FOAMED ASPHALT

Ammann does not focus on a particular method of introducing additives or foam bitumen because many more variables must be considered. The entire process chain is affected, starting with drying at a reduced temperature, continuing through to specific mixing sequences and including the introduction of recycled materials.

Benefits

• Lower manufacturing costs
• A safer working environment for road crews
• Reduced emissions at the jobsite
• Lower emission of CO₂ at the plant
• No need for new paving equipment; the same pavers and rollers are used

TENDERS

Foamed asphalt meets the quality requirements for hot-mix aggregate. The asphalt specifications and the paved layer remain the same. By observing the recommended procedures the same laboratory tests and processes can be used.

Many countries are now working on national projects aimed at incorporating low-temperature asphalt into the standards. Until they have been adopted, it is important to verify that work tenders explicitly state that use of low-temperature asphalt is permitted.

Low-temperature asphalt production is perfectly compatible with the use of reclaimed asphalt, because the lower mixing temperatures cause less oxidation of the bitumen contained in the RA. Since there is also less aging of the fresh bitumen during the mixing process, improved low-temperature behaviour can be expected from the blacktop.

Foamed bitumen is also used to aid paving in certain countries because it can increase the compactability of the asphalt.

Benefits

• Same product quality as hot asphalt
• Same recipes as those used for hot asphalt
• Same user guidelines as for hot asphalt
• Same testing procedures
• Fewer emissions on the jobsite
• Lower C0₂ emissions at plant
• Significantly less fuel consumption

MANUFACTURING

Ammann is convinced that the future lies with low temperature asphalt. In cooperation with customers and laboratories, we have developed the Ammann Foam process.

This process is based on the foaming of bitumen with water and is employed in continuous and batch plants. Ammann Foam works without any chemical additives and also can be retrofitted to existing plants with minimal effort.

The process begins when hot bitumen is pumped into the foam generator. Cold water with no chemical additive is injected under high pressure and mixed with the hot bitumen. This water/bitumen mix is then forced through the outlet. The water expands when the mix leaves the foam generator, and the so -called foam bitumen is created.

Benefits

• Heating of the raw aggregate to approximately 115 ° C
• Perfect mix of bitumen and aggregates
• Asphalt compaction at low temperatures
• Foam generator can be integrated into continuous and batch plants
• Retrofitting to existing plants is possible

FOAM GENERATOR

A foam bitumen installation enables expansion of your plant’s product portfolio. The foam generator from Ammann enables the foaming of various hardnesses of road construction bitumen and also polymer-modified bitumen.

The foam generator also can be used to manufacture cold base courses with 100 per cent recycled materials. This means that the use of foam bitumen optimally supplements the recycling feed in the mixer.

DISCONTINUOUS PROCESS (BATCH)

In the first phase of mixing, the rough granular aggregate is placed in the mixer. The foamed bitumen is introduced into the twin-shaft paddle mixer through the nozzle so that it also coats the rough granular aggregate at about 100° C. The remaining aggregate and filler is then introduced into the mixer.

CONTINUOUS PROCESS

The foamed bitumen is introduced into the mixer together with the aggregate at a temperature of about 100° C. The intensive mixing action of the twin-shaft paddle mixer, which operates continuously, ensures excellent coating of all granular aggregate.

CREDENTIALS

HANS WEIBEL AG, FOAM PROCESS

1500 TONNES OF LOW-TEMPERATURE ASPHALT FOR SWISS ROADS

In 2010, Hans Weibel AG laid 1,500 tonnes of low - temperature asphalt on the basis of the WAM Foam ® process on the busy cantonal road near Koppigen in the Swiss region of Emmental. The ACT 22 N W - ecophalt ® that was used was installed as a base and wearing course.

The asphalt was produced 40 kilometres away in Oberwangen. The Universal NG 320 asphalt mixing plant with warm reclaimed asphalt feed has a dual - row mixing tower, a 4 - tonne Amix mixer and a foamed bitumen installation for the production of low - temperature asphalt.

