1、Standard Specification for Reclaimed Concrete Aggregate for Unbound Soil-Aggregate Base Course AASHTO Designation: M 319-02 (2015) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1a M 319-1 AASHTO Standard Specific
2、ation for Reclaimed Concrete Aggregate for Unbound Soil-Aggregate Base Course AASHTO Designation: M 319-02 (2015) 1. SCOPE 1.1. This specification covers the use of reclaimed concrete aggregate as an unbound granular base course material. When properly processed, hauled, spread, and compacted on a p
3、repared grade to appropriate density standards, reclaimed concrete aggregate used alone or blended with natural or crushed aggregate can be expected to provide adequate stability and load support for use as road or highway base courses. The approach presented in this specification is suitable for th
4、e satisfactory installation of a reclaimed concrete aggregate base course. However, local experience, practices, or materials that have been successfully applied may be used in lieu of this specification. This specification is not intended for use in base courses in locations where surfacing will no
5、t be placed over the base course. 1.2. Since reclaimed concrete aggregate is a recycled material, various state and local jurisdiction laws and regulations may be applicable. The user of this specification is cautioned to contact state and local environmental and other local regulators to determine
6、what requirements are appropriate. 1.3. The values stated in SI units are to be regarded as the standard. The English unit equivalents shown in parentheses may be appropriate, except with regard to sieve sizes and aggregate size as determined by the use of testing sieves, in which case the standard
7、SI designation shown is the standard, as required by M 92. Note 1The engineer is cautioned to provide appropriate construction specifications to ensure compaction to an extent that further densification of the compacted pavement from traffic loadings will be insignificant. At the time of placement,
8、the reclaimed concrete aggregate material shall contain moisture approximately equal to the optimum moisture content necessary to make certain that the design density requirements are obtained when the material is compacted. Reclaimed concrete aggregate can be expected to exhibit higher absorption t
9、han natural aggregate materials. Accordingly, the engineer should expect to experience moderately higher optimum moisture content values than would be expected with natural aggregate materials. The reclaimed concrete aggregate shall be compacted using vibratory or other proven effective rollers or t
10、ampers to achieve the required density results. Further discussion of compaction issues is presented in Appendix X1. Note 2The engineer should be aware of the highly alkaline nature of reclaimed concrete aggregate, the relatively high degree of solubility of these alkaline materials, and the potenti
11、al increase in pH that could occur in waters percolating through a reclaimed concrete aggregate base. Depending on the sensitivity of local soils, surface waters, and groundwater to the presence of alkaline material, the engineer should set appropriate limits on the proximity of placement of reclaim
12、ed concrete aggregate relative to groundwater and surface waters. Additionally, the presence of water percolating through reclaimed concrete aggregate will induce a corrosive solution with a pH of approximately 11 to 12. Therefore, reclaimed concrete aggregate shall not be used in the vicinity of me
13、tal culverts, such as aluminum culverts, that are sensitive to highly alkaline environments. Note 3The engineer is cautioned to prevent, or minimize when possible, the use of reclaimed concrete aggregate over a geotextile drainage layer, gravel drain fields, drain field piping, or open 2015 by the A
14、merican Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a M 319-2 AASHTO soil-lined stormwater retention or detention facilities. Soluble minerals rich in calcium salts and calcium hydroxide can be hydraulically transpor
15、ted from the reclaimed concrete aggregate material. When this occurs and the reclaimed concrete aggregate is located above such porous drainage systems, there is a tendency for the referenced minerals to precipitate out of solution and bind the drainage structure. The mineral deposits formed are som
16、etimes referred to as tufa-like or portlandite deposits. Over time the permeability of the drainage system can be reduced. Further discussion of this topic and recommended drainage evaluation procedures are presented in Appendix X2. Note 4The engineer should be aware that reclaimed concrete aggregat
17、e used as a base course could, with time, gain strength and exhibit a corresponding loss of permeability in the base course layer. This is due to residual cementitious reactions in the concrete material. If the base course is intended for use as a drainage layer, then the fine portion of the reclaim
