Production of High Strength Concrete in Sudan

Transcription

1 IOSR Journal of Mchanical and Civil Enginring (IOSR-JMCE) -ISSN: ,p-ISSN: X, Volum 12, Issu 2 Vr. I (Mar - Apr. 2015), PP Ali Ahmd. A. Ahmd 1, Salih Elhadi. M. Ahmd 2 1 (Snior Concrt Enginr at SMEC Intrnational Pty.Ltd-Sudan, Sudan) 2 (Profssor of structural nginring / Sudan univrsity for scinc and tchnology, Sudan) Abstract: Th aim of this papr to valuat th prformanc of high strngth concrts containing supplmntary cmntitious matrials. Now a day concrt had dmanding rquirmnts both in trms tchnical prformanc and conomy. Th main aim of th invstigation program is first to prpar th of concrt of grad M80 with locally availabl ingrdints by using two diffrnt mthods to produc high strngth concrt, mthod on is statistical approach which was dscribd in ACI211.4, and mthod two is statistical approach by using statistical softwar program, namly, JMP statistical softwar program. In ths modls, ach rspons (rsultant concrt proprty) such as strngth, slump, is xprssd as an algbraic function of factors. Th concrt spcimns wr tstd at diffrnt ag lvls, 7-days and 28-days for mchanical proprtis, namly, cub comprs strngth, frsh proprtis, in trms of slump tst.this papr prsnts a part of an ongoing xprimntal laboratory invstigations bing carrid out for production and charactrization of high strngth concrt for hightning of an xisting concrt dam in th south of Sudan. Brif dscription of th main faturs of th dam and concrt works ar prsntd. Hundrds of spcimns wr prformd and tstd using local Sudans aggrgats with addition of supplmntary cmntitious matrials ( Fum and Fly Ash) and plasticizrs. Various prcntags of silica fum and fly ash wr addd at diffrnt watr/cmntitious matrials (w/cm) ratios. Thirty thr trial mix dsigns of grad (80 MPa) high strngth concrt had bn succssfully producd and thir mchanical proprtis wr masurd and documntd. Th rsults has offrd an important insight for optimizing th frsh and hardnd charactristics of high strngth concrt and prmittd to dvlop guidlins for optimum mix dsign mthods for high strngth concrt from locally availabl aggrgats in Sudan. It is concludd that local concrt matrials, in combination with supplmntary cmntitious matrials can b utilizd in producing high strngth concrt in Sudan. Kywords: strngth, Fly ash, High strngth concrt, fum, Statistical modl. I. Introduction High Concrt is a rlativly rcnt dvlopmnt in concrt tchnology mad possibly by th introduction of fficint watr-rducing admixturs and high strngth cmntitious matrials. This papr will discuss th matrials tchnology undrlying th dvlopmnt of high strngth concrt, xamining th slction of optimum constitunt matrials and considring th concrt mix dsign. Th proprtis of both frsh and hardnd high strngth concrt will b discussd; finally, th production of high strngth concrt, illustratd by trial mixs and two approachs will b xamind. It is intndd that this will lad to an undrstanding of th potntial bnfits and limitations of high strngth concrt, togthr with th xprinc rquird to produc and us th matrial in a practical and ffctiv mannr. (1) This papr prsnts a part of an ongoing xprimntal laboratory invstigation bing carrid out for production and charactrization of high strngth concrt for hightning of Rosirs Dam, which, locatd on Blu Nil Rivr in Sudan, was constructd in 1960s for powr gnration and irrigation purposs. It has bn dcidd to hightn this composit concrt buttrss and arth fill dam by 10m to incras its storag capacity. Th raising works of Rosirs concrt dam compris th addition of mass concrt, rinforcd concrt, and post-tnsioning rquirmnts into both crst and th downstram portions of th dam. Th concrt dam sction is dividd into 11 typical structurs along its 1km lngth. Th total numbrs wr 69 buttrsss. Bcaus ach structur has its spcific gomtry and function diffrnt dsign mthodologis ar ndd for ach. Whn considring high strngth concrt on must first dfin what is mant by high strngth th prcption of what lvl of comprs strngth constituts. High strngth has bn continually rvisd upwards ovr th past 20 yars or so, and may b continud to ris in th nar futur. A simpl dfinition for High strngth would b concrt with a comprs strngth gratr than that covrd by currnt cods and standards. In th UK this would includ concrt with a charactristic comprs strngth of 60 MPa or mor. (1) In USA concrt with a charactristic comprs strngth of 55 MPa or mor is considrd to b a high strngth concrt, but this is not a fixd lvl and may chang with a tim. High-strngth concrt mix proportioning is a mor critical procss than th dsign of normal strngth concrt mixturs. Usually, spcially slctd pozzolanic and chmical admixturs ar mployd, and th DOI: / Pag

