2024年1月12日发(作者：联想s410属于什么档次)

constructionandbuildingmaterialsBehavior and mix design development of concrete made with recycled aggregate from deconstructed lead-contaminated masonry a ,?, b , ba Department of Engineering Technology,Texas State University-San Marcos,San Marcos,TX 78666,United StatesbDepartment of Civil,Construction and Environmental Engineering,Iowa State University,Ames,IA 50011,United Statesa r t i c l e i n f o Article history:Available online xxxx Keywords:Aggregate Cement Concrete Lead Masonry Nomograph Recycleda b s t r a c tThe present study is to develop an effective method for using deconstructed,lead-contaminated masonry materials in new concrete so as to minimizethe environmental impact,cost,and time of the approach to this method is to use crushed masonry materials to replace naturalaggregate in conventional different types of masonry materials (concrete blocks and clay bricks)were collected,painted with lead-basedpaint (LBP),and then crushed to simulate recycled LBP-contaminated masonry types of cement (type I Portland cement,CalciumSulfoaluminate (CSA)cement,and Portland cement with 5%phosphate addition)were selected for sequestering lead in the recycled ete mix design matrix was developed with different water-to-cement ratios (w/c),aggregate-to-cement ratios (a/c),types of cements,and types ofmasonry on the test results,mix design nomographs were developed for concrete made with the recycled,LBP-contaminated results indicate that the lead can be sequestered,or rendered non-leachable,due to the high alkalinity of concrete thereforeno longer has the toxicity characteristic for lead and is suitable for various types of new construction,such as foundation and pavement,reinforcedbeams,columns,and walls.ó2012Elsevier rights uctionIn the United States,many masonry structures built before 1980s contain lead-based paint (LBP),which causes a considerable environmental andhealth the US Environmental Protection Agency (EPA)and the Occupational Safety and Health Administration (OSHA)have establishedregulations governing the management of LBP in truction of these struc-tures is often time consuming and costly due to the paintremoval and the hazardous material disposal [1–3].Clearly,a more cost effective,environmentally friendly method is urgently needed for remediatingand reusing deconstructed masonry materials con-taminated with a chemical point view,the degree of the hazard resulting from LBP is often de?ned by the solubility of lead in a solubility of lead ina material is generally controlled by the pH or alkalinity of the Eh–pH diagram for an aqueous lead-carbonate system indicates that leadwill be insoluble if the system has a pH value above 6or 7[4–6].In a cement-based material,the pH values of pore solutions often range from 11to13,thus possi-bly sequestering lead in the the above-mentioned concept,a study has been con-ducted to sequester lead by recycling the lead-contaminated deconstruction masonrymaterials as concrete aggregate.A key of this study is to design rational mix proportions so that the concrete cannot only sequester lead in therecycled aggregate but also meet general concrete construction and structural performance require-ments,such as having proper workability paper presents a rational mix design method for proportioning non-hazardous,well-performing,sustainable concrete utilizing therecycled,lead-contaminated aggregate for ?eld mix design development includes three major steps:(1)characterizing the recycled masonry materials –evaluating their toxicity,speci?cgravity,absorption,and strength,(2)proportion-ing concrete mixtures based on workability control –designing concrete mixtures to have low,mediumand high slumps so as to permit the concrete to be used for different construction applica-tions,and (3)performance evaluation –examining the leadleach-ing ability or sequestering effectiveness and strength of the concrete containing recycled,lead-contaminated deconstruction a result,a series of mix design nomograms are established that illustrate the relationships between the mix proportion parameters (suchas water-to-cement ratio,aggre-gate-to-cement ratio,and cement content)and concrete perfor-mance (such as lead sequestering effectiveness andstrength).0950-0618/$-see front matter ó2012Elsevier rights :10.1016/ldmat.2011.07.067

