Rheology of carbon fibre reinforced cement-based mortar Banfill, Phillip Frank Gower; Starrs, Gerard; McCarter, William John

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Herit-Watt University Herit-Watt University Research Gateway Rhelgy f carbn fibre reinfrced cement-based mrtar Banfill, Phillip Frank Gwer; Starrs, Gerard; McCarter, William Jhn Published in: The Vth

2458 Publicatin date: 2008 Dcument Versin Peer reviewed versin Link t publicatin in Herit-Watt University Research Gateway Citatin fr published versin (APA): Banfill, P. F. G., Starrs, G.

1 Herit-Watt University Herit-Watt University Research Gateway Rhelgy f carbn fibre reinfrced cement-based mrtar Banfill, Phillip Frank Gwer; Starrs, Gerard; McCarter, William Jhn Published in: The Vth Internatinal Cngress n Rhelgy - The Sciety f Rhelgy 80th Annual Meeting DI: 10.10/ Publicatin date: 2008 Dcument Versin Peer reviewed versin Link t publicatin in Herit-Watt University Research Gateway Citatin fr published versin (APA): Banfill, P. F. G., Starrs, G., & Mccarter, W. J. (2008). Rhelgy f carbn fibre reinfrced cement-based mrtar. In The Vth Internatinal Cngress n Rhelgy - The Sciety f Rhelgy 80th Annual Meeting (Vl. 1027, pp ). DI: 10.10/ General rights Cpyright and mral rights fr the publicatins made accessible in the public prtal are retained by the authrs and/r ther cpyright wners and it is a cnditin f accessing publicatins that users recgnise and abide by the legal requirements assciated with these rights. If yu believe that this dcument breaches cpyright please cntact us prviding details, and we will remve access t the wrk immediately and investigate yur claim.

2 Dwnlad date: 27. Apr. 2018

3 Rhelgy f Carbn Fibre Reinfrced Cement-Based Mrtar Phillip F.G. Banfill, Gerry Starrs and W. Jhn McCarter Schl f the Built Envirnment, Herit-Watt University, Edinburgh, EH14 4AS, UK Abstract. Carbn fibre reinfrced cement based materials (CFRCs) ffer the pssibility f fabricating "smart" electrically cnductive materials. Rhelgy f the fresh mix is crucial t satisfactry mulding and fresh CFRC cnfrms t the Bingham mdel with slight structural breakdwn. Bth yield stress and plastic viscsity increase with increasing fibre length and vlume cncentratin. Using a mdified Viskmat NT, the cncentratin dependence f CFRC rhelgy up t 1.5% fibre vlume is reprted. Keywrds: Carbn Fibre; Prtland Cement; Mrtars; Rhelgy. PACS: 8.0.La; 8.80.Hj INTRDUCTIN Carbn fibre reinfrced cement (CFRC) materials are f technlgical interest because f the electrical cnductivity f the hardened material. This changes in respnse t defrmatin and cracking and enables them t be self-mnitring in service ("smart"), with a range f ptential applicatins [1,2]. T realie its ptential as a smart material, fresh CFRC must be capable f being shaped, s its rhelgy is imprtant. A lwer limit f carbn fibre cntent, the perclatin threshld (typically % by vlume), must be exceeded in rder t cnfer the desired electrical prperties. An earlier paper [] cnfirmed that CFRCs cnfrm t the Bingham mdel, with slight structural breakdwn, and that increasing the fibre length and fibre vlume cncentratin increase bth yield stress and plastic viscsity. It established that the Viskmat NT can measure the rhelgy f CFRCs up t 0.5% fibre vlume but that mdificatins t the measurement system were needed in rder t exceed the perclatin threshld. This paper reprts an investigatin f mdified impellers fr CFRCs at up t 1.5% fibre vlume cncentratin. EPERIMENTAL The materials and prcedure were the same as described in []. Briefly, CEM I Prtland cement, siliceus sand f max particle sie 2mm, water-reducing plasticier at fixed dsage and carbn fibre (SIGRAFIL C - diameter 7.5 xm) were used in a standard mrtar with a sand/cement rati f 0.5 (by mass). The experimental variables were (i) water/cement ratis f 0.4, 0.45 and 0.5; (ii) fibre lengths f,, and mm; and (iii) fibre vlumes f 0, 0.5, 0.75, 1.0, 1.25 and 1.5% (by vlume f sample). In the Viskmat NT [4], as the cylindrical cntainer (diameter 8 mm) rtates at speed A^, mrtar flws thrugh the statinary impeller, generating a trque T, which is measured by a transducer. A series f trque and rtatinal speed readings, recrded by cmputer, fit a straight line f the frm T=g + hn (1) where g (Nmm) is related t yield stress (Pa) and h (Nmms) is related t plastic viscsity (Pa s). The standard impeller (diameter 4 mm) was used in the earlier wrk [] and additinal impellers (diameter 0 mm) and (diameter 50 mm) were fabricated in rder t extend the measurement range t deal with the stiffer CFRCs expected at higher fibre vlume cncentratin. All three impellers were calibrated by an established prcedure, based n the CP1027, The V^'^ Internatinal Cngress n Rhelgy, The Sciety f Rhelgy 8(}^ Annual edited by A. C, L. G. Leal, R. H. Clby and A. J. Giacmm 2008 American Institute f Physics /08/$2.00 Meeting 1402

