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Webinar Q & A Transcript – Surficial Slope Stability With Engineered Earth Armoring System Part 1



Q: If left unvegetated what is the UV resistance of Armormax® system? Would it survive years under the Australian sun?

A: Yes Propex endorse the longevity of the product for up to 100 years. Armormax is the combination of a Pyramat®75 High Performance Turf Reinforcement Mat (HPTRM) and percussion anchor system.

Available laboratory and field test results and monitoring data support the 100yrs design life of Pyramat75 HPTRM even under exposed conditions.

UV resistance is one of the most important components of the HPTRM and Armormax System. A minimum 10,000 hours UV Xenon Arc test (ASTM D-4355) test is recommended. A minimum 85% of retained strength @ 10,000hrs should be considered for the HPTRM in the design and specifications.

 

Q: What are considerations for areas with risk of bushfire?

A: Pyramat75 HPTRM is made of Polypropylene. The product does not propagate flame but will be damaged if in direct contact with fire.  In areas with significant risk of bushfire, covering the HPTRM with 50-75mm cover soil will mitigate damage to the product.

Q: How important is the matting component of the Armormax system in its overall  performance?

A: The properties of the HPTRM are critical. The tensile strength and UV resistance is very important and will affect the performance. The HPTRM must have a high tensile strength (≥ 44kN/m) and high UV resistance (≥ 85% retained strength after 10,000hrs of accelerated UV light exposure to ASTM D4355 test method) to ensure long term performance. Finite Element modelling has proved this and will be discussed in webinar #2 scheduled for 2nd December.

Note: For applications with hydraulic flows on the slope, such as flood protection levees, the large-scale flume test results should also be considered. Further information may be found in the link:

https://globalsynthetics.com.au/wp-content/uploads/2019/07/Advanced-Technology-for-Cyclones-Storm-Damage-Risk-Reduction-Systems-and-Flood-Protection-Levees.pdf

Q: What is the max particle size of the subgrade that would limit the installation of the standard anchors?

A: It depends on the size, depth of anchor and soil conditions. It is suggested to install the anchors using a percussion hammer and a ground rod driver. Areas that have large boulders (floaters) may need additional shorter length anchors to accommodate their location.  More details are  available in the Armomax installation guideline:

http://propexglobal.com/Portals/0/Product%20PDFs/Erosion%20Control/Installation%20Guidelines/ARMORMAX%20for%20Slope%20Installation%20and%20Maintenance%20Guidelines.pdf

 

Q: How does Armormax compare to rock rip rap?

A: Armormax is a sustainable solution with low carbon footprint, installed at typically 1/3 of the cost of hard amour alternatives. It is a strong and flexible, cost effective, environment-friendly solution.

Propex GeoSolutions recently became the first HPTRM manufacturer to verify the carbon footprint of its product. The cradle-to-grave carbon footprint of Pyramat®75 HPTRM is 2.7 kgCO2e per 1m2 of material. Propex TRMs and HPTRMS have more than 20yrs of installations and proven performance in Australia.

More information on the comparison between Armormax and Rock solutions may be found on the link:

https://globalsynthetics.com.au/wp-content/uploads/2018/10/Engineered-Earth-Anchoring-Systems-An-Altenative-Treatment-to-Rip-Rap.pdf



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