2 attainmnt of a low watr-cmntitious ratio is considrd ssntial. Many trial batchs ar oftn rquird to gnrat th data that nabls th rsarchr to idntify optimum mix proportions. (2) Thr is no scintific mthod for proportioning. This mans that thr is no chart that can b usd to driv th mixtur ingrdints to mt a spcifid lvl of prformanc. Thr ar simply too many variabls for such a chart to b dvlopd. Hr ar som gnral ruls for proportioning: (3) Prscriptiv spcifications, mans spcify concrt mixtur proportions to b usd for all similar projcts. This procdur may caus diffrncs in prformanc from projct to projct bcaus th prformanc of silica-fum concrt vry much dpnds upon th intraction of th spcific matrials usd. In this cas on should follow th prscriptiv proportions and tst to vrify that accptabl hardnd concrt proprtis ar achivd. If th spcification is prformanc basd, on should rmmbr that local matrials will dtrmin th final mixtur prformanc. It should not b assumd that a mixtur that was dvlopd and usd lswhr will provid th sam rsults whn local matrials ar usd. Mixturs usd lswhr ar xcllnt starting points, but th influnc of projct matrials on th rsults obtaind must b dtrmind. For a prformanc spcification, tim should not b wastd in dvloping a mixtur if th projct matrials hav not yt bn idntifid. (3) Tsts should b don at both th laboratory and production scal during mixtur dvlopmnt. Th procss is too complx to prdict what th outcom will b without appropriat tsting. A plnty of tim should b allowd for th ncssary tsting. (3) Finally, following th procdur dscribd in th ACI This procdur has volvd ovr many yars and is th bst rcondation currntly availabl. (4) Anothr approach is to us JMP statistical softwar program, rspons surfac dsigns wr usd for modling a curvd quadratic surfac to continuous factors, ths factors and its rangs by kg/m 3 ar prsnt in tabl (1), to modling and prdicting comprs strngth and workability for high strngth concrt dpnding on th tst rsults. (5) Both mthods nd many of trial mixs dsign, cubs and slump tst rsults for mix optimization. Hnc th purpos of this papr was to study th potntiality and possibility of us Sudans aggrgat with supplmntary cmntitious matrials silica fum and fly ash in high strngth concrt mixs, and to study th ffct of concrt ingrdints on comprs strngth, workability and cost of high strngth concrt. It is also aimd to mak a statistical modling to prdict comprs strngth and workability of high strngth concrt. Componnt ID Minimum Maximum -cmnt ratio w/cm x fum Typ KD-12 x Fly Ash Typ F x x aggrgat x aggrgat x II. Matrials Usd 2.1 In this rsarch, a locally producd ordinary Portland cmnt typ I, conforming to ASTM C150 (OPC 42.5N) (6) which is xtnly usd in Sudan, was usd in th trial batchs production. Th spcific gravity of cmnt usd was 3.15, initial and final stting tims wr 2.2 and 3.6, othr physical and mchanical proprtis for cmnt ar shown in Tabl (1). Tabl (1) Physical and Mchanical Proprtis of Tst according to BSEN196 Rsult Normal Consistncy 27.4% Stting Tim Initial Stting Tim 2.2 hour Final Stting Tim 3.6 hour Loss on ignition 1.95% 2 days 32.1 MPa 28 days 60.7 MPa 2.2 s Th coars and fin aggrgats usd in this study wr crushd marbl procssd from th local quarris around Damazin City, th quarry for Rosirs Dam Hightning Projct. Th maximum aggrgat siz was 20, Th spcific gravity and absorption of th coars aggrgats, dtrmind in according with ASTM C127 (7) wr 2.84 and 0.25rspctivly, whras thos of fin aggrgats, dtrmind in accordanc with DOI: / Pag

