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    CEMENTANDPergamon CONCRETECcmcnt ancl Concrclc Rcscarch 30 (2000 ) 1209- 12 14

    RESEARCH

    Effect of insoluble residue on properties of Portland cementKraiwood Kiattikomol, Chai Jaturapitakkul*, Jatuphon Tangpagasit

    Department of Civil Engineering, KKg Mongkut:~Universif), of Technology Thonhuri, Bangmod, Tungkru, Bangkok 1 0140 , ThailandReceived 13 July 1998; accepted 17 May 2000

    Abstract . .I: . . .8 .;... . :Insoluble residgo is ,$npn -cementing mate ridk hich is present id Portland ckment. This residli8 hate rialespecially its compressive strength. To control the non -cementing material in Po rtland cement, ASTM standard allows the insoluble residue t o

    be not higher than 0.75%. This limitation is much lower than the allowance provided by the British standard which is 1 .5%. To verify the effectof insoluble residue on the properties of Portland cement, artificial insoluble residue was prepared and replaced in Portland cement type I.Finely crushed sand was extracted to represent artificial insoluble residue. Setting times and compressive strengths of cement mortar mixedwith insoluble residue were investigated. The Portland cement was replaced by insoluble residue which varied in amounts o f 0%, 0.5% , 1.0%,1.5%, 2.0%, 3.0%, 5.0% and 7.0% by weight. T he results showed that the addition of the insoluble residue from 0.0% to 7 .0% by weight inPortland cement did not affect the normal consistency or setting times of cement. However, the compressive strength of cement mortar wasaffected during the early age, but the figure reduced a s the cement m ortar was older. With 7.28% of insoluble residue in the mortar at 1 day, thecompressive strength w as reduced by 11.5%, but after 60 days, the strength of the same mortar was only reduced by 5.5% as compared to thecontrol mortar. It was also found that the compressive strength of Portland cement mortar with insoluble residue provided by A STM standardor British standard was still higher than the compressive strength of Portland cement mortar type I allowed by the standards. The limit ofinsoluble residue given by AS TM standard as 0.75 is rather low and can possibly be increased to 1.5% according to British standard, or evenslightly higher, without significantly reducing the compressive strength of cement. 0 000 Elsevier Science Ltd. All rights resewed.Ke y wor ds Insoluble reqidue; Portland cement; Mortar; Compressive strength

    1. IntroductionInsoluble res idue i s a m easure o f adulte rat ion of cemen t ,

    a rge ly com ing f rom impur it ies in gypsum a nd can be foundby t rea t ing the cement wi th hydrochlor ic ac id and sodiumhydr ox ide [I ] . A ST M C 150 [2] l imits the insoluble residu ein Por t land cement type I not higher than 0 .75%. BS 12:1996 [3] sets the l imit for insoluble residue at 1.5% forcement not conta ining a minor addi t iona l const i tuent , andreleases the l imit to 5.0% for cemen t including a min oraddit ional consti tuent , such as granula ted blas t furnace s lag,na tura l pozzo lana, f ly ash o r f il ler [3].

    I t i s found tha t in modem cement , the re i s a higherc o n te n t o f C 3 S a n d a grea te r fineness than tha t o f 40 yearsago. As a consequence , cement mor ta r has , nowadays , a2 8 da y s c ompr e ss ive s tr e ng th pe r ha ps 25 M Pa h ighe r t ha n

    in 1925 [ I ] . I t seems tha t a higher insoluble res idue inPor t land cem ent can be increased to a higher va lue wi thouta ny ne ga t i ve e f f e c t on i t s s t r e ng th . T h i s p r e mi se w a sconf i rmed by Poupongphan [4] . They found tha t wi th0.5% o f finely c rushed br ick as an insoluble res idue inPor t land cement type I, the compress ive s t rength o f cementmor t a r w a s re duc e d by 1 .6%, a nd by i nc r e a s ing t heTable 1Chemical composition of Portland cement type I and finely crushed sandbefore and after dissolving in acid and basic solution

    Finely crushed Finely crushe d Portlandsand before sand after cementOxide (%) dissolving (%) dissolving (%) type I (%)Si0 2 88.94 91.27 20.2A1203 5.09 5.07 5.42Fe203 1.74 0.4 1 2.92CaO 2.79 0.09 63.82K20 2.79 2.83 0 .9Ti02 0.14 0.15 -* Corresponding author. Tel .: +66-2-470-9133; fax: +66-2-427-9063. Insoluble 92.8 1 100.0 0.28

    E-mail address: [email protected] (C. Jaturapitakkul). residue (%)0008-8846/00/$ - see front matter O 2000 Elsevier Science Ltd. All rights reset-ved.P II: S O O O 8 - 8 8 4 6 ( 0 0 ) 0 0 3 1 5 - X

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    Fig. 1. The XR D of finely crushed sand after dissolving in acid and basic solution.

    insoluble residue up to 1.5%, this mixture resulted in alowering of the cement mortar strength of less than 4%compared to the control cement mortar strength at 28 days.Normal consistency and setting times are not changed bythe addition of insoluble residue in cement. However, thispremise still needs more data for support and confirmationthat slightly increased rates of insoluble residue are not amajor factor affecting its strength.

