A BASIC STUDY ON FLUID PREDICTION OF MORTAR WITH VARIOUS POWDERS

Transcription

1 Internatonal Journal of GEOMATE, Feb., 8 Vol., Issue, pp.6-5 Geotec., Const. Mat. & Env., DOI: ISSN: (Prnt), (Onlne), Japan A BASIC STUDY ON FLUID PREDICTION OF MORTAR WITH VARIOUS POWDERS * Yuk Takag, Koj Takasu, Hdehro Koyamada and Hrok Suyama Graduate School of Envronmental Engneerng, The Unversty of Ktakyushu, Japan Faculty of Envronmental Engneerng, The Unversty of Ktakyushu, Japan *Correspondng Author, Receved: 5 May 7, Revsed: Dec. 7, Accepted: 8 Dec. 7 ABSTRACT: In the feld of concrete, Fly ash and crushed stone powder whch are by-product powders and lmes stone powder are used as admxture materals for concrete from the vewpont of envronmental load. Then we should use by-product powders as materals of the concrete as a substtute of fne. Therefore, t s necessary to predct fludty of the concrete wth powders n large quanttes. In ths study, we tred a flud evaluaton of mortar wth varous by-products powders and a flud predcton by graspng a flud tendency of mortar wth varous powders as a part of fne, and adopted the thckness of a surplus water flm theory and the relatve flow area rato as an evaluaton ndex. We clarfed when used by-product powders as a part of fne, we can use excess water flm for an ndex. But the value of the relatve flow area rato was dfferent because of the same thckness of a surplus water flm dependng on the knd of the powder. It was thought that the fludty of mortar was able to predct by applyng the correcton value proposed by ths study n varous mxtures that used the by-product powder. Keywords: Excess water flm thckness, Fresh propertes, Fly ash, Crashed stone sand. INTRODUCTION In late years, measures to depleton of natural resources and realzaton of the low-carbon socety are problems n the feld of Japanese concrete. So, the technque that usng by-products powders such as fly ash and crush stone powder or the lmestone fne powder as a concrete materal s consdered as soluton to these problems. Therefore, a flud evaluaton and predcton of the concrete usng byproduct powders are requred. T.C. Powers [] reported that many researchers have proposed a theoretcal mx proporton desgn method of concrete utlzng an deal partcle sze curve, the theory on dsperson of and partcle nterference and the theory such as formulas of varous requred water content so far. One of these theores s the excess paste theory proposed by C. T. Kennedy []. In ths theory, concrete s regarded as a two-phase materal composed of and paste, vods between s are flled wth paste, and s dspersed by the exstence of surplus paste, so that fludty s gven to fresh concrete. Regardng the possblty of applcaton to concrete formulaton desgn of ths theory, Matsushta et al. [] showed that t was possble to determne the optmum sand-total rato wth the thckness of the excess paste as an ndex, but reported that only approxmate values could be predcted for unt water content, and t was tred to evaluate fludty by experment n mortar. Also, Abe et al. [] showed that slump of concrete usng varous could not be evaluated only by the thckness of excess paste. Then, Matsushta et al. [5] clarfed the ndex whch could unformly evaluate the nfluence of the fne partcle sze, shape, and unt fne volume on the flow value of mortar. In addton, Teransh et al. [6] comprehensvely evaluated the nfluence of the partcle sze dstrbuton of, the content and sand-total rato on the fludty of concrete by utlzng the excess paste theory. However, studes utlzng the excess paste theory n consderaton of the nfluence of powder as cement substtute have hardly been carred out so far. In ths study, we confrm a flud tendency of mortar whch mxed several knds of powders as a substtute for fne and evaluated fludty usng excess water flm thckness (δ) and the relatve flow area rato (Γ).. THORY OF MORTOR FLOW. Excess Water Flm Thckness In ths study, excess water thckness was used as an ndex to show how the composton of mortar and byproduct-based powders nfluences fludty [][]. The excess water theory of Myake et al. [7] used n ths study consders the lqud phase as water and the sold phase as powder and fne ; the correlaton wth lqudty was reported, assumng that the excess water forms a unform water flm on each partcle. The followng formula proposed by Fukuyama [8] was used to calculate the thckness of the excess water flm. 6