Corresponding .:+;fax:+.E-mail address:@/doc/ ().prepared (Table 2).Air entraining agent with the recommended dosage was used in all of the concrete mixes methodsPhysical properties of the masonry materials were characterized,and their total and leachable lead contents were speci?c gravity andabsorption of the crushed masonry materials were measured according to ASTM C127and ASTM g analysis and bulk density (unitweight)tests were conducted for the painted and crushed masonry materials according to ASTM C136,and ASTM leachability oflead from the LBP-painted recycled aggregates and the concrete mixes made with those aggregates was tested using the Toxicity CharacteristicLeaching Procedure (TCLP),EPA Method 1311[9].The total lead con-tent in the materials was also evaluated using the California Waste ExtractionTest (WET)[10].Concrete was mixed based on the ASTM C192multiple-step mixing slump of fresh concrete was measured according to ASTMC143immediately after this study,the slump test was not only a measurement to evaluate the workability of concrete,more importantly,theslump value was used as a con-trol parameter for concrete mix ent slumps are required for different concrete tes with three different ranges of slumps were designed:(1)25–50mm slump for low workability concrete (generally used forpavements and slabs),(2)75–100mm slump for medium workability concrete (generally used for beams,walls,columns,reinforced concrete),and(3)150–175mm slump for high workability concrete (generally used for heavily reinforced components with complicated shapes).The entire samplepreparation and curing process followed ASTM ssive strength of hardened concrete was tested at the age of 3,7and 28days according to ASTM broken specimens fromcompression testing were further processed and then used for the TCLP soluble and total lead content (WET)s and terization of recycled,LBP-contaminated aggregate Table 3presents the physical properties and lead content of the lead-contaminatedmasonry materials test results indi-Table 1Oxide and chemical composition of cement (%).CaOSiO 2Al 2O 3Fe 2O 3MgO SO 3TiO 2Oxide composition (%)Portland cement 62.9620.96 4.54 3.48 2.91 2.77–CSA cement40.00 5.5537.50 1.50 1.7510.00 1.25C 3SC 2S C 3A C 4AF Gypsum Ca 4Al 6O 12SO 4Chemical composition (%)Portland cement 53.7119.58 6.1410.590.78–CSA cement0.4212.5910.64–ng with ng of LBP contaminated masonry that the recycled masonry materials had lower speci?c grav-ity (2.34–2.39)than natural aggregate (2.5–2.9),while the absorp-tion of the recycledaggregate (5.11–7.11%)was much higher than natural aggregate (0.2–4.0%)[11,12].The void contents of the four(a) Masonry A (b) Masonry BTable 2Concrete mix Masonry a/c w/c C (kg/m 3)Cement Masonry a/c w/c C (kg/m 3)1Portland A 3.00.2850025Portland C 6.00.362662Portland A 3.00.3145626Portland C6.00.422653Portland A 3.00.3247727Portland C 6.00.442554Portland A 4.50.3234828Portland D 3.00.394835Portland A 4.50.3433029Portland D3.00.434756Portland A 4.50.3732130Portland D 3.00.484367Portland A 6.00.3426531Portland D 4.50.503408Portland A 6.00.3626632Portland D4.50.523299Portland A 6.00.4125433Portland D 4.50.5633410Portland B 3.00.3450634Portland D 6.00.5626711Portland B 3.00.3547135Portland D6.00.6025712Portland B 3.00.4047336Portland D 6.00.7425313Portland B 4.50.3935137CSA B 3.00.4546814Portland B 4.50.4231838CSA B

