1、Designation: D7765 12Standard 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 revision.
2、A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers methods to use foundry sand asembankment and structural fill.1.2 It includes recommended construction (Section 5
3、), com-paction control (Section 6), and freeze-thaw durability (Section7) practices.1.3 The engineer should be aware that foundry sand is aby-product of metal casting industries. Various state, county,and local environmental laws and regulations may apply iffoundry sand is used as an alternative emb
4、ankment or fillmaterial. It is advised that foundry sand users contact state,county, and local environmental regulators to determine whatrequirements or limitations may exist.1.4 This standard applies to both green foundry sand andchemically bonded foundry sand.1.5 The values stated in SI units are
5、to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices a
6、nd determine the applica-bility of regulatory limitations prior to use.1.7 This guide offers an organized collection of informationor a series of options and does not recommend a specificcourse of action. This document cannot replace education orexperience and should be used in conjunction with prof
7、essionaljudgment. Not all aspects of this guide may be applicable in allcircumstances. This ASTM standard is not intended to repre-sent or replace the standard of care by which the adequacy ofa given professional service must be judged, nor should thisdocument be applied without consideration of a p
8、rojects manyunique aspects. The word “Standard” in the title of thisdocument means only that the document has been approvedthrough the ASTM consensus process.2. Referenced Documents2.1 ASTM Standards:2C837 Test Method for Methylene Blue Index of ClayD653 Terminology Relating to Soil, Rock, and Conta
9、inedFluidsD698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12 400 ft-lbf/ft3(600kN-m/m3)D1556 Test Method for Density and Unit Weight of Soil inPlace by Sand-Cone MethodD1557 Test Methods for Laboratory Compaction Character-istics of Soil Using Modified Eff
10、ort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D1883 Test Method for CBR (California Bearing Ratio) ofLaboratory-Compacted SoilsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD2974 Test Methods for Moisture, Ash, and Organic Matterof Peat and Other Organic S
11、oilsD4327 Test Method for Anions in Water by Suppressed IonChromatographyD5080 Test Method for Rapid Determination of PercentCompactionD5918 Test Methods for Frost Heave and Thaw WeakeningSusceptibility of SoilsD6026 Practice for Using Significant Digits in GeotechnicalDataD6938 Test Method for In-P
12、lace Density and Water Contentof Soil and Soil-Aggregate by Nuclear Methods (ShallowDepth)G51 Test Method for Measuring pH of Soil for Use inCorrosion TestingG187 Test Method for Measurement of Soil ResistivityUsing the Two-Electrode Soil Box Method3. Terminology3.1 For definitions related to geotec
13、hnical properties, seeTerminology D653.1This practice is under the jurisdiction of ASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.14 on Geotechnics ofSustainable Construction.Current edition approved June 1, 2012. Published August 2012. DOI: 10.1520/D7765-12.
14、2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C
15、700, West Conshohocken, PA 19428-2959. United States13.2 Definitions of Terms Specific to This Standard:3.2.1 active clay content, nthe clay fraction that still canbe hydrated.3.2.2 binders, nadditives used to hold the sand in therequired shape during the casting process. Binders may beinorganic, su
16、ch as bentonite clay and sodium silicate, ororganic such as phenolic-urethanes and epoxy-resins.3.2.3 chemically bonded sand, nfoundry sand that con-tains non-bentonite binders.3.2.4 foundry sand, na narrowly graded fine sand withsubangular to rounded grains that is a by-product of the steeland alum
17、inum casting industry.3.2.5 green foundry sand, na mixture of foundry sand,bentonite and seacoal. Most of foundry sand generated is greenfoundry sand that contains bentonite clay and carbonaceousadditives, such as seacoal. Bentonite content of the greenfoundry sands is the key characteristics affect
18、ing their behav-ior.3.2.6 seacoal, na carbonaceous material added to foundrysand to provide a reducing environment during casting and tohelp ease the release of the cooled metal from the mold.4. Significance and Use4.1 Earthwork associated with highway construction pro-vides an opportunity for high
19、volume reuse of green foundrysands discarded by the foundry industry. This practice coversmethods and recommendations to use of foundry sand asembankment and structural fill.4.2 This practice describes the unique construction consid-erations that may apply to foundry sands. The behavior mayvary due