2 Internatonal Journal of GEOMATE, Feb., 8 Vol., Issue, pp.6-5 Refer to Wexc s excess quantty of water (m /mortar m ), G s sold content n of the thng whch mxed fne wth powders (%), Gs s the volume of powders and fne rato n the mortar volume (%), Sp s surface area of powders n mortar m (cm /m ), Ss s surface area of fne s n mortar m (m /m ), δ s excess water flm thckness (µm). Further, n order to elmnate the nfluence of partcle sze dstrbuton, Myake et al. performed analyses wth a dmensonless value δ/d, where δ s found from the excess water flm and d s the volume-surface average partcle sze of the sold. The calculaton of δ/d s descrbed below. Gs d 6 () Sp + Ss Refer to Acs s mean rato surface area of cement and fne per volume (cm /m ), d s average partcle sze of cement and fne (µm). It s expressed by equaton () by dvdng equaton () n equaton () I found the rato surface area of fne n the followng equatons. Refer to Ssu s the rato surface area of fne (mm /mm ), X s Capacty percentage between seve openng l and l (%), + a s average partcle sze by the geometrc mean between seve openng l and l (mm) + (.5 l l ). + Wexc ( G Gs ) () Wexc 8 G Gs δ () Sp + Ss Sp + Ss Acs Sp + Ss 6 6 π ( d) ) 6 Gs π ( d δ G Gs d 6 Gs. The Relatve Flow Area Rato The relatve flow area rato (Γ) s a thng used for a self-fllng-related ndex, and fludty s hgh so that a value s bg. () X Ssu 6 (5) a d d ) d ( d Γ (6) Refer to d s the nsde dameter of the lower flow corn, d and d s I do t wth the value that measured the drecton that s a rght angle n greatest dmenson and that of mortar after the transformaton.. EXPERIMENT PROCEDURES Used materals showed n table. I used fly ash of the prescrbed II class equvalency for JIS A 6, crushed stone powder of the prescrbed for JIS A 5, crushed sand of the prescrbed for JIS A 55. In addton, I kept t more than hours and used these materals for a constant temperature room of degrees Celsus. Compoundng showed n table. The admxturefree mxes NS and N-CS were the standard formulatons, and the three byproduct components fly ash powder, lmestone fne powder, and crushed stone powder mxed to a concentraton of 5, 7.5, or 5% by volume were used as partal replacement of fne. In the experment, mxng was carred out wth the formulaton n Table. The s and 5 are excluded from the formulaton table because they could not be mxed wth ether sea sand or crushed sand. In contrast, /5-CS, whch was also Table: Materals Item Type Propertes Mark Cement Ordnary portland cement Densty.6g/cm C Water Tap water - W Admxture Fne Fly ash (JIS Ⅱclass) Lmestone powder Crushed stone powder Sea sand Crushed Sand Densty.g/cm Ignton loss.67% Blan's specfc surfacearea7cm /g Densty.7g/cm Blan's specfc surfacearea975cm /g Densty.7g/cm Blan's specfc surfacearea6cm /g Surface dry densty.59g/cm Water absorpton.76% Blan's specfc surfacearea55.9cm /g Fneness modulus. Sold content6.5% Surface dry densty.66g/cm Water absorpton.96% Blan's specfc surfacearea.6cm /g Fneness modulus. Sold content57.% S CS 7

3 Internatonal Journal of GEOMATE, Feb., 8 Vol., Issue, pp.6-5 Table: Mx proportons and Expermental Result Symbol W/C W/P Unt content(kg/m ) mn-slump G(%) Gs (%) δ(µm) Flow(mm) Ms(cm) (%) (%) W C S (CS) N-S N-S N-S N-S(CS) (6) 77.9(78.) 65(65).79(.8) 9(89) 7.(7.7) N-S S(CS) () 75.(7.) 66.(66.).8(.) (8) (6.) 7.5-S(CS) () 7.(7.8) 67(67).7(.6) 76(5) 6(.) -S(CS) (7) 7(7.) 67.6(67.6).5(.9) 8(5) 5.7(.) 5-S(CS) (9) S(CS) () 7.(7.) 66.(66.).(.) 8(67).8(.6) 7.5-S(CS) () 7.6(7.) 67(67).(.7) 66(6).(.) -S(CS) (7) 7.7(69.) 67.6(67.6).(.6) 5().7(.) 5-S(CS) (9) S(CS) () 7.(75.) 66.(66.). 5.7(.) 7.5-S(CS) () 7.(7.8) 67(67).5 9.6(.6) mpossble to mx, s lsted n the formulaton table because t could be mxed wth sea sand. As for the notaton method of the compoundng sgn, "" "" "" shows a use powders name followed by the wrtten number shows a substtuton rate. In addton, the "S" "CS" of the end expresses sand name whch I used, and the number of the end of the standard compoundng expresses a water cement rato. "P" n the compoundng lst means powders, and "W/P" expresses water powders mass rato. I worked t out usng a mortar mxer and mxed mortar. I measured a mortar flow and mn-slump, the sold content n of the thng whch mxed fne wth powders. For dervng the sold content concentraton n the mxture, a steel mortar form ( 5 mm, heght mm) was flled wth the mx n a mxer and tapped usng a flow table of once per second, and then the volume was derved from the snkng depth of the materal n the contaner; ths volume s dvded by the contaner volume to derve the sold content n. The number for