DANISH MOLES

GROUND LEVEL AND BELOW: For work at ground level and below, Denmark’s Per Aarsleff is among the world’s best. They are specialists in foundation work carried out by driving concrete piles down into the ground

Managing director Ebbe Malte Iversen, Per Aarsleff A/S

The method is known among contractors around the world as ’the Danish pile driving formula’, and is increasingly being used for creating solid foundations beneath building constructions. Reinforced concrete piles are driven into the ground until the piles reach the required load capacity, calculated on impact height, weight of the hammer, and the number of impacts for every 20 centimetres the concrete pile goes into the ground. When the number of impacts reaches a certain value, the pile has reached the required load capacity for the foundation to be laid onto it.

Cheaper

“The method is used for 95% of all foundation assignments in Denmark,” says managing director Ebbe Malte Iversen, Per Aarsleff A/S, Denmark’s largest contractor for civil engineering at ground level and below. The company has its own factories in Denmark, UK and Poland where the reinforced concrete piles are made.

“When foundations are made abroad, in the vast majority of cases a screw is used to drill a hole to sufficient depth, after which the hole is filled with concrete. It is not necessarily an inferior way to do it, but in a number of cases where the ground conditions are suitable, pile-driving is often a cheaper method. The markets reflect this, and we see great progress for this part of our business in the UK, Germany and Po-land.”

Pipe renovation

Aarsleff’s work at ’ground level and below’ should be taken literally. Two of its mainbusiness areas are pipe renovation and the aforementioned pile-driving. The company is also actively involved in infrastructure such as harbours, railways, roads, tunnels, bridges, energy supply, water supply and communication systems. Regarding construction above ground, Aarsleff enters partnership agreements with other companies.

Ebbe Malte Iversen divides the company into industry and projects. “Our most in-dustrialised activities are the prefabrication of foundation piles and renovation of pipes by means of tube lining. The lining tubes and associated curing systems are made at our own factory in Denmark.”

About 25% of Aarsleff’s revenues are generated from renovating old drains, which are provided with new lining. The method, known as tube lining, consists of installing a polyester impregnated tube into the existing pipe by means of water pressure. The tube is then cured by the application of heat, resulting in a smooth new pipe. Aarsleff is among the largest contractors in Europe using this technique. Photo: Ole Hein

Synergies

In addition to the activities associated with the company’s industrial products, Aarsleff has a large number of ongoing projects all over the world. Road construction in Central America, Africa and Asia. Water purification and drinking water facilities in Eastern Europe and Russia. All projects which require competencies in piping.

“We aim to exploit the synergies of our engineers who are special-individual areas,” says Ebbe “When we enter a project it spin-off from our industrial have to be able to do to earn on another.”

It can also work the other way, where project work – perhaps – starts developing into an industry. That is what experience shows from some large sewer projects which Aarsleff has carried out in Mumbai in India and Colombo in Sri Lanka.

Russian factory

“It was some major renovation work on pipes built by British engineers during the colonial period, involving large, egg shaped drains which had started to fall into disrepair,” says Iversen. “We have developed a technology where we make large composite based pipe segments which are lowered into the wells, after which they are pushed together inside the existing pipe so they form completely new pipes. The space between the new pipes and the old existing drain is then concreted. In both Mumbai and Colombo, we have produced the pipe segments locally at a site factory. But in association with similar work in Russia, we will now build our own factory for industrial manufacturing of these pipe segments in Moscow. It could become part of our industry in the long term.”

Aarsleff employs around 2,500 people. Revenues in 2005 were about DKK 3.5 billion (approx. EUR 475 million).

One of the largest assignments Aarsleff is currently involved in is the building of a tunnel in Malmø, Sweden, just across the sound from the Danish capital Copenha-gen. The Citytunnel comprises a 5 kilometre bored double tunnel and a 700 meter approach ramp. Inside the tunnel, a large space for a future metro station is being established. Aarsleff has 25% of the construction contract which is being carried out by an international contractor consortium.

Photo: Perry Nording