From concrete rubble to recycled concrete

Production buildings with a long history

Careful cleaning

Noise and vibrations

Work on the new buildings can commence

A sustainable development

Recycling rocks

In its vision of “Sustainability for the Novartis Campus,” the company has committed itself to a careful use of resources. Attention is also paid to the recycling of used materials when buildings are demolished. Particularly for old production buildings this is a complex task and entails well-coordinated work processes, as illustrated by the demolition of buildings WSJ 316, 318 and 319.

Text by Peter Herzog

Chemical-free interior of Building 316 prior to demolition.

Table of contents

From concrete rubble to recycled concrete

Production buildings with a long history

Careful cleaning

Noise and vibrations

Work on the new buildings can commence

A sustainable development

This article was originally published in October 2015.

Muffled thuds, loud bangs and the grinding noise of the mighty picker arms of an excavator shovel biting into the concrete: Construction noise has been an everyday occurrence on the campus in the past few months in the area around Hueningerstrasse and Gate 18. Workmen held thick hoses and sprayed water onto the site to prevent huge clouds of dust. Heavy construction machinery was used to raze buildings WSJ 316, 318 and 319 to the ground. In order to chop up the large chunks of concrete, a special crusher was used that shreds large pieces in the twinkling of an eye. Meanwhile, huge magnets extracted reinforcing steel.

On the site where the three buildings stood, the new Imhotep 5 laboratory and office building is being planned. It is to be designed by the Portuguese architect Gonçalo Byrne. The remaining area will be grassed and will serve as a building land reserve.

From concrete rubble to recycled concrete

Before the new building can be constructed, the old ones had to be removed. As project manager Gregor Martin explains, around 171 000 cubic meters of concrete rubble, construction waste and excavation material were taken away by truck. Ninety percent of the demolished concrete rubble is uncontaminated and can be recycled. This was established by drilling over 100 samples from the concrete walls, floors and ceilings prior to the demolition. Analysis of the samples revealed that most of the concrete construction was not contaminated either with chemicals or with any other substances.

The uncontaminated concrete rubble was taken to Meyer-Spinnler gravel and sand works in Muttenz where it was finely crushed. Following the crushing of the concrete material, gravel was added to create recycled concrete. This can then be used for lean concrete, which is only mixed with a small amount of cement, structural concrete or fair-faced concrete. “This recycled concrete is generally speaking equivalent to ‘normal’ concrete in qualitative terms,” explains Gregor Martin.

Owing to the growing scarcity of gravel resources, the conversion of concrete rubble to recycled concrete is becoming increasingly important in the construction trade and is economically attractive. For ex-ample, the new Letzigrund football stadium in Zurich was also constructed by recycling the concrete rubble of the old stadium.

The more highly contaminated material was taken to the soil washing plant in Ruemlang near Zurich, while the rest was transported to suitable landfills depending on the degree of contamination.

Production buildings with a long history

Until July 2014, buildings WSJ 316, 318 and 319 were in use for production by BioPharmOps and ChemOps Switzerland. The oldest of these three buildings is WSJ 316 and it has a long history. It was built between 1939 and 1941 as a two-story production building. In 1949, what was then Sandoz had started using WSJ 316 to produce the laxative Pursennid®, made of the leaves and pods of senna.

Production of the natural product ran for more than six decades. Parts of the facility, such as the extractors dating from 1948, originate from the early stage of senna production. Over the years the building was converted and extended several times as the ongoing production needs changed. Between 1959 and 1961 the two-story construction was significantly enlarged by four new stories. The entire building needed refurbishing in 1975. Further conversion work took place in 1987 and 1994.

The stone rubble from Building 316 is temporarily stored at Meyer-Spinnler AG before being used for new buildings.

