The effect of particle size distribution on the properties of blended cements incorporating GGBFS and natural pozzolan (NP)

Powder Technology 177 (2007) 140 – 147 www.elsevier.com/locate/powtec

The effect of particle size distribution on the properties of blended cements incorporating GGBFS and natural pozzolan (NP) Hanifi Binici a,⁎, Orhan Aksogan b , Ismail H. Cagatay b , Mustafa Tokyay c , Engin Emsen b a

K.S. University, Faculty of Engineering, Department of Civil Engineering, Avsar Campus, Kahramanmaras, Turkey Cukurova University, Faculty of Engineering and Architecture, Department of Civil Engineering, Adana, Turkey c Middle East Technical University, Department of Civil Engineering, Ankara, Turkey

b

Received 22 August 2006; received in revised form 1 February 2007; accepted 12 March 2007 Available online 23 March 2007

Abstract This paper investigates the effect of particle size distribution on the properties of blended cements incorporating ground granulated blastfurnace slag (GGBFS) and natural pozzolan (NP). Pure Portland cement (PPC), NP and GGBFS were used to obtain blended cements that contain 10, 20, 30% additives. The cements were produced by intergrinding and separate grinding and then blending. Each group had two different Blaine fineness of 280 m2/g and 480 m2/g. According to the particle size distribution (PSD) curves, 46% of the coarser specimens and 69% of the finer specimens passed through the 20 μm sieve. It was observed that the separately ground specimens were relatively finer than the interground ones and had higher compressive strength and sulfate resistance. The separately ground coarser specimens had the lowest heat of hydration. The separately ground finer specimens, which had the highest compressive strength and sulfate resistance, had the highest percent passing for each sieve size. For these specimens 34, 69, 81 and 99% passed through 5, 20, 30 and 55 μm sieves, respectively. For the interground specimens, which had the same fineness, the respective values for the same sieves were 32, 68, 75 and 94%. © 2007 Elsevier B.V. All rights reserved. Keywords: Blended cement; Compressive strength; Natural pozzolan; GGBFS; Particle Size Distribution (PSD)

1. Introduction The grindability and compressive strength of cements have been the main subjects of discussion in many international publications. All natural and artificial materials that can contribute to the quality of cement are called additives [1]. In blended cement production, mineral additives can be introduced into the cement either by separate grinding or intergrinding. These two methods of grinding may lead to blended cements with different characteristics. It has been shown that separately ground and interground GBFS-incorporated cements have different particle size distributions [2]. This result is due to the fact that harder GBFS slag particles have an additional abrasive effect on clinker particles during intergrinding [3]. ⁎ Corresponding author. Tel.: +90 344 2191278; fax: +90 344 2191052. E-mail addresses: [email protected] (H. Binici), [email protected] (O. Aksogan), [email protected] (I.H. Cagatay), [email protected] (M. Tokyay), [email protected] (E. Emsen). 0032-5910/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.powtec.2007.03.033

Many cement characteristics are directly affected by the fineness. Generally, fineness increases the early compressive strength of cement and this cement with a narrow size distribution shows a higher strength than that with a wide one. It was shown that intergrinding requires less energy than separate grinding, especially for the production of high-fineness products [4]. Hosten and Avsar [5] have claimed that the grindability of the mixtures of trass and clinker is not simply the weighted average of the grindabilities of clinker and trass. This information depicts that in blended cement production, by intergrinding, some interactions occur between the particles of different ingredients. Therefore it can be stated that interground and separately ground blended cements will have different particle size distributions. This renders particle size distribution a relevant factor in cement quality. Turkey is rich in natural pozzolans. The scoria used in this study which is also called as basaltic pumice in Turkish cement industry is one of them. Almost 155,000 km2 of the country is covered by Tertiary and Quaternary-age volcanic rocks.