20、to specific composition of the material and localconditions.4.3 The use of foundry sand in embankment and structuralfill may be regulated by state and local codes. These codesshould be consulted.4.4 This practice is intended for use with green foundrysands where bentonite is used as the binder. It m
21、ay not beapplicable for chemically bonded foundry sands.5. Construction Practices5.1 The following practices are recommended when con-structing foundry sand embankment and structural fill.5.1.1 Foundry sand should be conditioned for dust controland to prevent erosion by the addition of from 10 to 15
22、 percentwater by mass at the source site prior to delivery. Thisconditioning may include subsequent storage (stockpiling) ofthe foundry sand for a period of 24 h or more, after the additionof water, until the water is evenly dispersed. If the supplier candemonstrate that water is evenly distributed
23、throughout thefoundry sand, then stockpiling may not be required.5.1.2 Delivery of foundry sand should be in closed orcovered trucks.5.1.3 Large-scale storage (stockpiling) of foundry sand atthe site is permissible provided that the water content ismaintained at 10 to 15 percent by mass for dust con
24、trol.5.1.4 Foundry sand material should be spread into loose liftsof approximately 20 cm thickness. The engineer may considerthicker lift dimensions if it can be satisfactorily demonstratedwith a test section that adequate compaction can be achievedover the full depth of the thicker lift.5.1.5 If ne
25、cessary for proper compaction, water should beadded to the foundry sand by the use of water distribution tanktrucks. The water and foundry sand should be mixed using arototilling mixer or other approved method. At the time ofcompaction, the foundry sand should have a moisture contentthat will result
26、 in an after compaction dry density that complieswith the requirements of the project specifications. The drydensity is a function of the clay content.5.1.6 The first pass in the compaction process should beaccomplished by the method known as tracking. This involvesthe use of a bulldozer track to ac
27、complish initial compaction.The bulldozer is moved progressively across the foundry sanduntil the entire area is tracked.5.1.7 The foundry sand should subsequently be compactedusing pneumatic tired compaction equipment. Smooth steeldrum and vibratory steel drum compactors are not as effectiveas pneu
28、matic tired compactors for compacting foundry sand.5.1.8 The foundry sand embankment should be compactedas required by the specifying agency. The dry density is afunction of the clay content. Foundry sand with no clay shouldhave a dry density equal to or greater than 1602 kg/m3with anoptimum water c
29、ontent of approximately 9 %. Increasing claycontent will increase dry density and optimum water content.5.1.9 At the completion of each days work, the surface ofthe foundry sand embankment should be sealed. This meansthat it should be graded after compaction to the specificationrequirement and rolle
30、d with a smooth steel roller so that rainwill flow off the foundry sand instead of puddling.5.1.10 The contractor should use water or other dust pallia-tives, if necessary, to control the generation of dust due todrying of the foundry sand.6. Compaction Control6.1 The use of foundry sand as structur
31、al fill and embank-ment material can present compaction-related issues that maybe different from those encountered with conventional sandymaterials. Bentonite content of the green foundry sands is thekey characteristics affecting their constructability and perfor-mance behavior. The active clay cont
32、ent can be determined byusing methylene blue titration following Test Method C837.Adescription of the issues and recommended practices formitigation are presented below.6.1.1 The moisture-density relationship for foundry sandwill vary depending on the sand type and the amount of clay.Hydration of de
33、hydrated clay in foundry sands takes at least 1week.3Accordingly, in performing laboratory tests for index,compaction, and mechanical property, these characteristicsshould be recognized and an appropriate hydration time shouldbe allowed after adding water to simulate the expected condi-tion in the f
34、ield. Green sand compacted according to Test3Kleven, J. R., Edil, T. B., and Benson, C. H. “Evaluation of Excess FoundrySystem Sands for Use as Subbase Material,” Journal of the Transportation ResearchBoard, No. 1714, National Research Council, Washington D. C., 2000, pp. 40-48.D7765 122Methods D698
