1、Designation: D7765 18D7765 18aStandard Practice forUse of Foundry Sand in Structural Fill and Embankments1This standard is issued under the fixed designation D7765; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 This practice covers methods to use foundry sand as embankment and structural fill.1.2 This practice includes recomme
3、nded construction (Section 5), compaction control (Section 6), and freeze-thaw durability(Section 7) practices.1.3 The engineer should be aware that foundry sand is a by-product of metal casting industries. Various local, state/provincial/regional, or national/federal environmental laws and regulati
4、ons may apply if foundry sand is used as an alternative embankmentor fill material. It is advised that foundry sand users contact appropriate environmental regulators to determine what requirementsor limitations may exist.1.4 This standard primarily applies to both green foundry sand and also genera
5、lly to chemically bonded foundry sand.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof th
6、e user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability ofregulatory limitations prior to use.1.7 This practice offers a set of instructions for performing one or more specific operations. This document cannot replaceeducation or e
7、xperience and should be used in conjunction with professional judgment. Not all aspects of this guide may beapplicable in all circumstances. This ASTM standard is not intended to represent or replace the standard of care by which theadequacy of a given professional service must be judged, nor should
8、 this document be applied without consideration of a projectsmany unique aspects. The word “Standard” in the title of this document means only that the document has been approved throughthe ASTM consensus process.1.8 This international standard was developed in accordance with internationally recogn
9、ized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C837 Test Method for Met
10、hylene Blue Index of ClayD653 Terminology Relating to Soil, Rock, and Contained FluidsD698 Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3)D1556 Test Method for Density and Unit Weight of Soil in Place by Sand-Cone MethodD1557 Test
11、 Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700kN-m/m3)D1883 Test Method for California Bearing Ratio (CBR) of Laboratory-Compacted SoilsD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by MassD297
12、4 Test Methods for Moisture, Ash, and Organic Matter of Peat and Other Organic SoilsD4327 Test Method for Anions in Water by Suppressed Ion ChromatographyD5080 Test Method for Rapid Determination of Percent Compaction1 This practice is under the jurisdiction ofASTM Committee D18 on Soil and Rock and
13、 is the direct responsibility of Subcommittee D18.14 on Geotechnics of SustainableConstruction.Current edition approved Jan. 1, 2018May 1, 2018. Published February 2018May 2018. Originally approved in 2018. Last previous edition approved in 20122018 asD776512.18. DOI: 10.1520/D7765-18.10.1520/D7765-
14、18A.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended onl
15、y to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versi
16、onof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D5918 Test Methods for Frost Heave and T
17、haw Weakening Susceptibility of SoilsD6026 Practice for Using Significant Digits in Geotechnical DataD6938 Test Methods for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods (Shallow Depth)G51 Test Method for Measuring pH of Soil for Use in Corrosion TestingG187 Test M
18、ethod for Measurement of Soil Resistivity Using the Two-Electrode Soil Box Method3. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms in this standard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 active clay content, nthe clay fraction
19、that still can be hydrated.3.2.2 binders, nadditives used to hold the sand in the required shape during the casting process. Binders may be inorganic,such as bentonite clay and sodium silicate, or organic such as phenolic-urethanes and epoxy-resins.3.2.3 chemically bonded sand, nfoundry sand that co
20、ntains non-bentonite binders.3.2.4 foundry sand, na narrowly graded fine sand with subangular to rounded grains that is a by-product of the steel iron, steel,and aluminum casting industry.3.2.5 green foundry sand, na mixture of foundry sand, bentonite and seacoal. Most of foundry sand generated is g
21、reen foundrysand that contains bentonite clay and carbonaceous additives, such as seacoal. Bentonite content of the green foundry sands is thekey characteristic that affects their behavior.3.2.6 seacoal, na carbonaceous material added to foundry sand to provide a reducing environment during casting
22、and to helpease the release of the cooled metal from the mold.4. Significance and Use4.1 Earthwork associated with highway construction provides an opportunity for high volume reuse of green foundry sandsdiscarded by the foundry industry. This practice covers methods and recommendations to use of fo
23、undry sand as embankment andstructural fill.4.2 This practice describes the unique construction considerations that may apply to foundry sands. The behavior may vary dueto specific composition of the material and local conditions.4.3 The use of foundry sand in embankment and structural fill may be r
24、egulated by local, state/provincial/regional, ornational/federal regulations. These regulations should be consulted.4.4 This practice is intended for use with green foundry sands where bentonite is used as the binder. It may not be applicablefor chemically bonded foundry sands.5. Construction Practi
25、ces5.1 The following practices are recommended when constructing foundry sand embankment and structural fill.5.1.1 Foundry sand should be conditioned for dust control and to prevent erosion by the addition of between 10 and 15 percentwater by mass at the source site prior to delivery. This condition
26、ing may include subsequent storage (stockpiling) of the foundrysand for a period of 24 h or more, after the addition of water, until the water is evenly dispersed. If the supplier can demonstratethat water is evenly distributed throughout the foundry sand, then stockpiling may not be required.5.1.2
27、Delivery of foundry sand should be in closed or covered trucks.5.1.3 Large-scale storage (stockpiling) of foundry sand at the site is permissible provided that the water content is maintainedat 10 to 15 percent by mass for dust control.5.1.4 Foundry sand material should be spread into loose lifts of
28、 approximately 200 mm thickness. The engineer may considerthicker lift dimensions if it can be satisfactorily demonstrated with a test section that adequate compaction can be achieved overthe full depth of the thicker lift.5.1.5 If necessary for proper compaction, water should be added to the foundr
