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ptanyagA Sziliktipari Tudomnyos Egyeslet lapja

A TARTALOMBL:

Static indentation hardness

testing of concrete: a long

established method revived

Szemcss anyagok

csvezetkben

folyadkrammal valszlltsnak mretezse

1. rsz: Ksrleti berendezsek s modell

Applying master curve at the

grids strengthened asphalt

structures

Durability of H-class cement

and blast furnace slag-based

cementitious composites

Treatment, characterization

and Pb2+, Cu2+, Ni2+and Zn2+

adsorption behaviour of

chemically treated bentonite

clay: a comparative study

Development of hydraulic

binder using industrial wastes

2011/12

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tban

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tban

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SZERKESZTBIZOTTSGEDITORIALBOARDDr. GMZE A. Lszl elnk/presidentTTH-ASZTALOS Rka fszerkeszt/editor-in-chiefProf. dr. TALABR Jzsef rks tiszteletbeli elnk/senior president

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ROVATVEZETKCOLUMNISTSAnyagtudomny Materials science

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63. vf. 12. szm

A finomkermia-, veg-, cement-, msz-, beton-, tgla- s cserp-, k- s kavics-, tzllanyag-, szigetelanyag-ipargak szakmai lapja

TARTALOM

2 Egy rgi mdszer j nzpontbl: megszilrdult betonstatikus kemnysgmrse SZILGYI Katalin BOROSNYI Adorjn DOB Kristf

8 Folyiratszemle

10 Szemcss anyagok csvezetkben folyadkrammalval szlltsnak mretezse1. rsz: Ksrleti berendezsek s modell

FAITLI Jzsef

16 Mester grbk alkalmazsa a rcserstsaszfaltszerkezeteknl

ALMSSY Kornl TTH Csaba

18 H-osztly cement s nagyolvaszti salak alap kompozitcementek tartssga Mara Teresa FUENTES ROMERO Enrique ROCHA-RANGEL

Sebastin Diaz DE LA TORRE Manuela DAZ CRUZ

24 sszehasonlt vizsglatok egy bentonitos agyag kmiaikezelsrl, jellemzsrl, valamint Pb2+, Cu2+, Ni2+sZn2+adszorpcijrl

Makhlouf BOUFATIT Fettouma MOHAMMED-AZIZI Soraya DIB

28 Hidraulikus ktanyag fejlesztse ipari hulladkokbl MUCSI Gbor DEBRECZENI kos MDAI Viktor

DUDOK Tmea CSKE Barnabs

33 A magyar perlit 50 ve knyvajnl

34 Gbor Dnes-djat kapott Egyesletnk Elnke

36 vegipari Szakmai Konferencia FERENCI Pter

37 Egyesleti s Szakhrek

CONTENT

2 Static indentation hardness testing of concrete:a long established method revived Katalin SZILGYI Adorjn BOROSNYI Kristf DOB

8 Journal review

10 Design of transport of particulate materialsby fluid flow in pipelinesPart 1: Experimental equipment and model

Jzsef FAITLI

16 Applying master curve at the grids strengthenedasphalt structures

Kornl ALMSSY Csaba TTH

18 Durability of H-class cement and blast furnace slag-based cementitious composites Mara Teresa FUENTES ROMERO Enrique ROCHA-RANGEL Sebastin Diaz DE LA TORRE Manuela DAZ CRUZ

24 Treatment, characterization and Pb2+, Cu2+, Ni2+and Zn2+adsorption behaviour of chemically treatedbentonite clay: a comparative study

Makhlouf BOUFATIT Fettouma MOHAMMED-AZIZI Soraya DIB

28 Development of hydraulic binder using industrial wastes Gbor MUCSI kos DEBRECZENI Viktor MDAI

Tmea DUDOK Barnabs CSKE

33 50 years of Hungarian perlite book commendatory

34 President of the Society received Dennis Gabor Award

36 Glass Conference Pter FERENCI

37 Society and professional news

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ANYAGTECHNOLGIA MATERIALS TECHNOLOGY

Static indentation hardnesstesting of concrete: a longestablished method revived

KATALINSZILGYIBME Dept. of Construction Materials and Engineering [email protected]

ADORJNBOROSNYIBME Dept. of Construction Materials and Engineering [email protected]

KRISTFDOBBME Dept. of Construction Materials and Engineering [email protected]

Received: 06.02.2011. rkezett: 2011.02.06.

Hardness (even in-situ) testing of materials offers the potential of strength estimation by meansof a much simpler test than the direct compressive or tensile strength testing. Nevertheless, thetheoretical approaches of contact mechanics and hence that of hardness has several gaps. In thetechnical literature limited number of experimental studies is available on cement mortars andconcretes by static ball indentation hardness testing devices. It can be found that a power functioncan suitably characterize the relationship between the Brinell hardness and the compressivestrength of concretein those cases where one load level is applied for testing.A much detailed

analysis can be provided if several load levels are used. Power functions between the indenter load(F) and the residual impression diameter (d) can be formulated for different concrete strengths,F adn, of those empirical parameters aand nare material properties as it was demonstratedfor metals by Meyer in 1908. Objective of present experimental study was to thoroughly investigatenormal weight hardened concrete specimens by a static ball indentation hardness testing laboratorydevice at several load levels on a wide range of compressive strength and age of concrete attesting. It was found that the power in the Meyer relationship is apparently a constant for concrete,independently of the water-cement ratio and the age at testing, while the multiplier in the Meyerrelationship is very sensitive to both influencing factors. The results disproved the hypothesis ofthe power function relationship between the residual indentation diameter and the compressivestrength of concrete with a power of -4.0 published in the technical literature. The results confirmedthe existence of a linear general model for the relationship between the compressive strength andthe Brinell hardness of concrete, as an average power of 1.128 was found.Keywords: concrete, compressive strength, Brinell hardness, Meyer hardness, indentation

testing

Katalin SZILGYIis civil engineer (MSc), PhD candidate at the

Department of Construction Materials andEngineering Geology, Budapest University of

Technology and Economics. Main fields ofinterest: diagnostics of concrete structures,

non-destructive testing of concrete, concretetechnology, shrinkage compensation of

concretes. Member of the Hungarian Group of fib

and the SZTE Concrete Division.

Dr. Adorjn BOROSNYIis civil engineer (MSc), PhD, Associate Professor

at BME Dept. of Construction Materials andEngineering Geology. Main fields of interest:

cracking and deflection of reinforced concrete,application of non-metallic (FRP) reinforcements

for concrete structures, bond in concrete, non-destructive testing of concrete. Secretary of thefibTask Group 4.1 Serviceability Models and

Chairman of the SZTE Concrete Division.

Kristf DOBis civil engineer (BSc) student at BME Dept. of

Construction Materials and Engineering Geology.Main fields of interest: material modelling,

hardness testing of concrete.

1. Introduction

Hardness testing was the rst material testing practice romthe 1600s in geology and engineering through the scratchinghardness testing methods (1640, Barba; 1722, Raumur; 1768,Kvist; 1801, Hay; 1812, Mohs); appearing much earlier thanthe systematic material testing that is considered to be startedin 1857 when David Kirkaldy, Scottish engineer set up the rstmaterial testing laboratory in London, Southwark [1, 2, 3, 4,5]. Te theoretical hardness research was initialized by thepioneering work o Heinrich Hertz in the 1880s [6]. Hertzs

proposal ormed also the basis o the indentation hardnesstesting methods by Brinell (1900), Rockwell (1920), Vickers(1924) and Knoop (1934) [7]. Tese conventional methodsinvolve in different ways the measurement o the size o aresidual plastic deormation impression in the tested specimenas a unction o the indenter load. Amongst several differentindenter geometries the spherical indenters can be used ortesting both ductile materials (e.g. metals) and brittle materials(e.g. ceramics). Te response o materials to the indentationtest includes elastic (reversible) and plastic (irreversible)deormations as well as orming o cone cracks in brittlematerials; thereore, the denition o the term hardness is not

evident.Te scientic denition o hardness has been o considerable

interest rom the very beginning o hardness testing, however,

still today more than 100 yearsafer Hertzs original proposal no absolute denition ohardness is available in materialsciences. According to Hertz,hardness is the least value opressure beneath a sphericalindenter necessary to producea permanent set at the centre o

the area o contact. As Hertzscriterion has some practical

diffi culties, the hardness values dened by the practical methodsare usually indicating various different relationships between theindenter load and the tested specimens resistance to penetrationor permanent deormation.

Fig. 1.a.schematically indicates the deormation eld o anelastic-plastic medium under a spherical indenter during staticindentation hardness testing. A hemispherical, incompressiblecore o material can be considered directly beneath theindenter, being in hydrostatic stress eld [8]. Surrounding thecore there is a hemispherical plastic zone that connects the

elastically strained material. Te schematic load-deectioncurve (compliance curve) is given in Fig. 1.b. Te residualplastic deormation impression (h

r) can be measured and used

or the calculation o hardness afer unloading the indenter. Itcan be realized that the residual plastic deormation impressionis a result o a three-dimensional, constrained deormationeld that is strongly affected by the testing method itsel (e.g.the indenter can be a sphere, cone, pyramid, diamond etc.). Incase o ductile materials the plastic deormation is consideredto be started when the mean contact pressure is p

m= F/a2

1.1y(where

yis the uniaxial yield stress o the material and

the contact radius (a) can be predicted rom Hertzs proposal;aF2/3). Plastic deormation exists beneath the surace at higher

loads and constrained by the surrounding elastically strainedmaterial. With urther loading the plastic deormation extendsto the surace o the specimen as the mean contact pressure is

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MATERIALS TECHNOLOGY ANYAGTECHNOLGIA

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pm

= F/a2 2.8yand continues to grow in size but the mean

contact pressure is not increasing any more (the contact radius(a) can be predicted to be linearly increasing by loading; aF)[9]. Cone cracks are orming at the contact surace in the caseo elastic-brittle materials, however, plastic deormations canbe also realized due to the local densication through e.g.phase change o the material as a result o high compressive

stresses (which deormation is considerably different in naturerom the plastic yield o ductile materials) [7].Nevertheless, the theoretical approaches o contact mechanics

and hence that o hardness has several gaps, the hardness (evenin-situ) testing o materials offers the potential o strengthestimation by means o a much simpler test than the directcompressive or tensile strength testing. Tis is the reason whyseveral different hardness testers became available or materialtesting and the research on hardness o materials has been verydynamic rom the beginning up to present day.

2. Signicance and objectives o present studies

Hardness testing practice o cementitious materials such asconcrete exclusively applies nowadays the dynamic reboundsurace hardness testing devices (e.g. the Schmidt reboundhammer), rather than devices o plastic indentation hardnesstesting methods. Rebound hammers can be used very easilyand the measure o hardness (i.e. the rebound index) can beread directly on the display o the testing devices. However,the impact energy o the rebound hammers usually can not beadjusted by the operator, thus the material response available byrebound hammer testing can provide only limited inormation.Also, the rebound hammers give inormation about the elasticand damping properties o the very surace layer o concrete

that can not be necessarily related directly to the strength oconcrete.

