The paper presents the results of experimental research that dealt with the substitution of finely ground blast furnace slag for Portland cement in the course of simple concrete manufacturing. Physical and mechanical properties of experimental concrete mixtures based on finely ground blast furnace slag were observed

J. Daxner

T. Dvorský

V. Dirner

V. Václavík

Directory of Open Access Journals

461 METALURGIJA 51 (2012) 4, 461-464V. VÁCLAVÍK, V.  DIRNER, T. DVORSKÝ, J. DAXNERTHE USE OF BLAST FURNACE SLAGReceived – Prispjelo: 2011-12-25Accepted – Prihvaćeno: 2012-03-25Preliminary Note – Prethodno priopćenjeISSN 0543-5846METABK 51(4) 461-464 (2012)UDC – UDK 666.88:669.162.2:691.54=111V. Václavík, V. Dirner, Institute of Environmental Engineering, T. Dvorský, Faculty of Mining and Geology, VŠB - Technical University of Ostrava, J. Daxner, D&Daxner Technology, Ltd., Ostrava, Czech RepublicThe paper presents the results of experimental research that dealt with the substitution of fi  nely ground blast fur-nace slag for Portland cement in the course of simple concrete manufacturing. Physical and mechanical properties of experimental concrete mixtures based on fi  nely ground blast furnace slag were observed. Key words: slag, blast furnace, Portland cement, concrete, physical and mechanical propertiesKorištenje troske iz visoke peći. Rad predstavlja rezultate eksperimentalnog istraživanja koja se bave mogućnostima primjene fi  nozrnate troske iz visoke peći za Portland cement u jednostavnoj proizvodnji betona. Promatrana su fi  zikalna i mehanička svojstva smjesa betona of fi  nozrnate troske iz visoke peći.Ključne riječi: troska, visoka peći, zamjena, Portland cement, beton, fi  zikalna i mehanička svojstvaINTRODUCTION It is known generally that industrial waste recycling and utilisation save fundamental raw materials and en-ergy sources and, in addition, contribute to environmen-tal protection. A wide range of uses of recycled industrial waste is provided by the construction industry, where blast fur-nace slag and steel furnace slag are utilised as substi-tutes for natural aggregate most; nevertheless, e.g. ﬁ  ne-ly ground blast furnace slag is commonly used in mixed cement production. At present, wastes from blast fur-nace and steel furnace production are, however, proc-essed as secondary raw materials to a very limited ex-tent. A large quantity of these valuable secondary raw materials are deposited outside plants and dumped. This situation is unsustainable from the ecological as well as economical point of view. Granulated blast furnace slag is one of the types of metallurgical slag. It is the case of a by-product of iron making. Major components include SiO2, Al2O3, CaO; MgO, FeO and sulphides in the form of CaS, MnS and FeS are minor components. The reac-tions of activated blast furnace slag are analogous to those of Portland cement. The use of ﬁ  nely ground granulated blast furnace slag as a substitute for cement is a standard practice from the technological, economical and ecological point of view. It improves the mechanical properties of con-crete and its resistance to weak acids and salts [1, 2]. On a worldwide scale, attention is paid to research into mixtures of ﬁ  nely ground blast furnace slag and cement [3, 4]. The substitution of granulated blast furnace slag for cement clinker usually leads to a decrease in primary strength and an increase in time of setting, which limits the use of a large portion of slag in slag Portland ce-ment. To improve the reactivity of cement components [5 - 7], ﬁ  ne grinding and mechanical activation can be applied [8, 9].For experimental research into the substitution of blast furnace slag for Portland