Test and Classify The Source of Recycled Rubber user guide sustainable solutions is our business Funded by California Department of Resources Recycling and Recovery Test and Classify Recycled Rubber Click Here to Watch Video
Test and Classify the Source of Recycled Rubber User Guide and Video This User Guide, “Test and Classify the Source of Recycled Rubber” and accompanying Video were produced by Contractor DKE Enterprises, Inc. (DBA DK Enterprises) under the CalRecycle Feedstock Conversion Technical Assistance and Material Testing Services (FCS) Contract DRR18113. The statements and conclusions of the user guide and video are those of the contractor and not necessarily those of the California Department of Resources, Recycling and Recovery, its employees or the State of California. The State makes no warranty, expressed or implied, and assumes no liability for the information contracted in the succeeding text and video. DK Enterprises makes no representations or warranties, expressed or implied. Any mention of individual businesses and their commercial products should not be construed as an endorsement of such products or processes. Funded by Department of Resources, Recycling and Recovery
Table of Contents Designation: D5644−18 Standard Test Method for Rubber Compounding Materials—Determination Size Distribution of Recycled Vulcanizate Partic Rubber1 This standard is issued under the fixed designation D5644; the number immediately following th original adoption or, in the case of revision, the year of last revision. A number in parentheses in superscript epsilon (´) indicates an editorial change since the last revision or reapproval. cedures for determinl d vulcanizate 90 μm 3. Terminology 3.1 Definitio 3.1.1 paren product. 3.1.2 recy n onal standard was develop pment of International Standards, Designation: D5603−19 Standard Classification for Rubber Compounding Materials Particulate Rubber1 This standard is issued under the fixed designation D5603; the original adoption or, in the case of revision, the year of last rev superscript epsilon (´) indicates an editorial change since the covers the compounding ma d vulcanizate particulat ber is the prod ed b ational standard was develop opment of International Standards, Designation: D8268−19 Standard Practice for Rubber Compoundin Vulcanizate Particul This standard is issued under the fixed original adoption or, in the case of revi superscript epsilon (´) indicates an ed overs the evalu rcially tional standard was dev opment of International Standar Table of Contents................................................................................................3 About the User Guide .........................................................................................4 Classify the Source of Recycled Rubber ............................................................6 Test Method – Particle Size Distribution of Recycled Rubber ..........................10 Quality Control Practices ..................................................................................16 Test and Classify Recycled Rubber Video Tutorial...........................................15 Tire-Derived Products (TDP) and Link to California TDP Catalog....................20 Appendix A Glossary of Terms and Acronyms..................................................22 Appendix B Guidelines and Test Methods........................................................49
About This User Guide Purpose This User Guide and Video, Test and Classify the Source of Recycled Rubber, were developed to raise awareness about standards and testing in the design and development of recycled rubber products, new technologies and uses. Looking beyond the idea of just making a product, manufacturers are designing products that can be reusable. For example, the circular model includes designing waste out of the system and building economic, natural and social principles. Best Management Practices The following influence the success to developing a product, new technology or use: • Customer – products are customer driven • Tire-Derived Material (TDM) Feedstock Supplier • Tire-Derived Product (TDP) Manufacturer • Compounder • Specifier • Equipment – determines the quality and quantity of the feedstock required for a product and capability of the TDP Manufacturer to produce a product. • Testing Standards, Protocol, Testing Facility • Expected Timeline for Return on Investment The user guide and video support the importance of selecting the TDM supplier that can successfully provide consistent quality and quantity of feedstock material for a product. The Classification of recycled rubber is based on the source of rubber as identified in ASTM Designation D5603-19 Standard Classification for rubber compounding and is important in the design and development of new products, technologies and uses. The vibratory shaker system exemplifies one type of equipment that is use to determine the particle size distribution using ASTM Designation D5644-18 Standard Test Method. ASTM Designation D8268-19 Standard Practice identifies quality control practices for rubber compounding materials. Appendices Appendix A - Glossary of Terms and Acronyms Appendix B - Guidelines and Test Methods Acknowledgement The California Department of Resources Recycling and Recovery (CalRecycle) and DKE Enterprises, Inc. (dba DK Enterprises), contractor to the Feedstock Conversion Technical Assistance and Material Testing Services Contract, would like to thank all of the firms and individuals that have contributed information, time and resources in the production of the video tutorial and user guide.
