Market Trend – From Static Coefficient of Friction (SCOF) to Dynamic Coefficient of Friction (DCOF) Testing

In response to changing market demands, Sika Canada has begun the process of
replacing SCOF (Static Coefficient of Friction) test results derived from ASTM C1028 & ASTM D1894 with DCOF (Dynamic Coefficient of Friction) test results produced using ANSI A137.1-2012 / Section 9.6 methodology

Why?

For many years the North American resin flooring market has not had a strong, unified resin flooring association to generate and promote relevant specifications for our trade. Specifiers and manufacturers alike have typically relied on other related hard surface associations such as tile, terrazzo (TTMAC & TCNA), industrial coatings (SSPC & NACE) and concrete repair (ICRI & ACI) to generate meaningful industry standards. Our trade has selectively extracted relevant documentation from these organized groups and applied them to our unique market segment. Slip resistance values for resin flooring in Canada have long been associated with the ceramic tile industry specification CGSB M75.1-88 (withdrawn 2011) that specified ASTM C1028 method for reporting SCOF values.


During 2012, the North American tile industry abandoned SCOF testing ASTM C1028 method in favour of DCOF testing utilizing the BOT 3000 digital tribometer. This change has now become the new standard, increasing in acceptance over time based on the belief that DCOF is more commonly used worldwide and arguably relates better to slips occurring while a person is in motion. A more detailed explanation about the validity and reasons for this change is available in two TCNA documents: Coefficient of Friction / Technical Bulletin 2013 and Introducing the New Standard for Measuring Coefficient of Friction published in Tile Magazine May/June 2012, both are available on the TCNA web site at the following link: http://www.tcnatile.com/industry-issues/dcof-acutest.html


Definitions of SCOF and DCOF

Static Coefficient of Friction (SCOF)1
The force required to initiate relative motion between an object and a surface it
is resting on.

Dynamic Coefficient of Friction (DCOF)1
The force required to keep a sliding object in motion, once slipping has begun based on the ratio of sliding resistance to vertical force.

Technical Corner - From Static Coefficient of Friction (SCOF) to Dynamic Coefficient of Friction (DCOF) Testing

Left picture: ASTM C1028 / Pull-Meter Static Coefficient of Friction. Right picture: ANSI A137.1 / BOT 3000 Dynamic Coefficient of Friction

Comparing SCOF to DCOF2
The TCNA technical bulletin explains that in various studies of more than 300 tile surfaces, TCNA researchers found that 0.60 wet SCOF to ASTM C1028 correlated on average with 0.38 wet DCOF using the BOT 3000 equipment and methodology in ANSI A137.1-2012. “Considering both the TCNA research and years of research in Europe, the ANSI A108 Accredited Standards Committee decided to adopt the German recommendation and included in ANSI A137.1-2012 a required minimum threshold of 0.42 DCOF for level interior spaces expected to be walked on when wet. By requiring a value higher than 0.38, the new standard provides an additional measure of safety over the widely used ASTM C1028 wet SCOF value of 0.60”.


Sika Experience
Sika Canada purchased a BOT 3000 digital tribometer in 2015 and began the process of assessing Sikafloor® and Sikagard® resin flooring materials and systems for publication in the 2017 catalogue. To date, we have found the tribometer is capable of repeatedly measuring small variations in surface texture well beyond the capacity of the ASTM C1028 test method. The degree of measurable surface irregularity found is a direct function of the type of texture being tested: Smooth neat film applications produce the most consistent DCOF test results. Full aggregate or flake broadcast systems produce a slightly wider variance range highly depending upon aggregate or flake size / gradation and finish coat application thickness and uniformity. Finally, partial broadcast and back rolled textures consistently produces the widest DCOF variance a direct result of random aggregate dispersion.

Reference Sources;
1SSPC Technology Guide No.21, Guide to Evaluation of Slip and Fall Resistance of Flooring Surfaces, 2015
2TCNA Technical Bulletin 2013 / Coefficient of Friction and the DCOF AcuTest, 2013


Abbreviations:

ACI – American Concrete Institute
ANSI - American National Standard Institute
ASTM - American Society for Testing and Materials
ICRI - International Concrete Repair Institute
NACE - NACE International Institute
SSPC - The Society for Protective Coatings
TCNA - Tile Council of North America Inc.  
TTMAC - Terrazzo Tile & Marble Association of Canada

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