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B-1Â Â APPENDIX B Proposed AASHTO Standard Practice 1 SCOPE 1.1 The document is to provide guidance on how the rapid test methods for asphalt-treated cold recycled pavement can be used to make time-critical decisions regarding opening to traffic and surfacing of the recycled pavements. It also indicates how the variability can be reduced to obtain consistent and accurate test measurements. 1.2 This guide is applicable to asphalt-treated (emulsified or foamed asphalt) cold recycled pavement materials with or without active fillers such as lime and cement. Specifically included are the processes of full-depth reclamation (FDR), cold in-place recycling (CIR), and cold central-plant recycling (CCPR). This guide provides recommended procedures and performance criteria. This document cannot be used for acceptance purposes, but rather used as a guide to develop acceptance performance criteria by agencies. 1.3 This document should also be used in conjunction with current agency testing practices for inspection and testing practices for acceptance of cold recycled materials (for example: in-place density, moisture content, etc.). 1.4 This document 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 standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory regulations prior to use. 2 REFERENCED DOCUMENTS 2.1 AASHTO Standards and Publications T 256, Pavement Deflection Measurements. TP XXX, Evaluating Shear Resistance of Asphalt Treated Recycled Pavements. TP XXX, Evaluating Raveling Resistance in Asphalt Treated Recycled Pavements. 2.2 ASTM Standards D6951/D6951M - 18, Standard Test Method for Use of the Dynamic Cone Penetrometer in Shallow Pavement Applications. E2583, Standard Test Method for Measuring Deflections with a Light Weight Deflectometer (LWD). 2.3 Others. NCHRP Research Report 960 (Project 09-62). Basic Asphalt Recycling Manual (FHWA-HIF-14-001)
B-2 3 TERMINOLOGY 3.1 Full-Depth Reclamation â Full-depth reclamation (FDR) is defined as those processes in which all of the asphalt pavement layers and some portion of the underlying bound and unbound layers are pulverized, stabilized, and compacted in place. This is most commonly performed using hydraulic cement, lime, foamed asphalt, or asphalt emulsion as the primary stabilizing additives. 3.2 Cold In-Place Recycling â Cold in-place recycling (CIR) is defined as a process in which a portion of existing asphalt concrete pavement layers is pulverized, stabilized, and repaved in place. This is most commonly performed using foamed asphalt or emulsified asphalt as the primary stabilizing additive. The pavement may be milled, stabilized, and repaved using the same machine or machine train, or paved from a stabilized, windrowed material using traditional practices. 3.3 Cold Central-Plant Recyclingâ Cold central-plant recycling (CCPR) is a process in which recycled asphalt concrete pavement is processed and stabilized using foamed asphalt or emulsified asphalt at a plant and then placed using conventional asphalt paving equipment. 3.4 Qualified Technician â An engineering technician who is proficient at performing basic pavement materials tests and may be qualified by meeting some minimum education, experience, or qualifying body (e.g., agency, NICET) standard. 3.5 For other terminology used in the guide specification, refer to the relevant AASHTO or ASTM standards. 4 EQUIPMENT 4.1 Refer to the equipment section in the test methods. For the dynamic cone penetrometer equipment, an 8 kg (17.6 lb) DCP mass shall be used as described in ASTM D6951. 5 SIGNIFICANCE AND USE 5.1 The time required for reaching the desired properties for a new asphalt-treated cold recycled pavement changes depending on many factors. Examples include environmental conditions, emulsion composition and dose, presence of active filler, moisture and density of the compacted material, and the milled surface of the existing pavement. The test methods described in this guide specification assess the raveling potential, penetration resistance, shear resistance, and stiffness of a newly constructed cold recycled pavement and could be used to supplement current agency testing practices for inspection and testing for acceptance of cold recycled materials (for example, in-place density, moisture content). 5.2 This document can be used as guidance to developing draft standard specifications and/or special provisions for conducting the rapid tests listed below for making time-critical decisions regarding opening to traffic and surfacing of the cold recycled pavements. ⢠Evaluation of Raveling Resistance Using a Short-Pin Raveling Test. ⢠Evaluation of Shear Resistance Using a Long-Pin Shear Test. 6 EVALUATION OF RAVELING RESISTANCE USING A SHORT-PIN RAVELING TEST 6.1 The raveling test is conducted in accordance with the AASHTO standard TP XXX-XX. 6.2 Applicability of Test Method 6.2.1 This test method may be used on any asphalt-treated cold recycled pavements with thickness of 3 in. or more. The recommended values discussed in the guide specification may not be applicable for pavements with a thickness of less than 3 in. The test method could still be used for evaluating the raveling potential of the newly constructed cold recycled pavements at the engineerâs discretion.
