1、Designation: D7765 18Standard 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 This practice includes recommended construction
3、 (Sec-tion 5), compaction control (Section 6), and freeze-thawdurability (Section 7) practices.1.3 The engineer should be aware that foundry sand is aby-product of metal casting industries. Various local, state/provincial/regional, or national/federal environmental laws andregulations may apply if f
4、oundry sand is used as an alternativeembankment or fill material. It is advised that foundry sandusers contact appropriate environmental regulators to deter-mine what requirements or limitations may exist.1.4 This standard applies to both green foundry sand andchemically bonded foundry sand.1.5 The
5、values stated in SI units are 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
6、 safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.7 This practice offers a set of instructions for performingone or more specific operations. This document cannot replaceeducation or experience and should be used in conjunction wit
7、hprofessional judgment. Not all aspects of this guide may beapplicable in all circumstances. This ASTM standard is notintended to represent or replace the standard of care by whichthe adequacy of a given professional service must be judged,nor should this document be applied without consideration of
8、a projects many unique aspects. The word “Standard” in thetitle of this document means only that the document has beenapproved through the ASTM consensus process.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in
9、 the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C837 Test Method for Methylene Blue Index of ClayD653 Terminology Relati
10、ng to Soil, Rock, and ContainedFluidsD698 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
11、 of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)D1883 Test Method for California Bearing Ratio (CBR) 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 Matter
12、of Peat and Other Organic SoilsD4327 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 GeotechnicalDat
13、aD6938 Test Methods for In-Place 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 Method1This practice is under
14、 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 Jan. 1, 2018. Published February 2018. Last previousedition approved in 2012 as D776512. DOI: 10.1520/D7765-18.2For refer
15、enced 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 C700, West
16、Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trad
17、e Organization Technical Barriers to Trade (TBT) Committee.13. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms in thisstandard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 active clay content, nthe clay fraction that still canbe hydra
18、ted.3.2.2 binders, nadditives used to hold the sand in therequired shape during the casting process. Binders may beinorganic, such 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 bin
19、ders.3.2.4 foundry sand, na narrowly graded fine sand withsubangular to rounded grains that is a by-product of the steeland aluminum 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 bentonit
20、e clay and carbonaceousadditives, such as seacoal. Bentonite content of the greenfoundry sands is the key characteristic that affects theirbehavior.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
21、metal from the mold.4. Significance and Use4.1 Earthwork associated with highway construction pro-vides an opportunity for high volume reuse of green foundrysands discarded by the foundry industry. This practice coversmethods and recommendations to use of foundry sand asembankment and structural fil
22、l.4.2 This practice describes the unique construction consid-erations that may apply to foundry sands. The behavior mayvary due to specific composition of the material and localconditions.4.3 The use of foundry sand in embankment and structuralfill may be regulated by local, state/provincial/regiona
23、l, ornational/federal regulations. These regulations should be con-sulted.4.4 This practice is intended for use with green foundrysands where bentonite is used as the binder. It may not beapplicable for chemically bonded foundry sands.5. Construction Practices5.1 The following practices are recommen
24、ded 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 between 10 and 15percent water by mass at the source site prior to delivery. Thisconditioning may include subsequent storage (stockpil
25、ing) 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 throughout thefoundry sand, then stockpiling may not be required.5.1.2 Delivery of foundry sand should be in closed o
26、rcovered 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 control.5.1.4 Foundry sand material should be spread into loose liftsof approximately 200 mm thickness. The engineer may
27、 con-sider thicker lift dimensions if it can be satisfactorily demon-strated with a test section that adequate compaction can beachieved over the full depth of the thicker lift.5.1.5 If necessary for proper compaction, water should beadded to the foundry sand by the use of water distribution tanktru
28、cks. 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 in an after compaction dry density that complieswith the requirements of the project specifications. The dryden
29、sity 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 accomplish initial compaction.The bulldozer is moved progressively across the foundry sanduntil the entire area is
30、 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 pneumatic tired compactors for compacting foundry sand.5.1.8 The foundry sand embankment should be compactedas requi
31、red 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 1600 kg/m3with anoptimum water content of approximately 9 %. Increasing claycontent will increase dry density and optimum water content.5.1.9 At
32、 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 rolled with a smooth steel roller so that rainwill flow off the foundry sand instead of puddling.5.1.10 The contracto
33、r should use water or other dustpalliatives, if necessary, to control the generation of dust due todrying of the foundry sand.6. Compaction Control6.1 The use of foundry sand as structural fill and embank-ment material can present compaction-related issues that maybe different from those encountered
34、 with conventional sandymaterials. Bentonite content of the green foundry sands is thekey characteristic affecting their constructability and perfor-mance. The active clay content can be determined by usingmethylene blue titration following Test Method C837.Adescription of the issues and recommended
35、 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 dehydrated clay in foundry sands takes at least 1D7765 182week.3Accordingly, in performing laboratory tests for index,compacti
36、on, and mechanical properties, these characteristicsshould be recognized and an appropriate hydration time shouldbe allowed after adding water to simulate the expected condi-tions in the field. Green sand compacted according to TestMethods D698 with the exception of extending the hydrationperiod to
37、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 1600 kg/m3and 1850 kg/m3using Test Methods D698.3It is recommendedthat the water content be within
38、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 moisture density curve iscomparatively flatter with a poorly
39、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 Compaction techniques may vary among jurisdictions.Howeve
40、r, a loose lift thickness for foundry sand of 200 mm isgenerally preferred. A defined and effective rolling patternshould be developed. Foundry sand is best compacted usingpneumatic tired compaction equipment. Smooth steel drum andvibratory steel drum compactors are not as effective as pneu-matic ti
41、red 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. It should be noted that anuclear density gauge calibra
42、ted 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 density gauge, or that thegauge be recalibrated for foundry s
43、and 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 method. The usual value forthe acceptance of the lift is
44、 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 indicated by repeatablepercent compaction measurements in
45、 accordance with TestMethod D5080, the engineer may elect to allow a proceduralacceptance technique to be used. In this approach a test strip isestablished and the strip or lift is compacted. After each pass,where a pass is defined as all areas of the lift being compactedby the compaction equipment
46、one time, a test of the density ofthe lift is made. The actual density of the lift is compared withthe maximum dry density value as determined by Test MethodsD698 or Test Methods D1557.6.1.5 If other materials are blended with the foundry sand, itis likely that the gradation will change, and that th
47、is 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 rapidly determin-ing the percent compaction and the variatio
48、n 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 knowing the value ofthe moisture content. The soil used for the r
49、apid determinationof percent compaction is normally the same soil removed fromthe location of the in-place density test. On a given day, whenan in-place density test is performed, a companion sample offoundry sand is taken. The acceptance of the compaction forthe days production is based on these values. If there is a highdegree of variability in the foundry sand, it may be necessaryto establish a practice of performing rapid percent compactiontests on a morning and afternoon basis, or even more fre-quently.6.2 Appropriate testing for strength and other design-relatedparam