18、ed concrete aggregate should be removed or modified to reduce the potential for this occurrence. Note 5The engineer is cautioned that some reclaimed concrete aggregate materials will yield high soundness loss values when subjected to conventional sulfate soundness testing methods, and such testing m
19、ethods may not be suitable for reclaimed concrete aggregate soundness testing. Further discussion of this topic is presented in Section 6.3 and Appendix X3. Note 6The engineer is cautioned to ensure that reclaimed concrete source materials are not contaminated with extraneous solid waste or hazardou
20、s materials. Methods and criteria for examining and approving reclaimed concrete materials prior to use should be established by the specifying jurisdiction. This provision is further addressed in Section 7.3. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 92, Wire-Cloth Sieves for Testing Purpose
21、s M 146, Terms Relating to Subgrade, Soil-Aggregate, and Fill Materials M 147, Materials for Aggregate and Soil-Aggregate Subbase, Base, and Surface Courses R 58, Dry Preparation of Disturbed Soil and Soil-Aggregate Samples for Test T 2, Sampling of Aggregates T 11, Materials Finer Than 75-m (No. 20
22、0) Sieve in Mineral Aggregates by Washing T 27, Sieve Analysis of Fine and Coarse Aggregates T 88, Particle Size Analysis of Soils T 89, Determining the Liquid Limit of Soils T 90, Determining the Plastic Limit and Plasticity Index of Soils T 96, Resistance to Degradation of Small-Size Coarse Aggreg
23、ate by Abrasion and Impact in the Los Angeles Machine T 99, Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.) Drop T 103, Soundness of Aggregates by Freezing and Thawing T 104, Soundness of Aggregate by Use of Sodium Sulfate or Magnesium Sulfate T 176, Plastic
24、Fines in Graded Aggregates and Soils by Use of the Sand Equivalent Test T 180, Moisture-Density Relations of Soils Using a 4.54-kg (10-lb) Rammer and a 457-mm (18-in.) Drop T 193, The California Bearing Ratio T 307, Determining the Resilient Modulus of Soils and Aggregate Materials 2015 by the Ameri
25、can Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a M 319-3 AASHTO 2.2. ASTM Standards: D2940/D2940M, Standard Specification for Graded Aggregate Material for Bases or Subbases for Highways or Airports D5101, Standard
26、Test Method for Measuring the Filtration Compatibility of Soil-Geotextile Systems 2.3. Additional Standards: NY 703-08, Resistance of Coarse Aggregate to Freezing and Thawing (New York State Department of Transportation) LS-614, Freezing and Thawing of Coarse Aggregate (Ontario Ministry of Transport
27、ation) 3. TERMINOLOGY 3.1. The definitions of base course and other soil aggregate terms are given in M 146. For use in this specification, base course shall mean the uppermost unbound granular layer of the pavement structure. The definition for reclaimed concrete aggregate as used in this specifica
28、tion is a manufactured aggregate material that is derived from the crushing, processing, and classification of portland cement concrete construction debris recovered from roadways, sidewalks, buildings, bridges, and other sources. 4. ORDERING INFORMATION 4.1. The purchaser or specifier shall include
29、 the following information in the purchase order or contract documents: 4.1.1. Reference to this specification, including year; 4.1.2. Grading to be furnished for the granular base; 4.1.3. Soundness testing requirements; and 4.1.4. Exceptions or additions to this specification. 5. GRADING AND PROPOR
30、TIONS 5.1. Reclaimed concrete aggregate or reclaimed concrete aggregate combined with other approved natural or man-made aggregate materials shall comply with the gradation requirements of M 147, ASTM D2940, or the requirements of the specifying jurisdiction. 5.2. If the contractor/supplier wishes t
31、o use combinations of reclaimed concrete aggregate or reclaimed concrete aggregates with other approved aggregate materials, a request shall be made to the engineer for approval. The percentage of materials shall be established as part of a presubmitted blended aggregate combination. In cases where
32、the contractor/supplier wishes to change the approved combination, a special request for approval shall be made to the engineer. At the engineers discretion, revised density acceptance testing shall be required. 5.3. When the engineer permits the contractor/supplier to combine reclaimed concrete agg
33、regate with other approved aggregates, this shall be accomplished by mechanical interlock blending or belt blending to ensure uniform mixing. The contractor/supplier may use other methods of blending if it can be demonstrated to the engineer that the alternate blending method will prevent segregatio