    2. ObjectiveThe obje ctive of ;is study is to investigate the effect of

    insoluble residue on the properties of Portland cement.Finely crushed sand was used as the insoluble residue.The particle size distributions of the finely crushed sandand the Portland cement were tested and compared.Normal consistency and setting times of the Portlandcement mixed with insoluble residue were evaluated andcompared to the cement paste. The compressive strengthof cement mortar, with and without the insoluble residue,Table 2Added and tested results of the insoluble residue in cement

    Total insolubleSample Added insoluble material in ceme nt(%) Differencenumber material (%) Calculation Test (%)A00 0.0 0.28 0.28 0.0B05 0.5 0.78 0.54 0.24C10 1 .O 1.28 1.04 0.24D l5 1.5 1.78 1.50 0.28E20 2.0 2.28 2.14 0.14F30 3.0 3.28 3.04 0.24G50 5.0 5.28 4.96 0.32H7 0 7.0 7.28 6.86 0.42

    was also investigated. The results will provide cementresearchers an understanding of what happens to thePortland cement given the amount of insoluble residueprovided by the cement standards.

    3. Experimental programIn this experiment, river sand was used as an insolubleresidue. The artificial insoluble residue was prepared as

    follows. First, the river sand was crushed by using a ballmill and then sieved through a no. 20 0 sieve. Second, thefine powder was mixed with water and dissolved inhydrochloric acid followed, after filtration, by furtherdigestion in sodium hydroxide. An ammonium nitratesolution was then used in the final washing. To preventfinely ground insoluble residue from passing through thefilter paper, medium-textured paper was used as a filter.The procedure to obtain the artificial insoluble residuematerial followed ASTM C 114 [5] except that the

    Table 3Results of normal consistency and setting times of cement pastes mixedwith insoluble residue

    Insoluble NormalSample residue consistency Setting times (min)number (%I (%) Initial Final

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    -+- Portland Cement Type I

    1 10 100 1000Particle Siz e Distribution (micron)

    ,

    Fig. 2. Particle size distribution of cement and insoluble residue.

    concentrations of the acid and the basic solutions weretwo times higher than the concentration given by thestandard. This guaranteed that the obtained material wasnot dissolved in acid or basic solution. Chemical composi-tions between insoluble residue of the finely crushed sandand Portland cement were then compared.Portland cement type I was replaced with the insolubleresidue by 0%, 0.5%, 1.0%, 1.5% , 2.0% , 3.0%, 5.0%, and7.0% by weigh: of cement, plus the existing insolubleresidue in cement. The mixed cement specimens weretested to confirm their amount of insoluble residue usingthe ASTM C 778 [6] standard. Nonnal consistency andsetting times of the mixed cement were tested in accor-dance to ASTM C 187 [7] and ASTM C 191 181,respectively. The mixed ceinent was also used to preparemortar in according to ASTM C 109 191. After 24 h, themolds were removed and all the 5-cm cube specimenswere cured in saturated lime water. The compressivestrengths of mixed cement mortar were tested at the age

    of 1, 3, 7, 14, 28, and 60 days. At each date of testing, thedata are the average of seven specimens.

    4. Results and discussion4.1. Chemical composition of insoluble residue

    X-ray fluorescence spectrometry was used to test thechemical composition of Portland cement type I and finelycrushed sand, before and after dissolving in hydrochloricacid and sodium hydroxide. The results are shown in Table1. Portland cement and finely crushed sand, after dissol-ving in the acid and basic solution, consist of the insolubleresidue 0.28% and loo%, respectively. The major oxide ofthe residue material is silicon dioxide which is 91.27% ofthe total weight, while calcium oxide is the major oxide ofPortland cement. It is noted that the oxides of the finelycrushed sand before and after dissolving in hydrochlohc

    Fig. 3. Scanning electron microscopy of cement.