Fig. 1.a. Deormation eld o an elastic-plastic medium under a spherical indenterduring static indentation hardness testing

1.a. bra Rugalmas-kplkeny kzeg alakvltozsi mezje gmb alak szrszerszmalatt, statikus kemnysg vizsglat sorn

Fig. 1.b. Schematic load-deection curve (compliance curve) during static indentationhardness testing

1.b. bra Sematikus terhels-tehermentestsi grbe a statikus kemnysg vizsglatsorn

It was also demonstrated recently that the analysis o reboundhammer test data and strength estimation need specialconsiderations or which purpose no general theory wasavailable until now [10].

Objectives o present experimental studies were on one handto thoroughly investigate normal weight hardened concretespecimens by a static ball indentation hardness testing

laboratory device on a wide range o compressive strengthand age o concrete at testing; and on the other hand, tocompare measured data with rebound hardness results as wellas Youngs modulus and compressive strength values o thesame concretes. Te main purpose o the studies is to provideexperimental evidence i any between the relationshipo static and dynamic hardness values or concretes as wellas compressive strength and elastic properties to be able tosupport the better understanding o hardness o porous solidmaterials. Present paper intends to give a summary about thestatic ball indentation hardness results.

3. Previous studiesIn the 1920s and in the 1930s limited number o researchers

investigated cement mortars and concretes by the Brinell methodor similar developments o static ball indentation hardnesstesting devices [11, 12, 13, 14, 15] and later the research in theeld become even less requent [16]. Some studies applied onlyone or two load levels and tried to nd a relationship betweenthe Brinell hardness and the compressive strength o concreteor between the residual plastic deormation impression and thecompressive strength o concrete, while other studies appliedseveral load levels and took a wider look on the topic.

In the representation o the test results several differentrelationships can be ormulated. Te compressive strength canbe represented as a unction o the Brinell hardness (Fig. 2.a.)or the residual impression diameter (Fig. 2.b.) in those caseswhere one load level is applied or testing. It can be ound thata power unction can suitably characterize the relationshipbetween the Brinell hardness and the compressive strengtho concrete,

c aHBm (with a power o m 2) [15]. Te

relationship between the residual impression diameter (d)and the compressive strength o concrete can be characterizedby a logarithm unction, log

c a

1 - a

2d [12, 13, 14]. A

much detailed analysis can be provided i several load levels

are used (Fig. 2.c.). Power unctions between the indenterload (F) and the residual impression diameter (d) can beormulated or different concrete strengths, F adn, o thoseempirical parameters aand nare material properties as it wasdemonstrated or metals by Meyer in 1908 [17].

It was also indicated or metals that the Brinell hardness,HB and the Meyer hardness, HM (see appendix) are not load-independent measures, thereore they can not necessarilyprovide a reliable estimation or the strength i the load level othe indentation test is not chosen correctly [18].

Much more accurate parameters are however, attained in amore complicated way the empirical constants o the Meyer

power unctions that can be considered to be material properties[17]. Fig. 3.a3.c are prepared based on Meyers published datato demonstrate this behaviour or different metals.

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Based on the review o the available inormation in thetechnical literature in the eld o static ball indentationhardness testing o concrete one can realize that researchersdid not publish results that can be suitable or practical use andthe theoretical analysis o the hardness o cementitious porous

solids is also not provided. It can be also mentioned that nodata are available concerning the relationship between staticand dynamic hardness o cementitious porous solids.

4. esting method

An experimental programme was completed on a widerange o compressive strength o normal weight concretes inthe Budapest University o echnology and Economics (BME),Department o Construction Materials and EngineeringGeology, to study the static indentation hardness behaviour.

Concrete was mixed rom Danube sand and gravel using CEMI 42.5 N cement with w/c ratios o 0.40, 0.50 and 0.65. Consistencyo the tested concrete mixes was 50020 mm ow. Design aircontent o the compacted resh concretes was 1.0 V%.

Te specimens were cast into steel ormworks and thecompaction o concrete was carried out by a vibrating table.Te specimens were stored under water or 7 days as curing.Afer 7 days the specimens were stored at laboratory condition(i.e. 203 C temperature and 655% relative humidity).ests were perormed at the age o 3, 7, 14, 28, 56, 90 and 240days. 150 mm cube specimens and 120120360 mm prismspecimens were prepared or the experiments.

Static indentation tests were carried out by a Brinell testingdevice with ball diameter o 10 mm. esting loads o 187.5 kg to3000 kg were applied or 30 seconds on the concrete suraces.

F, kN fc

= a d-n R2 fc

= a HBm R2

2.5 f c= 672.9 d-2.346 0.741 f

c= 0.885 HB1.146 0.743

5.0 f c= 2384.0 d-2.844 0.800 f

c= 0.324 HB1.363 0.803

7.5 f c= 4783.7 d-2.949 0.918 f

c= 0.314 HB1.369 0.922

10.0 f c= 2532.3 d-2.381 0.774 f

c= 0.824 HB1.089 0.777

15.0 f c= 2651.0 d-2.156 0.741 f

c= 1.368 HB0.960 0.739

17.5 f c= 3058.3 d-2.122 0.775 f

c= 1.721 HB0.916 0.771

20.0 f c= 2008.6 d-1.804 0.704 f

c= 1.001 HB1.055 0.788

able 1. Regression curve (power unction) parameters

1. tblzat A regresszis grbk (hatvnyggvnyek) paramterei

Five individual tests were carried out at each load level andve residual impressions were prepared. Diameters o theresidual impressions were measured by a hand microscopeo 8 magnication. Further increase o loading was stoppedwhen the ormation o cone cracking was observed to begoverning during loading.

Compressive strength on the cube specimens, Youngsmodulus on the prism specimens and carbonation depths werealso recorded at the age o 3, 7, 14, 28, 56, 90 and 240 days.

Fig. 3.a. Meyer power functions between theindenter load (F) and the residual impres-

sion diameter (d) for different metals [17] 3.a. bra Klnbz fmek Meyer-fle hatvny-trvnye (a terhel er s a marad goly-nyom tmrje kztti sszefggs) [17]

Fig. 3.b. Relationships between the Meyer hard-ness (HM) and the indenter load (F) or

different metals [17] 3.b. bra Klnbz mek Meyer kemnysge sa terhel er kztti sszeggs [17]

Fig. 3.c. Relationships between the Brinell hard-ness (HB) and the indenter load (F) or

different metals [17] 3.c. bra Klnbz mek Brinell kemnysge sa terhel er kztti sszeggs [17]

Fig. 2.a. Relationship between the compressive strength(

c) and the Brinell hardness (HB) o concrete

2.a. bra A beton nyomszilrdsga (c) s Brinell

kemnysge (HB) kztti sszeggs

Fig. 2.b. Relationship between the compressive strength(

c) and the residual impression diameter (d)

o concrete 2.b. bra A beton nyomszilrdsga (f

c) s marad

golynyom tmrje (d) kztti sszefggs

Fig. 2.c. Relationship between the compressive strength(fc)

and the residual impression diameter (d) ofconcrete at several load levels

2.c. bra A beton nyomszilrdsga (fc) s a marad

golynyom tmrje (d) kztti sszefggs tbbteherszint alkalmazsa esetn

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90

80

70

60

50

40

30

20

10

0

2 3 4 5 6 7

d, mm

fc, N/mm 2

F = 2.5 kN

F = 5.0 kN

F = 7.5 kN

Fig. 4.a. Relationship between the compressive strength (fc) and the

residual impression diameter of concrete at different load levels

4.a. bra A beton nyomszilrdsga (fc) s a marad golynyom tmrje

(d) kztti sszefggs klnbz teherszintek alkalmazsa esetn

5. Results

Te correlation between the concrete compressive strengthand the residual indentation diameter is indicated in Fig. 4.a.or different load levels. It can be realized that power unctionscan characterize reasonably well the responses (correlationcoeffi cients are in the range o r2 = 0.70 to 0.92). Regressioncurve parameters are resulted in able 1. For the load level oF = 7.5 kN results are separated according to the applied threewater-cement ratio in Fig. 4.b.

Te Meyer power unctions or specimens o the three appliedw/c are indicated in Fig. 5.represented or three different agesat testing: at the age o 7 days (Fig. 5.a.), 28 days (Fig. 5.b.) and240 days (Fig. 5.c.). It can be studied that the Meyer powerunctions sensitively ollow the strength development in timeand the empirical constants have a tendency o change intime. Te Meyer parameters ound in present experimentalprogramme are represented in Fig 6.as a unction o time (Fig.6.a.) and o water-cement ratio (Fig. 6.b.). It can be seen thatthe power in the Meyer relationships is apparently a constantor concrete, independently o the water-cement ratio and theage at testing, while the multiplier in the Meyer relationships is

very sensitive to both inuencing actors.Brinell hardness, HB results are plotted in Fig. 7. against

the concrete compressive strength and an apparent linearrelationship can be seen between compressive strength andBrinell hardness, HB o concrete. Results are not separated

in the representation either by water-cement ratio or testingload to be able to study a possible general behaviour pattern.Regression curve parameters available or the applied loadlevels are summarized in able 1.

Fig. 8.a. indicates Brinell hardness, HB results in timeor specimens o w/c = 0.50 represented as a unction o thetesting load. It can be studied that an apparent peak hardness isshowing on each response. Te same behavioural scheme wasrealized or the Meyer hardness, HM results. I the hardness

values are represented as a unction o the residual indentationdiameter then the same increasing-decreasing tendencies areresulted (Fig. 8.b.). It is possible to read the peak hardness

values on each regression curve. Te peak hardness readingsare plotted in Fig. 9. against the compressive strength and anapparently linear relationship is resulted.

Fig. 4.b. Relationship between the compressive strength (fc) and the

residual impression diameter (d) of concrete at the load level of

F = 7.5 kN (data are separated according to the applied three

water-cement ratio)

4.b. bra A beton nyomszilrdsga (fc) s a marad golynyom tmrje

(d) kztti sszefggs F = 7,5 kN teherszint alkalmazsa esetn

(az adatokat a vz-cement tnyez alapjn elklntve brzoltuk)

Fig. 5. The Meyer power functions for specimens of w/c = 0.40, 0.50 and 0.65

a) at the age of 7 days; b) at the age of 28 days; c) at the age of

240 days 5. bra v/c = 0,40; 0,50 s 0,60 vz-cement tnyezj prbatestek Meyer-

fle hatvnytrvnye

a) 7 napos korban; b) 28 napos korban; c) 240 napos korban

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6. Discussion

Te technical literature indicates that the Meyer hardness, HMcan be used as a simpliying estimate o the Brinell hardness, HBwhen the residual indentation diameter (d) is 0.3 d/D 0.7(where D is the diameter o the ball indenter) [19, 20]. Results oFig. 4., Fig. 7. and able 1. conrm the interchangeability o the

two hardness parameters: i one expresses the Brinell hardness,HB as a unction o the residual indentation diameter romthe experimental data then a power unction or the residualindentation diameter is resulted with a power o about -2.0 (thesame as characterizes Meyer hardness, HM; see Appendix). Inour experiments the power was ound to be equal to -2.106 as anaverage. echnical literature conrms our results: an analysis othe experimental data published by Gaede (1957) has resulted apower o -2.187 as an average [21].