cement, ﬁ  nely granulated blast furnace slag (MSJŠ) from the company Kotouč Štramberk, Ltd. was used. An equipment ﬂ  owsheet of a grinding plant for granulated blast furnace slag is pre-sented in Figure 1. The ﬁ  ner is the grinding of slag, the better are some properties, especially strength (primary, ﬁ  nal), workability (plasticity) and bonding. The ﬁ  nely ground slag has a larger speciﬁ  c surface area and thus a larger water reaction surface area. Moreover, contact with ﬁ  ne additives and sand and gravel surfaces im-proves as well. For slag grinding, gravity grinding mills are utilised. The principle consists in material commi-nution by fall or impact and in powdering by grinding Figure 1   Equipment fl  owsheet of a grinding plant for granulated blast furnace slag462   METALURGIJA 51 (2012) 4, 461-464V. VÁCLAVÍK, et al.: USE OF BLAST FURNACE SLAGbodies. Gravity grinding mills are divided into ball, rod and autogenous mills.MATERIALS AND METHODSBlast furnace slagFinely ground granulated blast furnace slag for ex-perimental research was taken from the company Kotouč Štramberk, Ltd. Chemical analysis was made at the Nanotechnology Centre of VŠB – Technical Univer-sity of Ostrava. On a sample of ﬁ  nely ground granulated slag (MSJŠ), the following analyses were carried out: determination of SiO2, SO3, CaO, Al2O3, MgO, Fe2O3, K2O, and others as stated in Table 1.Table 1 Results of chemical analysis of slag MSJŠUnit of measure Result of determinationCaO % 36,3MgO % 11,7SiO2 % 42,5Al2O3 % 6,8Fe2O3 % 0,18SO3 % 1,56K2O % 0,36Cl µg·g-1 156,6Sr µg·g-1 377,3Ba µg·g-1 834,7The physical and mechanical properties of ﬁ  nely ground granulated slag are given in Table 2. The slag sample MSJŠ was subjected to a raster electron micro-scopic analysis. pyramidal particles of various sizes, which is caused by slag grinding. In a micrograph at 1000 x magniﬁ  cation (see Figure 2), slag is character-ised by a high content of undisturbed.AggregateAs aggregate for concrete based on ﬁ  nely ground blast furnace slag, aggregate of coarse fraction 8/16 mm from Dolní Benešov, gravel sand of fraction 4/8 mm from Dolní Benešov, aggregate of ﬁ  ne fraction 0/4 mm from Bohumín were used. Properties of the mentioned aggregate fractions are presented in Table 3.Table 2 Physical and mechanical properties of slag MSJŠObserved property Unit  ValuesMoisture % 0,15Absorption capacity % 21,26Fineness of grinding– sieve residue- sieve 0,045 mm %- sieve 0,063 mm %- sieve 0,090 mm % 1,58Fineness - Blaine cm2·g-1 3 852Bulk density kg·m-3 1 094CementAs a fundamental binder and later as an activator for ﬁ  nely ground blast furnace slag, Portland cement CEM I 42,5 R from the locality of Hranice na Moravě was used. Observed properties of cement according to EN 197-1 [10] are stated in Table 4.Table 3 Properties of aggregate fractions Property Unit Fraction 8/16/ mmFraction 4/8/ mmFraction 0/4/ mmbulk density- bulk state- packed statekg · m-3kg · m-31 4101 6701 6101 8901 6901 720density kg · m-3 2 600 2 600 2 631wash-off   particles% by mass0,42 1,75 2,51PlasticisersAs a plasticiser for improving the workability of concrete based on Portland cement and ﬁ  nely ground blast furnace slag, a plasticiser designated “ADDI-MENT plastiﬁ  kátor BV1” was used.Table 4 Observed properties of cementObserved parameter Unit Value Required level accord. to ČSN EN 197-12 days compressive strength N·mm-2 32,1 ≥ 20,028 days compressive strength N·mm-2 54,6 ≥ 42,5≤ 62,52 days bending tensile strengthN·mm-2 6,36 -28 days bending tensile strengthN·mm-2 9,91 -Initial setting time minutes 130 ≥ 60Soundness mm 1,0 ≤ 10Specifi  c gravity g·cm-3 3,07 -Specifi  c surface cm2·g-1 4182 -Sulphate content % by mass 2,84 ≤ 4,00Loss on ignition % by mass 1,46 ≤ 5,00Insoluble residue % by mass 0,44 ≤ 5,00Chloride content % by mass 0,022 ≤ 0,100Experimetal proceduresAs far as the fundamental composition of test mix-tures is concerned, the volume ratio of ﬁ  ne aggregate (fraction 0/4 mm) to coarse aggregate (fraction 4/8 mm,  Figure 2 Micrograph of slag MSJŠ (magnifi  ed 1000x)463 METALURGIJA 51 (2012) 4, 461-464V. VÁCLAVÍK, et al.: USE OF BLAST FURNACE SLAGfraction 8/16 mm) was 40:20:20. Furthermore, the part of cement of class CEM I 42,5 R was substituted by slag MSJS in the amounts of 0, 10, 20, 30, 40, 50, 60, 80 and 100 % of cement mass. The consumption of cement of the comparative mixture was 320 kg/m3.Consistency of Concrete MixtureFigure 3 presents the values of slump of experimen-tal mixes immediately after mixing and after 30 min-utes. In this ﬁ  gure, one can see that using ﬁ  nely ground slag in rather small amounts, namely less than 20 % substitution for cement, the consistency of the concrete mixture grows. It is interesting that at 20 % substitution for cement it has been found that the consistency of the mix decreased in comparison with the mix 3 and corre-sponds to the mix 2/5. Then, at 30 % substitution of ﬁ  nely ground slag for cement, the workability of the mixture increases as well both at the determination of slump immediately after mixing and also after 30 min-utes. At further increasing the substitution of slag for cement, the consistency of the mixes decreases immedi-ately after mixing the concrete mixture as well as after 30 minutes. However, at 80 and 100 % substitution of ﬁ  nely ground slag for cement, the consistency grows rapidly immediately after mixing the concrete mixture (by minutes) as well as after 30 minutes. ulated slag for cement (60, 80, 100 %), a decrease in initial strength of experimental mixes in comparison with that of the comparative mix (mix 2/5) takes place. This phenomenon can be seen clearly in the case of mixes 8, 9, 10.From Figure 5 it is obvious that at an increased rate of substitution of ﬁ  nely ground slag for cement, the val-ues of 28-day compressive strength of concrete de-crease, namely from 43 MPa in the mix 2/5 (compara-tive mix) to 25,8 MPa in the mix 8 (per cent decrease in strength between the mix 2/5 and the mix 8 is 33,7 %) and even to 16,2 MPa (decrease by 62,4 %) in the mix 9.Nevertheless, values of 90-day strength are compara-ble with the strength of the mix 2/5 (comparative mix, 0 % of slag). The 90-day strength of the mix 5 is 44,4 MPa (in this mix we can see an increase in strength by 3,2 % in comparison with the 90-day strength of the mix 2/5).At an increase in the rate of substitution of slag for cement, a decrease in 90-day strength occurs in com-parison with the comparative mix (mix 2/5) in the mix 6 to 39,3 MPa (decrease by 8,7 %) and in the mix 7 to 39,1 MPa (decrease by 9,1 %).The higher is the rate of substitution of ﬁ  nely ground slag for cement, the higher are gains in compressive strength of concrete; they move in the range from fc,cube90 to fc,cube28. This phenomenon can be seen in the mixes 6, Determination of cube strengthFor carrying out the test, 18 pieces of cubes with a side length of 150 mm were manufactured for every mix, i.e. altogether 198 pcs of test specimens containing 0, 10, 20, 30, 40, 50, 60, 80 and 100 % of ﬁ  nely ground blast furnace slag. The determination of cube strength of all 9 mixes was carried out after 3, 7, 14, 21, 28 and 90 days.In Figure 4 there are the results of determination of cube strength at selected combinations of substitution of ﬁ  nely ground slag for cement.According to the results of measurement one can say that at higher rates of substitution