Geosynthetics for erosion control: high performance tests and index properties
Geosynthetics For erosion control: high-performance testing and index properties
Soil erosion, a global problem, has intensified due to human activities. Each year, approximately 75 billion tons of soil are lost at a rate 13 to 40 times faster than natural erosion1. In this context, the call to action is clear: to mitigate the erosion caused by engineering projects and promote solutions that address this concerning situation.
In the search for effective solutions to combat soil erosion, civil engineers have carried out an extensive program of research and development on geosynthetic materials. These materials, which are key to soil protection, undergo rigorous performance and property testing to ensure their effectiveness under various environmental conditions. Let’s take a closer look at the fundamental tests that determine the quality and durability of these products.
- Coverage Factor (ASTM D7101-01): This test evaluates the ability of rolled products to control erosion without vegetation. Using rain simulators with varying intensities, the soil is exposed to the resulting spray and runoff. Samples with and without the erosion control mat are compared to determine the coverage factor, that is, the material’s efficiency in protecting the soil from the effects of rain and associated runoff.
- Shear Strength (ASTM D7207): Designed to evaluate the ability of erosion control mats to withstand hydraulic shear forces, this test simulates water flow conditions in channels or rivers. Shear strength is determined by measuring the load required to cause a predefined loss of soil. This process is repeated under controlled conditions with and without the protective mat, allowing for an evaluation of the material’s effectiveness.
- Environmental Exposure Resistance (ASTM D4355): This test is used to measure the durability of materials when exposed to light, humidity, heat, and climatic cycles. The samples are placed in chambers that simulate extreme conditions for at least 500 hours. Subsequently, tensile strength is evaluated and compared to the initial strength to determine the percentage of strength retention.
- Index Properties: These are properties that allow for quality control of the material during its manufacture.
The most important ones are:
Mass per unit area: determines the material's density and its ability to resist erosion.
Thickness: It refers to the measurement of a material's thickness and is related to its strength and durability.
Light transmission: This parameter makes it possible to determine the proportion of light that passes through the canopy, which is related to its coverage capacity and the ease with which vegetation can develop and grow.
Resilience: It assesses the material's ability to return to its original thickness after a load is applied.
Tensile Strength: It measures the material's resistance to tensile forces, providing key information about its structural performance.
These tests provide a comprehensive overview of the performance of erosion control mats, enabling civil engineers, forestry engineers, agricultural engineers, agronomists, and biologists, among others, to select solutions tailored to the specific conditions of each project. Modern engineering seeks not only effectiveness in terms of erosion control but also long-term sustainability, taking environmental and social aspects into account.
