Effect of Olivine Nano-silica Additions on Cement Based Systems

Transcription

1 Effect of Olivine Nno-silic Additions on Cement Bsed Systems G. Querci Binchi nd H.J.H. Brouwers Astrct In this study, the influence of olivine nno-silic (OnS) dditions in cement sed systems hs een ddressed. The otined results demonstrte tht the ddition of OnS ( % woc) increses the viscosity, yield point nd hydrtion degree of the cementitious systems, minly due to the increse of the totl specific surfce re of the mix. This holds lso for the cse when fixed mount of SP is pplied. Bsed on the performed nlysis, it is concluded tht the OnS cts s n ccelerting nd pozzolnic gent in concrete. Keywords Nno-silic Olivine Cement Mortr Self-compcting concrete 1 Introduction Olivine (Mg,Fe) 2 SiO 4 is the fstest wethering silicte minerl dissolving esily in cids. During the dissolution in cid, the metllic ions (Mg 2+,Fe 2+ ) re replced y H +, yielding Si(OH) 4 monomers nd metllic ions in solution. After clening tretments n morphous nno-silic is otined [ 1 ]. The produced olivine nno-silic (OnS) hs specific surfce re etween 1 nd 4 m 2 /g, depending upon the dissolution nd wshing conditions. The size of the primry prticles, which re gglomerted in clusters, rnges from 1 to 25 nm nd the impurity content is elow 5 % y weight. Literture relted with the ppliction of OnS in cement sed mterils is scrce, only one reserch work performed y Justnes nd Ostnor is ville [ 2 ], thus, the effect of dding OnS in cement sed systems hs not een studied. Bsed on this the present reserch ims to elucidte the effects of OnS in the fresh nd hrdened cement pstes, stndrd mortrs nd self-compcting concretes with low CO 2 footprint (eco-scc). G. Querci Binchi (*) Eindhoven University of Technology, Eindhoven, The Netherlnds Tricn Well Service Ltd, Clgry R&D Centre, Clgry, AB, Cnd e-mil: g.querci@tue.nl; gquerci@tricn.c H.J.H. Brouwers Eindhoven University of Technology, Eindhoven, The Netherlnds Springer Interntionl Pulishing Switzerlnd 215 K. Soolev, S.P. Shh (eds.), Nnotechnology in Construction, DOI 1.17/ _24 193

2 194 G. Querci Binchi nd H.J.H. Brouwers 2 Mterils nd Experimentl Methods Different olivine nno-silic ckes were used in dried or wter dispersed form. The OnS used were prepred from different tches synthesized on pilot scle [ 3 ]. The cements used for the experiment were CEM I 52.5 N, CEM I 52.5 R, CEM III/B 42.5 N LH/HS s clssified y CEN EN (2). For the mortr test, stndrd snd ( 2 mm) ws used ccording to CEN EN (2). In ddition, commercil superplsticizers (SP) sed on modified polycroxylic ether (PCE) nd nphthlene lignosulfonte ether (NLS) were used for the pste, mortr nd concrete experiment. For the self-compcting concrete (SCC) experiments, fluvil ggregtes in the frctions 8 nd 4 16 mm were used. In ddition, fluvil snd in the frctions 4 mm ws lso used. Finlly, commercil fly sh ws pplied s supplementry cementitious mteril nd filler. More detils on the physicochemicl chrcteristics of the mterils used cn e found in [ 3 ]. To study the effect of OnS nd SP, rheologicl mesurements nd the mini spredflow test were crried out to ssess chnges of the viscosity cused y the volumetric sustitutions of cement (.5, 1.5, 3., 4.5, 7. nd 1 %). The rheologicl tests were complemented with isotherml clorimetric mesurements (cement pstes with w/c of.5; nd with or without SP). Afterwrds, compressive nd flexurl strength of stndrd mortrs following the procedure estlished in EN (2) were crried out. Finlly, optimized eco-scc mixes were designed nd evluted s recommended y [ 4 ]. The reference mix design ws sed on commercil SCC formultion for sewge pipes (Tle 1 nd Fig. 1 ). For the optimized eco-scc mixes with OnS (Fig. 1 ), the mix design concepts descried y [ 5, 6 ] were used. In totl, four mixes were tested t the pilot scle, considering volume of 1 m 3. For this, two tches were cst with OnS ckes (DNOnS-14) produced from Norwegin olivine in The Netherlnds nd two tches with powder OnS produced from eneficited dunites in Greece (PGOnS-1). One dy efore the pilot test, severl wter sed dispersions with 1 wt% of OnS were prepred using oth type (Dutch nd Greek) nno-silic with n industril rotor sttor high energy mixer (3, rpm for 3 min). Tle 1 eco-scc mix designs using olivine nno-silic s cement (CEM I 52.5R) replcement Mterils (kg/m3 ) SCC- ref SCC-l SCC-1D SCC-2D SCC-1G SCC- 2G DNOnS-14 (1 wt% solid) PGOnS-1 (1 wt% solid) CEM I 52.5 R CEM III/B 42.5 N LH/LS Fly-Ash Fluvil grvel 8 mm Fluvil grvel 4 16 mm Wter SP (% wo) c c 4. c 3.5 c w/ (mesured fter csting) SP2 NLS-type (Cugl R11) SP3 PCE-type (H-Be Pntrhit RC 1) c SP5 PCE-type (H-Be Pntrhit PC 15)

