Demolition of retaining wall at Ostbahnhof Berlin with Betonamit swelling explosive

Project description

KUBATEC BMT AG was contacted by STRABAG Berlin and informed about the special demolition project. A 500m long concrete dam is to be cut in a horizontal line with the swelling explosive BETONAMIT so that the concrete fragments can then be easily removed and loaded. The company carrying out the work hopes to save an enormous amount of time and money as a result. The entire demolition project is scheduled to take around one month. Advice on the correct use of BETONAMIT blast concrete was provided by the manufacturer, KUBATEC BMT AG. The demolition of large concrete structures is a challenging task that requires careful planning and precise execution. In the past, conventional blasting methods were often used, but these are often associated with considerable risks. Nowadays, the use of swelling explosives offers a safe and effective alternative for demolishing large concrete structures. Swelling concrete, also known as blast concrete or swelling explosives, enables explosion-free demolition, which not only increases the safety of workers but also protects the surrounding environment. This method is particularly beneficial in urban areas or near sensitive infrastructure where vibration and noise must be minimized. On this page, you can find out more about the demolition of large concrete structures using swelling explosives, the processes involved and the benefits of this innovative technique.

Project schedule

The boreholes were drilled using a drill rig. This saved an enormous amount of time and protected the workers on the construction site. Once the angle of the carriage had been set, it was very easy to drill the holes. Drill the hole, pull the carriage out again, drive 80cm further and drill the next hole. In this way, over 30 holes could be drilled per hour, meaning that the drilling work for the demolition of the retaining wall took less than 3 days. The backfilling of the boreholes with the swelling explosive BETONAMIT was carried out on the side and did not represent any relevant effort. The cracks in the retaining wall were already clearly visible the next day and continued to widen. The concrete fragments were loosened exactly at the desired height and could only be pushed down with the excavator bucket and loaded. The process of demolishing large concrete structures with swelling explosives can be divided into several steps. First, a comprehensive analysis of the structure to be demolished is required. This involves determining the size, age and material properties of the concrete in order to select the appropriate methods and materials. Once the planning is complete, the preparation of the boreholes begins. The drill hole diameter must be between 25 mm and 45 mm to ensure the optimum expansion force of the swelling explosive. As a rule, the distance between the boreholes is ten times the diameter. When determining the borehole depth, it should be noted that this should be at least five times the diameter in order to ensure effective pressure distribution. After drilling, the boreholes are filled with swelling explosive. The recommended mixing ratio is 1.2 liters of water per 5 kg of swelling explosive. This mixture ensures that the swelling explosive can develop its full expansion force. After filling, there is an activation phase in which the pressure in the material is built up. The controlled expansion ensures that the concrete is crushed in a targeted and efficient manner without causing uncontrolled explosions.

Drilling information

Horizontal drilling line with an inclination angle of approx. 20° Borehole diameter: 43mm Borehole spacing: 80cm Borehole depth: 100cm The correct drilling information is crucial for the successful demolition of large concrete structures with swelling explosives. The drill hole diameter has a direct influence on the effectiveness of the process. A larger diameter leads to a higher expansion force, while smaller diameters should be preferred for thin surfaces such as over-concrete to ensure efficient cracking. The recommended drill hole diameters are between 25 mm and 45 mm, with the material consumption values per meter of drill hole being as follows: 25 mm: 0.9 kg/m 30 mm: 1.24 kg/m 35 mm: 1.68 kg/m 40 mm: 2.2 kg/m 45 mm: 2.78 kg/m This information is essential for planning material requirements and estimating costs. It is also important to consider the distances between the drill holes, as a smaller distance leads to faster cracking and therefore increases the efficiency of the crushing process.

Consumption

Total length of the concrete dam: 500m Borehole spacing: 0.8 meters Number of boreholes: 500 : 0.8 = 625 boreholes Borehole depth: 1 meter Total borehole meters: 625 holes x 1 meter = 625 meters Consumption/meter at DM 43mm: 2.54kg/m Consumption: 625 meters x 2.54 kg/m = 1,588 kg BETONAMIT The consumption of swelling explosives during the demolition of large concrete structures is a significant factor influencing the costs and efficiency of the project. On average, the consumption is around 10 kg of swelling explosive per cubic meter of crushed concrete. This figure helps to calculate the required amount of swelling explosive and the associated costs. The exact calculation of the material requirement depends on the specific conditions of the application site and the selected borehole diameters. Precise planning of consumption is not only crucial for the efficiency of the project, but also minimizes the risk of unexpected cost overruns. Too much material can drive up costs, while an insufficient amount can slow down the demolition process.

Time / Costs

As described above, around one month was planned for the demolition of the concrete dam. The project was completed in less than 2 weeks. This surprised even the manufacturer of the explosives in Liechtenstein. Unfortunately, we do not have any figures on the costs for the drilling work. The consumption of swelling explosives was around 1,600 kg and the costs amounted to around EUR 8,000. The time and cost factors when demolishing large concrete structures with swelling explosives are significantly advantageous compared to conventional methods. The explosion-free technique allows work to be carried out more quickly, saving time and resources. As the process generates minimal noise and vibration, work in urban or sensitive areas can be carried out efficiently and without major interruptions. The overall duration of the demolition process depends on various factors, including the size and complexity of the concrete structure. However, careful planning and the targeted use of swelling explosives can ensure speedy execution. This not only leads to greater customer satisfaction, but also to significant cost savings, which are of great importance in the construction industry.

Expert opinion

In summary, it can be said that the demolition project was a complete success and all parties were extremely satisfied. The strategy worked out as planned and far more costs and time were saved than expected or hoped for. It has been clearly confirmed that the use of swelling agent was exactly the right decision in this case. If a concrete retaining wall 500 meters long has to be demolished using conventional methods with a demolition hammer, this usually takes weeks or even months. In summary, the demolition of large concrete structures with explosives is a modern and safe method that offers numerous advantages. The use of these non-explosive explosives ensures that the demolition process is efficient and controlled without endangering the surrounding environment. The structured approach, from planning to execution, guarantees that all aspects of the project are taken into account and that the work is completed successfully. The advantages of this method are manifold: increased safety, reduced costs and time savings. In today's construction and demolition industry, it is crucial to offer innovative solutions that meet customer requirements. Swelling explosives represent exactly this solution and open up numerous possibilities for future projects.

Customer review

The feedback from STRABAG was very positive. Although we can also count STRABAG among our customers in Switzerland, Austria, the USA and other countries, this was the first project with the Berlin location. The collaboration was an enormous pleasure and we are looking forward to the next exciting projects. Our customers' experiences with demolition projects using swelling explosives have been consistently positive. Many customers appreciate the advantages of this explosion-free method, especially the safety and efficiency of the entire process. The demolition of large concrete structures could be carried out without significant disruption to the surrounding area, which has increased the satisfaction of local residents and the companies involved. In addition, the speed and effectiveness of the work was highlighted. Customers report that they have successfully completed projects on time and within budget. This feedback confirms the reliability and performance of our swelling explosive, which has established itself as the optimal solution for the demolition of large concrete structures. We are proud to offer a safe and effective method for the demolition of concrete structures that meets the highest demands of the construction industry.