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Classify the Source of Recycled Rubber Classification The source of rubber and particle size distribution are important factors in rubber compounding and identifying the appropriate rubber feedstrock for a product. Recycled rubber is used as a feedstock for many products and uses including molded rubber products, devulcanization, recovered carbon black, tire-derived aggregate, rubber asphalt, turf infill, thermal decomposition and other tire and non-tire derived products and end uses. Classification of recycled vulcanizate particulate rubber is based source of rubber on the in ASTM D5603-19 (Table1) and the particle size distribution (Table 2). Table 1 Table 1 captures eight classifications by the source of rubber. Identifying the source of the feedstock may add to the success in the development of products and technologies. Tire-derived material (TDM) and non-TDM feedstock are derived from a variety of processes using an array of equipment that can handle the tire and non-tire rubber. The classification of the source of rubber includes: Classification 1: Whole Tires Certain types Classification 2: of whole tires with further classification Classification 3: Non-highway tires Classification 4: Tread only from all highway tires Classification 5:Tread only from non-highway tires Classification 6:Tread and shoulder rubber from the retread process to produce buffings Classification 7:Tread, shoulder and sidewall rubber from the retread process to produce buffings Classification 8:Non-tire rubber Recycled rubber particulate is important in rubber compounding so that the results when the rubber has been processed by some means will obtain a desired particle size distribution. Recycled on the source of rubber in ASTM D5603-19 Table1)and the particle size distribution Table 2). Table 1 captures eight classifications as the source of rubber. from a variety of processes using an array of equipment that may that can handle the tire and non-tire rubber. The classification of the source of rubber includes: Classification 2: Certain types of whole tires with further Classification 4: Passenger car, light truck, truck and bus tires Classification 6: Tread and should from highway tires Classification 7: Tread, shoulder and sidewall from highway tires Classification 8: Non-tire rubber
Classify the Source of Recycled Rubber Table 1 (Continued) The demand for specific feedstock sources are determined by the type of equipment and use as a feedstock supply in the manufacture of vulcanized and devulcanized products or end uses or both. Classify the Source - Page 2 Table 1 Copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standards may be obtained from ASTM International ASTM.org
Classify the Source of Recycled Rubber Classification by Particle Size Particle size distribution is further identified by the range of sizes of the particulate material. The size reduced tire-derived material (TDM) and non TDM particle size designation portion of the classification is based on Test Method D5644-18, which is used to determine the particle size distribution. Table 2 Table 2 is designed to assist in the classification of recycled rubber that has been reduced in size to a limited size and is divided into two sections: 1. Table 2A Coarse sizes to a maximum of 1mm (18 mesh) 2. Table 2B Material sizes smaller than 1 mm (18 mesh) Table 2 Copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standards may be obtained from ASTM International ASTM.org Classify the Source - Page 3 i l i i i i i i i i i i l i l i i i i l i l i i i i l i i i i i i i i l i i i i l i i i i l i i i l i i li i i i i i i i l i i l i l i l l i t I t ti l, i , t , . f t l t t t i f I t ti l . l i
Quality Control Practices Quality Control - Page 2 Determination of Fiber Content 1. Perform a normal sieve analysis procedure in accordance with ASTM D5644-18 Standard Test Method. 2. As the test screens are disassembled, there may be free fabric in the form of bundles of fibers or “fabric balls” which can be removed from each screen level. 3. Accumulate the “fabric balls” as the screens are disassembled. 4. Weigh the “fabric balls” using a similar method used for the metal weighing procedure. Determine the weight in grams +/- 0.1 g. 5. Because the sample used is 100 grams, the mass recorded for the “fabric balls” represents the percentage of the fabric in the sample. 6. The “fabric balls” may entrap very small particles of rubber. It is permissible to attempt to dislodge these particles by shaking the “fabric balls” or dropping them on a clean surface. Weighing the “fabric balls” with entrapped rubber will tend to distort the fabric content to the higher value. 7. Report the result to the nearest 0.1 g.
Test Method Particle Size Distribution of Recycled Rubber Vibration Shaker System Test Method Overview This section of the User Guide, Test and Classify the Source of Recycled Rubber, will provide an overview of the steps to perform the vibratory shaker system test method and identify how to measure the results of the test. The shaker system testing process, which follows the steps in ASTM D5644-18 Standard Test Method, describes the procedures for determining the average particle size distribution of recycled particulate rubber for 90 µm (170 mesh) or larger particles. The values referenced in the user guide are identified in both the International System of Units (SI) and in U.S. measurements. The values stated in SI units shall be considered standard and values stated in inch-pound units shall be considered informative as per the ASTM International Standards. We are using the W.S. Tylor Ro-Tap® RX-29 Model, designed for 200 mm (8 inch) diameter test sieve trays to perform the ASTM Designation D5644-18 Test Method. The shaker system provides a horizontal, circular motion and a vertical, tapping motion. This action allows material particles to fall through critical openings in the sieve trays. The shaker trays are used for particle separation and to determine the average particle size distribution of the recycled rubber. Both this user guide and the accompanying 10-minute video tutorial located at https://vimeo.com/532603028 provide instructions that follow the ASTM Designation D5644-18 Standard Test Method.
Items Needed in Preparation of Testing Five Steps We will show the five steps to determine the particle size distribution. 1. Select the sieve screen trays 2. Prep the specimen 3. Prepare the flow agent 4. Screen the specimen 5. Evaluate the Results Step 1: Select the Test Sieve Screens The particle size and the number of test screens used depends on the particle size distribution that is requested by the customer or use. It is optional to use two or six sieve trays. Test Method Particle Size Distribution of Recycled Rubber Test Method - Page 2 1. Clean set of 200 mm (8 inch) sieve trays to perform test 2. Six - 200 mm (8 inch) brass or stainless-steel sieve trays 3. One - 200 mm (8 inch) receiver pan 4. One - 200 mm (8 inch) lid 5. Digital scale with tare function, with a sensitivity of weighing at a minimum of 0.1 grams 6. Assortment of brushes a. Soft brass wire brush for materials that are 425 µm (40 mesh) and coarser b. A nylon bristle brush for cleaning sieves finer than 425 µm (40 mesh) 7. Glass or measuring cup, with a capacity of 500 cm3 (pint) 8. Glass wide-mouth jar with lid, with capacity of 500 cm3 9. Rubber balls or plastic rings (two per sieve tray) 10.Flow agent (magnesium silicate, silica, talc) 11.Tweezers to extract small pieces of fiber (if present) 12.Magnet 13.Shop vac 14.Clean rags
Test Method - Page 3 Test Method Particle Size Distribution of Recycled Rubber Step 1: Select the Test Sieve Screens (Continued) 1.1 Select test sieve screens appropriate to the particle size distribution of the product being tested. The customer and manufacturer determine what is acceptable as a particle size for the product or use. We selected ASTM D5603-19 standard particle size 2.0 mm (10 mesh) to use as the example for testing. Once tested, the results recorded should show that the top screen 3.4 mm (6 mesh) has zero material retained in the top screen 3.4 mm (6 mesh) and not more than 5% of material in the 2.0 mm (10 mesh) sieve tray/pan to pass. It is optional rather to use two or six sieves when testing. We used the following six sieves for the test: 3.4 mm (6 mesh), 2 mm (10 mesh), 1.7 mm (12 mesh), 1.4 mm (14 mesh), 1.2 mm (16 mesh) and 1.0 mm (18 mesh). 1.2 Verify each sieve screen is clean. 1.3 Start stacking with the 200 mm (8 inch) receiver pan on the bottom. Then add two rubber balls or two plastic rings to each of the six sieve trays above the receiver pan. This is the standard to use the rubber balls or plastic rings if 425 mm (40 mesh) and coarser. The sieve trays are stacked in order of increasing mesh size with lower sieve size number on the top and the higher sieve size number on the bottom. Step 2: Preparation of Specimen 2.1 Obtain approximately 150 g to 200 g of vulcanizate particulate rubber from the lot. 2.2 Place an empty measuring cup on the digital scale. Press tare feature and the scale display should show zero. 2.3 Use the glass container or metal measuring to weigh 100 g of specimen to the nearest 0.1 gram. 2.4 Transfer the 100 g specimen into the open mouth glass jar.