35、 with the exception of extending the hydrationperiod to 1 week from 24 h will give a moisture density curvewith a well-defined maximum dry density peak with anoptimum water content between 9 and 14 percent.3Theexpected maximum dry density will fall between 1602 kg/m3and 1860 kg/m3using Test Methods
36、D698.3It is recommendedthat the water content be within 1 % of the optimum watercontent to achieve densities greater than 95 % standard proctoror 90 % modified Proctor. Chemically bonded foundry sandand green sand with no clay will have similar dry densities tothe green sand with clay, but the moist
37、ure density curve iscomparatively flatter with a poorly defined peak. The optimumwater content will be between 10 and 15 percent. While thewater content is not as critical for compaction, it is stillrecommended that the field water content be maintained within1 % of the optimum water content.6.1.2 C
38、ompaction techniques may vary among jurisdictions.However, a loose lift thickness for foundry sand of 20 cm isgenerally preferred. A defined and effective rolling patternshould be developed. Foundry sand is best compacted usingpneumatic tired compaction equipment. Smooth steel drum andvibratory stee
39、l drum compactors are not as effective as pneu-matic tired compactors for compacting foundry sand.6.1.3 Acceptance of each lift should be based on in-placedensity as a percentage of maximum dry density at 61%ofoptimum water content as determined by Test Method D1556or D6938, or an equivalent method.
40、 It should be noted that anuclear density gauge calibrated for well graded sand willlikely give an inaccurate value for foundry sand due to itsnarrow range of particle sizes. It is recommended that TestMethod D6938 and other tests be carried out to determine acorrection factor for the nuclear densit
41、y gauge, or that thegauge be recalibrated for foundry sand both for moisture anddensity using Test Method D2216 and Test Method D1556,respectively. From a practical point of view, the nuclear densitygauge will be used on other materials besides foundry sands, soa correction factor is the preferred m
42、ethod. The usual value forthe acceptance of the lift is 95 percent of the maximum drydensity as determined by Test Methods D698 or 90 percent ofthe maximum dry density as determined by Test MethodsD1557.6.1.4 When the contractor demonstrates a consistent abilityto achieve acceptable compaction as de
43、monstrated by repeat-able percent compaction measurements in accordance withTest Method D5080, the engineer may elect to allow aprocedural acceptance technique to be used. In this approach atest strip is established and the strip or lift is compacted. Aftereach pass, where a pass is defined as all a
44、reas of the lift beingcompacted by the compaction equipment one time, a test of thedensity of the lift is made. The actual density of the lift iscompared with the maximum dry density value as determinedby Test Methods D698 or Test Methods D1557.6.1.5 If other materials are blended with the foundry s
45、and, itis likely that the gradation will change, and that this will resultin changes to the moisture-density relationships. An effectivemethod of offsetting this variability problem is to use TestMethod D5080 for rapid determination of percent compaction.This test method describes the procedure for
46、rapidly determin-ing the percent compaction and the variation from optimummoisture content of an in-place soil for use in controllingconstruction of compacted earth. These values are obtained bydeveloping a three-point compaction curve at the same mois-ture content as the in-place soil without knowi
47、ng the value ofthe moisture content. The soil used for the compaction curve isnormally the same soil removed from the location of thein-place density test. On a given day, when an in-place densitytest is performed, a companion sample of foundry sand istaken. The acceptance of the compaction for the
48、days produc-tion is based on these values. If there is a high degree ofvariability in the foundry sand, it may be necessary to establisha practice of performing rapid percent compaction on amorning and afternoon basis, or even more frequently.6.2 Appropriate testing for strength and other design-rel
49、atedparameters as dictated by the intended end-use considerationsshould be made on foundry sands and the foundry sandsblended with other materials at the specified field densities.7. Electrochemical Limits7.1 Durability of metallic inclusions in the fill, such asmetallic pipes and steel reinforcement elements, requires thatthe fill material does not exceed certain electrochemical limits.The recommended electrochemical limits are as follows:4Property Standard Test ProcedureResistivity Ohm-cm 3000 Test Method G187pH 5 10 Test Method G51Organic Content #1 % Test Methods D2974C