B-3Â Â 6.3 Standardization and Calibration of Equipment Assembly 6.3.1 The weight assembly and short-pin fixture must be standardized and calibrated periodically. The torque wrench shall be calibrated following the recommended procedure by the manufacturer. The maximum interval between the consecutive calibrations of the torque wrench shall not exceed 12 months. The calibration frequency of the raveling resistance fixture can be established based on the usage of the fixture by the agency. However, the interval between two consecutive calibrations of the fixture shall not exceed 6 months. 6.3.2 The short-pin fixture, coupler, and torque wrench should be inspected for any defects before each test. 6.4 Test Frequency and Location 6.4.1 The raveling resistance test frequency can be similar to that of mat density measurement for recycled asphalt concrete layers set by the agency. Lot and sublot sizes should be established by the agency and used consistently for each of the test methods referenced in this guide specification. The lot and sublot definitions should be established to appropriately balance agency and contractor risk. They could be based on material quantity (volume) or roadway surface area per lift. 6.4.2 Test locations should be randomly selected and within a 4-ft radius of the location of mat density measurements. Three replicate tests should be conducted with a center-to-center spacing between tests of approximately 1 ft. The test location should be undisturbed, free from foreign objects and loose asphalt mixture, and representative of the newly constructed pavement. If loose asphalt particles are present on the surface, it can be swept with a soft brush (horsehair brush) without dislodging the fines on the pavement. Figure 1 illustrates an example of test locations when each of the test methods referenced in this guide specification are used. 6.4.3 The test location shall be 1 ft away from the edge or joint of the pavement. If the agency desires to evaluate the raveling potential of a joint, it could conduct the test within 6 in. from the joint. It is important to recognize that different criteria may be necessary for mat and joint test locations. 3 ft Raveling 1 Shear 1 Raveling 2 2 ft Shear 2 Raveling 3 Shear 3 Figure 1. Illustration of rapid test locations. 6.5 Test Criteria 6.5.1 If the raveling test data is to be used for acceptance purposes, the agency can establish the minimum number of tests and raveling test criteria similar to that of mat density measurement for asphalt concrete layers as described in Section 6.4. 6.5.2 The agency will establish the criteria for the raveling test parameters (number of blows and torque value) obtained in accordance with the standard, based on the type of the cold recycled pavement and traffic volume. Table 1 shows the preliminary criteria (average of three replicate measurements) established as part of NCHRP Project 09-62 research.