H. Binici et al. / Powder Technology 177 (2007) 140–147

Although there are many geological investigations on these volcanic rocks, their potential as natural pozzolans is not yet completely well established [6]. The natural pozzolan (basaltic pumice) cone deposits are of Quaternary age and are located in the Cukurova region (Southern Turkey), and there are reserves estimated to be approximately 1.000 million tons. There are two cement plants in the neighborhood of the large basaltic pumice reserve mentioned above. The use of this material in the production of the cement will reduce the total cost due to ease of grindability and low cost of transportation. Also, many dams have been constructed in Turkey and the heat of hydration and sulfate resistance is one of the major problems in mass concrete. The use of basaltic pumice in the production of cement may lead to reduction in the heat of hydration and high sulfate resistance. Considering the importance of this material for Turkey, due to its abundant reserves and the need for low heat of hydration in the nearby constructions, it is worthwhile to investigate on the subject. The current study was aimed to investigate the effect of particle size distribution on the compressive strength and sulfate resistance of blended cement mortars incorporating pure Portland cement (PPC), GGBFS and natural pozzolan (NP). Furthermore, the heat of hydration of blended cements and PPC were investigated. 2. Materials and methods The natural pozzolan used in this study, which is widely known as scoria, contains glass shards, mineral phases such as feldspar, quartz and biotite and some amount of volcanic rock. Clay minerals occur as alteration products in it. The high porosity of the natural pozzolan is an advantage for easy and economical crushing [7]. It has dark brown/blackish color, porous structure and low crystal water. Its hardness is about 5.2 in Mohs scale. The clinker used was obtained from Adana Cement Plant. GGBFS was provided by the Iskenderun Cement Grinding Plant. The proportions of the constituents of all cements prepared are given in Table 1. The chemical, mineralogical and physical characteristics of the materials used are given in Table 2. In this study, the blended cements were prepared using one type of clinker, gypsum (4% by weight of clinker), NP and GGBFS. 10, 20 and 30% mineral admixtures were incorporated in the blends. Cement mortars were prepared using the PPC and two types of grinding methods (intergrinding and separate grinding) and two Blaine values (280 ± 3 m2/kg and 480 ± 3 m2/ kg). Grinding process was carried out in a two-compartment laboratory type ball mill of 25 kg raw mix capacity. The materials were crushed to 16 mm maximum size by a jaw crusher before feeding into the mill. 3. Experimental study 3.1. Particle size distribution Different methods have been used to describe the particle size distribution of powders of various types and sizes up to now [8–12]. In this study, a laser diffractometer was used to

141

obtain the particle-size distribution (PSD) of the cements and PPC specimens interground and separately ground to 280 m2/kg and 480 m2/kg. Blaine values were determined according to the ASTM C 204 [13]. The particle size distributions are given in Figs. 1, 2, 3, 4, and 5. 3.2. PSD and fineness modulus To evaluate the relationship range with the nature of blended cement powder, the following modulus called “Fineness Modulus (FM)” can be used: FM ¼

300 X

cumulative passing percentage =100

i¼1

where i shows the selected sieve sizes (i = 300, 250, 200, 150, 100, 75, 45, 30, 20, 12, 5 and 1 μ). 3.3. Compressive strength Compressive strength tests were conducted to evaluate the effects of the particle size distribution, the fineness of the materials and the grinding method. The specimens were prepared in accordance with EN-196-1 [14] and the tests were carried out using a 20,000 kN capacity automatic compression machine according to EN-196-1. The compressive strengths of 3, 7, 28, 90 and 180 days were determined for the blended cements and PPC. 3.4. Sulfate resistance The sulfate resistance of the cements was determined up to 24 months and the effect of sodium sulfate solution on the Table 1 Cement specimens obtained by intergrinding and separate grinding Specimens

System of additions

Blaine values (m2/kg)

A1 A2 B1 separate grinding

Clinker + 4% gypsum + 0% additions Clinker + 4% gypsum + 0% additions Clinker + 4% gypsum + 5% GGBFS + 5% NP Clinker + 4% gypsum + 10% GGBFS + 10% NP Clinker + 4% gypsum + 15% GGBFS + 15% NP Clinker + 4% gypsum + 5% GGBFS + 5% NP Clinker + 4% gypsum + 10% GGBFS + 10% NP Clinker + 4% gypsum + 15% GGBFS + 15% NP Clinker + 4% gypsum + 5% GGBFS + 5% NP Clinker + 4% gypsum + 10% GGBFS + 10% NP Clinker + 4% gypsum + 15% GGBFS + 15% NP Clinker + 4% gypsum + 5% GGBFS + 5% NP Clinker + 4% gypsum + 10% GGBFS + 10% NP Clinker + 4% gypsum + 15% GGBFS + 15% NP

