Introduction
The InstaTurf® ShearForce™10 hybrid-turf instant armor mat has exceeded expectations in both intense laboratory testing environments and in harsh, real-world conditions, demonstrating extraordinary erosion control capabilities across a variety of erosion inducing conditions.
Executive Summary
Traditionally, rock rip rap is used for lining drainage channels where flow-induced shear forces are expected to exceed 4 pounds per sf. The InstaTurf ShearForce10 now makes it possible to use more environmentally friendly vegetation in lieu of rock and concrete with the added benefits of lower costs, easier installation, and long-term maintenance.
Over the past several years the InstaTurf ShearForce10 has undergone rigorous ASTM standardized testing procedures and has accumulated examples of real-world effectiveness in the face of extreme erosion conditions. ShearForce10 demonstrated excellent test results in both small-scale and large-scale testing environments as well as proving itself in real-world applications, including through many extreme weather events.
ShearForce10 has consistently excelled under ASTM standardized erosion control testing procedures. These tests proved InstaTurf ShearForce10 performed well in terms of:
- Soil loss.
- Sheer force.
- Ability to perform on a steep slope.
Results reveal that ShearForce10 to be effective on steep slopes of up to 18 degrees, can provide effective channel protection under flow-induced shear forces up to 12 lbs, and boasts soil retention rates of 99%.
Links to Testing Data
Data, Examples and Results
The following includes test results and comparisons to other competitive erosion control products:
Exceeded Small-Scale Testing:
ShearForce10 substantially outperforms conventional Turf Reinforcement Mats (TRMs) under severe small-scale erosion control testing conditions.
NTPEP – ASTM D7207: Ability to Protect Soil from Hydraulically Induced Shear Stresses
- Results: ShearForce10 kept soil loss well under the ½ inch failure criteria at the highest level of applied shear stress.
- Conclusion: All conventional TRMs that have been previously tested by NTPEP failed this test at shear stresses between 2 and 5 lbs/sf. With an extrapolated failure point in this test of over 13 lbs/sf for ShearForce10, the ShearForce10 occupies a class of its own. This heightened level of erosion protection further validates the results of other successful large-scale tests the ShearForce10 has been subjected to.
NTPEP – ASTM D7101: Ability to Protect Soil from Rain Splash and Associated Runoff on an 18-Degree Slope
- Results: ShearForce10 demonstrated extremely effective soil loss prevention ability, completing the test with room to spare.
- Conclusion: ShearForce10 demonstrates just over 99% effectiveness at controlling soil loss vs. the bare soil control group, which is fantastic for rolled erosion control products, and far greater than all turf reinforcement mat test results listed in the NTPEP database.
Equal to Rock Riprap on Large-Scale Testing:
SheerForce10 has proven permissible shear stresses equivalent to 30” rock riprap.
ASTM D6460: Standard test method for determination of rolled erosion control product (RECP) performance in protecting earthen channels from storm-induced erosion.
- Results: Unvegetated ShearForce10 never reached failure in this test, allowing an average of only .2 inches of cumulative soil loss through all 12 flow events, well under the ½ inch failure criteria.
- Conclusion: These excellent results were achieved under shear stresses exceeding 10 lbs/sf and flow velocities over 20 ft/sec, test conditions that are usually reserved for traditional erosion control solutions such as fully vegetated turf reinforcement mats, rock riprap, and tied concrete block mats. The testing demonstrated that ShearForce10, even without vegetation, was equal or superior to these other “traditional” erosion control materials.
In addition to excelling in both small-scale and large-scale laboratory testing, ShearForce10 has clearly proven that it can stand up to the test in real-world settings as well.
Real World Application:
ShearForce10 demonstrated effective erosion control during a near-hurricane strength storm.
Hurricane Isaias: A tropical hurricane that hit the East coast of the United Stated in August of 2020 and impacted a ShearForce10 customer in eastern Virginia that had only recently installed the product in an outfall area and drainage channel on the site just 2 weeks prior.
- How powerful was the storm?
- Making landfall as a Level 1 hurricane (wind speeds of 74+ mph) Isaias was officially downgraded to a “tropical storm” by the time it hit the site in eastern Virginia as wind speeds had narrowly dropped below the threshold.
- Although being technically downgraded, Isaias remained a strong tropical storm as the center crossed over the site. The strongest tropical storm winds occurred across eastern Virginia, causing vast destruction, downing numerous trees and power lines resulting in over 200,000 power outages.
- The area experienced wind speeds between 50-70 mph +/- 3mph
- The dump of water was extremely sudden and historically massive as storm Isaias released 14-times more than the normal amount of precipitation for that area during that time of year; over 6 inches of rainfall fell on the project site.
- Results: ShearForce10 performed exceptionally well at armoring the outfall area and channel bed against scour, exceeding the site manager’s expectations.
- Conclusion: At the site, nearby uncovered ground experienced significant erosion. However, much to the satisfaction of the customer, ShearForce10 held strong, preventing any observable erosion in the outfall and downstream channel, while facilitating vegetation growth within a few weeks after the destructive storm.
Takeaways
- ShearForce10 is a very cost-competitive alternative to other permanent erosion control materials, such as rock riprap or tied concrete block mats, for channel lining applications where shear stresses are expected to exceed 4 lbs/sf.
- ShearForce10 demonstrates similar erosion control effectiveness to other permanent materials from Day-1 of installation, while being less expensive and easier to transport and install without the need for heavy equipment.
- ShearForce10 has been tested time and time again and has continuously proven its effectiveness in both standardized laboratory testing as well as numerous real-world applications.
- Prior to vegetation establishment, ShearForce10 has demonstrated 99% effectiveness at controlling soil loss from rainfall and runoff on steep slopes of 3:1 slope gradient (18 degrees), and a permissible shear stress rating of up to 12 lbs/sf when used in concentrated flow areas such as drainage channels and streambanks.