of ﬁ  nely ground gran-Figure 3 Average slump values of experimental mixes Figure 4 Dependence of concrete strength on concrete ageFigure 5 Comparison of strength of concrete of individual mixes after 28 and 90 days 464   METALURGIJA 51 (2012) 4, 461-464V. VÁCLAVÍK, et al.: USE OF BLAST FURNACE SLAG7, 8 in comparison with the comparative mix. At further increasing the rate of substitution of ﬁ  nely ground slag for cement, this gain diminishes.CONCLUSIONBy research it has been proved that:•   at an increased rate of substitution for Portland ce-ment above 20 % by mass, the consistency of con-crete mixture grows;•   the strength of concrete based on ﬁ  nely ground granulated blast furnace slag in the amount of up to 60 per cent of content of Portland cement cor-responds to structural concrete; moreover, it has been found that the plastic deformation of this concrete diminishes, which has also been con-ﬁ  rmed by very brittle failure;•   the use of ﬁ  nely ground granulated blast furnace slag as a substitute for 100 per cent of cement for certain kinds of constructions (road and motorway base layers, construction of lay-bys, concrete en-casement of concrete sewage pipes, backﬁ  lling of underground workings, stabilization and solidiﬁ  -cation of soils and rocks in the course of road and dam construction, and others) is from the point of view of concrete strength very real and from the economical point of view highly effective. None-theless, this statement should be supported by fur-ther experimental research into the physical and mechanical properties of concrete based on ﬁ  nely ground blast furnace slag. REFERENCES[1]  S.E. Chidiac and D.K. Panesar, Evolution of mechanical properties of concrete containing ground granulated blast furnace slag and effects on the scaling resistance test at 28 days, Cem Concr Comp 30 (2008)2, 63-71.[2]  M. Sharfuddin Ahmed, O. Kayali and W. Anderson, Chlo-ride penetration in binary and ternary blended cement con-cretes as measured by two different rapid methods, Cem Concr Comp 30 (2008)7, 576-582.[3]  Li Dongxu, Wu Xuequan, Shen Jinlin and Wang Yujiang, The inﬂ  uence of compound admixtures on the properties of high-content slag cement, Cem Concr Res 30 (2000) (2000), 45-50.[4]  Xinghua Fu, Wenping Hou, Chunxia Yang, Dongxu Li and Xuequan Wu, Studies on portland cement with large amount of slag, Cem Concr Res 30 (2000), 645-649.[5]  Venkateswaran D, Bhat IK, Cursetji RM. Mechano-chemi-cal reactions induced by ﬁ  ne grinding of ordinary portland cement. In: Proceeding eighth NCB international seminar on cement and building materials, 18-21 Nov, New Delhi, India; 2003. p. 83-87.[6]  Kumar Sanjay, Bandopadhyay A, Rajinikanth V, Alex TC, Mishra IB, Singh KK, et al. Attrition milling for improved processing of blended cement. In: Proceeding eighth NCB international seminar on cement and building materials 18–21 Nov, New Delhi, India; 2003. p.73-79.[7]  Sanjay Kumar, A. Bandopadhyay, V. Rajinikanth, T.C. Alex and Rakesh Kumar, Improved processing of blended slag cement through mechanical activation, J Mat Sci 39 (2004), 3449-3452.[8]  V.V. Boldyrew, S.V. Polov and E.L. Goldberg, Interrela-tion between ﬁ  ne grinding and mechanical activation, Int J Min Process 44–45 (1996), 181–185.[9]  V.V. Boldyrev, Mechanical activation of solid and its appli-cation to technology, J Chim Phys 83 (1986) 11/12, 821-822.[10]  CSN EN 197-1 Cement - Part 1: Composition, speciﬁ  ca-tions and conformity criteria for common cementNote:   The responsible for English language is Radmila Jelínková, Os-trava, Czech Republic

The use of blast furnace slag

Abstract

Similar works

Full text

Available Versions

Directory of Open Access Journals