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Nilex Jun17

Author: Ian Corne

The use of ACBs has been growing over the past number of years as their economic, environmental, and performance advantages over rip-rap and other revetment systems have become clear. With growing technology adoption comes increased scrutiny on product performance. Owners and designers considering technology new to their jurisdictions and practices need modern evaluation tools to help choose products and asses alternatives.

Until recently, the hydraulic conveyance design industry has been working with design values from product testing and evaluation executed under the United States Department of Transportation Federal Highways Administration (FHWA) in 1988 and 1989. The testing protocols still stand and product testing data collected since 1988 remain valid. The ACB industry has enjoyed 28 years of field experience to inform and validate data points and design methodologies.

Over the last dozen years, the hydraulic design and academic community, as well as ACB manufacturers and distributors, have been working to come to consensus under ASTM scrutiny, on the topic of “Analysis and Interpretation” of all the test data collected since 1988. In 2016, the community’s consensus was reached, represented by the renewal of all four ASTM standards relating to ACB systems.

ASTM standards are recognized as the hallmark of standardized testing and protocols in the ACB industry. These standards allow industry professionals to design with confidence that the materials they are using are suitable for their project, using third-party, unbiased design and testing criteria.

The four ASTM standards pertaining to ACB systems work in unison to provide the designer with a comprehensive set of thoroughly considered standards to guide design and installation of ACB products manufactured and evaluated under exacting scrutiny. Strict QA/QC protocols can be established when four standards are referenced in specifying an ACB system.

It is important to consider that most erosion control testing standards are event-based protocols with data sets collected to illustrate discrete performance in the test, or simulated design event. As these standards are based on an overtopping event in a rectangular flume to arrive at performance benchmarks, care and judgment must be exercised in applying values to non-rectangular structures.

ASTM standards are to be used in conjunction with professional judgment informed by education and experience.

Four ASTM Standards Pertaining to ACB Systems:

D7277: Performance Testing of Articulating Concrete Block Systems for Hydraulic Stability in Open Channel Flow
Scope: “The purpose of this test method is to provide specifications for the hydraulic testing
of full-scale articulating concrete block (ACB) systems under controlled laboratory conditions
for purposes of identifying stability performance in steep slope, high velocity flows.”(1)

D7276: Analysis and Interpretation of Test Data for Articulating Concrete Block (ACB) Systems in Open Channel Flow
Scope: D7267 is intended to be used in conjunction with D7277. “The purpose of this guide is to provide recommended guidelines for the analysis and interpretation of hydraulic test data for articulating concrete block (ACB) systems under steep slope, high velocity flow conditions in a rectangular open channel. Data from tests performed under controlled laboratory conditions are used to quantify stability performance of ACB systems under hydraulic loading.”(2)

D6684: Standard Specification for Materials and Manufacture of Articulating Concrete Block(ACB) Systems
Scope: “The purpose of this Standard is to provide specifications for articulating concrete block (ACB) system structural components, material composition and physical properties, manufacturing methods and testing requirements.”(3)

D6884: Standard Practice for Installation of Articulating Concrete Block (ACB) Systems
Scope: “The purpose of this standard is to provide recommended guidelines for the proper installation of articulating concrete block (ACB) systems.”(4)

1 ASTM 7277, page 1
2 ASTM 7276, page 1
3 ASTM 6684, page 1
4 ASTM 6884, page 1

This article was reprinted with permission from Nilex, a leader in the geosynthetics industry providing innovative solutions to support the unique challenges of civil, resource and environmental construction projects. For more, visit www.nilex.com

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