ASTM's new rCB standard intended to ensure quality

WEST CONSHOHOCKEN, Pa.—Business leaders and industry experts are calling the new ASTM International standard that classifies recovered carbon black a step in the right direction.

Recovered carbon black has gained momentum over the past several years, in both the number of rCB suppliers and in interest from major tire manufacturers, for its green credentials.

About 65 percent of tire makers cite rCB as the "best material to achieve sustainability goals," according to a recent Smithers report on sustainable CB production methods.

"This ASTM item will be arguably the most useful standard for recovered carbon black," stated Martin von Wolfersdorff, a Berlin-based consultant on the rCB industry, in his January newsletter. "It will help producers to know what to produce and buyers to know what they purchase."

According to ASTM, the new standard for rCB, approved Jan. 31 and officially known as D8474, spawned out of the D36 committee (the D24 committee conducts tests and classifications for standard furnace black).

Within the D36 committee is a subcommittee, D36.70, known as "rCB Testing in Rubber," which counts tire majors such as Continental A.G., Bridgestone Corp. and Michelin, and CB suppliers Birla Carbon, Cabot Corp. and Orion Engineered Carbons, as participants.

Essentially, the D8474 classification provides quality control via a test that can help differentiate rCBs. According to ASTM, the test is a thermogravimetric technique that determines organic residue, overall fixed carbon content and ash content in rCB.

To date, rCBs have been refined from the non-virgin material that comes from a pile of tires into semi-reinforcing grades, including N700, N600 and N500 grades.

"The new standard will be a useful tool specifically for quality control and can be used for off-take agreements, technical data sheets and certificates of analysis," said ASTM member Pieter ter Haar, of London-based Circtec Group.

Circtec, a pyrolysis and renewable fuels company, in 2021 began a partnership with Birla Carbon to produce rCB.

"This will be most useful for manufacturers, as well as users and consumers," ter Haar said in a Jan. 31 release from ASTM.

Recovered carbon black uses a more sustainable production method than furnace black processes, as rCB is produced via pyrolysis on end-of-life tires, the energy feedstock rather than fossil fuels.

Pyrolysis, by nature, also is a thermal process, so rCB production, while 100-percent recycled, still maintains a carbon footprint.

Von Wolfersdorff, in his newsletter, cites another work item being analyzed by ASTM, "Standard Guide for Sustainability of recovered carbon black" (WK84622), saying this "will be very important because green credentials like the carbon footprint are an important part of the value proposition for recovered carbon black."

"However, on the topic of carbon footprint, I recommend reporting the carbon footprint with transparency and honesty instead of greenwashing with a life cycle analysis based on the avoidance of emissions," von Wolfersdorff said. "I recommend reporting the three scopes of emissions."

As listed in the Global Reporting Initiative, Scope 1 includes direct emissions from production; Scope 2 includes the purchase of energy; and Scope 3 includes upstream and downstream supply chain emissions.

"I also think that a recovered carbon black classification will only work when the whole industry agrees and when existing proposals for classifications are harmonized into this system," von Wolfersdorff notes.

ASTM said efforts to establish the new standard and testing method are "directly related" to the U.N.'s Sustainable Goal No. 12 "on responsible consumption and production."

"This standard will improve the adoption of rCB," ter Haar said. "Recovered carbon black can complement or substitute conventional carbon black in many applications, including the production of new, more sustainable tires."

ASTM welcomes participation in the development of its standards. Become a member at www.astm.org/JOIN.

"We are always looking for technical input and testing capabilities for the development of new standards," ter Haar said. "We're also looking for labs with TGA capability to help develop bias and precision studies for new standards."

To purchase standards, contact ASTM International at 877-909-ASTM; or email [email protected].