tappng was set at 5 tmes on the bass of a prelmnary test.. RESULT AND DISCUSSION. Excess Water Flm Thckness And Fludty Fgs., showed a water flm thckness and relatons of the relatve flow area rato, mnslump. In both Fgs. and, there was a tendency n all formulatons for the relatve flow area and the mn-slump to ncrease as the excessve water flm became thcker. Ths s taken to ndcate that the change n the excess water flm thckness nfluences the fresh state, such as the relatve flow area and the mn-slump of mortar. However, when comparng the powders n Fgs. and, t can be seen that there s a large dfference n relatve flow area and mn-slump between them, even when the water flm The relatve flow area rato mn-slump[cm] N-S -S -S -S N-CS.5 -CS -CS -CS Excess water flm thckness[μm] Fg. Water flm thckness and Relatve flow area rato 8 6 N-S -S -S -S N-CS -CS -CS -CS Excess water flm thckness[μm] Fg. Water flm thckness and Mn-slump thcknesses are the same. Ths seems to ndcate the nfluence of the propertes of the powders. A possble nfluencng factor s the dfference n partcle shape. Whereas fly ash has a smooth sphercal shape, t s reported that for crushed powder wth fne surface rregulartes, the BETspecfc surface area s larger than for other types of powders [8]. That s, we assume that the dfference n partcle shape nfluenced fludty. Also, n the process usng fly ash, the relatve flow area and mn-slump were dffered sharply between sea sand 8

4 Internatonal Journal of GEOMATE, Feb., 8 Vol., Issue, pp.6-5 Excess water flm thckness[μm] y x R.98 y x R.8.87 N-S δ -S δ -S δ.95 -S δ.5 approxmaton straght lneδ.6 N-S Γ -S Γ -S Γ -S Γ.5 approxmaton straght lneγ The volume of the water per total surface area[ml/ m ] Fg. volume of the water per total surface area andδ,γ and crushed sand, whle n the standard formulaton, lttle fne choce had lttle nfluence. 5. FLUID PREDICTION 5. Examnaton By Excess Water Flm Thckness From the results of precedng secton, t can be nferred that t s dffcult to predct fludty from only water flm thckness when comparng between processes that use dfferent powders. We consder whether t s possble to predct the fludty usng water flm thckness by applyng a correcton value for each powder, assumng that the way the unque propertes of each powder nfluences fludty can be evaluated from ts water flm thckness. To do so, we need an ntermedary ndcator that correlates wth both water flm thckness and relatve flow area. It has been confrmed n a prevous study [7] that the unt amount of water relatve to the total surface area of the powder s correlated wth fludty. In ths, Water volume per total surface area was used as an ndex to evaluate both water flm thckness and relatve flow area. Even wthn ths experment, n each powder, the water volume per total surface area was correlated wth the rato between water flm thckness and relatve flow area, as shown n Fg.. In order to evaluate the characterstcs pecular to the powder, the y-axs was adjusted on the graph so that the reference formulaton s approxmately a straght lne. Fgure shows the ftted curves. Here, a lnear approxmaton was found for the cases N-S,, and 5; n these, a lnear relatonshp was clearly observed. It s assumed from ths that the dfferences between the curves of water flm thckness and relatve flow area for each powder (Fg. ) are due to the characterstcs pecular to the powder. Therefore, approxmately straght lnes were drawn for the.5.5 The relatve flow area rato curves of water flm thckness and relatve flow area for the powders, and the correcton value was obtaned by averagng the dfference between the straght lnes and convertng t nto water flm thckness; the water flm thckness The relatve flow area rato Mn-slump [cm] y x R.8 Standard compoundng Before correct.5 approxmaton straght lne Excess water flm thckness[μm] Fg. Before and after correct-δ, Γ y x R.8 Standard compoundng Before correct approxmaton straght lne Excess water flm thckness[μm] Fg.5 Before and after correct-δ, Mn-slump calculated usng the correcton value was taken as the corrected water flm thckness. A smlar technque was also used for the mnslump. By correctng the water flm thckness for each powder usng the correcton value, t was possble to express the relaton between water flm thckness and relatve flow area and mn-slump as a straght lne. In other words, t s assumed that fludty can be approxmately evaluated and predcted usng both correcton values and straghtlne approxmatons, as seen n Fgs. and 5. Lookng at the correcton values n Table, sgnfcant dfferences were observed accordng to powder. The correcton value of fly ash s larger than that of other types of powders. Ths seems to be due to the ball-bearng effect caused by the smooth and round shape of the fly ash, whch mproves the fludty such that the fludty becomes theoretcally large aganst the water flm thckness. In contrast, wth the crushed powder, the correcton value for the relatve flow area and mn slump s negatve. Ths s nterpreted as beng because fne rregulartes on the partcle surface of the crushed stone powder decrease the fludty, and so the fludty becomes theoretcally small aganst the water flm thckness. 9