B-4 Table 1. Raveling resistance test criteria for cold recycled pavement, average of three replicate measurements. Recycling Number of Torque Process Blows Value, ft-lbs FDR CIR 7.1 20.2 CCPR 6.5.3 Alternatively, if the agency is to set the time for opening the cold recycled pavement to traffic, it can construct a test strip using representative materials in an environment close to the project location and in compliance with the project specifications. Based on the mat density and/or stiffness, the agency can establish the construction practice (lift thickness, rolling pattern, rerolling, etc.). The raveling resistance test can be conducted on the test strip at multiple intervals (0.5 hour, 1 hour, 2 hour, etc.) to determine when the raveling test criteria is met and use that to establish the time for opening the pavement to traffic as long as similar environmental conditions exist. A new test location shall be established for each time interval. 7 EVALUATION OF SHEAR RESISTANCE USING A LONG-PIN SHEAR TEST 7.1 The shear resistance test is conducted in accordance with the AASHTO standard TP XXX-XX. 7.2 Applicability of Test Method 7.2.1 This test method may be used on any asphalt-treated cold recycled pavements with thickness of 3 in. or more. The recommended values discussed in the guide specification may not be applicable for pavements with a thickness of less than 3 in. The test method could still be used for evaluating the shear resistance of the newly constructed cold recycled pavements at the engineerâs discretion. 7.3 Standardization and Calibration of Equipment Assembly 7.3.1 The weight assembly and long-pin fixture must be standardized and calibrated periodically. The torque wrench shall be calibrated following the recommended procedure by the manufacturer. The maximum interval between the consecutive calibrations of the torque wrench shall not exceed 12 months. The calibration frequency of the fixture for the shear resistance test can be established based on the usage of the fixture by the agency. However, the interval between two consecutive calibrations of the fixture shall not exceed 6 months. 7.3.2 The long-pin fixture, coupler, and torque wrench should be inspected for any defects before each test. 7.4 Test Frequency and Location 7.4.1 The shear resistance test frequency can be similar to that of mat density measurement for recycled asphalt concrete layers set by the agency. Lot and sublot sizes should be established by the agency and used consistently for each of the test methods referenced in this guide specification. The lot and sublot definitions should be established to appropriately balance agency and contractor risk. They could be based on material quantity (volume) or roadway surface area per lift. 7.4.2 Test locations should be randomly selected and within a 4-ft radius of the location of mat density measurements. Three replicate tests should be conducted with a center-to-center spacing between tests of approximately 1 ft. The test location should be undisturbed; free from foreign objects and loose asphalt mixture; and representative of the newly constructed pavement. If loose asphalt particles are present on the surface, it can be swept with a soft brush (horsehair brush) without dislodging the fines on the pavement. 7.4.3 The test location shall be 1 ft away from the edge or joint of the pavement. If the agency desires to evaluate the shear resistance of the mat closer to a joint, it could conduct the test within 6 in. from the joint. It is important to recognize the different criteria may be necessary for mat and joint test locations. Figure 1 illustrates an example of test locations when each of the test methods referenced in this guide specification are used.
B-5Â Â 7.5 Test Criteria 7.5.1 If the data from the shear resistance test is to be used for acceptance purposes, the agency can establish the minimum number of tests and shear resistance test criteria similar to that of mat density measurement for asphalt concrete layer as described in Section 7.4. 7.5.2 The agency can establish the criteria for one or more shear resistance test parameters (number of blows and peak torque) obtained in accordance with the standard, based on the type of the cold recycled pavement and traffic volume. Table 2 shows the preliminary criteria (average of three replicate measurements) established as part of NCHRP Project 09-62 research. Table 2. Shear resistance test criteria for cold recycled pavement, average of three measurements. Recycling Number of Torque Process Blows Value, ft-lbs FDR CIR 19.3 62.9 CCPR 7.5.3 Alternatively, if the agency is to set the time for surfacing the cold recycled pavement, it can construct a test strip using representative materials in an environment close to the project location and in compliance with the project specifications. Based on the mat density and/or stiffness, the agency can establish the construction practice (lift thickness, rolling pattern, rerolling, etc.). The shear resistance test can be conducted on the test strip at multiple intervals (0.5 hour, 1 hour, 2 hours, 1 hour, 2 hours, etc.) to determine when the shear test criteria are met and use that to establish the time for surfacing the cold recycled pavement as long as similar environmental conditions exists. A new test location shall be established for each time interval. 8 INSPECTION AND TESTING 8.1 All the test methods discussed in this guide specification shall be conducted by technicians experienced with testing pavements and pavement materials. 8.2 The engineer shall approve the inspection and testing plan for the project prior to construction. It can be similar to the specification requirements for mat density measurements for recycled asphalt concrete layers set by the agency.