3 ASTM C128 (8) wr and 0.45 rspctivly. All th sand sampls wr tstd for thir absorption prcntag in saturatd surfac dry (SSD) condition. Organic impuritis in sand wr tstd in accordanc with ASTM C-40. Th watr-cmnt ratio of all trial mixs wr basd on saturatd surfac dry condition (SSD) of th aggrgats, diffrnt typ of aggrgats from anothr quarry was usd. To compar with marbl, granit aggrgats from Mrwi Dam (anothr rcntly constructd concrt dam in th north of Sudan) location wr usd. 2.3 Chmical Admixturs (plasticizr) Th suprplasticizr usd in this study has th trad nam of PCA-(I) from Jiangsu Bot nw Matrials Company-China. PCA-(I) is a polycarboxylat polymr-basdcomposit admixtur. It is a liquid which has th prformanc of high rang watr rduction, xcllnt slump rtntion and strngthning. Th spcific gravity of th suprplasticizr was and th PH was 8.11 with nil chlorid contnt prcntag by wight. It is spcially adaptd for th production of high durability concrt, slf-compacting concrt, high comprs strngth concrt, and high workability concrt. PCA-(I) suprplasticizr is formulatd to comply with th ASTM spcifications for concrt admixtur: ASTM494, Typ G (9). 2.4 Fum Th fum(sf ) usd in this study was in accordanc with th most intrnational standards such th Europan BS EN fum for concrt, Part 1:2005 Dfinitions, rquirmnts and conformity critria Part 2:2005 Conformity valuation, and th Amrican ASTM C b, Standard spcification for silica fum for us as a minral admixtur in hydraulic- cmnt concrt, mortar and grout. (10) Tabl (2) Physical Proprtis of KD-12 Fum Tst itms Spcifid limits according to ASTM C12405, BS EN13263 Tst Rsults Absolut dnsity Loss on ignition (%) particl SiO 2 (%) Carbon contnt (%) Moistur (%) Spcific ara (m 2 /g) Fly ash Fly ash usd in this study was manufactur by Zouxian powr plant-china. Th proprtis of fly ash ar prsntd in Tabls 3,4. ASTM C618; th rquirmnt for Class F and Class C fly ashs, and th raw or calcind natural pozzolans, Class N, for us in concrt. Fly ash proprtis may vary considrably in diffrnt aras and from diffrnt sourcs within th sam ara. Th prfrrd fly ashs for us in high strngth concrt hav a loss on ignition not gratr than 3 prcnt, hav a high finnss, and com from a sourc with a uniformity mting ASTM C 618 rquirmnts (11). Tabl( 3) Chmical Proprtis of Fly Ash Tst itms Spcifid limits according to BS 3892 Tst Rsults SO 3 (%) Max.2.0% 1.68% Chlorid (%) Max.0.1% 0.03% Calcium Oxid (%) Max.10% 8.4% Tabl( 4) Physical Proprtis of Fly Ash Tst itms Spcifid limits according to BS 3892 Tst Rsults Loss on ignition (%) Max.7.0% 1.39% Moistur Contnt Max.0.5% 0.29% nss Max.12% 8.24% Particl Dnsity Min.2000kg/m kg/m 3 Rquirmnt Max.95% 92% (30%Fly Ash+70%) Soundnss Max Factor Min III. Exprimntal Progra 4.1 Tst: Aftr mixing, a portion of th frsh concrt was placd asid for plastic proprtis dtrmination. of frsh concrt was masurd according to ASTM C143. Prcautions wr takn to kp th slump btwn to obtain pumpabl concrt for dam construction. (12) DOI: / Pag