Test Method - Page 4 Test Method Particle Size Distribution of Recycled Rubber Step 3: Prepare of Flow Agent The flow agent lubricates the rubber so that it can go through the mesh during the sieve shaker process. 3.1 Place empty 500 cm3 glass or metal measuring cup on the digital scale. Press tare feature and the scale display should show zero. 3.2 Measure 5.0 +/- 0.1g of flow agent for designated coarser than 300 µm (50 mesh). Measure 15.0 +/- 0.1g of flow agent for products that are designated 300 µm (50 mesh) or finer. 3.3 Add the flow agent to the specimen in glass jar containing the rubber sample and seal the jar by closing the lid. 3.4 Shake the glass jar for a minimum of one minute until agglomerates are broken and flow agent is uniformly mixed or dispersed. Step 4: Screening the Specimen 4.1 Empty mixture of the rubber and flow agent from glass jar and place on top screen and place lid on top of stack. 4.2 Place the stack in the shaker. 4.3 Turn on the shaker system. 4.4 Activate the shaker for 10 min for products designated coarser than 300 µm (50 mesh). And, for products designated 300 µm (50 mesh) or finer, activate the shaker for 20 min. 4.5 After the shaker completes the appropriate cycle, remove the stack. Step 5: Determine Weight Retained on Each Sieve and Record Results 5.1 Determine the empty weight of empty glass container or measuring cup. Place the glass container or metal measuring cup on the digital scale. Press the tare feature and the scale display should show zero. 5.2 Starting with the top sieve, remove the screened fraction by gently tapping its contents to one side and pour the contents into the glass container or metal cup.
5.3 Brush any material that sticks to the bottom of the screen onto the next finer screen. Any material released by back brushing the sieve should be included in the measurement of the tray. 5.4 Record the mass to the nearest 0.1 g on the sieve data report. Record any mass less than 0.1 g as trace. 5.5 Repeat steps 5.1 to 5.4 until all sieves in the stack and the bottom collection pan have been emptied, weighed, and recorded. This gives the weight retained on each screen. 5.6 Total the numbers on the sieve analysis. The total should be within 2 grams of the starting specimen weight that included 100 g of rubber and the amount of flow agent used. If the sum of the weights is not within 2 grams of the initial sample weight, then retest. Test Method Particle Size Distribution of Recycled Rubber Test Method - Page 5 Step 5: Determine Weight Retained on Each Sieve and Record Results (Continued) We selected ASTM D5603-19 Standard particle size 2.0 mm (10 mesh) to use as the example for testing. Once tested, the results recorded should show that the top screen 3.4 mm (6 mesh) has zero material retained in the top screen 3.4 mm (6 mesh) and not more than 5% of material in the 2.0 mm (10 mesh) sieve tray/pan to pass. Tested 2.0 mm (10 Mesh)
Test Method - Page 4 Test Method Particle Size Distribution of Recycled Rubber Step 3: Prepare of Flow Agent The flow agent lubricates the the rubber so it can go through the mesh during the sieve shaker process. 3.1 Place empty 500 cm3 glass or metal measuring cup on the digital scale. Press tare feature and the scale display should show zero. 3.2 Measure 5.0 +/- 0.1g of flow agent for designated coarser than 300 µm (50 mesh). Measure 15.0 +/- 0.1g of flow agent for products that are designated 300 µm (50 mesh) or finer. 3.3 Add the flow agent to the specimen in glass jar containing the rubber sample and seal the jar by closing the lid. 3.4 Shake the glass jar for a minimum of one minute until agglomerates are broken and flow agent is uniformly mixed or dispersed. Step 4: Screening the Specimen 4.1 Empty mixture of the rubber and flow agent from glass jar and place on top screen and place lid on top of stack. 4.2 Place the stack in the shaker. 4.3 Turn on the shaker system. 4.4 Activate the shaker for 10 min for products designated coarser than 300 µm (50 mesh). And, for products designated 300 µm (50 mesh) or finer, activate the shaker for 20 min. 4.5 After the shaker completes the appropriate cycle, remove the stack. Step 5: Determine Weight Retained on Each Sieve and Record Results 5.1 Determine the empty weight of empty glass container or measuring cup. Place the glass container or metal measuring cup on the digital scale. Press the tare feature and the scale display should show zero. 5.2 Starting with the top sieve, remove the screened fraction by gently tapping its contents to one side and pour the contents into the glass container or metal cup.