4 Metner-tt principle that the mean effective shear rate KN in a mixer is prprtinal t the rtatinal speed [5,], using Newtnian liquids (silicne il at different temperatures) and pwer law liquids (aqueus slutins f diutan gum at a single temperature). Using this prcedure the Bingham yield stress TQ and plastic viscsity /u are given by T = (K/G)g (2) fi = {l/g)h () The values f G and K s btained fllw a trend with impeller sie and enable the measurements using all three impellers t be put n a cmmn scale (see Table 1). Impeller TABLE 1. Calibratin cnstants fr the standard and mdified impellers Diameter mm K/G 1/G Mrtars were tested using the same prtcl as in [], namely a flw curve ramping up frm 0 t. rev/s and back t 0 ver 7 minutes, fllwed by sequential additin f fibres and retesting up t the highest fibre cntent, with strict adherence t times f testing t ensure reprducibility.. rev/s crrespnds t a mean effective shear rate, calculated frm K abve, f abut 2, 0 and 27 s"' fr impellers, and, respectively. The Viskmat NT has a trque cut-ut device t prevent verlading abve the maximum f 200 Nmm, s different impellers were used in the tests, as apprpriate t keep within this limit (Table 2). RESULTS Results f tw test prgrammes are presented here. Series A is fr up t 0.5% fibre vlume and values were cnverted frm the data in [] using the calibratin cnstants fr impeller. Series B is fr fibre vlumes 0-1.5%. Table 2 cnfirms that impeller is able t test all the CFRCs at 0.5% fibre and shws that it was necessary t use the prgressively smaller impellers and as the mixes gt stiffer. The CFRCs at 0.4 water/cement rati and 1.0% r mre fibre were t stiff t test even with the smallest impeller, causing trque verlad. Thus the smaller impellers successfully extend the testing range f the instrument. Water / Cement Fibre Length mm 0.5% fibre 0.75% fibre 1.0% fibre 1.25% fibre 1.5% fibre TABLE 2. Test series B: ability f impellers, and t test CFRCs ( dentes t stiff t test) CFRCs at 0 and 0.5% fibre were tested in bth series and Figure 1 shws that there is gd agreement between the yield stresses btained in each series but less gd agreement fr plastic viscsities. The experimental errr n plastic viscsity is greater due t the scatter f pints n the flw curve and the dashed lines indicate the experimental errrs f + 10% and + 25% respectively. Additinally, in Series A the 0.5% fibre CFRC was tested last in the sequence, while in Series B it was tested early, and this difference f abut 45 minutes in the time frm mixing t testing culd be enugh t cause a systematic bias t higher values in the Series B results. Despite this reservatin, it seems reasnable t present the trends in the data btained frm the tw series n cmpsite graphs. Figure 2 summarises all the results frm bth series, btained at water/cement rati 0.5. The impeller used in any particular test can be identified by reference t Table

(a) ield stress (Pa) (b) Plastic viscsity (Pa s) 500 m 400 ">.2 00 W 200 100 0, / 11 A cr,',r>'' 200 400 Series A,g''>'' 00 W/C.4 D W/C0.45 AW/C.5 m m 0.8 fi 04 0? 0.'' C'-' ^'<^ 0.

5 (a) ield stress (Pa) (b) Plastic viscsity (Pa s) 500 m 400 ">.2 00 W , / 11 A cr,',r>'' Series A,g''>'' 00 W/C.4 D W/C0.45 AW/C.5 m m 0.8 fi 04 0? 0.'' C'-' ^'<^ 0.5 Series A / * ' ^ '' ^ ^ W/C 0.4 n W/C 0.45 AW/C.5 FIGURE 1. Crrelatin between (a) yield stress and (b) plastic viscsity fr Series A and B, using standard impeller. (a) (b) ' " == Vlume (%) Length (mm) Vlume (%) e Length (mm) FIGURE 2. Effect f fibre length and vlume cncentratin n (a) yield stress and (b) plastic viscsity f CFRC. DISCUSSIN AND CNCLUSIN The results shw that using smaller impellers extends the Viskmat NT's testing capability t fibre vlume cncentratins well abve the perclatin threshld. The yield stresses and plastic viscsities withut fibres are within the accepted range f values fr mrtars [5] and increase with increasing fibre length, increasing fibre vlume cncentratin and decreasing water/cement rati. The results extend the range f data frm that previusly reprted t facilitate the develpment f practical, muldable mix frmulatins fr smart, electrically cnductive CFRCs. ACKNWLEDGEMENTS We are grateful fr the financial supprt f the Engineering and Physical Sciences Research Cuncil, grant GR/S41/01, and t Judith Petrie, Aurre Mntier and lga Rdrigue fr experimental assistance. REFERENCES 1. S. Wen and D. D. L. Chung, Cem. Cnr. Res. 1, 5-7 (2001). 2. S. Wang, D. P. Kwalik, and D. D. L. Chung, Smart Mater. Struct. 2, 22-0 (1).. P. F. G. Banfill, G. Starrs, G. Derruau, W. J. McCarter and T. M. Chrisp, Cem. Cncr. Cmpsites, 28, ll?>-im ( (accessed 11/0/08). 5. P. F. G. Banfill, Mag. Cncr. Res. 42, (1.. A. B. Metner and R. E. tt, /. Am. Inst. Chem. Engrs,, -10 (157). 1404

3D FE Modeling Simulation of Cold Rotary Forging with Double Symmetry Rolls X. H. Han 1, a, L. Hua 1, b, Y. M. Zhao 1, c

3D FE Modeling Simulation of Cold Rotary Forging with Double Symmetry Rolls X. H. Han 1, a, L. Hua 1, b, Y. M. Zhao 1, c Materials Science Frum Online: 2009-08-31 ISSN: 1662-9752, Vls. 628-629, pp 623-628 di:10.4028/www.scientific.net/msf.628-629.623 2009 Trans Tech Publicatins, Switzerland 3D FE Mdeling Simulatin f Cld