5 Internatonal Journal of GEOMATE, Feb., 8 Vol., Issue, pp Examnaton by δ/d In comparson wth the excess water flm thckness, whch s derved by dvdng excess Table: Water flm correcton value Powder Fne water volume by total surface area, and so depends on the surface area, the ndex δ/d proposed by Myake et al. [7] excludes the nfluence of the partcle sze dstrbuton and s more concse than the water flm thckness, whch does not nclude the surface area n the dervaton. Therefore, a consderaton smlar to that made for water flm thckness was also made for the ndex δ/d. Before the correcton, the relatve flow area rato and mn-slump ncreased wth δ/d, as n the case of the water flm thckness, but when comparng dfferent powders for the same value of δ/d, varatons were observed from powder to powder. However, we could derve a lnear relatonshp between δ/d and relatve flow area and mn-slump through correctons. Also, lookng at the correcton values n Table, the correcton value of fly ash was large, and the correcton value of the crushed powder was negatve, a result smlar to the result for water flm thckness; therefore, δ/d seems adequate to use as an ndex of fludty. 6. CONCLUSION Water flm correcton value Γ(µm) Water flm correcton value Ms(µm) S CS S CS S CS ) Even when a byproduct-based powder s mxed as a water flm thckness as an ndex of fludty, though the propertes of the powders must be taken nto account when dong so. ) The correcton value was gven as a converted water flm thckness to ndcate the nfluence of the characterstcs of the powder on the fludty, and the corrected water flm was obtaned by addng the correcton value to the theoretcal water flm thckness. By usng the corrected value for the water flm, the relaton the between corrected water flm and relatve flow area and mn-slump, whch serves as an ndex of fludty, can be gven by a straght lne. From ths, t seems that the lqudty can be approxmately evaluated and predcted smply by usng water flm thckness, even for a process usng byproductbased powders. 7. ACKNOWLEDGEMENTS The authors acknowledge the assstance n ths work provded by Mr. Ej Mkura, Ms. Saor Itanam, Mr. Akra Ire. Ths research was fnancally supported by Envronmental Restoraton and Conservaton Agency (ERCA) No. -7 Development of advanced recyclng technology for fly ash to enable cement-free concrete. Table: δ/d correcton value Powder Fne 8. REFERENCES δ/dcorrecton value Γ (µm) δ/dcorrecton value Ms(µm) S CS S CS S CS [] T. C. Powers: Propertes of fresh concrete, John Wley & Sons, Inc., 968. [] C. T. Kennedy: The Desgn of Concrete Mxtures, Proceedng of Ad, 6, pp. 7-, 9. [] H. Matsushta, T. Chkada: Study on Applcaton of Excess Paste Theory to Concrete Mx Desgn, Cement Scence and Concrete Technology, Vol., pp.8-89, 989 [] M. Abe, E. Koh: A Study on Mx Proporton Desgn of Concrete Usng Crushed Stone Sand, Proceedngs of the Japan Concrete Insttute, Vol., pp.65-68, 979 (In Japanese) [5] H. Matsushta, T. Chkada, Y. Maeda: Fundamental Study on The Applcaton of Excess Paste Theory for Mx Desgn of Concrete, Journal of The Japan Socety of Cvl Engneers, No. 578, V-7, pp.57-7, 997. [6] K. Teransh, Y. Masuda, H. Jnna, T. Kage, T. Ito: Effect of Fne Aggregate and Mx Proporton on Workablty of Concrete, Journal of Structural and Constructon Engneerng (Transacton of AIJ), Vol. 8, No. 77, pp.9-8, 5. [7] Myake Jyunch, Matsushta Hrotsugu, Tor Tsuyosh: Consderaton about the fresh tme property of dfferent mortar of paste levels and the powders classfcaton, Concrete Engne-erng Annual Memors,Vol.,No., pp. 997-, 5 [8] Fukuyama Tomohro: Study on Use as Mxture Materals for Hgh Flow Concrete of The Crush Stone Powder, Concrete Engneerng Annual Memors, Vol.5,No.,pp ,.7 Copyrght Int. J. of GEOMATE. All rghts reserved, ncludng the makng of copes unless permsson s obtaned from the copyrght propretors. 5