Trisoplast® is an innovative mineral barrierthat provides a large number of benefits in comparison with the traditional mineral liners. In the Netherlands, this material has reached an advanced stage of technical development and has been successfully tested by several independent laboratories regarding its performance. Since 1992, more countries have approved the use of this material as a waterproofing barrier for various applications, becoming the preferred solution. Independent testing carried out on the material and ongoing research have already confirmed the outstanding performance of this product.

Trisoplast® is a registered trade mark. The system was developed by Trisoplast® Mineral Liners and is protected by patents. Trisoplast® is produced under the license of Trisoplast® International.

Trisoplast® consists of the following main components:

  • granular material, e.g. sand
  • bentonite;
  • polymer

These components are mixed in mixing plants and small amounts of water are added if required. Thus Trisoplast® is installed and compacted at water contents close to but below the proctor optimum. In a first step the bentonite powder and polymer powder are blended, secondly the sand and the bentonite-polymer premixture are mixed in a mechanical mixer until achieving a homogeneous material.

!n order to control the dosing of the components, the water contents of the bentonite and granular component must be determined in advance and taken into account when calculating the masses for the correct settings of the mixing plant.

The final mixture is loose, has a granular appearance, is lumps free and easy to handle. The Trisoplast® mixture is handled and compacted with conventional earth construction equipment (telescopic or long-reach excavators and light, smooth drum compactors) in a single layer on a well prepared subgrade of sufficient load bearing capacity. The initial moisture content at mixing causes a first initial binding within the material resulting in a cohesive material which is positive for creating a well compacted layer.

A unique clay-gel is formed from a mixture of sodium activated calcium bentonite and polymers, as soon as additional moisture reaches the applied layer. A very compact gel structure is developed by the network of chemical compounds formed by the clay mineral particles and the polymer (see Figure 1 for additional details).

                                    Fig. 1 Schematic representation of the interaction between bentonite and polymers

The Trisoplast® layer is installed on a dry, well compacted (so that it does not subside) and stable subgrade requiring (like other bentonite-based sealing) a sufficient surcharge of at least 5 to 6 kN/m2 (equals approximately 25 to 30 cm of covering soil or equivalent). A thicker covering layer (normally at least 1 m) is commonly used for landfill applications. In any case the design for a project depends on the application and remains the responsibility of the design engineer.

In comparison with conventional barriers, consisting of natural clays and wet compacted Trisoplast® has the following essential advantages:

  • very homogeneous sealing material made of well-defined components, manufactured in highly accurate mixing plants under the application of quality assurance measures: due to the low diversification of the material properties, the non-existence of excessive particle sizes, the low water permeability and the low compaction requirements, the material can be applied in a single layer of low thickness;
  • very fast application, therefore considerably better coordination with the company installing
    the geomembrane and better protection against the weather influences;
  • lower material consumption and less transport effort;
  • geomembrane protection by the lack of oversized or sharp particles;
  • plastic deformation far superior, allowing the installation of final sealing systems in difficult areas without additional temporary measures;
  • better long-term performance due to a considerably reduced risk of desiccation and shrinkage cracks (compaction at water content under the optimum, delayed releasing of water due to the insulating effect of the polymer);
  • better long-term performance due to the considerably slower liberation of water necessary for the plant roots’ development;
  • better long-term performance due to the inhibition of the ion exchange;
  • lower thickness of the covering layer, allowing a higher waste disposal volume.

In the Netherlands, Trisoplast® was tested, evaluated and approved for use within the sealing systems of the landfills, by various official or private institutes under the supervision of NOVEM (Nederlandse Organisatie Voor Energie en Milieu - Netherlands State Agency for Energy and the Environment). Since then more than 4.6 million m2 (in December 2003) have been sealed with Trisoplast® in the Netherlands from which: 1.2 million m2 bottom liners, 2.6 million m2 in landfill covers and more than 0.8 million m2 for other applications. Further applications in landfills and contaminated sites were realized in the following countries: Germany, Belgium, Finland, Sweden, Italy and Romania.

In Germany Trisoplast® was also examined by the "Trisoplast" working committee formed by the representatives of the environmental government agencies as well as by independent experts from universities and federal agencies, consultant engineers and scientists. Trisoplast® has passed all tests and has been approved as being generally suitable for the surface sealing of waste disposal sites in August 2002.The working committee concluded that a layer of 7 cm Trisoplast® is equivalent to 50 cm thickness of mineral barrier according to TASi (German Landfill Directive for landfills). Since then, Trisoplast® has already been applied in many projects in Germany .

In Romania, Trisoplast® has been applied in Cluj to a hazardous landfill owned by a pharmaceutical company named TERAPIA SA. For this work, the company IRIDEX GROUP CONSTRUCTII took THE QUALITY TROPHY, 2005 awarded by ARACO.