Quality Control Practices Test Methods Specific to this Standard Practice Items needed in preparation for determining metal content, fiber content and bulk density for the particulate rubber test samples. 1. Nonmagnetic surface or container capable of holding a 100 g rubber sample 2. Small horseshoe magnet 3. Digital scale with tare function, with a sensitivity of weighing at a minimum of 0.1 g 4. Assortment of stiff bristled cleaning brushes 5. Cylindrical Container, 1,000 cm3, having uniform height and no pouring lip or deformation of the walls of the container 6. Straightedge or Spatula, at least 150 mm in length Determination of Metal Content 1. Weigh out a 100 g +/- 0.1 g sample of recycled vulcanizate particulate rubber to be tested. 2. Place the 100 g sample on a flat nonmagnetic surface or container. Drag a small horseshoe magnet over and through the specimen for 60 seconds. 3. Place a clean nonmagnetic weighing tray on the scale and press the tare button. The scale should display zero. 4. Using a stiff bristled nylon brush, clean the metal fragments off the magnet into the weighing tray. 5. Weigh the metal fragments to the nearest 0.1 g. The mass represents the percentage of free ferromagnetic metal in the sample. 6. Report the result to the nearest 0.1 g.
Quality Control Practices Quality Control - Page 2 Determination of Fiber Content 1. Perform a normal sieve analysis procedure in accordance with ASTM D5644-18 Standard Test Method. 2. As the test screens are disassembled, there may be free fabric in the form of bundles of fibers or “fabric balls” which can be removed from each screen level. 3. Accumulate the “fabric balls” as the screens are disassembled. 4. Weigh the “fabric balls” using a similar method used for the metal weighing procedure. Determine the weight in grams +/- 0.1 g. 5. Because the sample used is 100 grams, the mass recorded for the “fabric balls” represents the percentage of the fabric in the sample. 6. The “fabric balls” may entrap very small particles of rubber. It is permissible to attempt to dislodge these particles by shaking the “fabric balls” or dropping them on a clean surface. Weighing the “fabric balls” with entrapped rubber will tend to distort the fabric content to the higher value. 7. Report the result to the nearest 0.1 g.
Quality Control Practices 1. Obtain approximately 275 +/- 25 g of recycled rubber from the lot. See Practice E105). 2. Place a 1,000 cm3 +/- 0.1 cm3 cylindrical container on the scale and push the tare button. The scale should display zero. 3. Fill the cylindrical 1,000 cm3 +/- 0.1 cm3 container with enough sample to be higher than the edge of the container by pouring the sample into the center of the container from no higher than 50 mm above the rim of the container. 4. Depending on the particle sizes of the sample, this could be somewhere between 250 g to 500 g. 5. Level the overfilled container by a single sweep of the straightedge or spatula held perpendicular to and in firm contact with the lip of the container. 6. Record the weight (mass) of the rubber sample to the nearest 0.1 g. 2. Report a. Record the date of test b. Identification of samples c. Report the result to the nearest 0.1 kg/m3 Determination of Bulk Density The measurement of bulk density will provide a relative indication of uniformity of process samples. Control of the particle size will directly affect the bulk density of the processed sample. The more uniform large particles will have a lower bulk density than samples that contain a large number of fines/ fiber. The bulk density of recycled vulcanizate particulate rubber is determined from the mass of the particulate rubber contained in a cyclindrical container with the volume of 1000 +/- cm3. Calculation 1. Calculate the bulk density DB to the nearest 0.1 kg/m3 as follows: DB = W/Vc * 1000 where: DB = bulk density, in kg/m3 W = mass of recycled vulcanizate particulate rubber in the tared cylindrical container, in grams Vc = volume of cylindrical container, in cm3 Quality Control - Page 3
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Roofing ADA Levelers Walking Path Rotating PlatformTurntable Rooftop Safety Rooftop Tiles Pipe Sealent Roofing Sport Flooring Antifatigue Mats Walking Path Permeable Pavers Bloxx Flexi T-Wall Commercial Turntable Ballistic Mats Traffic Safety Test Particle Size ADA Ramp Permeable Blocks, Pavers and Pavement Uses Revised November 2020 California Tire-Derived Product Catalog https://www.e-productcatalog.com/TDPCatalog
Guardrail Weed Mats Pipe Sealants Civil Engineering Roofing Paving Patch Permeable Pavement Play Surfacing Rubber Mulch ADA Levelers Weed Mat Highway Median Pavers Roofing Sustainable Pavers Sport Flooring Traffic Safety Tire-Derived Aggregate Rubber Asphalt Paving Sports Flooring Crumb Rubber Transport Bike Pathway
Glossary of Terms and Acronyms Page 1 | 27 Appendix A Glossary of Terms and Acronyms A Abatement Removal of scrap tires from stockpiles or other sites which have accumulation of whole or size reduced scrap tires. Accelerator A chemical that affects the rate of vulcanization of rubber compounds. Activator Chemicals added to rubber compounds to activate accelerators to speed up the vulcanization process. Adhesion Bond between two cured surfaces. Aging Evolution or change of physical and chemical properties of rubber by oxidation, heat, operating stresses or moisture over a period of time. Ambient Temperature Temperature (°F or °C) of immediate surroundings, usually room temperature. Alternative Daily Cover (ADC) ADC is a means to cover other than earthen material (e.g., soil) the surface of the active face of municipal solid waste landfills at the end of an operating day to control vectors, fires, odors, blowing litter and scavenging. Ambient Grinding An ambient system includes size reduction steps of rubber, tires or other feedstock through a process (e.g. granulator, cracker mill) at or near room temperature. The ambient system is also referred to as Mechanical. Ambient grinding is a multi-step processing technology that uses a series of machines (usually three) to separate the rubber, metal, and fabric components of the tire. Ambient Ground Rubber Scrap rubber processed at or above ordinary room temperature. Produces a rough texture with increased surface area due to a tearing process. See Ground Rubber.
