sustainable and ecological, yet still economical
Our company has developed a reliable method for soil compaction that achieves a Co2 reduction of up to 78% in road construction and is 100% environmentally friendly and sustainable. The comparison between the methods shows that the required time for one kilometer of road, with a width of ten meters, could be reduced down to two days.
Road construction: sealed surfaces, heavy equipment, massive interference with soil ecosystems: How does that fit with ecology and sustainability? Together with our partner, we have found a way to compact soils as gently as possible – and in a reversible way that does not pose a disposal problem.
Whenever construction takes place, the subgrade must be prepared. In order to support a surface of asphalt, compaction of the soil is basically a prerequisite – conventionally, this means a long construction period with extensive logistics, high expense and later problematic disposal of the materials used. With Underbold, our company has created a material that allows the sustainable preparation of the soil. At our company, soil compaction is now ecological – and at the same time economical. What kind of process technology is this?
High density and stablility
Through the Underbold method we achieve a very high density. This is because the air pockets in the soil are still filled with the nanoparticles even in the micro range. They do not remain empty. And this is exactly what provides the desired stability. In comparison, conventional methods only achieve a lower density. This is because the air pockets in the soil remain even after compaction. They remain empty or occasionally fill with water – and this causes movement in the material particles. So the subsoil is not stable, but mobile. And that, in turn, can cause damage to the asphalt surface over time as weather conditions change.
Our company’s new technology also scores in terms of resistance to temperature changes: the soil layers are not permeable to water. On the contrary, they are extremely impermeable to water due to the dense structure without air pockets. If temperatures change between day and night or between summer and winter, no cracks form in the soil.This is because the soil is always the same density; it does not change its volume. With the conventional method, things are different: the soil remains water-permeable, the soil works with temperature changes, and this leads to cracks in the asphalt surface.
The mixture of soil and wax emulsion can be adjusted as desired via cement admixtures. Ultimately, therefore, there is no limit to the load-bearing capacity. This also distinguishes this method from conventional construction methods. Until now, the load-bearing capacity has always depended on the existing soil material. Only a thicker asphalt layer could increase the bearing capacity. This is far less economical than increasing the bearing capacity by adjusting the mix ratio.
About the Underbold
Wax emulsion enables soil consolidation and soil improvement
The Underbold system works with a wax emulsion and makes it possible to convert existing soils for the superstructure into a frost-proof base course by using a cold recycling milling machine. This is so simple and advantageous because the system does not require any additional equipment. Conventional methods are different, requiring heavy equipment. But we will come to the advantages of the new technology later. So what exactly is this product?
Ultimately, Underbold is a specially developed wax emulsion that is worked into the soil and applied for soil compaction. This wax emulsion binds and is water repellent. After processing, it is frost and heat resistant. This makes the subgrade very durable. After incorporation, the emulsion tightly surrounds each individual soil grain and forms a homogeneous mass. Pressure compresses the soil with the binder, creating a permanently stable bond. The material is now very resistant to pressure, which is firstly advantageous for high road loads and secondly even prevents rutting.
The process is based on the ZTVE-StB 2009, optionally our company has launched an additive. The patented additive PR-Plast prevents the formation of ruts and is suitable for the production of PMA for bituminous asphalt layers. It is therefore not incorporated into the subgrade, but usefully supplements the particularly stable subgrade. With a particle size of about 3 millimeters, it improves the properties of bituminous mixes for surface and binder courses. The polymer-modified asphalt prevents rutting even at high temperatures and improves the e-modulus of the asphalt by about 25 percent. The additive eliminates the need for a PMP production plant, as it is easy to use and is added directly in the mixer.
Soil compaction method
Comparison & Benefits
If we now compare the Underbold technology with conventional methods, a number of differences stand out. In the local environment, for example, the binder is immobilized, so the material does not have to be disposed of at high cost. This protects the environment. With conventional methods, on the other hand, all existing contamination and pollution must be disposed of in landfills at a cost.
The global environment also benefits from the shortened construction time with the new method: CO2 pollution is significantly reduced. To illustrate how big the impact of the streamlined logistics and shorter construction time is compared with conventional methods, let’s compare the CO2 impact of renovating a 17-kilometer stretch of highway: With our company’s new method, the CO2 impact is 37,673 kilograms. With the conventional method, 863,537 kilograms are released.
With Underbold, our customers have achieved a 78% reduction in CO2 emissions compared to conventional methods.
Ecological & Sustainable
Soil compacted with Underbold can be reworked after being broken up mechanically and does not require special disposal.
Our experience with Underbold shows that a time saving of up to 80% can be achieved in soil compaction.
Material cost savings
Problem of disposal do not exist!