Fig. 6.a. Te power o the Meyer unction as a unction o time 6.a. bra A Meyer-le hatvnytrvny kitevje az id ggvnyben

Fig. 6.b. Te multiplier o the Meyer unction as a unction o time 6.b. bra A Meyer-le hatvnytrvny szorzja az id ggvnyben

Te technical literature also indicates that the relationshipbetween the residual indentation diameter and the compressivestrength is a power unction with a power o -4.0 (based onsimplied analysis) [19, 20]. Our experimental results do notconrm this hypothesis.

Te power values can be studied in able 1. Average value o-2.372 can be considered to be valid or present experiments.

echnical literature conrms our results: afer a rigorousanalysis o the paper o Kolek (1958) it was realized that the

linear regression was carried out inaccurately in the paperand the accurate value o the power is -2.584 rather than -4.0indicated originally [19].

It can be ound in the technical literature that a linear responsecan model the relationship between the compressive strengthand the Brinell hardness, HB o concrete [22]. Te results oFig. 7., Fig. 9.and able 1.conrm this supposition. In presentexperiments an average power o 1.128 was ound.

Te observations o Fig. 8.a. and Fig. 8.b. are very specialand no similar ndings were published earlier in the technical

literature. However, the observed perormance clearly illustratethe elastic-plastic behaviour o concrete under the ball indenteras well as the mechanism o local densiication and theormation o cone cracking.

Te mechanisms are summarized as ollows. At lower loadsno ull plastic response o the concrete can be developed andthe densication under the ball indenter is not pronounced.Increasing load results increasing hardness values. At higherloads the local collapsing o the capillary walls in the hardenedcement paste and the local micro-crushing o small aggregateparticles near the contact area results more pronounceddensication; that can be realized in an apparent peak hardness

when ull plastic response o the concrete is utilized.As load is urther increased the ormation o cone cracks

is started at the contact surace (always clearly visible duringtesting) and the sofening o the cracked concrete is realized inthe apparent decreasing hardness values. Te same behaviouralscheme can be studied i one represents the Meyer hardness, HMinstead o the Brinell hardness, HB. Based on the observationso Fig. 8.a. and Fig. 8.b. it can be reasonable to choose theapparent peak hardness as the representative value o hardnesscorresponding to the compressive strength o concrete.

7. Conclusions

In the technical literature limited number o researchersinvestigated cement mortars and concretes by the Brinellmethod and most o the studies applied only one or two loadlevels trying to nd a relationship between the Brinell hardnessand the compressive strength o concrete.

Present paper summarizes the indings o static ballindentation studies on hardened concretes with water-cementratios o 0.40, 0.50 and 0.65 tested at the age o 3, 7, 14, 28, 56,90 and 240 days, at several load levels.

Fig. 7. Te general linear relationship between compressive strength and Brinellhardness o concrete (results are separated neither by water-cement ratio nor

testing load) 7. bra A beton nyomszilrdsga s Brinell kemnysge kztti ltalnos lineris

kapcsolat (az eredmnyeket sem a v/c, sem a terhelsi szint szerint nemklntettk el)

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Fig. 8.a. Brinell hardness (HB) results in time or specimens o w/c = 0.50 as a unction o

the testing load

8.a. bra A v/c = 0,50 vz-cement tnyezj prbatestek Brinell kemnysge az id s a

teherszint ggvnyben

Fig. 8.b. Brinell hardness (HB) results in time or specimens o w/c = 0.50 as a unction

o the residual indentation diameter 8.b. bra A v/c = 0,50 vz-cement tnyezj prbatestek Brinell kemnysge az id s a

marad golynyom tmrjnek ggvnyben

Fig. 9. Te linear relationship between the compressive strength and the peak Brinell

hardness o concrete

9. bra A beton nyomszilrdsga s a maximlis Brinell kemnysge kztti lineris

sszeggs

Te results demonstrated that the Meyer power unctions canbe ormulated or concrete in a similar way to that o metals.

It was ound that the power in the Meyer relationship isapparently constant or concrete, independently o the water-

cement ratio and the age at testing, while the multiplier inthe Meyer relationship is very sensitive to both inuencingactors.

Te results disproved the hypothesis o the power unctionrelationship between the residual indentation diameter and thecompressive strength o concrete with a power o -4.0 publishedearlier in the technical literature. Te results conrmedthe existence o a linear general model or the relationshipbetween the compressive strength and the Brinell hardness,HB o concrete. During the experiments a special observationwas made that clearly illustrates the elastic-plastic behaviouro concrete under the ball indenter as well as the mechanismo local densication and the ormation o cone cracking. Teresults can add to the undamental understanding o hardnesso concrete and mark the direction o uture research in theeld.

8. Appendix Hardness values

Te Brinell hardness, HB can be calculated as the ratio othe indenter load and the surace area o the residual spherical

imprint:

Te Meyer hardness, HM can be calculated as the ratio o theindenter load and the projected area o the residual imprint:

9. Acknowledgements

Te authors grateully acknowledge the support o the BolyaiJnos research scholarship by the Hungarian Academy oSciences (MA). Te authors are obliged to Dr. Rita Nemesorthe thorough prooread o the manuscript.

Reerences

[1] Barba, A. A.: Te art o metals(1640) (Arte de los metales), Reprint. Lima,1817 (in Spanish)

[2] Raumur, R. A. F.: (1722) Te art o converting iron into steel (Lart de convertirle er org en acier), French Academy o Sciences. Paris, 1722 (in French)

[3] Mohs, F.: rial o an elementary method to determine natural history andidentication o ossils(Versuch einer Elementar-Methode zur Naturhisto-rischen Bestimmung und Erkennung von Fossilien), sterreich Lexikon.

1812 (in German)[4] imoshenko, S. P.: History o strength o materials, McGraw-Hill. NewYork, 1953. 452 p.

[5] Szymanski, A. Szymanski, J. M.: Hardness estimation o minerals, rocksand ceramic materials. Elsevier. Amsterdam, 1989. 330 p.

[6] Hertz, H.:About the contact o elastic solid bodies(ber die Berhrung es-ter elastischer Krper). J Reine Angew Math 1881. 5:1223. (in German)

[7] Fischer-Cripps, A. C.: Introduction to Contact Mechanics. Springer. NewYork, 2000. 243 p.

[8] Johnson, K. L.: Contact mechanics. Cambridge University Press. 1985. 452 p.

[9] abor, D.: Te hardness o metals. Oxord University Press. 1951. 175 p.

[10] Szilgyi, K. Borosnyi, A. Zsigovics, I.: Rebound surace hardness oconcrete: Introduction o an empirical constitutive model. Construction andBuilding Materials. Vol. 25, Issue 5, May 2011. pp. 24802487.

[11] Crepps, R. B. Mills, R. E.: Ball est Applied to Cement Mortar and Conc-rete. Bulletin No. 12., Engineering Experiment Station, Purdue University.LaFayette, Indiana, May 1923. 32 p.

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Egy rgi mdszer j nzpontbl: megszilrdult betonstatikus kemnysgmrseA kemnysgvizsglat lehetsget nyjt arra, hogy az anyagokszilrdsgrl a kzvetlen nyomszilrdsg s hzszilrdsgvizsglatnl egyszerbb mdon jussunk informcihoz. Mind-azonltal a kemnysg kontaktmechanikai megkzeltsbens ezzel a kemnysg elmleti htterben szmos tisztzatlanterlet van napjainkban is. A szakirodalomban csak korlto-

zott szmban ll rendelkezsre cementhabarcs s beton sta-tikus kemnysgvizsglatval kapcsolatos ksrleti eredmny.A szakirodalomban azt talltuk, hogy a Brinell kemnysg sa nyomszilrdsg kapcsolatnak lersra alkalmas lehetegy hatvnyfggvny abban az esetben, ha a vizsglat sornegyetlen teherszintet alkalmazunk. Viszont sokkal rszle-tesebb elemzsre nylik lehetsg, ha a vizsglatot tbb te-herszinten vgezzk el. Ez esetben a terheler s a maradgolynyom tmrje kztti sszefggsekre beton szilrd-sgi osztlyonknt (ill. vz-cement tnyeznknt) kln hat-vnyfggvnyeket illeszthetnk, F adn, amelyeknek para-mterei Meyer (1908) ksrletei szerint fmek esetbenanyagjellemzknek tekinthetk. Jelen kutats clja normltestsrsg beton prbatestek statikus kemnysgvizs-glata tbb teherszinten, Brinell elven, golybenyomdssalvizsglva, a beton szles szilrdsgi tartomnyban, szmosvizsglati korban. Ksrleti eredmnyeink alapjn gy talltuk,hogy a Meyer-fle hatvnytrvny kitevje ltszlag konstans,fggetlenl a vz-cement tnyeztl s a beton kortl, mga szorzja mindkt befolysol tnyezre rzkeny. Az ered-mnyek szerint a szakirodalomban publiklt nyomszilrdsgs marad golynyom kapcsolatt ler hatvnyfggvny -4-eskitevje nem vals felttelezs. Az eredmnyek megerstik anyomszilrdsg s a Brinell kemnysg kztt felttelezhetltalnos lineris sszefggst; az ezt ler hatvnyfggvnytlagos kitevje 1,128-ra addott.Kulcsszavak: beton, nyomszilrdsg, Brinell kemnysg,

Meyer kemnysg

[12] Dutron R.: Ball tests or the determination o compressive strength o neatcement mortars (Essais la bille pour la determination de la rsistance la compression des pates de ciment pur). Brochure, Le laboratoireGroupement Proessionnel des Fabricants de Ciment Portland articial deBelgique. Bruxelles, Belgium, 1927. (in French)

[13] Vandone I.: Indentation testing or the determination o compressive strengtho cements(La prova dimpronta per determinare la resistenza a compres-sione dei cementi). Le Strade 1933. 15(9):381389. (in Italian)

[14] Sestini Q.: Strength test o cementitious materials by Brinell testing(La pro-

va Brinell applicata al materiali cementizi come prova di resistenza). LeStrade 1934. 16(7):255264, (in Italian)

[15] Steinwede K.: Application o ball hardness tests or the determination ostrength o concrete(ber die Anwendung des Kugelhrteversuches zurBestimmung der Festigkeit des Betons). Doctoral Tesis, University oHannover, Faculty o Civil Engineering. 20 Feb 1937. Gebrder Jnecke,Hannover. p. 69. (in German)

[16] Kholmyansky, M. Kogan, E. Kovler, K.: On the hardness determinationo ne grained concrete. Materials and Structures. Vol. 27, No. 10, Decem-ber 1994. pp. 584587.

[17] Meyer, E.: Studies o hardness testing and hardness (Untersuchungen berHrteprung und Hrte), Zeitschrif des Vereines Deutscher Ingenieure.Vol. 52, No. 17, April 1908- pp. 645654, 740748, 835844. (in German)

[18] Gillemot, L.:Material science and testing(Anyagszerkezettan s anyagvizs-glat), anknyvkiad. Budapest, 1967. 429 p. (in Hungarian)

[19] Kolek, J.: An Appreciation o the Schmidt Rebound Hammer, Mag ConcrRes 1958. 10(28):2736.[20] Gaede, K.: Impact ball testing o concrete(Die Kugelschlagprung von Be-

ton), DAStb 1952. Hef 107, p. 73. (in German)[21] Gaede, K.: Impact ball testing o hardened concrete: Inuence o testing age

(Kugelschlagprung von Beton mit dichtem Gege: Einuss des Pral-ters), DAStb 1957. Hef 128, p. 17. (in German)

[22] Gaede, K. Schmidt, E.: Rebound testing o hardened concrete(Rckprallp-rung von Beton mit dichtem Gege). DAStb 1964. Hef 158, p. 37. (inGerman)

Re.:

Katalin Szilgyi Adorjn Borosnyi Krist Dob: Static indenta-tion hardness testing o concrete: a long established method revived. ptanyag, 63. v. 1-2. szm (2011), 28. p.