280 480 280

B2 separate grinding B3 separate grinding C1 separate grinding C2 separate grinding C3 separate grinding D1 intergrinding D2 intergrinding D3 intergrinding E1 intergrinding E2 intergrinding E3 intergrinding

280 280 480 480 480 280 280 280 480 480 480

142

H. Binici et al. / Powder Technology 177 (2007) 140–147

Table 2 Chemical, mineralogical and physical characteristics of materials used Specimens

Oxides (%) SiO2

Al2O3

Fe2O3

CaO

MgO

SO3

LOI (loss on ignition)

A 1 = A2 NP GGBFS

19.4 51.8 41.6

5.5 22.1 13.7

3.9 7.3 7.3

63.4 6.2 28.2

1.8 8.3 4.9

2.0 – 1.8

– 0.4 0.01

Specimens

Cement modulus HM

SM

AM

LM

C3S

C2S

C3A

C4AF

2.1

2.0

1.4

99.7

66.5

5.6

8.1

11.9

A 1 = A2 Materials

Bouge component

Physical properties of materials Sieve analysis (%)

NP GGBFS Clinker

Specific gravity (kg/m3)

Blaine values (m2/g)

Residue on 90 μm

Residue on 200 μm

2970 2890 3190

280 and 480 280 and 480 280 and 480

0.2 0.3 0.3

0.06 0.09 0.09

TS 12142 standard requirements for NP and GGBFS [14] SiO2 + Al2O3 + Fe2O3 N61  HM : Hydraulic Modulus ¼

AM : Aluminate Modulus ¼

SO3 b3.5

LOI b10

CaO SiO2 ; SM : Silicate Modulus ¼ SiO2 þ Al2 O3 þ Fe2 O3 Al2 O3 þ Fe2 O3

Al2 O3 100:CaO ; LM : Lime Modulus ¼ 2:8SiO2 þ 1:1Al2 O3 þ 0:7Fe2 O3 Fe2 O3

compressive strength was determined at 6, 12, and 24 months ages. Mortars were cured in lime-saturated water for 28 days prior to testing. The pH of the Na2SO4 solution was monitored daily to keep it in the range of 11–12 and every month the solution was replaced by a fresh one throughout the whole storage period. The concentration of the sodium sulfate solutions was 5%. 3.5. Heat of hydration measurements The heat of hydration was monitored at a constant temperature of 25 °C using a Tonical Isothermal Conduction



Calorimeter. 4.2 g cement and 2.1 g water were used. The measurements were made over 100 h. 4. Results and discussion 4.1. Compressive strength The compressive strength is usually the main property that is related with the cement quality. The compressive strength test results of the mechanical tests are shown in Table 3. The compressive strength after 180 days, generally, increases with an increase in the percentage of the additives. For separately

Fig. 1. PSD curves for A.

H. Binici et al. / Powder Technology 177 (2007) 140–147

143

Fig. 2. PSD curves for B.

Fig. 3. PSD curves for C.

Fig. 4. PSD curves for D.

ground specimens with 480 m2/kg Blaine values, the compressive strength is higher than that of PPC. However, for specimens with 280 m2/kg Blaine values, this is true only for specimens with 10% mineral admixtures. In the case of separate grinding the blended cements with 480 m2/kg Blaine values containing 20% additives showed the highest strength development after the age of 90 days. The compressive strength of all the blended

cements was found to be higher than the minimum value stated by EN TS 12142 [15]. From Table 3, it can be seen that the average compressive strength of the separately ground blended cement specimens at 28 days was higher by about 8% than that of the interground ones. The strength of the mortars improves with an increase in the Blaine values of the cement. For example, for specimen C2 it is

144

H. Binici et al. / Powder Technology 177 (2007) 140–147

Fig. 5. PSD curves for E.

