Rhoca-Gil
Encyclopedia
Rhoca-Gil is a type of industrial sealant
produced by Rhône-Poulenc
, used in the construction of tunnels to block the passage of groundwater
into the tunnel. The sealant begins as a liquid, is then injected into cavities which need to be sealed, and polymerises
, causing it to harden.
and methylolacrylamide. The mixed solution becomes a viscous fluid that penetrates cracks and holes in the rock, where the fluid reacts - polymerizes
- to a tight plastic substance. When it is completely polymerized it is stable and will not exhaust any toxic compounds.
in Sweden
began, with opening plans for 1995. Groundwater leaking into the tunnel was however a major problem, slowing the progress, and Rhoca-Gil had to be used. In 1997, fish and local cattle started dying as a result of Rhoca-Gil in its liquid form leaking into the water supply, contaminating it with acrylamide, a known carcinogen
and mutagen
. Furthermore, the contamination of the area led to a ban on agricultural products from the area, as well as a ban on using water from the area affecting local residents.
The main contractor, Skanska
, along with Rhône-Poulenc and the Swedish Rail Administration had all criminal charges brought against them. Some senior executives resigned. Construction was halted in late 1997. The main critique of the use of Rhoca-Gil was against Rhône-Poulenc for not pointing out the risks of using the sealant, as well as against Skanska for not informing local residents about the usage of Rhoca-Gil.
A similar incident occurred at the construction of Gardermobanen
in Norway
, leading to a ban of the substance in Norway
in 1997.
Sealant
A sealant may be viscous material that has little or no flow characteristics and stay where they are applied or thin and runny so as to allow it to penetrate the substrate by means of capillary reaction...
produced by Rhône-Poulenc
Rhône-Poulenc
-History of the company:The Company was founded in 1928 through the merger of Société des Usines Chimiques du Rhône from Lyon and Établissements Poulenc Frères from Paris founded by Étienne Poulenc, a 19th century Parisian apothecary and brought to prominence by his second and third sons Emile...
, used in the construction of tunnels to block the passage of groundwater
Groundwater
Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. The depth at which soil pore spaces or fractures and voids in rock...
into the tunnel. The sealant begins as a liquid, is then injected into cavities which need to be sealed, and polymerises
Polymerization
In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...
, causing it to harden.
Process
Rhoca-Gil consists of two fluids, that are mixed, thinned out with water and then sprayed into cracks in the bedrock. One of the fluids contains acrylamideAcrylamide
Acrylamide is a chemical compound with the chemical formula C3H5NO. Its IUPAC name is prop-2-enamide. It is a white odourless crystalline solid, soluble in water, ethanol, ether, and chloroform. Acrylamide is incompatible with acids, bases, oxidizing agents, iron, and iron salts...
and methylolacrylamide. The mixed solution becomes a viscous fluid that penetrates cracks and holes in the rock, where the fluid reacts - polymerizes
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
- to a tight plastic substance. When it is completely polymerized it is stable and will not exhaust any toxic compounds.
Controversies
In 1992 construction of the Hallandsås tunnelHallandsås tunnel
The Hallandsås Tunnel , also known as the Hallandsås Ridge Tunnel or Scanlink, is a railway tunnel under construction in Sweden. It will go between the north and the south side of the Hallandsås. The planned length is . It will be utilized by the West Coast Line, on the section between Ängelholm...
in Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
began, with opening plans for 1995. Groundwater leaking into the tunnel was however a major problem, slowing the progress, and Rhoca-Gil had to be used. In 1997, fish and local cattle started dying as a result of Rhoca-Gil in its liquid form leaking into the water supply, contaminating it with acrylamide, a known carcinogen
Carcinogen
A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...
and mutagen
Mutagen
In genetics, a mutagen is a physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level. As many mutations cause cancer, mutagens are therefore also likely to be carcinogens...
. Furthermore, the contamination of the area led to a ban on agricultural products from the area, as well as a ban on using water from the area affecting local residents.
The main contractor, Skanska
Skanska
Skanska AB, is a multinational construction and development company based in Sweden, where it also is the largest construction company. The company's head office is in Solna, north of Stockholm.-History:...
, along with Rhône-Poulenc and the Swedish Rail Administration had all criminal charges brought against them. Some senior executives resigned. Construction was halted in late 1997. The main critique of the use of Rhoca-Gil was against Rhône-Poulenc for not pointing out the risks of using the sealant, as well as against Skanska for not informing local residents about the usage of Rhoca-Gil.
A similar incident occurred at the construction of Gardermobanen
Gardermobanen
The Gardermoen Line is a high-speed railway line between Oslo and Eidsvoll, Norway, running past Lillestrøm and Oslo Airport, Gardermoen. The line is long and replaced the older Hoved Line as the main line north-east of Oslo...
in Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
, leading to a ban of the substance in Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
in 1997.