Glossary of Terms and Acronyms Page 2 | 27 Asphalt Binder A viscous, tar-like petroleum product used as a cement that binds stone and sand together in asphalt pavements. Asphalt Rubber Asphalt cement modified with crumb rubber modifier (CRM). ASTM International ASTM International, formerly the American Society for Testing and Materials (ASTM), is a voluntary standards organization that develops and publishes thousands of international voluntary consensus standards per year for materials, products, systems and services. The worldwide standards intend to improve product quality, enhance safety, facilitate market access and trade, and build consumer confidence. Working in an open and transparent process, ASTM producers, users and consumer members participate in developing industry standards that include test methods, classification, specification, guides, practices and terminology that support industries and governments worldwide. ASTM standards that apply to rubber recycling are listed below. The definitions found within these standards are used to define some of the terms listed in the Glossary. The Glossary provides a reference to the specific standard definition when it is used. ASTM D1566- 21 Standard Terminology Relating to Rubber ASTM D3053 - 20 Terminology Relating to Carbon Black Material consisting essentially of elemental carbon in the form of near-spherical colloidal particles and coalesced particle aggregates of colloidal size, obtained by partial combustion or thermal decomposition of hydrocarbons. ASTM D5603-19 Standard Classification for Rubber Compounding Materials - Recycled Vulcanizate Particulate Rubber This standard classifies the compounding material – recycled vulcanizate particulate rubber – according to maximum particle size, size distribution and parent materials including passenger car tires, light truck, truck, bus, agriculture, off-the-road (OTR) tires; tire peels, buffings generated from the tire tread and shoulder, buffings generated from tire tread, shoulder and sidewall and non-tire rubber. ASTM D5644-18 Standard Test Method for Rubber Compounding Materials - Determination of Particle Size Distribution of Recycled Vulcanizate Particulate Rubber Describes the procedures for determining average particle size distribution of recycled vulcanizate particulate rubber using a mechanical sieve shaker for 90 μm (170 mesh) or larger particles.
Glossary of Terms and Acronyms Page 3 | 27 ASTM D8268-19 Standard Practice for Rubber Compounding Materials—Evaluation of Recycled Vulcanizate Particulate Rubber Provides references for standard test methods for composition analysis of rubber and offers a guide for methods widely applied by the recycling industry. ASTM D6270-17 Standard Practice for Use of Scrap Tires in Civil Engineering Applications Provides guidance for testing the physical properties, design considerations, construction practices, and leachate generation potential of processed or whole scrap tires in lieu of conventional civil engineering materials, such as stone, gravel, soil, sand, lightweight aggregate, or other fill material. This practice is intended for use of scrap tires including tire derived aggregate (TDA) comprised of pieces of scrap tires, TDA/soil mixtures, tire sidewalls, and whole scrap tires in civil engineering applications. This includes use of TDA and TDA/soil mixtures as lightweight embankment fill, lightweight retaining wall backfill, drainage layers for roads, landfills, and other applications, thermal insulation to limit frost penetration beneath roads, insulating backfill to limit heat loss from buildings, vibration damping layers for rail lines, and replacement for soil or rock in other fill applications. ASTM D6700-19 Standard Practice for Use of Scrap Tire Derived Fuel Provides guidance for the material recovery of scrap tires for their fuel value. The conversion of a whole scrap tire into a chipped formed for use as a fuel produces a product called tire-derived fuel (TDF). This guide explains TDF’s use when blended and combusted under normal operating conditions with originally specified fuels. Whole-tire combustion for energy recovery is not discussed herein, since whole-tire usage does not require tire processing to a defined fuel specification. This recovery guide has moved from a pioneering concept in the early 1980s to a proven and continuous use in the United States with industrial and utility applications. B Bagel Cut Cutting a tire in half along its circumference. Baling A method of volume reduction whereby tires are compressed into a bundle and banded together. Banbury An enclosed machine for mixing rubber and compounds. Barrel Stack A means of storage in which tires are stacked flat on top of each other in a vertical position.