3 Effect of Olivine Nno-silic Additions on Cement Bsed Systems 195 Cumultive finer (Vol. %) Prticle size (μm) Trget Function q=.3 CEM I 52.5 R Fly sh Fluvil grvel -8 mm Cumultive finer (Vol. %) Prticle size (μm) Composed Mix CEM III/B 42.5 LH/HS DOnS-14 Fluvil grvel 4-16 mm Fig. 1 PSD of the mterils used, ( ) reference eco-scc with trget function sed on q =.27 ( D min = 513 nm nd D mx = 18.9 mm, ( ) initil eco-scc (OnS) with trget function sed on q =.3 ( D min = 65 nm nd D mx = 18.9 mm), dshed lines re the corresponding test mixes 3 Results nd Discussion 3.1 Effects on Cement Pste The otined flow curves for ll tested pstes re displyed in Fig. 2 the experimentl dt were fitted to the Herschel-Bulkley fluid model using the methodology recommended y [ 7 ]. This fluid model ws selected s cement pstes show sher thinning ehvior. The prmeters determined y the rheologicl tests were compred with vlues otined on mortr scle using the spred-flow test. It is demonstrted tht the yield point of the pste is proportionl to the spred flow nd the totl specific surfce re [ 3 ]. The increse in the viscosity nd in the yield point of the pste is result of the incresed specific surfce re of the pste due to the ddition of OnS. In this cse it is demonstrted for fix mount of SP tht the workility of the cement pste decresed with incresing OnS content. In ddition, it ws found tht the pstes presented self-flowing chrcteristic when the cement pste possesses yield point vlues lower thn 9 P. The otined het flow nd totl het curves for ll tested pstes re displyed in Fig. 3. For the first system studied, where no SP ws dded (Fig. 3 ), the het flow curves re close to the reference smple. The min difference oserved ws in the so clled dormnt period, which is clerly reduced with incresing volumetric sustitution of cement y OnS. In ddition, slight increse in the min hydrtion pek (C 3 S phse) ws oserved. This increse is produced y the higher rectivity of the OnS (pozzolnic ehvior). In the second system studied (with SP) the retrding effect due to the ddition of SP is still evident (Fig. 3 ). Nevertheless, the ccelerting

4 196 G. Querci Binchi nd H.J.H. Brouwers Sher stress - τ (P) τ = τ + k. γ n Sher stress - τ (P) τ = τ + k. γ n SP dosge =.12 g SP/g H 2 O Sher rte - γ (1/s) Sher rte - γ (1/s) CEM I 52.5N.5% 1.5% 3.% 4.5% 7.% 1.% Fig. 2 Flow curves of the cement/ons pste mesured nd djusted to the Herschel-Bulkley fluid model: ( ) without SP, ( ) with fixed SP (.6 % woc) Het flow (mw/gcement) ΔHF CEM I 52.5N.5% 1.5% 3.% 4.5% 7.% 1.% Time (h) Het flow (mw/gcement) 5 AFm Induction period Time (h) Fig. 3 Het flow nd totl het ehviour of cement/ons pste: ( ) without SP, ( ) with fixed SP (.6 % woc) effect cused y the ddition of OnS is lso influentil. In ddition to this, n effect on the hydrtion of lumintes phses (secondry ettringite formtion) is displyed for 1 vol% sustitution level. 3.2 Effects on Stndrd Mortrs The mechnicl properties of mortrs with different OnS dditions nd fixed SP content re shown in Fig. 4. In generl, lmost ll flexurl strength vlues dropped when OnS ws dded. This fct is cused y the high gglomerted stte of the OnS, which produced more porous interprticle trnsition zone (ITZ). On the contrry, it is possile to oserve in Fig. 4 tht the compressive strength increses until mximum tht depends on the ge of the smples. Once the mximum is reched the compressive strength dropped in comprison to the reference. The highest vlue t 28-dy ws otined with 1.5 vol% of cement replcement y OnS.