With all conventional methods of soil compaction, it is difficult to extract the used material from the soil again. It cannot be recycled. However, our company has also thought of this problem: the processed soil can be loosened again with a milling machine. The wax emulsion can remain in the soil, and the soil regenerates over time – because both the binder and the wax emulsion are environmentally compatible. If the road is not to be destroyed but renewed, the material can simply be reused. The soil can therefore be worked and compacted again after the upper layers have been removed.
This makes clear that ecologically soil construction methods with environmentally and climate-friendly technologies are by no means at odds with economic interests. With wax emulsion and its processing, we have found a simple and sustainable way to make soil compaction even more durable and stable.
Less equipment, shorter construction phase, economic advantages
The use of Underbold does not require any significant additional equipment compared to conventional soil consolidation. Using a suitable milling machine, existing soils in the superstructure are converted into frost-resistant base courses using the “mixed-in-place method”.
After 3 days, the surface course can be applied and the area can be released for use. The main advantage here is the cost-effective conversion of existing soils without the resource-intensive provision of aggregates for frost protection layer and base layers. Of course, all other soil treatments in the substructure (embankment area) and building ground, such as soil consolidation and soil improvement, can also be realized.
A major advantage is the cost-effective conversion of existing soils, without the need to supply gravel mixes, into frost protection layer and base course. Of course, all other soil treatments in the structure (embankment area) and in the structure, such as soil consolidation and soil improvement, can also be realized quickly, permanently and cost-effectively.
A cold recycling milling machine (mixed in place) is used to convert existing soils in the superstructure into frost-resistant base courses. The application of the Underbold does not require any significant additional equipment for conventional soil consolidation and soil improvement.
How the system is applied
Milling with Underbold-water mixture
While conventional methods require several work steps with sometimes quite special, heavy equipment, the wax emulsion is mixed into the soil with the milling machine in a single work step. A homogeneous mixture is created immediately. The tiller not only opens the soil and takes up the soil, but also mixes in the wax emulsion and returns the homogeneously mixed mass to the soil.
In the next work step, the loosely applied mixture of soil and wax emulsion is pre-compacted. This returns the soil to its original level. And, above all, the soil is now so firm that the following construction machines can drive over it safely – they do not sink in. This enables uniform cultivation at the required depth. So here, leveling and precompaction are combined in a single work step. In the next step, a hydraulic binder is spread by a gritting vehicle. The soil under the construction vehicles now shows three different layers: At the very bottom is still natural, unworked soil. Above this is a layer of soil mixed with wax emulsion and compacted. Both are water-permeable and moist. Above this, a layer of binder has been applied in the last work step.
Mixing with hydraulic binder
Binding material is mixed into the soil with a rotary tiller.
The binder applied by the gritting vehicle is mixed into the pre-compacted layer of the base with a milling machine. Since a wax emulsion has already been incorporated here, only a small amount of binder is needed. After this work step, the subgrade must also be leveled and compacted again. This is the only way to make the floor stable. However, this is already a final compaction: the soil is compressed in such a way that Underbold® can develop its optimum effect.
Through Underbold and the compacting process we achieve a very high density. This is because the air pockets in the soil are still filled with the nanoparticles even in the micro range. They do not remain empty. And this is exactly what provides the desired stability. In comparison, conventional methods only achieve a lower density. This is because the air pockets in the soil remain even after compaction. They remain empty or occasionally fill with water – and this causes movement in the material particles. So the subsoil is not stable, but mobile. And that, in turn, can cause damage to the asphalt surface over time as weather conditions change.
In addition to the economic advantages, the material and processing have other advantages
The advantages of Underbold over conventional technologies and methods are obvious. It is an ecologically as well as economically very sensible product – in several respects. For not only does the shortened construction time have a positive effect on environmental and climate protection as well as financing, but also the reusability of already existing materials. As a result, the cost of materials can be reduced just as much as the costs arising from a (previously) quite long construction period. If the PR-Plast additive is used together with the new compaction method, further advantages arise. In short, the new method of soil compaction offers:
- Significant time saving due to a shorter construction period,
- Better adaptation of the bound superstructure to the traffic load and thus a reduction of the layers,
- More economical use of cement through said better adjustment,
- Longer shelf life,
- Reduced maintenance costs,
- The avoidance of ground movement outside the gradient adjustments,
- The elimination of landfill and disposal fees outside of the gradient adjustments, and less impact on flowing traffic due to the shortened construction period
- Higher load capacity
- Higher modulus of rigidity
- Higher elasticity
- Shorter setting time outside the processing period
- Less tendency to shrink
- No cracking
- No load input from the setting reactions of the overlying layers
- Reduction of the depth of water penetration
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