4.50.4635415Portland B 4.50.4831739CSA B 6.00.5026916Portland B 6.00.4526940CSA D 3.00.4647017Portland B 6.00.4825641CSA D4.50.5134918Portland B 6.00.5523642CSAD 6.00.6126519Portland C 3.00.3049943Phosphate B 3.00.3748320Portland C 3.00.3348644Phosphate B 4.50.4134921Portland C3.00.3647545Phosphate B 6.00.4925322Portland C 4.50.3333946Phosphate D 3.00.4347323Portland C 4.50.3634447Phosphate D 4.50.5333624PortlandC4.50.3933448PhosphateD6.00.62263Note :Here,a/c is aggregate-to-cement ratio;w/c is water-to-cement ratio;and C is cement et al./Construction and Building Materials xxx (2012)xxx–xxx3and 10.1g/Kg,larger than 1g/Kg,which shall be de?ned as hazard materials based on the California y C and D had TCLP leadcontent of 142and 77mg/L and the total lead content from WET tests of 12.5and 5.82g/Kg,which were de?ned as haz-ard materials based on both theRCRA and California critical issue in the present study is to ?nd out whether or not the concrete made with these hazard materialsstill have tox-icity content and lead leachability of concreteThe above mentioned lead-contaminated masonry materials were crushed and used as aggregate in the concrete mixes as de-signed in Table P lead,TCLP pH and total lead of the 48designed mixes were determined at the concrete age of s of compressivestrengths,together with lead content and lead leachability of all 48mixes can be found in Table ed test results and analysis can be found inWang et al.[8].Fig.5presents the TCLP pH value and leachable Pb content of concrete mixes gh the total lead in the concrete mixes were high (up to2.2%),the ?gure shows that all concrete mixes studied,except four mixes with masonry material D,had TCLP leachable Pb content less than1mg/L,much lower than the RCRA limit of 5mg Pb/ a result,these concrete mixes are con-sidered as nonhazardous materials under RCRAalthough their aggregate is four mixes that showed hazard charac-teristic were mixes 34and 36(Table 1),which had a high a/c(6.0)and low Portland cement content (267and 253kg/m 3)and mixes 40and 42,which was made of CSA cement with a/c of result is probably due to the fact that the CSA cement was less alkaline than Portland cement,and the con-crete made with CSAcement had lower pH values than the corre-sponding concrete made with Portland cement,thus being less effective for sequestering lead in theconcrete.A mix design withhigher cement content or high alkaline cement may be used to in-crease the alkalinity of the concrete and reduce its TCLP Pb on of5%phosphate in Portland cement did not signi?-cantly change the TCLP lead concentrations and total lead in the is believed that if highlyinsoluble hydroxypyromorph-ite [Pb 5(PO 4)3OH]was formed in the concrete system through the lead phosphate reaction,it would have sequesteredlead from the highly acidic conditions of the total lead might have sug-gested a means for rendering LBP-contaminated masonry nonhaz-ardous under California reaction,however,did not occur in the present concentrations of phosphate added ran-ged from 31%to62%of the amounts needed to stoichiometrically convert the lead in the concrete to hydroxypyromorphite but did not result in proportionate reductionsin detectable total /doc/ pressive strength of concreteCompressive strength of all concrete mixes was tested at ages of 3days,7days,and .6illustrates the effects of materials and mix parameterson the concrete trends of the ef-fects were similar for the concrete at three different testing lly,concrete strength decreasedwith increased water-to-cement ratios (w/c)and aggregate-to-cement ratios (a/c).As observed in Fig.6,for a given w/c,masonry B and D resulted in higher concrete strength than masonry A and C,which is prob-ably related to theconcrete workability and strength of the recy-cled aggregate, a given mix proportion,concrete made with CSA cement provided higherearly age compressive strength than the corresponding concrete made with Portland large strength and workability ranges implythat,with appropriate design,the concrete made with recycled aggregate from deconstructed masonry materials can be used for variousTable 3Physical properties and lead content of lead-contraindicated masonry te blocks Clay bricks A

B C D Speci?c gravity 2.34 2.39 2.37 2.39Absorption (%)7.70 5.95 6.52 5.11Voids between aggregate particle (compacted)(%)36.7937.2041.3239.92Voids between aggregate particle (uncompacted)(%)38.5241.9847.746.33Compressive strength (MPa)21.0732.7973.65101.53TCLP pH6.737.02 5.11 4.88TCLP Pb,mg/L (toxicity limit:5mg/L) 4.17 1.2914277WET Total Pb,g/Kg (toxicity limit:1g/Kg)15.410.112.55.82Note :The underlined values indicate that these materials are classi?ed as toxic materials based on RCRA or California ion of the aggregate recycled masonry materials studied.(Note:DOT-C3and C4are natural aggregate used for conventional pavementconcrete USA)types of constructions,such as foundation,pavement,reinforced beams,columns,and walls.A cost effective analysis by the authorsshowed that a signi?cant saving can be achieved by using LBP-con-taminated masonry materials as recycled aggregate in cost savingsmay result from eliminating LBP removal and waste material disposal,which will minimize the use of secure land?lls,eliminate the time and equipmentrequired for sieving and re-grading recycled aggregate,and reduce natural aggregate consumption for concrete s of this cost effec-tive analysis can be found in a separated publication [13]. design nomograph developmentIn the present study,a nomograph was developed for concrete made with each type of recycled,LBP-contaminated aggregate and/doc/ ing the mix design nomograph,proper mix propor-tions can be selected for the desiredworkability and nomograph combines three relationships developed for the prop-erties of fresh and hardened concrete into mix de-sign nomograph uses three correlations:Abrams’law,Lyse’s law,and Molinari’s law [14,15].Abrams’law correlates the compressive strength of concrete with the w/c as:f 0c ?k 1k w =c2e1Twhere k 1,and k 2are constants depending on the materials ’s law correlates the water-to-cement ratio (w/c)with the aggregate-to-cementratio (a/c)(by weight)as:ea =c T?k 3ew =c Ttk 4e2Twhere a/c is the aggregate-to-cement ratio,k 3,and k 4are constants depend on the materials ri’s law correlates the cement content and aggregate-to-cement ratio as:C ?1000k 5ea =c Ttk 6e3Twhere C is the cement content,k 5,and k 6are constants depend on the materials .6shows samples of general mix design nomograph can be used to determine the concrete mix proportion (a)for a givencompressive strength but different workability (slump)requirements (Fig.7a)or (b)for a given workability but different strength requirements (Fig.7b).Asshown in Fig.6a,according to the required compressive strength f 0c ;1;2;3,one can determined the w/c for concrete mixtures (w/c