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    1212 K. Kioffikotilol et ol. / Cerizetrt and (

    Fig. 4 . Scanning electron nnicroscopy of insoluble residue.

    acid and sodium hydroxide are almost the same exceptthat the CaO and Fe203 contents were reduced from2.79% and 1.74%, respectively, to 0.09% and 0.41%,while Si02 is increased from 88.94% to 91.27%. Finelycrushed sand, before and after dissolving, has little differ-ence in chemical composition.

    Fig. 1 showed the result of chemical compositionanalyzed by X-ray diffraction (XRD). The graph showsthe crystalline phase and the amorphous phase of inso-luble residue. The quartz content in the sand is very highand similar to the analysis result by X-ray fluorescencespectrometry. XRD analysis reveals that quartz is in theform of the brystalline phase. This means that the finelycrushed sand after dissolving in acid and basic solutioncan be used as an insoluble material which does not reactwith cement.4.2. Insoluble residue in Portland cement and in thereplaced cement

    After the insoluble material was replaced in cement atthe proposed percentage, the cement and insoluble resi-dues were mixed together to make the sample uniform.Then, the percentage of insoluble residue in the mix waschecked. The proposed and the tested results of the

    Table 4Compressive strength of cement mortar containing insoluble residue

    Insoluble Compressive strength (MPa)Sample residue 1 3 7 14 28 60number (%) day days days days days days

    insoluble residue material in the mix are shown in Table2. It is seen that the insoluble residue of cement (sampleAOO) is very low; it is 0.28% which is lower than thelimit given by the ASTM (0.75%) and BS (1.5%)standards. All of the test results show the lower percen-tage of insoluble residue compared to the calculatedinsoluble residue. The difference of insoluble residueranges from 0.24% in sample B05 (0.5%) to 0.42% insample H70 (7.0%). However, these figures are still veryclose to the proposed values.4.3. Effect of insoluble residue on normal consistency andsetting time of Portland cement

    The effect of insoluble residue for each percentage as acement replacement on normal consistency and setting timeswere presented in Table 3. The replacement of insolubleresidue up to 7.0% did not change the normal consistency ofcement. The required water for normal consistency was stillthe same and remains at 26.8%. This is due to the sameparticle size distribution of the insoluble residue and thecement. Fig. 2 shows the particle size distribution of twomaterials determined by Particle Analyzer Microtrac 11.Since both materials had almost the same particle size

    Table 5Percentage o f comp ressive strength of cement mortar containing insolubleresidue comparing to the control mortar

    Insoluble Percentage o f compressive strength (%)Sample residue 1 3 7 14 28 6 0number (%) day days days days days days

    MA00MB05MClOMD15ME20MF30MG50MH70

    MA00MB05MClOMD15ME20MF30MG50MH70

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    k: h'itrllilior~roljt ol. / G.rrrcrr/ orrd Corr~rcr~,evccrr.ch 30 (2000) 1209-1214

    0 2 4 6 8 10Insoluble Residue (%)

    Fig. 5. Relationship between compressive strength of cement mortar and percent of insoluble residue.

    distribution, they needed the same amount of water tomaintain the same normal consistency.Figs. 3 and 4 show pictures of cement and insolubleresidue taken by scanning electron microscopy. Both cementand insoluble residues have an irregular, angular andcrushed shaped with no spheres. These pictures confirmthat the insoluble residue has little effect of normal con-sistency since cement and insoluble residue had the sameshaped particles.Initial and final setting times of sample A00 (only cementpaste) were 108 and 195 min, respectively. With the

    replacement of cement by insoluble residue up to 7.0%,the setting times were changed little; they varied from 102to 111 min for the initial setting time and from 195 to 210min for the final setting time. This means that there is noeffect of insoluble residue on setting time of cemen t paste byreplacing insoluble residue up to 7.0%.4 .4 . Eflect on compressive strength

    The compressive strengths of cement mortar containinginsoluble residue up to 7.28% at various ages are shown

    65 -

    0 2 4 6 8 10Insoluble Residue (%)

    Fig. 6. Relationship between percentage compressive strength of cement mortar and replacement of insoluble residue in the mix.