29、y sand by the use of water distribution tank trucks.The water and foundry sand should be mixed using a rototilling mixer or other approved method. At the time of compaction, thefoundry sand should have a moisture content that will result in an after compaction dry density that complies with the requ
30、irementsof the project specifications. The dry density is a function of the clay content.5.1.6 The first pass in the compaction process should be accomplished by the method known as tracking. This involves the useof a bulldozer track to accomplish initial compaction. The bulldozer is moved progressi
31、vely across the foundry sand until the entirearea is tracked.5.1.7 The foundry sand should subsequently be compacted using pneumatic tired compaction equipment. Smooth steel drumand vibratory steel drum compactors are not as effective as pneumatic tired compactors for compacting foundry sand.D7765 1
32、8a25.1.8 The foundry sand embankment should be compacted as required by the specifying agency. The dry density is a functionof the clay content. Foundry sand with no clay should have a dry density equal to or greater than 1600 kg/m3 with an optimumwater content of approximately 9 %. Increasing clay
33、content will increase dry density and optimum water content.5.1.9 At the completion of each days work, the surface of the foundry sand embankment should be sealed. This means that itshould be graded after compaction to the specification requirement and rolled with a smooth steel roller so that rain
34、will flow offthe foundry sand instead of puddling.5.1.10 The contractor should use water or other dust palliatives, if necessary, to control the generation of dust due to drying ofthe foundry sand.6. Compaction Control6.1 The use of foundry sand as structural fill and embankment material can present
35、 compaction-related issues that may bedifferent from those encountered with conventional sandy materials. Bentonite content of the green foundry sands is the keycharacteristic affecting their constructability and performance. The active clay content can be determined by using methylene bluetitration
36、 following Test Method C837. A description of the issues and recommended practices for mitigation are presented below.6.1.1 The moisture-density relationship for foundry sand will vary depending on the sand type and the amount of clay.Hydration of dehydrated clay in foundry sands takes at least 1 we
37、ek.3 Accordingly, in performing laboratory tests for index,compaction, and mechanical properties, these characteristics should be recognized and an appropriate hydration time should beallowed after adding water to simulate the expected conditions in the field. Green sand compacted according to Test
38、Methods D698with the exception of extending the hydration period to 1 week from 24 h will give a moisture density curve with a well-definedmaximum dry density peak with an optimum water content between 9 and 14 percent.3 The expected maximum dry density willfall between 1600 kg/m3 and 1850 kg/m3 usi
39、ng Test Methods D698.3 It is recommended that the water content be within 1 % ofthe optimum water content to achieve densities greater than 95 % standard Proctor or 90 % modified Proctor. Chemically bondedfoundry sand and green sand with no clay will have similar dry densities to the green sand with
40、 clay, but the moisture density curveis comparatively flatter with a poorly defined peak. The optimum water content will be between 10 and 15 percent. While the watercontent is not as critical for compaction, it is still recommended that the field water content be maintained within 1 % of theoptimum
41、 water content.6.1.2 Compaction techniques may vary among jurisdictions. However, a loose lift thickness for foundry sand of 200 mm isgenerally preferred. A defined and effective rolling pattern should be developed. Foundry sand is best compacted using pneumatictired compaction equipment. Smooth ste
42、el drum and vibratory steel drum compactors are not as effective as pneumatic tiredcompactors for compacting foundry sand.6.1.3 Acceptance of each lift should be based on in-place density as a percentage of maximum dry density at 61 % of optimumwater content as determined by Test Method D1556 or D69
43、38, or an equivalent method. It should be noted that a nuclear densitygauge calibrated for well graded sand will likely give an inaccurate value for foundry sand due to its narrow range of particle sizes.It is recommended that Test Method D6938 and other tests be carried out to determine a correctio
44、n factor for the nuclear densitygauge, or that the gauge be recalibrated for foundry sand both for moisture and density using Test Method D2216 and Test MethodD1556, respectively. From a practical point of view, the nuclear density gauge will be used on other materials besides foundrysands, so a cor
45、rection factor is the preferred method. The usual value for the acceptance of the lift is 95 percent of the maximumdry density as determined by Test Methods D698 or 90 percent of the maximum dry density as determined by Test Methods D1557.6.1.4 When the contractor demonstrates a consistent ability t
46、o achieve acceptable compaction as indicated by repeatable percentcompaction measurements in accordance with Test Method D5080, the engineer may elect to allow a procedural acceptancetechnique to be used. In this approach a test strip is established and the strip or lift is compacted. After each pas
47、s, where a passis defined as all areas of the lift being compacted by the compaction equipment one time, a test of the density of the lift is made.The actual density of the lift is compared with the maximum dry density value as determined by Test Methods D698 or TestMethods D1557.6.1.5 If other mate
48、rials are blended with the foundry sand, it is likely that the gradation will change, and that this will resultin changes to the moisture-density relationships. An effective method of offsetting this variability problem is to use Test MethodD5080 for rapid determination of percent compaction. This t
49、est method describes the procedure for rapidly determining the percentcompaction and the variation from optimum moisture content of an in-place soil for use in controlling construction of compactedearth. These values are obtained by developing a three-point compaction curve at the same moisture content as the in-place soilwithout knowing the value of the moisture content. The soil used for the rapid determination of percent compaction is normallythe same soil removed from the location of the in-place density test. On a given day, when an in-place density test is performe
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