The advantages of using the new kind of asphalt became apparent as soon as installation started : It reached the construction site at a temperature of around 110°C and was compacted using an AV 95 - 2 at temperatures below 80°C. Working on the construction site was therefore comfortable despite high summer temperatures because of reduced bitumen vapours and substantially less heat radiating from the asphalt.

The asphalt surface demonstrated the required degree of compaction at every measured point despite the demanding logistical situation, as a drill core analysis revealed. Road marking work began shortly after the last pass of the roller to enable the release of the road to traffic the next morning.

CAMANDONA SA INSTALLS A FOAM GENERATOR

RETROFITTING AN ASPHALT MIXING PLANT

About 8,000 m² of low - temperature asphalt has been laid on the parking area at the headquarters of an international corporation near Lausanne, Switzerland. Apart from foamed bitumen technology, this project also made use of Ammannʹs recycling addition system with 40 per cent reclaimed asphalt.

In the low - temperature production process using Ammann Foam, conventional bitumen is foamed with a very small quantity of water. This ensures the same aggregate coating as is achieved with hot mix asphalt.

Foamed bitumen makes it possible to reduce the asphalt production temperature to about 115 ° C. The key benefits : lower energy consumption, less CO₂ at the plant and vastly reduced emissions on the road-building site.

Low - temperature asphalts based on foamed bitumen can be laid in the same way as conventional hot mix. Most importantly, the on - site compaction temperature can also be lowered, leaving sufficient time to achieve good compaction.

The asphalt mixing plant dating from the 1990 s was retrofitted with an Ammann foam generator. The foam generator is entirely integrated into the plantʹs as1 Control System. In addition to the foam generator, the plant at Daillens also features a reclaimed asphalt dryer with variable rotation speeds. This ensures that the exhaust gases do not condense, and that the filter reaches its target performance – even at lower production temperatures.

BERAG AG, FOAMED BITUMEN ASPHALT ON SWISS ROADS FOAMED ASPHALT

IN THE SWISS MOUNTAINS

Starting position
Old gravel roads require substantial and costly maintenance. The access roads to the farms of Andreas Kilcher and Christian Zbinden were no exception.

The construction of two asphalt roads in collaboration with engineering company Keller AG was approved following an inspection by the department for structural improvements and production of the Bernese authority for agriculture and nature. The asphalt used was produced by means of environmental friendly Ammann Foam technology.

The „Studerli” farm
It was indeed a challenge. Christian ¬Zbinden’s farm is located in the middle of a hill in Sangernboden. The serpentine - like road has quite an incline to it. Project scheduling had to take various factors into account, including cattle driving as the farmer drives his herd up to the Alps in the summer. „Things are quieter on the farm after that”, says the farmer. And therefore an ideal opportunity to build an asphalt road.

The „Ottenleuebad” farm
As Andreas Kilcher’s cows were driven to the Alps a week earlier, construction company Walo Bertschinger AG began working on his farm first. The task was to lay asphalt on the access road and the courtyard. Andreas Kilcher and his wife knew exactly how they wanted their farm to look. That is why asphalt was laid all the way to the terrace. The challenge here lay in the fact that the asphalt around the courtyard had to be laid by hand due to spatial constraints. But that wasn’t a problem, either.

Blacktop that is twice as environmentally friendly
An environmentally friendly blacktop on the basis of Ammann Foam was used for both of the roads. The ACT 22 L blacktop with foamed bitumen stands out because it is produced at a temperature of around just 115 ° C and can be laid at even lower temperatures. A normal bitumen of type B160/220 was foamed at the Universal S asphalt mixing plant in Rubigen.

The process produced around 750 kg fewer CO₂ emissions thanks to the drop in temperature alone. But that wasn’t all: the blacktop was made using around 50 per cent reclaimed asphalt. Keeping the asphalt temperature at a constant 115° C was easy thanks to a combined feed of hot and cold reclaimed asphalt.

The blacktop composition matched the specifications exactly. This was made possible by modern plant technology and the Ammann as1 control software.

The result is indeed impressive. The blacktop surface is smooth and the finished composition meets the required quality specifications. By the end of the project 150 tonnes, or 2,000 m2, of blacktop were installed on each farm without a trace of on-site emissions thanks to the low installation temperature.