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    in Table 4. Table 5 shows thc percentage of co~nprcssivcstrength of cement mortar mixcd with insoluble residuecompared to the control (sample MAOO) mortar strength.Fig. 5 shows the relationship between the compressivestrength of cement mortar and pcrcentage of insolubleresidue in the mix. Fig. 6 shows the relationship betweenthe percentage of compressive strength of cement mortarand percentage of insoluble residue.It is seen that the higher the percentage is of insolubleresidue in cemen t mortar, the lower the compressive strengthbecomes. T he com pressive strengths of control samples varyfrom 18.2 MPa a t 1 day to 49.2 M Pa at 60 days. The samplewith 0.5% replacement of insoluble residue has the com-pressive stren gths of 17.8 MP a at 1 day and increases to 48.6MP a at 60 days. These strengths are lower than the controlstren* 552% at 1 day and 1.2% at 60 days, respectively. Theco*f$ssrive s w a g t h i of cum@pt m ortar with 1.5% ofinsoluble tesidos, sample @ ~ 1 $ ,418 ,ypgct i iely, ,g\2diMPa at 1 day and 47.9 MPa at 60 d ay s. '~ he y re lower thanthe control strength- bout 5.5% at 1 day and 2.6% at 60days. It is noted that the reduction of strength due toinsolvble residue is rather high at the early ages and tendsto reduce when the age of cement mortar increases.@ the highest amount of insoluble residue in themix; 7.28%, in sample MH70, it is found that thecomfjressive strength is still higher than the limit givenby ASTM C 150 [2]. For ASTM C 150 [2], the cementmortar strength with 0.75% of insoluble residue has to benot lower than ,12.4 MPa at 3 days and 19.3 MPa at 7days for Portland cement type I. Sample MH70 givescompressive strength of mortar at 3, 7 and 28 days equalto 26.8, 34.0 and 42.3 MPa, respectively. This means thatthe frikatdBle miflue'' p to 7.28% in :t?mntbr is aot4seriously harmful to its strength. It reduce; the strengthof cement mortar, but it is not the main factor affectingthe strength of cement mortar. The value of the insolubleresidue limited by ASTM C 150 [2], 0.75%, seems to berather low and can be slightly increased without loweringthe standard of cement.5. Conclusions

    From the results of these experiments, the followingconclusions can be drawn.

    (2) The normal consistency and setting times of cementwere not significantly affected by finely divided sand atcement insoluble residue material levels up to and including7.28%. This may be because the particle size distril.;utionand the shape of the insoluble residue were similar to that ofthe Portland cement..(3) The compressive strength of ASTM C 109 mortarcubes reduced progressively as the insoluble residue wasincreased. The strength reduction was greater at 1 and 3days than at test ages from 7 to 60 days.(4) The limit of insoluble residue given by ASTM C150 at 0.75% may be rather low and could possibly beincreased to 1.5% (as in BS 12: 1996), or even slightlyhigher without significantly reducing the compressivestrength of cement mortar.

    The authors would like to thank the research teamcomprised of Mr. Mitree Sakulkitimasak and Mr. ChansakLeesomprasong. This project was supported by theDepartment of Civil Engineering, King Mongkut's Uni-versity of Technology Thonburi for which we are alsomost grateful.

    References[I] A.M. Neville, Properties of Concrete, 3rd edn., Pitman Book, London,

    1982, p. 10.[2] ASTM C 150, Standard specification for Portland cement, ASTM C150 -95 , in: Annual Book of ASTM , Vol. 04.01, 1995.!$3]~3s$%fkh& '*fapeaifi$#l@q. fqk+&ttland~.~i#ent, 1.jQ edn., .Britishstanda rds Institution, Ldndon, 1996.[4] P. Poupongphan, S. Boonsiri, V. Karunyavanich, Effect of insolublematerial on properties of hydraulic cement, Bachelor Degree Project,Department of Civil Engineering, King M ongkut's Institute of Technol-ogy Thonburi, 1992.[5] ASTM C 114, Standard test method for chemical analysis of hy-

    draulic cement, ASTM C 114-94, in: Annual Book of ASTM, Vol.04.01, 1995.[6] AST M C 778, Standard specification for standard sand, ASTM C 77 8 -92, in: Annual Book o f ASTM , Vol. 04.0 1, 1995.[7] ASTM C 187, Standard test method for normal consistency ofhydraulic cement, ASTM C 187-86, in: Annual Book of ASTM,Vol. 04.01, 1995.[R] AST M C 191, Standard test method for time of setting of hydraulic

    (1) The ma jor constituent of the insoluble residue used in cement by vicat needle, ASTM C 1'9 1- 92 , in: Annual Book o f ASTM ,Vol. 04.01, 1995.this research was silicon dioxide (quartz) derive d from ac id- [91 ASTM c 109, Standard test method for compressive strength of hy-treated river sand. Quartz is normally recognised to be a draulic cement mortars (using 2-in . o r 50- mm cube specimen), ASTMnon -ceme nting material. C 109-95, in: Annual Book of ASTM, Vol. 04.01, 1995.