ACI Materials Journal

2011. janur-februr, pp. 4654.

Kay Wille, Antoine E. Naaman, Gustavo J. Parra-Montesinos:Ultra nagy teljestkpessg betonok 150 MPa rtketmeghalad nyomszilrdsggal: Egy egyszer mdszer(Ultra-High Performance Concrete wit Compressive StrengthExceeding 150 MPa (22 ksi): A Simpler Way)

A szerzk kiterjedt laboratriumi ksrletsorozatot vgeztek ab-bl a clbl, hogy ultra nagy teljestkpessg beton (UHPC) ksz-tsnek olyan technolgijt dolgozzk ki, amelyben az ptiparipiacon egyszeren beszerezhet alapanyagok felhasznlsval,specilis betonkever berendezsek s hrlels nlkl lehet elr-ni legalbb 150 MPa beton nyomszilrdsgot.

Eredmnyeik alapjn a kvetkez megllaptsokat s javasla-tokat tettk az UHPC beton sszettelre vonatkozan:

A legkedvezbb reolgiai tulajdonsgok s a legnagyobbnyomszilrdsg kis C

3A (

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Beton und Stahlbetonbau

2011. janur, pp. 39-44.

Michael Cyllok, Marcus Achenbach:Vasbeton oszlopokmretezse tzteherre: A nemlineris zna mdszerpontossgnak ellenrzse laborksrletekkel(Bemessung von Stahlbetonsttzen im Brandfall: Absicherung

der nicht-linearen Zonenmethode durch Laborversuche)

A szerzk Ha laborksrletei sorn vizsglt oszlopok tzteherretrtn mretezst vgeztk el a nemlineris znamdszerrel.Ha ksrletei sorn 47 darab oszlop tzterhelst hajtottk vgre,a ksrlet a kvetkez vltoz paramtereket tartalmazta:

oszlop hossza 3,75,76 m; keresztmetszet mretei 200200, 300300 illetve

300400 mm; hosszvasak szma 4, 6, 10 illetve 20; hosszvasak tmrje 14, 20 illetve 25 mm; a hosszvasak folysi feszltsgnek karakterisztikus

rtke 404 vagy 544 N/mm2; a beton nyomszilrdsgnak karakterisztikus rtke

2953 N/mm2; a hosszvasak tengelytvolsga az elem szltl 30, 38

illetve 40 mm; a terhel er nagysga 901802 kN, az er klpontossga 0600 mm.A szerzk az oszlopok tzteherre trtn mretezsnek m-

dostst azrt rezik szksgesnek, mert a DIN V ENV 1992-1-2szerinti szmts esetn a szmtott rtk s a laborksrletekltal meghatrozott teherbrs hnyadosa 0,57 s 1,959 kzttmozgott. Bizonyos esetekben, gy a szmts sorn majdnem50%-os alulmretezs trtnne.

A nemlineris znamdszer Hertz znamdszern alapul, mely-ben az acl alakvltozst nyom ignybevtel esetn 0,2%-al csk-

kentik a hmrskletnek megfelel szilrdsgcskkents utn,abban az esetben, ha az aclbettek hmrskletnek kzpr-tke meghaladja a 75 C-ot. A szmts sorn a DIN EN 1992-1-2szerinti teherbrsi vonalakat hasznljk. A szmtst az izotermavonalak meghatrozsa utn vgzik el. Az izoterma vonalakat egyvgeselemes programmal hatrozzk meg, ahol figyelembe veszika beton nedvessgtartalmt, a htbocst- s a hvezet kpes-sgt is.

A nemlineris znamdszer a megfelel alkalmazsi tar-tomnyokon bell egy megbzhat szmtsi mdszernek bizonyultaz oszlopok tzteherre val mretezse sorn.

Dr. Majorosn Lubly va

Ziegelindustrie International2011. 1-2.

Prof. Dr. Ing. E. Sprecht M. Sc. P Meng:Solid-solid-rekupertor A knyszerkeringtetses alagtkemenceenergiafelhasznlsnak javtsra

A solid-solid rekupertoros (SSR) alagtkemence az ellenramalagtkemence elvn alapul, annak tovbbfejlesztett vltozata.Ennl a kemencetpusnl a kzpen kettvlasztott alagtban,kt snpron, egymssal szemben mozognak a kemencekocsik.Kompresszorok segtsgvel a kemenceatmoszfra a kt alagt-rsz kztt vltoztathat. Ezltal a h a forr rakatokrl a hide-gekre (s fordtva) tvihet.

A solid-solid rekupertoros alagtkemence legnagyobb elnyeaz egyrtelmen csekly energiafelhasznls. A vizsglatok kimu-tattk, hogy magnl a kemencnl 6265% az energia-megta-

karts. Ez az rtk a szrtsi s getsi folyamatban egyttesen(belertve teht 25% vz eltvoltsnak energiaszksglett s afstgzvesztesget is) 4446%-ra cskken.

Tovbbi elnye a hagyomnyos alagtkemenckkel szemben,hogy a hmrsklet eloszlsa a kemence hosszban s szl-tben igen kiegyenltett, amelynek kvetkeztben egyenletesgyrtmnyminsg rhet el.

A leveg axilis ramlst gy lehet belltani, hogy az az ajtk-tl az get zna fel ramlik. Ezltal az esetleges svlgzok akemencn bell elgnek s gy elgetlen sznhidrognek nem lp-nek fel a fstgzban. Mivel a fstgz mennyisge a hagyomnyoskemencvel szemben csak a tizedrsze, minimlis fstgztiszttsikltsggel lehet szmolni.

Az SSR alagtkemencnl elfelttel, hogy azonos a hmrskletigrbe lefutsa az elmelegt s hlznban. Ezrt a kemencealkalmazsa elssorban a kevs szervesanyagot s karbontottartalmaz tglknl elnys. Htrnya a rendszernek, hogy amegvltoztatott snrendszer miatt nagyobb kltsgekkel s helyi-gnnyel kell szmolni.

M. Kormannn D. Palenzuela O. Dupont:

Nedvessgramls az reges tglkban

A tglafalazatokon keresztli nedvessgramls dnt jelen-tsggel br az pletek energia-felhasznlsra, a bentlakkkomfortrzetre, valamint magnak az pletszerkezetnek azllkonysgra.

Az reges tglk CE-jellsben megadott anyagjellemzk fel-hasznlhatk a tglafalazatokban val nedvessgramls kiszm-tsra. A nmetorszgi Fraunhofer Intzetben elvgzett vizsgla-tok alapjn kialaktott j mdszerrel lehetsg nylik arra, hogy azreges tglk nedvessgfgg tulajdonsgait a cserpjellemzkismeretben meghatrozzk.

A ksrletek sorn hrom reges tgln s egyttal annak anya-

gn mrtk a nedvessgfgg tulajdonsgokat s a Wufi 2D,h- s nedvessgramlsra kifejlesztett szoftverrel elvgeztk aszmtsokat.

Ezzel a mdszerrel lehetsges, hogy egy termkcsaldnak(egytt a kiegszt elemekkel) egy CE-jellse legyen. Elszrmegmrik a tgla anyagnak nedvessgfgg tulajdonsgait,amely a csald minden tagjnl azonos, majd a tglacsald tag-

jainak eltr tulajdonsgait (a klnbz tglamretek, kiegszttglk) hatrozzk meg.

j, fokozott hszigetel kpessg tglt mutattak be aNrbergi Feltallk Vsrn

Az eddigi rendelkezsre ll nagy hszigetel kpessg anya-gok mellett a vsron egy rdekes, jonnan kifejlesztettet mutat-tak be, amellyel a blokktglk regeit feltltve, fokozott hszigetelkpessg termkek nyerhetk.

A Weimri Kutatintzet s egy tglagyr egyttmkdsblszrmazik ez az jfajta hszigetel habanyag, amely cement sklcium-szilikt-hidrt hulladk anyagok bzisn alapul.

Az intzetben klnbz regeltsg, klnfle tglatermkekesetben vgeztk el a vizsglatokat. Az alkalmazott hszigetelszraz hab trfogati tmege kisebb, mint 0,150 g/cm3, hvezetkpessge pedig kisebb, mint 0,045 W/mK.

A kedvez rfekvs, alak- s hll habostott cementenyv kiin-dulsi anyagait elszr elklnlten sszekeverik, majd egy habo-st berendezsben lltjk el azt a hszigetel habot, amelyet a

tgla regeibe tltenek.

Sopronyi Gbor

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Szemcss anyagok csvezetkben folyadkrammal val szlltsnakmretezse1. rsz: Ksrleti berendezsek s modell

FAITLI JZSEFMiskolci Egyetem, Nyersanyagelksztsi s Krnyezeti Eljrstechnikai Intzet [email protected]

rkezett: 2011. 04. 04. Received: 04. 04. 2011.

Design of transport of particulate materials by fluid flow in pipelinesPart 1: Experimental equipment and modelScientific field of mechanical process engineering deals with the flow of solid liquid mixturesin pipes, called as hydraulic transport. In the construction industry the two most importantapplications are the underwater hydraulic sand and gravel mining and the pipe transport of themixed concrete into the place of usage. In Hungary the longest slurry pipeline is situated in theslag fly ash deposition system of the Mtra Power Plant. Common feature of all the mentionedthree applications, that the solid phase is composed by really fine and coarse particles as well.There are many hundreds km long slurry pipelines in the world. Of course, flowing suspensionsand slurries in pipes can be found in many other industries, for example in mineral processingplants with wet technologies. This paper summarizes results achieved at the Institute of RawMaterials Preparation and Environmental Processing of the University of Miskolc during the last20 years. Perhaps the most important result was the so called fine suspension coarse mixtureflow model. The model is a hydraulic transport design method based on physical material testingand pilot scale hydraulic transport experiments. Our partner, the EGI Ltd. has designed many flyash handling systems based on the model and our material testing. Established installations are:Jacksonville Power Plant USA, Craiova 2, Isalnita, Rovinari, Turceni Power Plants Romnia,Mtra Power Plant, etc

Dr. FAITLI Jzsef(1965) egyetemi docens, a Miskolci Egyetem

Nyersanyagelksztsi s KrnyezetiEljrstechnikai Intzetnek oktatja. 1989-ben

a Miskolci Nehzipari Mszaki Egyetemenszerzett bnyagpsz- s villamos mrnk

diplomt, amelyet kveten az EljrstechnikaiTanszken helyezkedett el s amelynek jelenlegis oktatja. Hosszabb klfldi tanulmnyutakat

(Louvain-la-neuve, Belgium, Tempus sztndj,7 hnap, 1991, Chicago, USA, Fulbright

sztndj, 12 hnap, 199394.) kveten1998-ban szerzett PhD oklevelet, mechanikai

eljrstechnika tudomnyterleten. F oktatsis kutatsi terlete a tbbfzis ramlsok,

szemcsemozgs, mintavtelezs, porlevlaszts,stb Tudomnyos publikciinak szma 75.