18% higher than that of specimen B2 for the same additive amount (20%).

fineness modules of finer specimens are about 13% higher than those of the coarser ones.

4.2. The relationship between fineness modulus and compressive strength

4.3. Sulfate resistance

The fineness modulus can be used as an index for cement characterization. The comparison of different cements can give valuable information to designers both in the determination of the fresh properties and in the prediction of the mechanical performance. The fineness modulus of cements showed similar trends with compressive strength (See Fig. 6). Hence, using blended cements with higher fineness modulus will end up with mortar having higher compressive strength. It can be observed from Table 4 that there is no significant relation between the grinding type and fineness modulus. However, the Blaine values seem to have a close relationship with the fineness modulus. The

Table 3 Compressive strength of PPC and blended cement specimens (MPa) Specimens

Days 3

7

28

90

180

A1 A2 B1 B2 B3 C1 C2 C3 Average compressive strength of separately ground blended cement specimens D1 D2 D3 E1 E2 E3 Average compressive strength of interground blended cement specimens

25.8 40.4 29.0 25.3 23.4 38.9 34.8 30.1 30.25

35.4 51.5 36.0 34.7 25.9 49.8 43.7 38.4 38.08

48.9 59.2 47.6 47.5 39.7 60.8 56.6 52.9 50.85

54.8 62.7 55.4 51.3 47.6 64.6 63.8 62.3 57.5

56.3 63.5 58.5 57.2 51.6 67.5 69.1 66.3 61.7

24.2 22.4 20.8 38.5 33.9 28.9 28.11

33.3 29.7 23.1 47.6 41.7 34.5 34.98

46.7 41.7 33.5 59.6 51.6 47.8 46.81

54.3 50.8 42.6 62.7 60.8 56.9 54.68

57.5 56.4 48.7 65.8 64.8 60.6 58.96

The results of the sulfate resistance tests carried out on the blended cement and PPC specimens are shown in Table 5. The blended cements perform better in sulfate environment than the control Portland cements. As the amount of mineral admixture used increases the reduction in strength due to sulfate action decreases. Other researchers have reported similar observations mentioning that both natural and artificial additives could contribute to the enhancement of the chemical resistance of concrete [16]. The first two authors of this paper investigated the effects of the type of grinding and Blaine values on the sulfate resistance of basaltic pumice and GBFS as an ingredient in cement production [17]. In that study, it was observed, that separate grinding of basaltic pumice and GBFS resulted in better sulfate resistance than interground ones. Specific surface area is an important property causing interground specimens to have longer dormant periods (the period in which sulfates have no important effect) than their separately ground counterparts. It is observed from Table 5 that there is a relationship between sulfate resistance of the mortars and the grinding process. The sulfate resistance of the separately ground blended cement specimen at 24 months was higher by about 7.7% than that of the interground ones. The relative compressive strength of the PPC decreased rapidly. The specimens were completely damaged at about 24 months, while all blended cement mortars preserved their integrity till then. Blended cement C exhibited greater sulfate resistance than any of the other specimens (see Table 5). 4.4. The effect of the grinding method and admixture dosage on the cumulative heat of hydration The pozzolan-incorporated mortars usually have decreased heat of hydration when compared with Portland cement during the first few hours of the test. However, between 5 and 12 h of the test, the reactions of the cement are strongly exothermic, which makes the ascending slope of the curves very steep. After

H. Binici et al. / Powder Technology 177 (2007) 140–147

145

Fig. 6. The relation between compressive strength and fineness modulus.

48 h the temperature begins to stabilize and the heat given off is of little significance [18]. The results of the heat of hydration of, PPC and blended cement specimens are given in Table 6. Table 6 and Figs. 1, 2, 3, 4, and 5 show that a higher amount of mineral admixtures, a better fineness and a narrower particle size distribution, result in, a decrease in the cumulative heat of hydration of cement as expected. The separately ground blended cements release less heat of hydration than the interground ones and PPC. This may be attributed to the abrasive effect of GBFS during grinding. Intergrinding results in finer clinker portion which leads to higher early heat evolution. Among the separately ground specimens, group B had the lowest heat of hydration. 4.5. The relation of particle size distribution to compressive strength, sulfate resistance and heat of hydration Products of intergrinding and separately grinding do not have the same particle size distributions at the same Blaine Table 4 Fineness modules of cements Specimens no.