34、n. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a M 319-4 AASHTO 6. PHYSICAL PROPERTIES 6.1. Reclaimed concrete aggregate shall consist of crushed concrete material and natural aggregate particles
35、, derived from the crushing of portland cement concrete, that are hard, durable fragments of stone, gravel, slag, crushed concrete, or sand. 6.2. Reclaimed concrete aggregate shall be limited in plastic soils such that the minus 0.425-mm (No. 40) sieve material when tested for liquid limit (T 89) sh
36、all not be greater than 30 and the plasticity index (T 90) shall not be greater than four, and/or, at the discretion of the engineer, the sand equivalent value (T 176) of the minus 0.425-mm (No. 40) sieve material shall be a minimum of 25 percent. 6.3. Reclaimed concrete aggregate shall have a perce
37、ntage of wear by the Los Angeles abrasion test (T 96) of not more than 50 percent. 6.4. Reclaimed concrete aggregate soundness testing shall be required at the discretion of the engineer. Appendix X3 lists permissible alternative soundness test methods and acceptance criteria. (See Note 5.) 7. DELET
38、ERIOUS SUBSTANCES 7.1. Reclaimed concrete aggregate shall contain not more than 5 percent bituminous concrete materials by mass. (See Note 7.) 7.2. Reclaimed concrete aggregate shall contain not more than 5 percent brick by mass. (See Note 7.) 7.3. Reclaimed concrete aggregate material shall be free
39、 of all materials that fall under the category of solid waste or hazardous materials as defined by the state or local jurisdiction. (See Note 8.) 7.4. Reclaimed concrete aggregate shall be substantially free of wood, metal, plaster, and gypsum board, when these materials are not classified as solid
40、waste as defined in Section 7.3. (See Notes 8 and 9.) Note 7If the engineer wishes to specify reclaimed concrete aggregate material where the percentages of bituminous concrete and/or brick exceed those shown above, an evaluation method for approving higher percentages is presented in Appendix X4. N
41、ote 8The engineer may select stockpiling as an approach to assist in qualitatively identifying the presence of deleterious materials. Stockpiling can also be used as a means to qualitatively assess the uniformity of the material. When such an approach is used, the stockpile may represent all or part
42、 of the material to be used on a project and should be constructed in a manner that will minimize segregation and permit a complete visual examination of the material. Note 9Substantially free, in the context of this specification, shall mean percentages of undesirable materials that are less than t
43、he following: wood0.1 percent maximum; metals0.1 percent maximum; plaster and gypsum board0.1 percent maximum. At the engineers discretion these respective quantities may be adjusted if, in the engineers opinion, such adjustment will not impact the performance of the base course. 2015 by the America
44、n Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a M 319-5 AASHTO 8. METHODS OF SAMPLING AND TESTING 8.1. Sample and test the aggregate in accordance with the following standard methods of the American Association of St
45、ate Highway and Transportation Officials, except as otherwise provided in this specification: 8.1.1. T 2, Sampling; 8.1.2. T 11, Elutriation; 8.1.3. T 27, Grading; 8.1.4. R 58, Sample Preparation; 8.1.5. T 88, Particle Size Analysis; 8.1.6. T 89, Liquid Limit; 8.1.7. T 90, Plastic Limit and Plastici
46、ty Index; 8.1.8. T 96, L.A. Abrasion; 8.1.9. T 104, Aggregate; and/or 8.1.10. T 176, Sand Equivalent Test. APPENDIXES (Nonmandatory Information) X1. DENSITY CONTROL METHODS FOR RECLAIMED CONCRETE MATERIALS X1.1. The traditional method to control density is to perform a proctor test and compare in-pl
47、ace density values with the maximum dry density. Procedural methods have also been used and are based on the performance of standard compaction techniques performed for a designated number of passes, and are usually based on the experience of the specifying agency. In this second approach, once the
48、required numbers of passes are made, the lift is accepted. Both of the previously referenced methods have been successfully applied to reclaimed concrete materials. If reclaimed concrete from different sources is used on a specific job site, however, or if the reclaimed concrete is blended with othe
49、r natural or manufactured aggregates, density control problems may result. An alternate compaction control method to account for variations in the specific gravity of reclaimed concrete aggregate is presented below. X1.2. This alternative field control method allows for variations in source materials and automatically adjusts for those changes to ensure maximum compaction of the reclaimed concrete material in the field. In overview, the procedure involves the use of a variable acceptance criteria for compaction based on testin
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