1、Standard Specification for Mix Design of Cold Recycled Mixture with Foamed Asphalt AASHTO Designation: MP 38-18Technical Section: 2d, Bituminous Materials Release: Group 3 (August) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington,
2、 D.C. 20001 TS-2d MP 38-1 AASHTO Standard Specification for Mix Design of Cold Recycled Mixture with Foamed Asphalt AASHTO Designation: MP 38-18 Technical Section: 2d, Bituminous Materials Release: Group 3 (August) 1. SCOPE 1.1. This specification for cold recycling mix design with foamed asphalt us
3、es mixture properties to produce a job mix formula for cold in-place recycling (CIR) or cold central plant recycling (CCPR). 1.2. This standard specifies minimum quality requirements for cold recycled mixtures and foamed asphalt. 1.3. The values stated in SI units are to be regarded as the standard.
4、 1.4. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this procedure to establish appropriate safety and health practices and determine the
5、applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 85, Portland Cement M 216, Lime for Soil Stabilization M 320, Performance-Graded Asphalt Binder M 332, Performance-Graded Asphalt Binder Using Multiple Stress Creep Recovery (MSCR) Test PP 94, Dete
6、rmination of Optimum Asphalt Content of Cold Recycled Mixture with Foamed Asphalt T 283, Resistance of Compacted Hot Mix Asphalt (HMA) to Moisture-Induced Damage 2.2. Other References: LTPP Seasonal Asphalt Concrete Pavement Temperature Models, LTPPBind 3.1 Basic Asphalt Recycling Manual, Asphalt Re
7、cycling and Reclaiming Association and FHWA-HIF-14-001, Annapolis, MD, 2014. Wirtgen Cold Recycling Technology, Wirtgen GmbH, Windhagen, Germany, 2012. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS
8、-2d MP 38-2 AASHTO 3. TERMINOLOGY 3.1. reclaimed asphalt pavement (RAP)removed and/or processed pavement materials containing asphalt binder and aggregate. 3.2. cold in-place recycling (CIR)the on-site recycling process in which the existing asphalt pavement is recycled using a specialized train equ
9、ipment (tanker trucks, cold planing machines, crushing/screening or sizing units, mixers, pavers, and compaction rollers). The CIR process uses 100 percent of the on-site generated RAP, and a foamed asphalt with or without a combination of additives (e.g., lime, cement, and aggregate) to produce CIR
10、 mixture, and typically treats an asphalt pavement with a depth of 75 to 100 mm (3 to 4 in.). The CIR mixture is used as a base layer overlaid with a surface treatment or asphalt overlay. 3.3. cold central-plant recycling (CCPR)the process in which the asphalt recycling takes place at a central loca
11、tion using a stationary cold mix plant. The stationary plant could be a specifically designed plant or a CIR train minus the cold planing machine set up in a stationary configuration. The CCPR mixture is used as a base layer overlaid with a surface treatment or asphalt overlay. 4. SIGNIFICANCE AND U
12、SE 4.1. This standard may be used to select and evaluate materials for cold recycling mix designs. 5. RAP REQUIREMENTS 5.1. Process the RAP that is collected from an existing stockpile or crushed from cores to produce two of the three gradation bands shown in Table 1. Alternatively, if experience ha
13、s demonstrated consistent field gradations from milling, process the RAP to that gradation. Table 1RAP Gradation Requirements Sieve Size Fine Gradation Medium Gradation Coarse Gradation Percent Passing 31.5 mm (1.25 in.) 100 100 100 25 mm (1 in.) 100 100 85-100 19 mm (3/4in.) 95-100 85-96 75-92 4.75
14、 mm (No. 4) 65-75 40-65 30-45 600 m (No. 30) 15-35 4-14 1-7 Note 1Adjustment of the gradation bands to local conditions and construction equipment is recommended. Gradations on a project will vary from sample to sample. Slight adjustments in the field to the design foamed asphalt content are often n
15、ecessary to obtain optimum mixture performance. Ensure RAP meets agency quality requirements for at least an asphalt base mixture. Performing the mix design at two gradations can determine an acceptable range of foamed asphalt contents for the project. Note 2A small amount (1 percent by mass) of act
16、ive filler (cement or hydrated lime) is usually used to enhance the dispersion of the foamed asphalt and reduce moisture susceptibility. When the tensile strength ratio (TSR) of the mix with no active filler added is greater than 0.6, the mix design should be undertaken with no active filler. 5.2. I
17、f additional aggregate is required, additional aggregate shall meet the agency quality requirements for at least an asphalt mixture. For CCPR material, the percentage of additional aggregate used in the mixture shall not exceed 50 percent. 2018 by the American Association of State Highway and Transp
18、ortation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2d MP 38-3 AASHTO 6. FOAMED ASPHALT AND ADDITIVE REQUIREMENTS 6.1. Foamed Asphalt: 6.1.1. The asphalt binder shall be a performance-graded (PG) binder, meeting the requirements of M 320 or M 332, which is approp
19、riate for the climate and traffic-loading conditions at the site of the paving project or as specified by the contract documents. 6.1.2. For foamed asphalt, use LTPPBind 3.1 software to select the low temperature PG requirements from M 320 for the asphalt binder. In the LTPPBind 3.1 software, the ne
20、arest weather station is selected for the project. The depth to the top of the cold recycled layer is input as the depth of layer. The desired reliability is established by agency policy. A spread of 89 or less between the high PG and the low PG temperatures is normally acceptable in choosing an asp
21、halt binder. Determine the optimum foaming water content to achieve the desirable workability of foamed asphalt mixtures. Determine the other properties of the foamed asphalt to meet mixture requirements. Note 3The selection of desired reliability may be influenced by the initial cost of the materia
22、ls and the subsequent maintenance costs. Note 4The low temperature requirement can be more conservative in temperate climates or for a CIR layer with a thick overlay. For example, if LTPPBind determines a cold temperature minimum of 10C (14F) in a temperate climate and the predominant grade for that
23、 climate is 16C (3F), then an asphalt binder of 16C (3F) or 22C (8F) is acceptable for foaming. 6.2. Other Additives: 6.2.1. If Type I or II cement is used it shall meet the requirements of M 85. 6.2.2. If hydrated lime is used it shall meet the requirements of M 216. 7. COLD RECYCLED MIXTURE DESIGN
24、 REQUIREMENTS 7.1. The cold recycled design at optimum foamed asphalt content shall meet the requirements specified in Table 2 when prepared in accordance with PP 94. Table 2Cold Recycling Mixture Design Requirements Test Method Criteria Property Choose either indirect tensile strength test Indirect
25、 Tensile Strength, dry subset, T 283 Minimum 310 kPa (45 psi) Cured Strength Tensile strength ratio, T 283 Minimum 0.70 (cement) Resistance to Moisture Induced Damage Minimum 0.60 (hydrated lime ) Minimum 0.60 (no additive) 8. KEYWORDS 8.1. CCPR; CIR; cold central plant recycling; cold in-place recycling; cold recycled; foamed asphalt; RAP; reclaimed asphalt pavement. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
