Resistance to Biological Effects

However, biological impacts can be classified according to damage mechanisms (Albertson 1992) as well  

Biophysical effects where mechanical impacts cause damage like cracks and holes, e.g. bites by animals or the bursting and swelling pressure of growing cell agglomerations of plant roots. 

Primary biochemical effects (or direct enzymatic actions) where the materials are directly included into the metabolism of the organisms by enzymatic degradation. 

In the certification guideline of DIBt and DIN 16726 the resistance to root penetration is tested by iel5dng on the following test procedure. Unglazed clay pots are used as eontainers. The humidity soil layer and the reclamation soil layer consist of field soils. Lupins of the lupinus albus sort are sown in the reclamation soil layer. A sheet of bitumen 85/40 serves as a reference specimen. The test usually takes between 6 to 8 weeks. 

Working group 4 of the CEN Technical committee 254 has issued a draft standard EN 13948 2000 Flexible Sheets for Waterproofing - Bitumen, Plastic and Rubber Sheets for Roof Waterproofing - Determination of Resistance to Root Penetration in analogy to the test procedure of FLL. However, modifications were introduced which found strong criticism by the experts of FLL. 

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