Fineness Module (FM)

Blaine value type of Average Fineness Module (AFM)

Grinding type of Average Fineness Module (AFM)

A1 A2 B1 B2 B3 Average C1 C2 C3 Average D1 D2 D3 Average E1 E2 E3 Average

8.15 9.32 8.30 8.29 7.94 8.17 9.37 9.35 9.34 9.35 8.11 8.18 8.07 8.12 9.36 9.21 9.31 9.29

8.15 9.32

8.15 9.32

8.14 8.76

9.32

8.14 8.70

9.32

values. This means that during intergrinding, different ingredients do not show the same behaviour as in the case of separate grinding. Therefore, it was understood that during intergrinding some interactions occur between the particles of different ingredients of blended cements as mentioned by Erdogdu et al. [19]. It was found out that the interactions between the ingredients in intergrinding is much stronger for coarser particle size ranges since the difference between the particle size distributions of the products of different grinding types is higher at those levels. GBFS is harder than clinker and therefore more difficult to grind. Thus, when clinker and GBFS are interground, the finer portion of the blended cement is mostly ground clinker whereas the coarser portion is mostly GGBFS. This can be attributed not only to the action of the grinding media in the mill but also to the abrasive effect of harder GBFS particles on clinker particles. On the other hand, a mineral admixture which is softer than clinker would result in an opposite interaction. That is, the mineral admixture will be more in the finer portion and clinker will remain relatively coarse, for a given fineness, thus, improving the durability of the mortar. In the separately ground blended cements, with an increase in the amount of material above a specific size, the compressive Table 5 Sulfate resistance of PPC and blended cement specimens (MPa) Specimens no.

For 28 days in pure water

For 6 months

For 12 months

For 24 months

A1 A2 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3

48.9 59.2 47.6 47.5 39.7 60.9 56.5 52.8 46.5 41.7 33.5 59.6 51.6 46.9

49.6 60.1 48.1 49.7 40.6 62.2 59.8 58.4 47.5 48.6 36.7 61.4 53.4 54.1

25.8 30.4 36.7 38.6 38.8 48.4 50.1 49.3 34.6 36.9 31.4 46.8 48.4 48.2

Dispersed Dispersed 23.4 23.8 25.2 35.3 36.8 33.3 22.2 23.8 21.8 32.3 33.5 32.8

146

H. Binici et al. / Powder Technology 177 (2007) 140–147

Table 6 The heat of hydration of PPC and blended cement specimens (J/g) Specimens no.

Time (h) 1.15

4.09

8.41

12.20

24.5

72.9

100

A1 A2 B1 B2 B3 C1 C2 C3 D1 D2 D3 E1 E2 E3

19.7 19.3 15.4 13.7 10.1 16.9 17.1 14.1 13.1 11.7 10.4 17.3 15.7 14.4

18.4 32.6 20.8 16.4 12.8 25.2 25 19.7 16.4 14.9 12.2 24.8 22.6 20.9

40.2 93.2 53.8 46.3 30.1 70.2 74.5 54.2 38.7 35.4 23.1 46.9 64 57.6

73.4 156.9 89.5 82.3 53.9 126.7 121.5 99.7 69.4 64.9 42.4 121 113.9 97.1

160.4 255.9 160.4 157 120.6 212.5 195.4 170.8 145.7 138.1 112.4 210.7 191.3 164.6

233.6 345.3 215.9 207.8 175.6 373.7 260.8 219.8 214.6 210 187.8 276.5 270.7 236.5