4 4.2 tst: Lim saturatd-watr curing mthod was usd in this study. Concrt casting was prformd according to BS EN :2000. (13) Molds wr covrd to prvnt loss of watr from vaporation. Spcimns wr kpt for 24 hours in molds at a tmpratur of about 23 C in casting room, and thn curd for th spcifid tim at approximatly 23 C ± 2 C. (14) Th spcimns wr tstd in dry stat for comprs strngths tsts, in accordanc with BS EN :2002. (15) IV. Optimization Of Mixs Two approachs was usd, th statistical approach which has bn dscribd in ACI and anothr on is th JMP statistical program to mak a modling for prdicting and for high strngth concrt. V. Rsults Tabl (6) prsnts th optimum mix proportions for grad 80 (MPa), Tabl (8) prsnts th optimum mix proportions for grad 90 (MPa) and Tabl (10) prsnts th optimum mix proportions for grad 100 (MPa) which wr usd in th dam construction projct. From th tabls it is clar that thr ar thr diffrnt grads of high strngth concrt (80, 90, 100MPa) succssfully producd using local Sudans aggrgats and silica fum and silica fum with fly ash. w/cm ratios rangs btwn 0.19~0.3. fum and fly ash rplacmnts in th rang of 6.7 to 15% and zro to 15% of cmntunis matrials rspctivly. contnt is rang btwn 390 and 560 Kg/m3 for th thr grads. Trial batchs wr carrid out, tst spcimns ar fabricatd and tstd, and rsults ar analyzd using standard statistical mthods. Mthod on is th statistical approach which dscribd in ACI211.4 and mthod two is th statistical approach by using statistical softwar program, calld, JMP statistical softwar program. Ths mthods includ fitting mpirical modls to th data for ach prformanc critrion. In ths modls, ach rspons,rsultant concrt proprty, such as strngth, slump, is xprssd as an algbraic function of factors,individual componnt proportions, such as w/cm, coars aggrgat, fin aggrgat, chmical admixtur dosag, and supplmntary cmntitious matrials contnt has bn fd in % maximum % quartil % mdian % quartil % minimum 80 Figur (2) Catgoris of (MPa) for (abov 80 MPa, abov 90 MPa and abov 100 MPa) Tabl (5) Concrt strngth abov 80MPa and Cost stimation Tst Typs Fumtyp Fly Ash KD-12 Aggrgat Cost of m3 $ 1 30-Oct Nov Marbl Oct Nov Marbl Nov-09 4-Dc Marbl Nov Dc Marbl Dc-09 4-Jan Marbl Jan Fb Granit Jan Fb Granit Jan Fb Granit Jan Fb Granit Jan Fb Granit Jan Fb Granit Fb-10 8-Mar Granit DOI: / Pag

5 100.0% maximum % quartil % mdian % quartil % minimum No Figur (3) Distributions Cost of m 3 $for comprs strngth abov 80 MPa Tst Tabl (6) th optimum mix proportions for grad 80 MPa. Aggrgat Typs Fumtyp Fly Ash KD-12 Aggrgat Tabl (7) Concrt strngth abov 90MPa and Cost stimation Aggrgat Cost of m3 $ Jan Fb Granit Oct Nov Marbl Oct Nov Marbl Tst Typs Fumtyp Fly Ash KD-12 Aggrgat Cost of m3 $ 4 11-Nov-09 9-Dc Marbl Dc-09 2-Jan Marbl Dc-09 3-Jan Marbl Dc-09 4-Jan Marbl Jan Fb Granit Jan Fb Granit Fb Mar Granit Fb Mar Granit Mar Mar Granit Mar Apr Granit No Figur (4) Distributions Cost of m 3 $ for comprs strngth abov 90 MPa Tst 100.0% maximum % quartil % mdian % quartil % minimum Tabl (8) th optimum mix proportions for grad 90 MPa. Aggrgat Typs Fumtyp Fly Ash KD-12 Aggrgat Aggrgat Cost of m3 $ Mar Mar Granit Mar Apr Granit Fb Mar Granit DOI: / Pag

6 Tabl (9) Concrt strngth abov 100MPa and Cost stimation Tst Typs Fumtyp Fly Ash KD-12 Aggrgat Cost of m3 $ Jan Fb Granit Fb Mar Granit Fb Mar Granit Fb Mar Granit Fb Mar Granit Fb Mar Granit Fb Mar Granit Fb Mar Granit Mar Apr Marbl Apr May Marbl Apr May Marbl % maximum % quartil % mdian % quartil % minimum No Figur (5) Distributions Cost of m 3 $ for comprs strngth abov 100 MPa Tabl (10) th optimum mix proportions for grad 100 MPa. Tst Aggrgat Typs Fumtyp Fly Ash KD-12 Aggrgat Aggrgat Cost of m3 $ Mar Apr Marbl Apr May Marbl Fb Mar Granit Figur( 6) Th Actual 28 days strngth (MPa) and th Prdictd 28 days strngth (MPa) (as pr JMP Modling) DOI: / Pag