Bevezets

A Miskolci Egyetem Nyersanyagelksztsi s Krnyezeti

Eljrstechnikai Intzetben, korbban Eljrstechnikai an-szk arjn s Debreczeni alapozta meg a szilrd-olyadkkeverkek ramlsnak a vizsglatt 19751990 kztt. 1989-ben kerltem a tanszkre, s azta ez a tma az egyik ter-letem. Intenzv kutatsokat olytattam arjn Proesszor rral,majd ksbb nllan is. A tmaterlet kutatshoz 2004-bencsatlakozott Gombkt Imre, aki leg az extrm nagy koncent-rci hatst vizsglja. Az eltelt idszakban a legtbbet a vilgszmos pontjrl ideszlltott (Neyveli, Ashtech s BusawalErmvek India, Nicola esla Erm Szerbia, Eren Erm rkorszg, Mtrai, Berentei, atabnyai, iszajvrosiErmvek, stb...), klnle szn- s lignittzels ermvekbl

szrmaz salak s pernye anyagokat vizsgltuk. Vgeztnk

keverkramlsi vizsglatokat hulladkgeti pernykkel, per-littel, homokkal - kaviccsal, lvzi iszapokkal, veghomokkal,

bentonittal, klnle elksztstechnikai s bnyszati ma-radvnyanyagokkal, pl. Gyngysoroszi otcis meddvel,vrsiszappal, stb...

A kutatsi eredmnyek bemutatsa

Ksrleti berendezs

Nagy kapacits, hidraulikus, szilrd anyag - szlltsi rend-szerek tervezse esetn elengedhetetlen, hogy elzetesen k-lnle vizsglatokat vgezznk az anyagokkal, e nlkl nemlehet elelsen megtervezni a technolgit. A nom szusz-penziramls vizsglatra kiejlesztett ksrleti berendezs a

csviszkozimter (1. bra).

1. Kevertartly2. Lyukasztott trcss keverk3. Csigaszivatty4. Mr csszakaszok5. Nyomsklnbsg-mrk6. Mrsadatgyjt7. Htcs8. Mintavev legazs9. Nyomsmr10. Zrszerelvny

11. Tartlyos trfogatram-mr 1. bra A hrom mrcsves csviszkozimter Fig. 1. Te tube viscometer with three measuring pipes


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A csviszkozimterbe kb. 100 l szuszpenzit lehet beke-verni, amit merev karakterisztikj csigaszivatty (3) szlltkrbe. A mrs elve az, hogy laminris csramls mellett kellaz ramlsi sebessget s a nyomsvesztesget mrni. A meg-ptett ksrleti berendezsben hrom kb. 6 m hossz 16, 21 s27 mm bels tmrj mrcs (4) van. Rszben azrt szk-sges hrom mrcs, mivel adott szuszpenzi trogatrammellett gy kzvetlenl hrom mrt pont ll a rendelkezsre,amelyre hromparamteres reolgit, pl. relplasztikus modell,lehet illeszteni. Msrszt ellenrzs cljbl, mivel a kln-le tmrj csvekben mrt pszeudo nyrsi pontoknak alaminris tartomnyon egy grbre kell esnik. Az intzeti

csviszkozimter mr tbb mint 15 ves, azonban jelenleg isrendszeresen vgznk rajt mrseket a mr jl bevlt mrsiprotokoll szerint.

A durva keverkramls ill. a durva keverkramls a -nom szuszpenziramlsban vizsglatra alkalmas lzemimret hidraulikus szllts mrkrt ptettnk. Az veksorn az adott eladatnak megelelen a mrkrt gyakrantptettk. A legtbb vizsglatot Warman orglaptos zagyszi-

vattyval vgeztk, azonban hasznltunk membrn dugattyss csiga szivattykat is. ltalban a vizsglatokat gy vgeztk,hogy a olyadk betltsvel kezddtt a mrs, majd a szilrdanyagot okozatosan adagoltuk a rendszerbe, a zagy olyamato-

san krbe jrt. Vgeztnk gy is mrseket, hogy a cs vgndobszitval levlasztottuk a szilrd anyagot, majd csiga segts-gvel jra pontos mennyisgben beadagoltuk azt. A 2. brnahidraulikus mrkr egy elnys kialaktsa lthat.

A hidraulikus szlltst vizsgl mrkr egy elmszerezettlzemi mret (400 l tltsi trogat, max. 60 m3/h szlltsikapacits), zrt krolyam zagyszllt berendezs, amelybena zagyszivatty (1) a tartlybl (6) a mr csvezetkeken (45)keresztl visszaszlltja a tartlyba a bekevert zagyot. Az ilyenzrt krolyam berendezsekben a htsrl gondoskodnikell, mivel az ramlsi srldsi vesztesg elmelegti a zagyot.Erre a clra egy egyenes duplaal csszakaszt (3) ptettnk

a rendszerbe, a kls gyr alak trben pedig olyamato-san htvizet keringtettnk. A megptett ksrleti krkmindegyikbe ptettnk mintavev csonkokat (19). Csapok

2. bra Flzemi mret hidraulikus szllts mrkr Fig. 2. Pilot scale hydraulic test loop

segtsgvel a teljes zagyram, vagy a csbe ptett vzszinteselvlaszt lemez segtsgvel a cs els ill. als elben lvzagyram a mintavev ednybe juttathat. A szemcsesrsgismeretben, amelyet elzleg piknomterben kell megmrni a szlltsi koncentrci (szilrd anyag trogatram / zagytrogatram) a minta trogata s tmege alapjn megha-trozhat. A mr csszakaszba ptett tappancsok (15) segt-sgvel a lerakdott anyagrteg vastagsgt tudtuk mrni. Anyomsvesztesg mrsre holttr nlkli tlnyoms tvadkat(1314) alkalmaztunk. A keresztmetszeti tlagsebessg mr-sre indukcis ramlsmrt (8) ptettnk be. Az indukcisramlsmr elektrdi kzt raml tltsek hatsra in-

dukldik jel a mszerben, azaz az raml kzegben tltsselrendelkez rszeknek (elektronok ionok) kell lennik. Ezrtdesztilllt vz sebessgnek a mrsre nem alkalmas az in-dukcis ramlsmr, norml csapvzre azonban mr igen. Amrsi elvbl az kvetkezik, hogy az indukcis ramlsmrcsak a vz (olyadk) zis sebessgt mri, ami csak abban azesetben egyezik meg a zagy sebessgvel, ha a szemcsk pon-tosan a olyadk sebessgvel mozognak, azaz nincs szlip. Vz-szintes csvezetkben a nagyobb szemcsk a tehetetlensgkmiatt lemaradhatnak a olyadkhoz kpest, mg gglegescsben, leel irnyul ramlsban pedig elre siethetnek.Ennek megelelen, adott pillanatban a csben a helyi kon-

centrci megnhet, vagy lecskkenhet a csvgi kiolyshozkpest, meg kell klnbztetni az un. szlltsi (C

) s helyi

(CU) koncentrcikat. Nyugalomban lv szilrd-olyadk ke-

verkek esetn a szemcsk relatv mennyisgt, azaz a koncent-rcit trogatok, tmegek ill. kevert mennyisgek arnyakntis megadhatjuk. A tudomnyos letben a trogati koncentrci(szilrd anyag trogata / zagy trogata) hasznlatos, mg aziparban inkbb a tmegkoncentrcit alkalmazzk. A szllt-si- s helyi trogati koncentrci a kvetkezkpp rhat el.

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3. bra A szllts- s helyi koncentrci Fig. 3. Te transport and in situ concentrations

Az 1. egyenletben hrom ismeretlen szerepel. A hidraulikusszlltsi ksrleti berendezsben az az rdekes eset llhat el,hogy annak ellenre, hogy a beptett indukcis ramlsmrmri a olyadk zis sebessgt, ha a szliprl nincs in-ormcink, nem tudjuk a zagy ramlsi sebessgt, a mrskirtkelhetetlen. A megolds az, hogy mrni kell a szlltsi- sa helyi koncentrcit is. A szlltsi koncentrci a kiolysblmrhengerrel vett minta trogatnak s tmegnek a mrsealapjn a szemcsesrsg ismeretben meghatrozhat. Eznem on-line olyamatos, hanem szakaszos mrsi mdszer s

a mrsadatgyjt rendszer sem rzkeli, azonban minden-lekpp rdemes idnknt elvgezni ellenrzs cljbl. A helyikoncentrci mrsre alkalmazhatk a kereskedelmi orga-lomban kaphat izotpos srsgmr eszkzk, azonban ezekdrgk s veszlyesek. A kvetkez eszkzket ejlesztettk ki aszlltsi- ill. a helyi koncentrci mrsre.

On-line szlltsi koncentrci mr berendezs

A ksrleti berendezsbe fggleges

csszakaszokat ptettnk, amelyekbe

4 db holttr nlkli, rozsdamentes acl

membrn tlnyoms tvadt szerel-tnk. Nyugalomban lv, de felkevert

zagy aljba, ha ilyen nyomsmrt

helyeznk, az a zagy hidrosztatikai

nyomst, kzvetve a zagy tlagos

srsgt mri. A jelensget a fg-

gleges fel- ill. leramls esetn az

bonyoltja, hogy felfel ramlsnl

a szemcsk lemaradnak a helyi kon-

centrci nvekszik, mg leramls-

nl a szemcsk elre sietnek a helyi

koncentrci cskken. Mindezek

alapjn gy gondoltuk, hogy a kthats tlagaknt a helyi koncentrci,

azaz adott idpillanatban a csben

tartzkod zagy tlagos srsg-

vel arnyos mennyisg lesz a ngy

tlnyoms rtkbl szmtott sszes

nyomsklnbsg. Az elvgzett

szisztematikus mrsek s elmleti megfontolsok alapjn [8]

azonban bebizonytottuk, hogy nagyon kis hibval ez az eszkz a

szlltsi koncentrcit mri. A szlltsi trfogati koncentrcit

a kvetkez sszefggs segtsgvel hatrozhatjuk meg:

(2)

4. bra A szlltsikoncentrci mrse 4

db nyoms tvadval Fig. 4. Measurement

o the transportconcentration by 4pressure transducers

On-line helyi koncentrci mr berendezs

A korbbiakban belttuk, hogy az ltalban acl csvekbenraml zagyok tlagos sebessgnek a meghatrozsra azindukcis ramlsmr mellett szksg van olyan eszkzre,ami kln kpes a olyadk s a szilrd anyag sebessgnek,

vagy a szlltsi- s a helyi koncentrcinak a mrsre. A helyikoncentrci mrsre ejlesztettk ki azt a mrberendezst,amely a mr csszakasznak a tmegt mri a benne lvzaggyal egytt, amibl az raml zagy srsge, kzvetve a he-lyi koncentrci meghatrozhat.