1,2,3)throughTable 4Compressive strength,lead content and lead-leachability of concrete mixtures.f 0c ;3(MPa)f 0c ;7(MPa)f 0c ;28(MPa)TCLP pH TCLP Pb (mg/L)Total Pb(g/Kg)124.730.035.211.050.4219.6216.720.926.611.430.3216.1318.022.025.911.160.3016.0412.615.820.610.610.3217.158.211.514.011.270.2716.066.610.012.611.360.4916.07 5.67.310.310.780.0621.48 5.68.812.010.690.0520.69 4.5 6.59.110.410.3817.31031.535.846.011.011.168.371121.126.334.211.41 2.1910.41219.325.032.611.190.499.11313.718.523.511.070.359.0149.412.816.111.33 1.088.515 6.49.311.910.871.210.78168.310.514.610.850.2510.1117 5.37.410.011.25 1.2710.7618 2.9 3.9 5.610.89 1.110.821922.326.032.810.910.758.872018.625.430.310.961.168.02115.318.227.411.23 1.097.6228.113.419.610.220.277.623 6.210.913.810.60.948.6824 4.88.915.510.570.447.5250.07.29.58.042.419.67260.0 4.37.69.68 1.369.99270.0 2.5 5.49.79 1.189.172828.433.338.0110.83 4.192922.331.340.911.150.16 4.43015.019.826.410.980.765.23113.816.728.211.460.95 5.03212.015.923.810.40.63 5.513311.712.218.59.750.58 4.19347.413.117.07.33 6.14 6.30357.710.516.38.86 1.436.2436 3.8 6.87.9 6.4133 5.513719.623.825.910.290.227.943816.717.921.810.40.328.93911.212.013.310.540.3711.14026.428.730.2 pH value and Pb content of concrete mixes et al./Construction and Building Materials xxx (2012)xxx–xxx5Abram’s ,the a/c ratio (a/c 1,2,3)can be evaluated through Lyse’s Law based on the w/c and required workability (slump)y,thecement content (C 1,2,3)can be determined based on the Molinari’s Law from a/ concrete mix design is there-fore determined based on thesethree parameters:w/c,a/c,and order to comply a set of mix design nomograph,a series of mixes with different proportion components (w/c,a/c andC)gen-erally need to be prepared based on controlled

et al./Construction and Building Materials xxx (2012)xxx–xxxperformance (such as compressive strength)of these mixtures are then evaluated and incorporated into the nomograph so as to establish the relationbetween mix proportion parameters (w/c,a/c and C).Fig.8provides four examples of nomographs of concrete made with different masonry materials and different types of thesenomographs,compressive strength at three different ages (3,7,and 28days)was considered as the concrete performance crite-ria in addition nomographs demonstrate sim-ilar trends to those published in the literature [14].Similar nomographs can also be developed if otherperformance test re-sults,such as ?exural strength,are used to replace concrete strength values in the ?,concrete can be designed to meetthe other performance nomographs resulting from the present study can be found in the reference reported by Wang et al.[8].The mix design nomographs developed in this study can help ?eld engineers select the proper mix proportion parameters to meet speci?ed concreteperformance tes with desir-able compressive strengths and workability levels can be designed using LBP-contaminated these con-cretes might have high concentrations of total lead (up to 2.2%in this study),they would not have a toxicity characteristicfor lead and would not be classi?ed as hazardous materials under RCRA.