Careful cleaning

ChemOps Switzerland ceased production of Pursennid in WSJ 316 in the fall of 2013. The operating license expired. Furthermore, according to the prevailing regulations of Canton Basel-City regarding earthquake protection, the building would have needed renovation. However, before the excavators were allowed to enter the campus, a large number of preliminary tasks had to be executed: First of all the buildings had to be cleaned in a chemical-free manner. This also included a “historical survey of the buildings and production” in order to find out what had been produced in these facilities over the years, as the engineer responsible, Johann Kreschek, explains.

Various samples were taken and analyzed in the laboratory to elicit the contamination burden of the buildings and infrastructure. It was only on the basis of these insights that the complex cleaning operations commenced. Afterwards in a second process step the production facilities were removed. The infrastructure of the building, such as electrical fittings, heating systems and the elevator, was also dismantled.

The various construction materials originating from different decades repeatedly gave cause for surprise among the analysts. “As is frequently the case in old buildings, one of the problems was asbestos,” explains Johann Kreschek. In previous decades asbestos was often installed to provide insulation or as a fire-resistant material in suspended ceilings or walls, so it was not visible at first sight. “We removed the asbestos in close cooperation with the HSE (Health, Safety & Environment) experts,” says Kreschek. This was a tricky stage of the proceedings involving the removal of all interior walls, ceilings and windows. The actual demolition only started once the buildings had been reduced to a construction skeleton.

Workmen crush Building 316.

Noise and vibrations

Demolition work not only causes noise and dust but also vibrations, as project manager Gregor Martin points out: “In this respect we faced extreme demands because intensive work was taking place in the neighboring buildings. Furthermore, the Chipperfield Building only a few meters away from the construction site contains extremely sensitive equipment for analytical tests that must not be subjected to any kind of vibration whatsoever.”

The noise threshold also had to be strictly observed and the construction workers faced the same question every day: “When are we allowed to drill, when are we allowed to extract?” And the work was still not over when the buildings had been razed to the ground. The old underground tanks had to be removed as well. The earth was extracted and disposed of down to a depth of around 12 meters because a big part of it was contaminated.

Work on the new buildings can commence

First of all, energy supply tunnels for the new building were constructed once every single stone of the foundations laid in 1939 for the former production buildings had been taken away. A large number of pipes were laid in these tunnels, which transport utilities such as steam, water, brine, gas, compressed air, warm supply water, nitrogen or controlled compressed air. The electrical wiring wending its way underground throughout the campus and connecting the individual buildings with each other is also fed through these tunnels. Once the tunnels were in place, the engineers dug even deeper to enable the planned Imhotep 5 laboratory and office building to be supplied entirely with renewable energy for electricity and heating. Around 30 geothermal probes were drilled 200 meters deep for the new construction's geo-storage facility. The principle of the geo-storage facility is that in the summer water is circulated to cool the building. The warm water is pumped down into the ground where it gives off heat and in doing so cools down. In the winter the geo-storage facility acts like a huge cherry stone pillow that has stored the heat from the summer. The water warmed by the earth is then used to heat the building.

Foundations of the new campus of the University of Applied Sciences and Arts Northwestern Switzerland consisting partially of the excavation material from Building 316.

A sustainable development

Just like the geo-storage facility for the new buildings, Novartis also aims to find environmentally friendly, sustainable solutions for the excavation material of the old buildings. To this end the company stands to benefit from the huge progress made by recycling technology in recent years. Furthermore, the recycling of materials from old buildings in order to conserve resources is gaining increasingly broader support among the authorities and others.

Meanwhile, the concrete rubble from WSJ buildings 316, 318 and 319 has already found a new home, as Julien Herzog, operations manager of the recycling department at Meyer-Spinnler, reports.

“We are pleased to have made use of the recycled concrete from the St-Johann site for projects such as the new building for the Kunstmuseum Basel and the campus of the University of Applied Sciences and Arts Northwestern Switzerland in Muttenz, where the canton actually explicitly stipulates the use of concrete rubble,” he explains.

Recycling rocks

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