5. bra A helyi koncentrci mrse a mrcsszakasz mrlegelsvel Fig. 5. Measurement o the in - situ concentration by weighting o the measuring pipe

A mr csszakaszt gumi kzcsvek kz kell pteni. A

gumi rugalmassgi modulusa legalbb 3 nagysgrenddel eltraz acltl. A cs kt vgre olyan mrlegkarokat (1718) kellpteni, amelyek egyik karja a csvet tartja, a msik karja pedigermr tvadn keresztl egy-egy x ponthoz van rgztve. Amrcsnek pontosan egytengelynek kell lennie a csatlakozcsszakaszokkal, azrt hogy a be- s kilp zagyram impulzusereje ne okozzon hibt. Ezt a hibt egybknt tiszta vzzel vg-zett kalibrl mrs alapjn a szmtgpes mrsadatgyjtsegtsgvel korriglni is lehet. Mivel a mrlegkarok mindktkarja pontosan ki van egyenltve s a nylsmr blyegesermr cellk igen kicsi elmozduls mellett rzkelik az ert,a mrcs mindig egytengely pozcij. A mrcs belstrogata (V), azaz a benne elr zagy trogata adott. A be-rendezs kalibrlsakor tiszta olyadkkal kell a mrcsveteltlteni s ebben az llapotban kell az ermrket kinul-lzni, gy tnyleges mrskor a olyadkot kiszort nagyobbsrsg szilrd anyag miatti (m) tmeg klnbsget mria berendezs, amelybl a helyi koncentrci a kvetkezkppszmthat:

(3)

Modell: A nom szuszpenzi - durva keverkramlsmodell

A nyugati szakirodalomban elterjedt modell a cs gglegestengelye menti koncentrci eloszls alapjn osztlyozni a szi-lrd-olyadk tbbzis ramlst. Amennyiben a koncentrcieloszlsa szimmetrikus homogn keverkramlsrl, amennyi-ben aszimmetrikus heterogn keverkramlsrl beszlnek, seszerint vlasztjk meg a nyomsvesztesg szmtsra szolglsszeggseket is.

Mg nagymret szemcsk esetn is, ha a keresztmetszetitlagsebessg elegenden nagy (nagyobb, mint v

M1) a szem-

csket szuszpendlja a nagy turbulencia, az anyag szimmetri-

kus koncentrci eloszls mellett szllthat (homogn keve-rkramls). Cskken sebessgnl elszr a koncentrcieloszls aszimmetrikuss vlik, majd elbb megjelenik a cssz

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gy, mg kisebb sebessgeknl az ll gy, vgl bekvetkezika duguls. A PhD rtekezsemben szk veghomok rakcikklnbz koncentrcij keverkeit, azaz a szemcsemrethatst vizsgltam szisztematikusan, csviszkozimterben. Aksrletek alapjn megllaptottam, hogy adott anyag, adottmret csben, azonos olyadk s zemi paramterek melletta szemcsenagysg ggvnyben egszen eltren viselkedik.

Pldul a vizsglt kzel monodiszperz homok, ha egyszer20 m majd 1 mm nagysg, a nyomsvesztesg grbk alakja

jellegzetesen ms.

6. bra A koncentrci eloszlsa a sebessg ggvnyben

Fig. 6. Concentration distribution as unction o the velocity

A tiszta vz nyomsvesztesg grbje kis sebessgek esetn,a laminris tartomnyon egyenes (Re < 2320), a meredeksg

a viszkozitssal arnyos. Ipari mret csvezetkekben ehheznagyon kicsi sebessgek tartoznak, olyannyira, hogy az zemisebessgtartomnyban brzolva a nyomsvesztesget a linerisszakasz szinte nem is ltszik. urbulens ramlsban s simaal csben a nyomsvesztesg a sebessgnek kzel a msodikhatvnyval arnyos, a nyomsvesztesg grbe hatvnygg-

vny. Amennyiben a szilrd anyagot kis szemcsemretben (pl.20 m-es homok) keverjk be, az gy kpzett ktzis keve-rk nyomsvesztesg grbje teljesen hasonl a vzhez, csaknagyobb meredeksg a nagyobb viszkozitssal arnyosan (2.grbe a 7. brn). Abban az esetben, ha az azonos mennyisg

szilrd anyagot nagymret szemcsk ormjban (pl. 1 mm-es homok) keverjk be, a nyomsvesztesg grbe tipikus Du-rand ggvny [4] alak (3. grbe a 7. brn). Egszen nagysebessgek esetn a olyadkram kpes a nom s a durvaszemcsket is szuszpendlni, mindkt esetben szimmetrikus akoncentrci eloszls, a korbbi minsts szerint mindketthomogn keverkramls, azonban egyrtelm hogy a kt esetteljesen eltr jelleg. rdekes az, hogy nagy sebessgek mel-lett ugyanannyi szilrd anyag lnyegesen kisebb energivalszllthat nagyobb szemcsemret ormjban. Kis sebessgekesetn a helyzet ppen ellenttes, a nagyobb szemcsk esetnaz lepeds elkezd dominlni s megjelenik az aszimmetrikus

koncentrci eloszls esetleg a cssz ill. az ll anyaggy. Kissebessgeknl a kisebb szemcsemret szilrd anyag szllthatkisebb energival.

7. bra ipikus nyomsvesztesg grbk Fig. 7. ypical pressure loss curves

Az elvgzett ksrleti munka s elmleti megontolsok alapjnj modellt vezettnk be, amelyet nom szuszpenzi durvakeverkramls modellnek neveztnk el. Adott szilrd anyag solyadk ill. csvezetk esetn meghatrozhat egy olyan hatrszemcsemret, amelynl, ha nomabb szemcskbl ksztnkszuszpenzit, az nom szuszpenziramlsban og a csbenmozogni ggetlenl az ramlsi sebessg nagysgtl (v > 0).Ilyen esetben ez a szuszpenzi nll egyzis olyadknaktekinthet, sajt olysi viselkedssel s srsggel, mskppogalmazva, ramlstani szempontbl azaz mozgs kzbenez az anyag egyzis kontinumknt viselkedik. Nyugalombantermszetesen elbb-utbb a olyadknl nagyobb srsgszemcsk lelepednek, akkor jra clszer ktzis keverk-knt kezelni. A jelensg magyarzatra a kvetkez hipotzist

lltottam el. urbulens csramlsban a al mellett kialakul alaminris hatrrteg, amelyben az ersen nyrt olyadkrtegeksebessgprolja lineris, vagyis a nyreszltsg konstans. Haa szemcse olyan pici, hogy beler ebbe a hatrrtegbe, azonos(kzel azonos) nyr eszltsg s sebessg veszi krl s nemalakul ki olyan er, amely a altl szeretn eltasztani, gy ahelyzetnl ogva a laminris hatrrtegben nagyobb al mentinyr eszltsget, azaz nagyobb ramlsi srldsi vesztesgetokoz.

8. bra A nom szuszpenziramls elvi magyarzata Fig. 8. Teoretical explanation o ne suspension ows

A megnvekedett nyomsvesztesg annak a kvetkezmnye,hogy a csal menti hatrrtegben a nom szemcsk s a vzalkotta nom szuszpenzi reolgiai viselkedse megvltozika vzhez kpest, a viszkozits megn, st akr a olysi jellegis megvltozik s nem-Newtoni olysi viselkedst mutatnak

ezek az raml szuszpenzik. A ellltott modellbl mr kvet-kezik, hogy a nom szuszpenziramls nyomsvesztesgt akzeg olysi viselkedst jellemz olysi modell (tipikusan:

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Newtoni, Bingham plasztikus, Hatvnyggvnnyel lerhats Relplasztikus) s az abban szerepl reolgiai paramterekalapjn szmthatjuk.

A hatr szemcsemretnl nagyobb szemcskbl ksztett szi-lrd-olyadk keverkek csramlsa esetn az ramls jellegeegszen ms, mint az elzkben lert nom szemcsk esetben.Ebben az esetben a durva szemcse, jellemzen nem r bele

a laminris hatrrtegbe. A szemcse csalhoz kzeli eln anyreszltsg nagy, a sebessg pedig kicsi, a bels eln pedigpp ellenttesen a nyreszltsg kicsi s a sebessg nagy. Haezt az aszimmetrikus eszltsg eloszlst kiintegrljuk a durvaszemcse elletre egy ert kapunk, amely a szemcst a altleltasztja.

(4)

9. bra A durva keverkramls elvi magyarzata Fig. 9. Teoretical explanation o course mixture ows

Nagyobb sebessgek esetn ez az er egyre nagyobb, azaza szemcse egyre kevsb tud a allal srldni. Ez a hipotzismagyarzatot ad arra a sokszor mrt tnyre, hogy nagysebessgek esetn a durva szemcss zagyot szinte pontosan

akkora energia beektetsvel lehet a csben szlltani, mint-ha csak vizet szivattyznnk. Kisebb sebessgek esetn ez aaltl eltaszt er egyre kevsb jtszik szerepet, ekkor azlepeds elkezd dominlni s a durva szemcsk mechanikaikontaktusba kerlnek a csallal. A szemcsk s a csal kzttmechanikai srld er bred, amely a testeket norml irny-ban sszeszort ertl s a srldsi tnyeztl gg, s nemgg a testek kztti sebessgtl. Ezzel ellenttben a csalmellett bred ramlsi srldsi vesztesg gg a sebessgtl,sima al csben, turbulens vzramlsban a nyomsvesztesga sebessg kzel msodik hatvnyval arnyos. Ezek alapjn adurva szemcskbl bekevert zagyok csramlst durva keve-

rkramlsnak neveztk el. Ez egy valban ktzis (szilrd-olyadk) mechanikai rendszer, amelyben valjban csak aolyadk ramlsrl beszlhetnk, s amelyben a szemcskmechanikai erk hatsra mozognak. Amikor a oly grgetia sziklkat, jl rzkelhet ez a modell. Akkor viszont, amikoradott csvezetkben, adott sebessg mellett, lland nyomvesz-tesggel, stabil zemben szlltjuk a durva szemcss anyagot,megtveszt a helyzet. Olyan mintha a zagy ramolna, rad-sul a nyomsvesztesgbl knnyen meghatrozhatunk egyltszlagos zagy viszkozits rtket is. A nom szuszpenzi durva keverkramls modell alkalmazsa megmutatja, hogyez a megkzelts hibs, clszer ezt a rendszert gy tekinteni,

hogy a olyadk ramlik a olysi viselkedse ltal meghatro-zott mdon s ez szlltja a szemcsket, amelyek mozgstmechanikai erk hatrozzk meg. A nyomsvesztesg megha-

trozsa elmleti ton ezrt rendkvl nehz, tulajdonkppnincs ilyen a szakirodalomban. Ami viszont igen, az a rend-kvl nagyszm mrsi eredmny s az azokra illesztett em-pirikus sszeggs. Ezeket az sszeggseket nevezhetjkDurand tpus sszeggseknek, mivel az eltr anyagokkals mretekben elvgzett hidraulikus szlltsi vizsglatok ered-mnyeire meghatrozott sszeggsek kzl az elst Durand

publiklta. A Durand egyenletben kt konstans tallhat. AFroude szm kitevje 3, ami a grbe grblett hatrozzameg, s egy szorz konstans, ami a grbe magassgt hatrozzameg, ami 81. Az eltelt tbb mint 20 vben elvgzett mrsekalapjn a durva keverkramls nyomsvesztesgnek a szm-tsra j kzeltssel alkalmaztuk a Durand egyenletet, azzal aklnbsggel, hogy a kt konstanst (n = 3 s K = 81) anyagtlgg paramternek tekintettk, s az egyenletet mdostottDurand egyenletnek neveztk. Az n s K anyagi paramterekmeghatrozsra, adott anyagokra lzemi mret hidrau-likus szlltsi vizsglatokat kell vgezni.