Glossary of Terms and Acronyms Page 4 | 27 Bead The anchoring part of the tire which is shaped to fit the rim/wheel; made of high tensile steel wires wrapped and reinforced by the plies. Belt A reinforced cord layer located circumferentially around the tire and under the tread. Belt Plies Belt plies are two or more strong layers of cord just under the tread area of the tire. The primary function of belt plies is to provide strength and stability to the tire tread. They play a role in improving tire mileage, impact resistance, and traction. Steel is the most common cord material used in belt plies. Beneficial Reuse Turning would be waste into a valuable commodity. Facilities are reusing byproducts or waste materials in their own operations or sending them elsewhere for reuse or substitute raw material. (e.g., approved material used at a landfill for purposes other than cover). Bias Belted Tire A tire with a bias ply carcass and stiff reinforcing belts extending from shoulder-to-shoulder usually at about a 25-degree angle. There are very few bias belted tires produced at this time. However, there are some Off-the-Road tires (OTRs) that have cord or steel stabilizing belts attached to the bias ply cords under the tread. Bias Ply Tire A tire with cords running at an acute angle to the circumferential center line of the tire (usually about 36-degree angle). Bonding The joining of two materials by use of adhesives or vulcanization. Brand Number A number branded into one or both sidewalls of a tire for identification purposes. Buffer A machine used to rasp the old tread from the casing. A powered rotary rasp provides a clean, even surface for adhesion of the new tread rubber. A buffer produces buffings. Buffings Removal of the previously vulcanized rubber surface. Rubber buffings are derived from grinding the outer layer of truck tires in preparation of receiving new tread. These grindings are vacuumed through a special process and sold as a value-added product in the manufacturing of molded rubber products (e.g., tiles, roofing, pour-in-place playgrounds, running tracks, walkways, pathways, mats).
Glossary of Terms and Acronyms Page 5 | 27 Buffing Rubber Particulate rubber produced as a byproduct of the buffing operation in the carcass preparation stage of tire retreading, characterized by a wide range of particle sizes that are predominately elongated or acicular in shape. See Particulate Rubber. (ASTM D1566-21). Butadiene Rubber (BR) BR is a synthetic rubber used in various parts of the tire. In the sidewall it helps to improve fatigue due to continuous flexing and in the tread area to improve wear abrasion. Butyl Rubber A general-purpose synthetic elastomer (rubber) produced by copolymerizing isobutylene with small amounts of isoprene. Butyl rubber has a high resistance to chemicals and low permeability to gases. Its permeability to air is 70 percent better than that of natural rubber and for this reason is superior for tire tubes and tubeless tire inner liners. C Calcium Carbonate A chemical compound with the formula CaCO3. It is a raw material found in rocks as the mineral calcite and aragonite, most notably as limestone, and is the main component of eggshells, snail shells and pearls. Calcium carbonate is a low oil absorption ingredient used for carpet backing. Calender Machine with two or more parallel, counter rotating rolls with a controllable, roll-to-roll spacing, rotating at selected surface speeds and controlled temperatures, used for sheeting, laminating, skim coating (topping) and friction coating, to a controlled thickness and/or surface condition. (ASTM D1566 - 21) Calendering A mechanical process used in the manufacturing industry by which either plastic or rubber is pressed into textiles (fabric, tire cord) forming composite sheets. In the calendaring process, fabric and rubber or plastic material is passed through a series of rollers to flatten, smooth and commingle the two or more materials. Calendered sheets can have multiple layers of both the elastomeric and polymer “sandwiched” together. Calibrate To measure against and adjust to a standard. California Air Resources Board (CARB) CARB is charged with protecting the public from the harmful effects of air pollution and developing programs and actions to fight climate change.
Glossary of Terms and Acronyms Page 6 | 27 California Department of Transportation (Caltrans) Caltrans manages more than 50,000 miles of California's highway and freeway lanes, provides inter-city rail services, permits more than 400 public-use airports and special-use hospital heliports, and works with local agencies. Caltrans carries out its mission with six primary programs: Aeronautics, Highway Transportation, Mass Transportation, Transportation Planning, Administration and the Equipment Service Center. Carbon Black A material consisting essentially of elemental carbon in the form of near-spherical colloidal particles and coalesced particle aggregates of colloidal size, obtained by partial combustion or thermal decomposition of hydrocarbons. ASTM D1566 – 21 and D3053 - 20. It is used principally in rubber goods, pigments, and printers’ ink. It is not an inert filler but enhances and reinforces various properties of rubber. It is a primary ingredient in the compounding of tires. Casing A whole used tire generally in a worn state to which additional tread may be attached for the purpose of retreading. Cement, Rubber Adhesive that is either a liquid dispersion or solution of raw or compounded rubber, or both. Char Residue remaining after pyrolysis of a tire. ASTM D3053 - 20 defines char as an unprocessed material which is a low value and may contain steel and textile waste in addition to all the additives from rubber production. It is a fine particulate composed of carbon black, ash, and other inorganic materials such as zinc oxide, carbonates and silicates. Chemical Compounds, 6PPD and 6PPD-quinone (6PPD-q) 6PPD is an organic chemical widely used as a stabilizing additive in rubbers such as NR, SBR and BR, all of which are common in all layers of a vehicle tire but the inner layer. 6PPD, is an effective antioxidant used because of its antiozonant performance (e.g., prevents degradation and cracking of rubber compounds caused by oxygen, ozone and temperature fluctuation). 6PPD-q may form when 6PPD reacts with oxygen and ozone. 6PPD research and proposed alternatives. Chopped Tire A tire cut into randomly sized pieces which have no uniformity.
