrete are removed, while maintaining the reinforcing cage.
When using this method, the risk of microcracks is eliminated and a structurally sound basis is created for subsequent repair or restoration work. At the same time, other members of the construction team are released, who can perform other work, for example, install formwork for concreting, so as not to break out of the work schedule.
One contractor who had to correct errors due to formwork displacement in a small viaduct construction project was forced to dismantle part of the superstructure and bridge heels to a depth of 0.9 meters and re-pour the concrete to correct the error. Through the use of hydro-dismantling technology, the contractor was able to carry out the dismantling with minimal impact on the entire structure.
Segregation of the concrete mixture and other problems that may be associated with a batch of concrete of poor quality
Another contractor used the water jet demolition method to solve a difficult problem resulting from the separation of the concrete mixture. After the penetration of water under the concrete in the formwork, the cement paste was washed out, leaving only the filler.
By adjusting the parameters of the demolition robot, the contractor was only able to remove the delaminated material. The solid part of the concrete structure remained intact and was ready for repair work.
Contractors using hydraulic demolition robots have the ability to adjust the robot’s stroke to control the depth of cut and change the amount of water pressure depending on whether the robot is used to break loose, worn concrete layers or to remove a layer of sound concrete to a predetermined depth.
After setting the parameters, the robot carefully performs its work, maneuvering over the designated area and removing material according to the set values. In some cases, this may involve the removal of concrete from the entire surface to a certain depth. In other cases, demolition work may only involve the removal of weak or worn concrete.
In addition, the ability to selectively demolish with hydraulic demolition robots provides a solution to other concrete placement problems. For example, in one recent bridge project, a batch of poor quality concrete threatened to disrupt the entire project.
The concrete was curing as the crew had already poured concrete into the formwork. Vibrating and other devices were not suitable to correct defects in concreting.
Concrete settled by 350 mm, leaving bare reinforcing mesh. In order to selectively remove low-quality concrete without damaging the reinforcement and without violating the overall stability of the structure, the contractor used the hydraulic demolition method.
Thanks to the high productivity of the demolition robot, defects were eliminated without compromising the overall project schedule. The cost of repairs was kept to a minimum as the rebar and existing structure were preserved.
Embedded in concrete materials that do not meet the requirements of specifications
Sometimes the cause of problems with concrete is not the concrete mix itself. In situations where it becomes necessary to remove materials from cured concrete that do not meet requirements, such as rebar or anchors, hydraulic demolition technology provides the power and precision to do it quickly and efficiently.
In addition to the fact that hydraulic demolition robots allow you to adjust the amount of their stroke and water pressure, these devices can be programmed to cut geometric shapes such as circles, triangles, squares or parallelograms.
Contractors are able to remove just enough material to reach the concreted part, whether the part is just below the surface or several meters deep.
There was a case where a contractor found that it was necessary to replace the bolts on anchors that were 1 meter deep in concrete. The contractor was able to cut round holes large enough to remove the anchors, minimizing the amount of concrete removed and increasing the efficiency of the concrete repair project. Thanks to the hydraulic demolition robot, the contractor was able to dismantle and replace 12 to 15 anchors in a 12-hour shift.