Az iparban elordul szemcss anyagok, amelyeket

csvezetkben szlltanak olyadkramban valjban min-dig polidiszperzek, azaz szemcsemret-, szemcsealak- sszemcsesrsg-eloszlsrl kell beszlnnk. A szlltott szi-lrd anyag tartalmazhat nom s durva szemcsket egyarnt.Wasp [10] a homogn heterogn keverkramlsi modellalkalmazsval dolgozta ki az un. vehicle (szlltjrm)modellt. Ennek az a lnyege, hogy adott keverkramlsisebessg mellett a cs legels pontjban kialakul pillanat-nyi, helyi koncentrcinak megelel zagy hordoz kzegknt

viselkedik s a szimmetrikus koncentrci eloszlson kvliszemcsket ez a zagy szlltja. A korbbiakban ers kritikvalillettk a homogn heterogn osztlyozsi rendszert, azon-

ban a szlltjrm koncepci brilins. Elvi megontolsokalapjn kidolgoztuk a durva keverkramls a nom szusz-penziramlsban modellt. A PhD rtekezsemben kidol-gozott modell, szmos diszkrt szemcserakcira bontotta aszilrd anyagot s a nyomsvesztesget a szemcserakcik ltalkln-kln okozott vesztesgek sszegeknt hatrozta meg,gy kezelni tudta, akr a szles szemcsemret tartomnyt ill.az eltr, homogn-heterogn viselkedst is. Az idkzbenelvgzett jabb vizsglatok alapjn alakult ki, az azta mrrutinszeren alkalmazott durva keverkramls a nomszuszpenziramlsban modell. Eszerint csak kt rakcirardemes bontani a szilrd anyagot: nom s durva rakcira.

A hatr szemcsemretet szisztematikus vizsglatokkal kellmeghatrozni adott anyagra. Az anyagbl kzel monodisz-perz szemcserakcikat kell kszteni szitlssal, majd ezeketa csviszkozimterbe klnbz koncentrciban bekeverve anyomsvesztesg grbket kell mrssel meghatrozni. A nyo-msvesztesg grbk matematikai elemzse alapjn (kvetkezejezet) a keverkramlsi jelleg s gy a hatr szemcsemretmeghatrozhat. A kt legontosabb anyagra, sznermipernye-salakokra (kb. 160 m) s homokra (kb. 50 m) ezeketa vizsglatokat elvgeztk. A modell szerint a hatrszemcsnlkisebb szemcsk a hordoz olyadkkal a csramlsban nomszuszpenzit alkotnak s ez a nom szuszpenziramls nem

pedig a olyadkramls ogja a durva szemcsket durva keve-rkramls ormjban szlltani. A nom szuszpenziram-ls nyomsvesztesgnek a szmtshoz a nom szuszpenzi

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srsgnek, a olysi viselkedsnek s az annak megelelreolgiai paramtereknek az ismeretre van szksg, s nincsszksg a szemcss anyag jellemzire, mint pl. szemcsemret-eloszls, hiszen a modell szerint ez egy egyzis olyadk. Adurva keverkramls nyomsvesztesgnek szmtsra amdostott Durand egyenletet hasznljuk. A durva szemcskokozta mechanikai srlds jelentsen gg a szemcsk sllye-

dsi sebessgtl, a durva szemcserakci zikai tulajdonsgaitgyelembe kell venni. A durva szemcse rakci jellemzsre azx

D80-as (a hatrszemcsemretnl nagyobb durva rakci 80%-a

kisebb, mint xD80

) szemcst vlasztottuk. A biztonsg rdek-ben val tveds rdekben vlasztottunk nagyobb szemcst,de csak annyira, ami mg jl mrhet. A szemcsehalmazt egy

jellemz szemcsvel jellemezni a szmtsban, termszetesenjelents egyszersts. Azonban, a mdostott Durand egyen-letben szerepl n s K anyagi paramtereket a nagy hidraulikuskrn elvgzett lzemi mrsekkel hatrozzuk meg, amikora ggvnyillesztst gy vgezzk el, hogy a szitlssal megha-trozott x

D80 alapjn szmtjuk ki a sllyedsi vgsebessget

s az ellenllstnyezt (egy db xD80szemcse sllyed a nomszuszpenziban), vagyis a jellemz 80%-os szemcsre kalib-rljuk a modellt. Ez a modell gy sokkal egyszerbb s ponto-san kalibrlhat, szemben a nagyobb szemcsk sok rakcira

val bontsval. A durva keverkramls a nom szuszpen-ziramlsban modellre az elmlt 20 vben elvgzett vizsgla-tok kzl tbb is empirikus bizonytkul szolglt, tovbb apartnernk az EGI Engineering Ltd. a modell alapjn tervezettszmos pernyekezel rendszert a vilg tbb pontjn (Jackson-

ville USA, Craiova 2, Isalnita, Rovinari, urceni Romnia,Mtrai Erm, stb).

10. bra Durva keverkramls a nom szuszpenziramlsban Fig. 10. Coarse mixture ow in the ne suspension ow

A 10. brna Mtrai Ermbl szrmaz R4 nev receptraszerint sszekevert salak-pernye-vz 33,8% trogati szlltsikoncentrcij keverk, 75 mm-es bels tmrj csben valramlsnak mrt nyomsvesztesg grbje lthat. A hrom-szggel jellt pontok a mrt pontok. A diagramban a zikais reolgiai anyagvizsglatok s a modell alapjn szmtottgrbket is brzoltam. Az (1) jel grbe a tiszta vz szmtottnyomsvesztesg grbje az adott csben. Az anyagvizsglatok

eredmnyei (nom szuszpenzi koncentrcija, srsge, re-olgija) alapjn szmtottam ki a nom szuszpenziramls(2) nyomsvesztesg grbjt. Majd az empirikusan megha-

trozott n s K segtsgvel a durva keverkramls a nomszuszpenziramlsban modell segtsgvel addott a mrsre

vonatkoz elmleti nyomsvesztesg grbe (3). Az empirikusbizonytkot az jelenti, hogy nagy sebessgek esetn a mrtpontok nem a vz (1) grbjhez tartanak, hanem egy olyangrbhez, a nom szuszpenziramls grbjhez (2), amelyetms eszkzkn elvgzett kln mrsek (szitls, piknom-teres srsgmrs, csviszkozimteres reolgiai mrsek)eredmnyei alapjn a modell szerint szmtottam.

Hivatkozsok

[1] Bhm J. Debreczeni . Faitli J. Gombkt I. Meggyes .: High-concentration hydraulic transport o tailings. In Land Contamination andReclamation, Vol.15 Num. 2; p. 195217, ISSN:0967-0513, 2007.

[2] Gombkt I. Faitli L.: Application o paste technology or tailings han-dling. In Proceedings o XXIV International Mineral Processing Congress,p. 35223529, XXIV International Mineral Processing Congress, Beijing2008, ISBN: 978-7-900249-54-8/D.1, 2008.

[3] Govier, G. W. Aziz, K.: Te ow o complex mixtures in pipes. Van

Nostrand Reinhold, 1972.[4] Durand R. Condolios E.: Deuxime Journe de lhydraulique. Soc. Hyd.de France, Grenoble. 1952.

[5] Hanks R.W.: Low Reynolds number turbulent pipeline ow o pseudohomo-geneous slurries. Hydrotransport 5, Hannover BHRA Fluid Engineering.1978.

[6] arjn I.: A mechanikai eljrstechnika alapjai. Miskolci Egyetemi Kiad.2006.

[7] arjn I. Debreczeni E.: A hidraulikus szllits s hidromechaniz-ci vizsglata s bnyszati alkalmazsa. (Examination o the hydraulictransport and hydromechanization and applications in mining) DoctoralTesis Miskolc. 1989.

[8] arjn, I. Faitli, J.: Te Measurement o the ransport Concentration oSuspension Flows by Pressure Measurements on Vertical Pipes. MineralEconomy Journal (Gospodarka Surowcani Mineralnymi) om 11 - Zeszyt

4, pp. 467478. 1995.

[9] arjn I. Faitli J.: Te Distinction o the Fine Suspension Flow rom theCoarse Mixture Flow by Measuring o the Pressure Loss on a Horizontal

Pipe. Mineral Economy Journal (Gospodarka Surowcani Mineralnymi)Volume 14 Number 3, page 6171. 1998.

[10] Wasp, E. J. Kenny, J. P. Gandhi, R. L.: Solid-liquid ow Slurry Pipelineransportation. rans. echn. Publications, Clausthal, 1977.

[11] Gombkt I.: Krnyezetbart meddzagy kezels. Bnyszati s KohszatiLapok. 2007. 140. volyam 3. szm. pp. 20-25.

[12] Faitli J.: Calculation Process or the Determination o Head Loss o Steady-state Solid Liquid Mixtures Flow in Horizontal Pipelines. PhD rtekezs,Miskolc, pp.1148. 1998.

[13] Faitli J.: Pressure Loss Calculation Model or Well-Graded Solid-Liquid PipeFlows on the Basis o Systematic Pilot Plant Investigations . Intellectual Ser-vice or Oil and Gas Industry: Analysis, Solution, Perspectives Co-Pro-ceedings o Ua State Petroleum echnical University and University oMiskolc, Ua. 2000.

[14]Mtrai Ermi salak pernyk csvezetki szlltsnak ksrleti vizsglata.Mszaki szakrti tanulmnyok. 1996. 1997. 1998.

[15]Astech pernyeminta reolgiai vizsglata.Mszaki szakrti tanulmny. 2009.

[16]rk pernyeminta zikai anyagvizsglata.Mszaki szakrti tanulmny.Miskolc. 2011.

Re.:

Faitli Jzse: Szemcss anyagok csvezetkben olyadkrammal

val szlltsnak mretezse. 1. rsz: Ksrleti berendezsek s mo-

dell.ptanyag, 63. v. 12. szm (2011), 1015. p.

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Applying master curve at the gridsstrengthened asphalt structures

KORNLALMSSY, MSC.Department of Highway and Railway Engineering [email protected], MSC.Department of Highway and Railway Engineering [email protected]: 26.08.2010. rkezett: 2010.08.26.