Glossary of Terms and Acronyms Page 7 | 27 Circular Economy An economic system where products and services are traded in closed loops or cycles. It tackles global challenges like climate change, biodiversity loss, waste and pollution. Circular Economy aims to redefine growth, focusing on positive society-wide benefits. It is based on three principles: Design out waste and pollution; keep products and materials in use; regenerate natural systems. Civil Engineering A professional engineering discipline that deals with the design, construction and maintenance of the physical and naturally build environment. Civil engineering applications include reusing scrap/waste tires, either whole or shredded, in place of naturally occurring materials in construction. Uses include as an aggregate replacement in leachate collection systems, as lightweight fill material, stormwater drainage, bridge abutment backfills, slope stabilization and vibration dampening. Additional Information regarding civil engineering information and properties of Tire Derived Aggregate (TDA). Classification by Source of Rubber Table 1 captures the classification and category descriptions of tire and non-tire rubber. See ASTM D5603 – 19. Classification by Particle Size Table 2 A (Coarse Sizes, 1 mm 18 mesh and larger) and Table 2 B (Fine Sizes, smaller than 1 mm 18 mesh) is designed to assist in the classification of particulate rubber. See ASTM D5603 – 19. Classifier Any apparatus for separating mixtures of material into their constituents according to size and density. Collection The act of picking up and moving take-off tires from the location of their generation to sorting stations or tire recycling facilities. Collection Fee Fee charged to collect and/or haul and/or transport take-off tires or shredded tire material. Compound Intimate admixture of a polymer(s) with all the materials necessary for the finished article. (ASTM D1566 – 21) Compounding Material Substance used as part of a rubber mix. (ASTM D1566 – 21)
Glossary of Terms and Acronyms Page 8 | 27 Comprehensive Trip Log (CTL) Paper or electronic forms used by haulers and waste tire facilities to document waste and used tire pickup or delivery transactions. Forms are submitted to CalRecycle and entered in the Waste Tire Manifest System database. Compression Molding Molding process in which the material is placed directly in the mold cavity and compressed to shape by closure of the mold. (ASTM D1566 – 21) Compression Set Residual deformation of a material after removal of the compressive stress. (ASTM D1566 – 21) Copolymer Polymer formed from two different monomers. (ASTM D1566 – 21) Cracker Mill A machine that tears apart scrap tire rubber by passing the material between rotating corrugated hardened steel rolls, reducing the rubber to various sizes. Crosslink Density Number of crosslinks per unit mass or volume of vulcanizate. DISCUSSION—The units of crosslink density will indicate whether it is per unit mass or per unit volume. (ASTM D1566 – 21) Crosslinking (the act of) Formation of chemical bonds between polymer chains to give a network structure. (ASTM D1566 – 21) Crumb Rubber CalRecycle defines crumb rubber as equal to or less than 6.3 mm (1/4 inch) in size. Crumb rubber is produced by size reducing the whole tires through additional granulators and classifiers. The Tire Industry Association Environmental Advisory Council considers 9.5 mm (3/8 inch) to 425 mm (40 mesh) as crumb rubber and defines the material as being derived by reducing scrap tires or other rubber into uniform granules with the inherent reinforcing materials such as steel and fiber removed along with any other type of inert contaminates such as dust, glass, or rock. Crumb Rubber Modifier (CRM) A general term for scrap tire rubber that is reduced in size and used as a modifier in asphalt paving materials.
Glossary of Terms and Acronyms Page 9 | 27 Cryogenics A technology for processing materials at very low temperatures. For processing rubber, liquid nitrogen, or commercial refrigeration methods are commonly used to embrittle rubber. The embrittled rubber is then processedin a hammermill or granulator to a desired product size. Cryogenic Crumb Rubber A cryogenic process includes grinding a tire and separating and freezing the smooth clean particles using liquid nitrogen or commercial refrigeration to a temperature of below – 80 degrees Celsius (-112 degrees Fahrenheit) to embrittle the rubber. The embrittled rubber is crushed in a mill to the desired particle size. Cryogenic grinding avoids heat degradation of the rubber and produces a high yield of product that is free of almost all fiber or steel, which is liberated during the process. Cryogenically Ground Rubber Rubber that results from the process of freezing scrap tire rubber or other rubber and crushing the rubber to the particle size desired. D Density Mass per unit volume of a material. (ASTM D1566 – 21, E126, E20) Density, Bulk Mass per unit volume of a material, including any voids present. (ASTM D1566 – 21) Depolymerization A process that reduces a polymer to individual elements. For rubber, this reduction permits the blending of these individual elements with other polymers. Devulcanization Destruction of the chemical crosslinks in a vulcanized rubber. (ASTM D1566 – 21) A process in which crumb rubber is subjected to treatment by heat, pressure, or the addition of softening agents to regenerate the rubber compound to its original plastic state. Chemical, thermophysical, or biological means are used to break apart the sulfur bonds found in rubber. Dry Process Paving The addition of chemically engineered tire rubber during the hot mix asphalt production process. Rubber-binder interactions, after mixing and mechanical changes in the mix, promote greater pavement resistance to both rutting and cracking. Dry process mix modification is commonly used as an alternative to polymer modification of asphalt binders and wet process modification with tire rubber.
Glossary of Terms and Acronyms Page 10 | 27 Department of Transportation (DOT) The letters “DOT” precedes the tire identification number (TIN) and must be molded into the sidewall of all over-the-highway tires produced by tire manufacturers and retreaders that distribute and sell tires in the U.S. This mark certifies that the tire meets or exceeds all applicable safety standards established by the Code of Federal Regulations, Federal Motor Vehicle Safety Standards. Durometer An Instrument for measuring the indentation hardness of rubber. (ASTM D1566 – 21) Durometer Hardness A numerical value obtained from the durometer that measures the resistance to indentation (hardness) of the rubber. E Elastomer An elastic polymer. (ASTM D1566 – 21) Elongation Extension produced by a tensile stress. (ASTM D1566 – 21) End of Life (EOL) Product A product at the end of the product lifecycle which prevents users from receiving updates, indicating the product is at the end of its useful life. End-of-Life Tires (ELT) Refers to all tires that have reached the end of their useful life when the tire can no longer be used on vehicles (after having been retreaded or regrooved) and are ready to be discarded and managed, whether through reuse, recycling, landfill disposal, or another means. End User An entity that purchases and uses tire derived material (TDM) as a finished use or tire- derived product (TDP) for its intended use. End Use Application The ultimate application for which a product has been designed or for which it is ultimately used. Energy Recovery The extraction of the fuel or heat value from whole processed tires through incineration.