7 Figur (7) Th Actual () and th Prdictd () (as pr JMP Modling) Tabl (11) Th Prdictd 28 days comprs strngth (MPa) and th Prdictd (), Compard with actual on(as pr JMP Modling) Th Prdictd Th Prdictd () () (MPa) (MPa) Tabl (12) Th suggstd mixtur proportion and it Prdictd 28 days comprs strngth (MPa) and () (as pr JMP Modling) Fum typ KD-12 Fly Ash r typ Th Prdictd (MPa) Th Prdictd DOI: / Pag

8 VI. Conclusions On th basis of tst rsults th following major conclusions can b drawn: 1. local aggrgats with supplmntary matrials (silica fum and fly ash) and ordinary Portland cmnt with thir optimum proportioning can b succssfully usd with othr chmical admixturs (-plasticizr) to produc high strngth concrt. 2. Th prsnt study shows that th maximum valus of comprs strngth for diffrnt grads wr obtaind at watr-cmntitious matrials ratios btwn 0.19 and Th rlationship btwn comprs strngth 28 days (MPa) and cost is dirct rlationship. 4. Prdictd quations wr givn from JMP statistical program to prdict 28 days comprs strngth (MPa) and () for high strngth concrt whr local Sudans aggrgat granit and marbl wr usd. 5. Mthod No two gav suggstions for a nw mixtur proportions for high strngth concrt in Sudan and it was prdict 28 days comprs strngth (MPa) and (). Acknowldgmnts I would lik to thank SMEC Intrnational Company for thir coopration during th part of th xprimntal tsting program of this rsarch. Also I would lik to thank th Dams Implmntation Unit (DIU) of Sudan for allowing th authors to us th information and photographs ndd in this rsarch papr. Rfrncs [1]. John Nwman and Ban Sng Choo, Advancd Concrt Tchnology Procsss (Elsvir Ltd, First publishd, 2003). [2]. Amrican Concrt Institut, Stat-of-th-Art Rport on High- Concrt, ACI [3]. Fum Association, Tchnical Rport- Fum Usr s Manual, USA, [4]. Amrican Concrt Institut, Guid for Slcting Proportions for High- Concrt Using Portland and Othr itious Matrials, ACI 211.4R [5]. JMP, A Businss Unit of SAS Institut Inc, Dsign of Exprimnts Guid, USA, [6]. Amrican Socity for Tsting and Matrials, ASTM C-150 Standard Spcifications for Ordinary Portland, Typ I,2003. [7]. Amrican Socity for Tsting and Matrials, ASTM C-127 Standard tst mthod for Dtrmination of Th Spcific Gravity and Absorption of th s,2000. [8]. Amrican Socity for Tsting and Matrials, ASTM C-128 Standard tst mthod for Dtrmination of Th Spcific Gravity and Absorption of th s,2000. [9]. Amrican Socity for Tsting and Matrials, ASTM C-494: Standard Spcifications for Concrt plasticizing Admixturs,2003. [10]. Amrican Socity for Tsting and Matrials, Standard Spcifications for silica fum for us as a minral admixtur in hydrauliccmnt concrt, mortar and grout, ASTM C-1240,97. [11]. Amrican Socity for Tsting and Matrials, ASTM C-618: Standard Tst Mthod for Physical Proprtis of Fly Ash,2001. [12]. Amrican Socity for Tsting and Matrials, Standard Tst Mthod for of Hydraulic- Concrt, ASTM C-143,2003. [13]. British Standards Institution, Shap, dimnsions and othr rquirmnts for spcimns and moulds, BS EN , [14]. British Standards Institution, Making and curing spcimns for strngth tsts, BS EN , [15]. British Standards Institution, strngth of tst spcimns, BS EN , DOI: / Pag