et al./Construction and Building Materials xxx (2012)xxx–xxx sionsA variety of concrete mixes was made with four different aggre-gates recycled from lead-contaminated masonry materials,three different kinds ofcement,three different aggregate-to-cement ra-tios,and a wide range of water-to-cement concrete workability,compressive strength,totallead and lead leachability of the concrete mixes were on the test results,mix design nomographs were followingconclu-sions can be made: in the LBP-contaminated masonry materials can be sequestered in concrete due to the high alkalinity gh some masonry materials were classi?ed as hazard materials due to leachable lead content,concrete mixes made with suchmaterials showed no toxicity characteristic for lead according to the Resource Conservation and Recovery Act (RCRA).gh having low speci?c gravity and high absorption,crushed masonry materials,without sieving and re-grading process,can be simply used toreplace all natural aggregate

et al./Construction and Building Materials xxx (2012)xxx–xxxand to produce new concrete that meets structural and con-structability of Calcium Sulfoaluminate (CSA)cement signi?cantly increased concrete strength at early ages but had a little effect on the 28-daycompressive CSA cement was less alkaline than Portland cement,and the concrete made with CSA cement had lower pH values thanthe corresponding con-crete made with Portland cement,thus being less effective for sequestering lead in the tically,phosphate cold react with lead to form hydrox-ypyromorphite,thus resulting in sequestration of -ever,such a reaction did notoccur in the present study and the addition of 5%phosphate had no signi?cant effect on appar-ent total lead content,lead leachability,or well designed and well processed,the concrete made with all recycled aggregate from deconstructed masonry mate-rials can have a largerange of workability and strength,thus applicable to various new concrete constructions,such as foun-dation and pavement,reinforcedbeams,columns,and mix design nomograph developed in this study can be used to decide concrete mix design with desired strengths and methodcan be easily adapted by ?eld engineers for designing concrete with aggregates recycled from different ?eld deconstruction ledgementsThe authors gratefully acknowledge the Strategic Environmen-tal Research and Development Program (SERDP)for sponsor the re-search projectand the support provided by the National Concrete Pavement Technology Center (CP Tech Center).Special thanks are given to Steffes, White, Ge,and Lindquist for their assistance in the lab and Lathum at the Department of Environmental Healthand Safety,Iowa StateUniversity for providing advice and assistance in dealing with occupational safety and hazardous waste issues associated with this r and Otto at the Holcim provided donations of masonry materials and cement.

References[1]ESTCP (Environmental Security Technology Certi?cation Program).ThermalSpray Removal of Lead-Containing Paint of Steel Structures,US Department of Defense,Cost and Performance Report (CP-9607);1999.[2]Hock VF,Edwards-Daniels demonstration of lead-based paint removaland inorganic stabilization nmental Quality Management Inc.;2001.[3]Jacobs DE,Mielke H,Pavur high cost of improper removal of lead-basedpaint from housing:a case nmental Health Perspectives;2003.p.111.[4]Garrels RM,Christ CK,Solutions,minerals,and and Row;1965.[5]Brookins –pH diagrams for er-Verlag;1988.[6]Cao X,Ma LQ,Chen M,Hardison DW,Harris ring of lead bulletsand their environmental effects at outdoor shooting ranges.J Environ Quality 2003;32:526–634.[7]ASTM (American Society for Testing and Materials).Annual Book of ASTMStandards;2010.[8]Wang K,Gaunt JA,Hu tering lead in paint by utilizing deconstructedmasonry materials as recycled aggregate in concrete,Strategic Environmental Research and Development Program (SERDP)Project SI 1548;2008.[9]US 1311Toxicity Characteristic Leaching Procedure,CD-ROM,Revision 0;1992.[10]California Code of rnia State of Waste Extraction Test (WET)rnia Code of Regulations,Title 22,Division 4.5,Chapter 11,Appendix II;2005.[11]Kosmatka SH,Kerkhoff B,Panarese and control of concretemixture.14th nd Cement Association;2002.[12]Neville ties of concrete.4th and Longman;1996.[13]Hu J,Wang K,Gaunt tering lead by utilizing lead based paintcontaminated masonry materials as recycled aggregate in ,Conserv Recy 2010;54(12):1453–60.[14]Levy SM,Helen lity of recycled aggregates concrete:a safe way tosustainable Concr Res 2004;34:1975–80.[15]Monteiro PJM,Helene PRL,Kang ing concrete mixtures for strength,elastic modulus and fracture Struct/Materiaux et Construc 1993;26:443– et al./Construction and Building Materials xxx (2012)xxx–xxx9