Glossary of Terms and Acronyms Page 11 | 27 Engineered Crumb Rubber (ECR) The modification of very fine crumbs of tire rubber with chemical treatments that enhance rubber-binder interactions and improve the performance of asphalt mixes. ECR is typically added to hot mix asphalt during production using the dry process method. EPDM Ethylene Propylene Diene Monomer: a synthetic rubber used in a range of applications including various seals used in the automotive and construction industries. Recycled post- industrial EPDM rubber granules mixed with polyurethane is used as a top layer, typically over a recycled tire rubber base, in pour-in-place surfacing. Extruder A machine designed to force a rubber or rubber mix through an orifice, which is often shaped to the geometry of the desired product. (ASTM D1566 – 21) Extrusion A process of mechanically forcing material (such as blended crumb rubber) through a confined opening to produce film, strip, tubing, or other shapes. F Feedstock Conversion The process whereby a manufacturer replaces a portion of the raw materials (e.g., virgin rubber, EPDM, plastic, aggregate or other raw material) with recycled tire rubber in the manufacturer of a tire-derived product or use. Fines Naturally occurring small rubber particles created during the shredding process. Fines pass through a standard size screen on which coarser fragments are retained. For example, a 20-mesh screen may produce a small percentage of material that is smaller than the 20mesh size. Flow Control A legal or economic means that directs the movement of materials to a specific destination. Fluff (Fiber) The textile or reinforcing materials liberated from scrap tires or other rubber reinforced products during processing for crumb rubber. G
Glossary of Terms and Acronyms Page 12 | 27 Gasification Any chemical or heat process used to convert rubber to gas. Green Tire A built tire (new or retreaded) before being cured. Generator Any person or business entity who produces or accumulates worn or scrap tires through personal use or in the ordinary course of business. Granulated Rubber Particulate rubber composed of mainly non-spherical particles that span a broad range of maximum “particle dimension” from 425 μm (40 mesh) to 12 mm (0.47 in.); the key feature of this type of particulate rubber is the fraction of the material in the greater than 1-mm (0.08-in.) up to 12-mm (0.47-in.) maximum “particle dimension” range. (ASTM 1566-21) Granulator A high-speed machine used predominately for processing wire free tire chips at ambient temperature. The machine consists of flat rotating knives that come in very close contact with stationary knives. This interaction creates a cutting and tearing process best suited for liberating the fiber from the tire rubber and reducing the size. An internal interchangeable screen consisting of round holes is used to control the size of the rubber produced. Granulators are best suited for processing wire free rubber from 1-inch (25mm) and below to ½- inch (12mm) and ¼- inch (6mm) sizes. Ground Rubber Tire-derived material greater than ¼ inch and up to 1 inch in size, sometimes referred to as nuggets depending on the specification and application. Ground Tire Rubber (GTR) A granular reduction of vulcanized tire rubber that typically has the wire removed. Ground tire rubber has become the preferred term used for rubberized asphalt applications. H Hammermill A high-speed machine used predominately for processing wire free tire rubber that has been frozen. The machine consists of rotating hammers that impact material at high velocity against a grate. The hammer size, speed and velocity as well as the openings between the grates control the size of the rubber produced. A hammermill is best suited for reducing tire rubber from 1 inch (25MM) and below sizes down to 100 mesh.
Glossary of Terms and Acronyms Page 13 | 27 Hauler Those persons, firms, corporations, or governmental agencies responsible (under oral or written contract, or otherwise and licensed if required) for the collection of take-off tires, whole scrap tires, or rubber materials within the geographic boundaries of the contract community(s), and the transportation of such materials to sorting stations, recycling centers or end markets. Hysteresis Measure of energy loss expressed in degree of temperature build up. I Infrastructure The general term for the basic physical systems of a business, region, or nation. Examples include transportation systems, communication networks, sewage, water, and electric systems. These systems tend to be capital intensive and high-cost investments and are vital to a country's economic development and prosperity. Injection Molding process by which a rubber compound is forced into a closed mold by pressure other than the mold clamping force. International System of Units (SI) SI is the modern form of the metric units. The values stated in SI units are regarded as standard in the ASTM Designated Standards. Other units of measurements are considered as informational in ASTM Standards. See Appendix B Table 1 (Conversion of Metric Units to U.S. Standard Units Shortcut) and Table 2 (Metric Unit Symbol, Name and Description and/or Quantity). J K Kilopascal (kPa) A unit of pressure. 1 kPa = 0.1450 psi.
Glossary of Terms and Acronyms Page 14 | 27 L Lacing Tires A method of arranging tires to maximize the use of space. This method can be used to store tires indoors or outdoors, or to transport tires. Laced Tires Picture Laser Diffraction The modern particle analyzers reflect the state of art in scientific instruments designed to measure the consistency of the particle size in dry powders or in liquid dispersions by utilizing diffraction patterns of a laser beam passed through any object ranging from nanometers to millimeters in size to quickly measure geometrical dimensions of a particle. Low Profile Tire A tire in which the ratio of cross-section height to section width (80% or less) is lower than that of a conventional tire. M Managed Tire Site A tire pile or storage facility where the owner/operator stores or processes scrap tires in compliance with the appropriate regulations.
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