The master curve is an appropriate tool to describe the behavior of the different asphalt mixtures.We can analyze the attitude of the asphalt at very special time and frequency range usingmaster curve method and in this extreme condition we could not solve without it. Different shiftcoefficients calculations methods were showed in this study. According to a Dutch (Sigmoid)method, the slope of the master curve determines the fatigue characteristic of the asphaltmixture. In this article we analyze and compare the master curves of the grid strengthened andnon grid asphalt structures.Keywords: asphalt mixtures, master curve, grids, shift factor, stifness

Dr. Kornl ALMSSYgraduated in 1999 at Budapest University of

Technology and Economics, Faculty of CivilEngineering and in 2002 at Faculty of Economic

Science (Master of Business Administration -MBA). He was Chairman of the National Student

Union of Hungary (20012003), Chairman of theYouth Democratic Forum (Youth of the Hungarian

Democratic Forum) (20042006) and Vice-

Chairman of the Hungarian Democratic Forum(20042008). He was Member of the HungarianParliament (20062010). Now he is the director

of road maintenance departement of theMetropolitan Public Space Maintenance Company.

Dr. Csaba TTHgraduated in 1997 at Budapest University of

Technology and Economics and in 2008 atQuality and Production Management (Master ofBusiness Administration - MBA). He is manager

of Makadm 2000 ttervez Mrnk Iroda since2000. He is Assistant Professor at Budapest

University of Technology and Economics Department of Highway and Railway Engineering. Hismain fields of interest is the road pavement structure designing.


1. Introduction

In the last decade the era o build in mesh and grid inasphalt pavement commenced. In this period different typesand qualities o mesh were built into asphalt reconstructionsin Hungary with little technological experience and qualitycontrol. Te Department o Road and Railway Building atBudapest University o echnology and Economics started aresearch about applying grids in asphalt pavement ve yearsago. One part o the research work is dealing with a specialmethod o asphalt laboratory testing called the master curve.Te master curve is an appropriate tool to describe thebehaviour o different asphalt mixtures. Tis study is aimedto determine the master curve o a grid strengthened asphaltstructure as a special parameter. Under extreme conditions agood comparison o the behaviours o the grid strengthened andnon-strengthened asphalt structures was ound. (As we know,this was the rst time when master curves were determined orgrid/mesh strengthened asphalt specimens.)

2. Processing test results by means of master curves

a. ime-temperature similarity principle

It is commonly known that the behaviour o one o themost used construction materials the asphalt mixture greatlydepends on the load character and the test temperature.Determination o stiffness values at different temperatures

and load levels characterizes the material behaviour however,there is no simple method to evaluate the values. In Hungarythe usual processing method o stiffness values is obtainedto present them according to isotherms; however, this is lesssuitable or demonstrating the differences between mixtures.

Tus, during evaluation we also wanted to nd in which otherorms the results o the stiffness tests carried out at differenttemperatures and loads. Having reviewed the internationalliterature, it became obvious that the temperature-timesimilarity principle o rheology could be a well suited tool orstudying the behaviour o asphalt mixtures.

Te similarity o the orm o temperature modulus and time

modulus lets conclude that both temperature and time causerheological changes in the same direction; this makes bothquantities convertible into each other [1, 2].

According to this principle, as the elasticity modulus is aunction o testing time (t) and testing temperature (), a certainmodulus E (

1; t

1) determined at a temperature (

1) and a load

time (t1) can be converted to a given reerence temperature (

2 t

1) dependent on that temperature. Te basic

mathematical relation o the principle is as ollows:

where (a) is the so-called temperature-time shif coeffi cient:

indicating a shif in logarithmic time scale.

Knowing this shif coeffi cient, the common illustration andevaluation o the modulus time and modulus temperaturerelations can be established by means o so-called master curve.

With the assistance o master curve, it is possible to jointlypresent the measured isotherms, handle them together andcompare mixtures in a more complex way.

b. Te shif actor o ArrheniusTe domestic regulation is considerably succinct regarding

the master curve determination. Te standard MSZ EN 12697-26 on Asphalt Mixtures; est Methods or Hot Mix Asphalt.Part 26: Stiffness [3] describes the principle o determining themaster curve generally. Master curve at a given temperaturehas to be determined by shifing the isotherms plotted at othertemperatures strictly parallel to the axle o the load durationonly. Te determination o the value o the shif coeffi cient isnot described in the standard.

Based on data rom the literature, we chose the shif coeffi cientaccording to the relation o Arrhenius. Te Arrhenius Law

reers in its original orm to the dependence o chemicalreactions rom temperature, but it is used in the rheology todetermine the shif coeffi cient in the ollowing orm:

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wherea

= shif coeffi cient

= test temperature (K)

re = reerence temperature (K)

C = constant (K)H = activation energy (J/mol)R = universal gas constant, 8,314 J/mol K

As or the constant (C) to be used or asphalt mixtures, some datacan be ound in the international literature [4]. Francken, based onhis tests with bitumen and asphalts, proposed a value o 50 kcal/molor the activation energy, which yields a value o (10920K) or theconstant (C). Others, e.g. Lytton et al and Jacobs (1995) proposedthe values (C= 13030K) and (C= 7680K), respectively.

c. Sigmoid model

Consequently, knowing the shif coeffi cient, we have to

determine the master curve related to a given temperature, byshifing the isotherms plotted at other temperatures. However,this means determining one discrete series o points only; it isuseul, i we could describe it in orm o some unction relationto be able to analyze at a later time. Tis used to be achieved bymeans o polynomials earlier.

Related to the tested mixtures, we used the shif coeffi ciento Arrhenius when determining the master curves and tted aunction o sigmoid orm (1) onto the received point series.

(1)

where

E* = complex modulus (MPa), , , = constant parameters characterizing the

mixturered = reduced requency (Hz)

Te parameters o the unction which describes the relationbetween stiffness and load at a specic reerence temperature can be determined by the so-called simultaneous optimizationtechnique. In essence, this method simultaneously changes theshif coeffi cient and the sigmoid model parameters, while wetry to nd the unction that best ts to the measurement points.However, this search or the optimum values can be perormedrelatively simply by using the solver module o Excel.

By also treating the parameter (C) o the shif coeffi cient as avariable, the master curves determined at 20 C are shown in Fig. 1.

3. Master curve o the grid strengthened and non

grid asphalt specimens

d. esting and evaluation

o determine the master curve we use the method o the4 point bending beam test, but only still the 100 cycle, whenwe read the starting stiffness o the asphalt structure. For thetesting we used two layer asphalt specimen made by AC-11without any grid and two layer asphalt specimen also made by

AC-11 strengthened with GlasGrid 8502 asphalt grid.With the denition o the master curve we were curious or

stiffness differences o the grid reinorced and unreinorced

specimens value. We would like to know when to start workthe grid, to set orth positive impact. Fig. 1. shows the mastercurves o the specimens with and without grids. (KH meansspecimens with grids and KR means reerence specimenswithout any grids.)

Master curves at 20 C

Stiffness

0

5 000 000

10 000 000

15 000 000

20 000 000

25 000 000

30 000 000

0,1 1 10 100 1000 10000

log fred

KH1

KH2

KH3

KR1

KR2

KR3

Fig. 1. Master curves at 20 C or strengthened and normal specimens

(without grids) 1. bra A rcsersts s rcs nlkli prbatestek mestergrbi 20 C-on

(KH jel: rcs, KR jel: reerencia)

In Fig. 1. the stiffness o the asphalt structure increase at thehigher requency range or the benet o the reinorced specimen.At medium requency level the grid reinorced specimen has thesame stiffness value like the unreinorced sample.

Dissection o the master curves justied our previous testexperience wheel tracking and bending test that at thelower quality asphalt mixture get on lot better the impact othe stiffer asphalt grid.

Reerences

[1] th, S. (2000): Rheology, Rheometry.Publishing House o the Universityo Veszprm

[2] Bodor, G. Vas, L. M. (2005): Polymer Material Science. Publishing Houseo the echnical University

[3] MSZ EN 12697-26

[4] Medani, . O. Huurman, M. (2003): Constructing the Stiffness MasterCurves or Asphaltic Mixes.Report 7-01-127-3 ISSN 0169-9288. Delf Uni-versity o echnology

[5] Almssy, K. Jo, A. L.: Special materials in the road building Grids andnetts application terms or improving the pavement structures.ptanyag,2009/2, pp 55-59.

Re.:

Kornl Almssy Csaba th: Applying master curve at the gridsstrengthened asphalt structures. ptanyag, 63. v. 12. szm(2011), 1617. p.

Mester grbk alkalmazsa a rcserstsaszfaltszerkezeteknlA mester grbk nagyon pontos lerst adnak a klnbzaszfaltkeverkek tulajdonsgairl. A mestergrbk megha-trozsval olyan id s frekvencia tartomnyokban vizsgl-hatjuk az aszfaltok viselkedst, amelyet ksrletileg nem, vagycsak nagyon nehezen lehetne megoldani. A mestergrbkmeghatrozshoz szksges gynevezett eltolsi tnyezkiszmtsi mdszereit mutatjuk be a tanulmny sorn. Egyholland, gynevezett Szigmoid eljrssal meghatrozottmestergrbk meredeksge fontos informcit ad az aszfalt-keverkek tnkremeneteli karakterisztikjval kapcsolatban.A cikkben a rcserstssel, illetve anlkl kszlt aszfalt-szerkezetek mestergrbit elemezzk s hasonltjuk ssze.Kulcsszavak: aszfalt keverkek, mester grbe, rcs, eltolsitnyez, merevsg

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Durability of H-class cement andblast furnace slag-based cementitiouscomposites

MARIATERESAFUENTES-ROMERODepartamento de Ingeniera Metalrgica, ESIQIE-IPN

ENRIQUEROCHA-RANGELUniversidad Politcnica de VictoriaSEBASTIANDIAZDE LA TORRECIITEC-IPNMANUELADAZ CRUZDepartamento de Ingeniera Metalrgica, ESIQIE-IPNReceived: 04.01.2011. rkezett: 2011.01.04.

The usage of residual slag generated in the steel making process has been highlighted both as anecological and/or economical alternative for the production of innovative cement and/or specialcement composites. However, the effect of granulated blast furnace slag (GBFS) on the durabilityof cement still requires experimental research. This paper discusses the durability of H-classcement considered suitable for cementing oil wells, which was mixed with blast furnace slag andactivated with NaOH alkali. This research has been conducting in accordance to the methodsestablished under Mexican standards for assessing the technical suitability in developing analternative cementitious product. The characterization of the products thus obtained wascarried out through chemical analyses, compressive resistance and sulfate attack testing. Themicrostructure of obtained composites was also analyzed by scanning electron microscopy.Results show a limited durability of the cementitious composites, revealing a decrease in theirmechanical resistance to compression as the percentage of slag increases, as well as a poorperformance when exposed to sulfates media. As the slag percentage in H-class cement wasincreased a certain reduction on the expansion level of the composite was observed.Keywords: cementitious composites, aggregated alkali, granulated blast furnace slag, durability,resistance to sulfates

Mara Teresa FUENTES ROMEROis actually works in the external service

department of the Technology of SuperiorStudies from Monterrey, Campus Estado

de Mexico. She has gotten her bachelor inMetallurgical Engineering and Master in

Metallurgy and Materials both in the IPN.

Enrique ROCHA-RANGEL

is actually is titular professor at the PolitechniqueUniversity of Victoria in Tamaulipas Mexico.

He has gotten his bachelor and master inMetallurgical Engineering by the IPN. His doctoral

was in the field of Metallurgy and Materials inthe IPN. Also he has had Research Stay and

Postdoctoral Studies in The Toyohashi Universityof Technology, Japan and Oak Ridge National

Laboratory, USA re

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