5 Effect of Olivine Nno-silic Additions on Cement Bsed Systems 197 Flexurl strength (N/mm 2 ) CEM I 52.5N (.6% SP).5% OnS (.6% SP) 1.5% OnS (.6% SP) 3.% OnS (.6% SP) 4.5% OnS (.6% SP) 7.% OnS (.6% SP) 1% OnS (.6% SP) Age (dys) Comp. strength (N/mm 2 ) CEM I 52.5N (.6% SP).5% OnS (.6% SP) 1.5% OnS (.6% SP) 3.% OnS (.6% SP) 4.5% OnS (.6% SP) 7.% OnS (.6% SP) 1% OnS (.6% SP) Age (dys) Fig. 4 Mechnicl properties of mortrs with different content of OnS (w/c =.5 nd.6 % SP): ( ) Flexurl strength, ( ) compressive strength 3.3 Ecologicl Self-Compcting Concrete (Pilot Test) All resulting properties of the eco-scc of the conducted pilot test tests re given in Tle 2. As it cn e seen in Tle 2, only lower slump-flow thn the medin vlue of 758 mm ws otined for the mix SCC- 2D. The vlues of the others test re within the production specifictions of the compny. Bsed on this oservtion, it is possile to conclude tht the SCC mixes met the required slump flow set y the compny. On the other hnd, high V-funnel times cn e relted to low deformility due to high pste viscosity, high interprticle friction or lockge of the funnel. Directly linked to this oservtion re the long V-funnel vlues oserved for SCC- 2G mix. Also, the higher V-funnel time of mix SCC- 1G is the result of lower mount of SP nd wter use. In the cse of the mechnicl properties, severl oservtions cn e mde. Both type of OnS tests show lower 16-h compressive strength thn the required minimum (Tle 2 ). Despite the lower 16-h strength of the mixes, the finl cst products (grden pls) were de- molded without prolems or filures. The lower 16-h compressive strength is the result of the lower totl inder content of the mix compred to the reference (382 kg/ m 3 vs. 369 kg/m 3 ). On the contrry, the 28-dys compressive strength vlues were higher thn the minimum vlue of the reference (55 N/mm 2 ) for oth SCC types with OnS (Tle 2 ). The higher 28-dy strength is consequence of the improved fly sh nd slg rectivity induced y the OnS prticles, s it ws confirmed y [ 3 ]. Tking into ccount the fresh nd hrdened properties comined with the finl product qulity, the pilot testing ws qulified s success y the concrete producer. As further nlysis, n estimtion of the CO 2 foot-print of the resulted eco-scc ws performed using the equivlent CO 2 foot-print of ech compound tken from [ 3 ]. The nlysis demonstrted tht CO 2 foot-print of n eco-scc (151 kgco 2 /m3 ) is 18 % lower thn tht the references SCC mix (184 kgco 2 /m3 ). Not only ws the equivlent CO 2 foot-print ws reduced, it ws lso demonstrted tht the use of 3.8 % woc of OnS nd the mix design tool developed y [ 5 ] cn enhnce the use of other inders (slg nd fly sh). Thus, the totl inder content in the SCC ws reduced from 382 to 369 kg/m 3 (13 kg less).

6 198 G. Querci Binchi nd H.J.H. Brouwers Tle 2 Fresh nd hrdened properties of eco-scc pilot test mixes Mix S(mm) V-funnel time (s) Stility time (s) Blocking (mm) 16-hs C.S. (N/mm 2 ) 7-dy C.S. (N/mm 2 ) Reference <3 <1 >8 N/S >55 SCC-1D SCC- 2D SCC- 1G SCC- 2G dy C.S. (N/mm 2 ) 4 Conclusions In this study, the influence of olivine nno-silic (OnS) dditions in cement sed systems hs een ddressed. The tests results demonstrted tht the ddition of OnS increses the viscosity nd the yield point of the cement system. This holds lso for the cse in which commercil superplsticizers re pplied. The increse in the viscosity nd the yield point of the pste is the result of the incresed specific surfce re of the pste. Bsed on the isotherml clorimetric mesurements nd the nlysis performed, it is possile to conclude tht the OnS cts s n ccelerting gent in concrete. The experiments lso demonstrted tht the possile optimum replcement level of OnS would e etween 1.5 nd 4.5 % y vol. to otin concrete with reduced CO 2 foot-print. References 1. Lzro, A., Brouwers, H. J. H., Querci, G., & Geus, J. W. (212). The properties of morphous nno-silic synthesized y the dissolution of olivine. Chemicl Engineering Journl, , Justnes, H., & Ostnor, T. (21). Pozzolnic, morphous silic produced from the minerl Olivine. In V. M. Mlhotr (Eds.), Proceedings of the 7th CANMET/ACI interntionl conference on Fly sh, Silic fume, Slg, nd Nturl pozzolns in Concrete (Vol. II), Chenni. Americn Concrete Institute (ACI) Specil Puliction 199, (DOI /1547 ). 3. Querci, G. (214). Appliction of nno-silic in concrete (pp ). PhD disserttion, Eindhoven University of Technology, Eindhoven. 4. EFNARC. (25). Specifi ction nd guidelines for Self Compcting Concrete-SCC. Report, Europen Federtion of Producers nd Contrctors of Specilist Products for Structures, Surrey. 5. Hüsken, G., & Brouwers, H. J. H. (28). A new mix design concept for erth-moist concrete: A theoreticl nd experimentl study. Cement nd Concrete Reserch, 38, Hunger, M. (21). An integrl design concept for ecologicl self-compcting concrete (pp. 1 26). PhD thesis, Eindhoven University of Technology, Eindhoven. 7. Klotz, J. A., & Brighm, W. E. (1998). To determine Herschel-Bulkley coefficients. Journl of Petroleum Technology, 5, 8 81.