245.1 373.4 221.6 204.6 170.8 289 276.8 240.6 218.4 209.7 194.6 289.6 280.5 237.1

strength and sulfate resistance increase, expressed as a percentage of the values of the interground blended cements (see Tables 3 and 5). From these tables, it is observed that the higher compressive strength and sulfate resistance obtained from separately ground cements are consequences of the finer particle size distributions. These results support those of Beixing et al. [20]. At the same Blaine values, separately ground blended cements are finer than interground blended cements. This means that particle size distribution difference between the products of intergrinding and separate grinding decreases when the size considered gets smaller. This is attributed to fewer interactions among the ingredients of interground cements at small particle sizes. Thus, it can be claimed that the interactions among the ingredients of separately ground blended cements take place mostly among larger particle sizes. For checking the quality in the cement industry, the fineness is easily determined by means of the residues on standard sieves such as 75 μm and 45 μm. It is generally agreed that cement particles larger than 45 μm are difficult to hydrate and those larger than 75 μm hardly hydrate completely [21]. It is observed from Figs. 1, 2, 3, 4, and 5 that, the amount of particles passing the sieves below 45 μm of the separately ground blended cement was more than that of the interground ones by about 3.5%. The particle size distribution curves in Fig. 4 indicate that the interground blended cement specimen D is the coarsest of the five cements studied. However, from Fig. 1, it is observed that PPC (A1) specimen contains more of the particles above 75 μm than the other ones. Compared to the separately ground blended cements, the interground ones had lower frequency percentages (see Figs. 2–5). The higher strength and better sulfate resistance of the separately ground blended cements at all the tested ages, compared to the interground ones of the same composition, may be explained by the particle size distribution of these cements. In contrast, in previous studies the authors indicated that, intergrinding provides more homogeneous products, which as they claimed, may be the reason for the higher strengths of the interground cements [4,19,22]. This contradiction may be due

to the different grindability characteristics of the different materials. It was observed that specimen C gave slightly better results compared to others. For the same grinding method and mineral admixture content, the heat of hydration of the finer specimens are higher than those of the coarser ones and for the same fineness and grinding method, increasing the mineral admixture content results in reduced heat of hydration. Separately ground blended cement had lower heat of hydration than the interground ones and PPC (see Table 6). 5. Conclusions The following conclusions are drawn based on the test results of this study: 1. The separately ground specimens were relatively finer than the interground ones and had higher compressive strength and sulfate resistance. The separately ground finer specimens, which had the highest compressive strength and sulfate resistance, had the highest percent passing for every sieve size. For these specimens 34, 69, 81 and 99% passed through 5, 20, 30 and 55 μm sieves, respectively. For the interground specimens, which had the same Blaine fineness, the respective values for the same sieves were 32, 68, 75 and 94%. 2. Specimens C and E had similar particle size distribution curves. However, the frequency percentage of group C was 1.11 times greater than that of group E. The reason for this difference may be explained by the different grindability characteristics of the materials used. 3. Compared to the separately ground blended cements; the interground ones had lower frequency percentages. 4. A higher addition dosage, a better fineness and a narrower particle size distribution, as well as, the grinding process, caused a decrease in the cumulative heat of hydration of the cements. During the 100 h of the measurement, the separately ground blended cements released less heat of hydration than the interground ones and PPC. Furthermore, separately ground specimens, especially specimens of group B, had the lowest heat of hydration. The above conclusions depicting improvements in the compressive strength, the sulfate resistance, the particle size distribution and the heat of hydration of blended cements render the southern Turkey natural pozzolan (basaltic pumice) a suitable material for blended cement production. Acknowledgement The authors wish to acknowledge the valuable assistance given by the Iskenderun Cement Factory. References [1] A. Barahma, Compared influences of the physical and chemical properties of the Portland cement, Cement and Concrete Technology in the 2000 s, September 6–10-2000 Istanbul, Turkey, vol. 1, 2000, pp. 393–402.

H. Binici et al. / Powder Technology 177 (2007) 140–147 [2] G. Blunk, J. Brand, H. Kollo, U. Ludwing, Effect of particle size distribution of granulated blast furnace slag and clinker on the properties of blast furnace cements, Zement Kalk Gips (English Version) 2 (1989) 41–44. [3] L. Opoczky, Problems relating to grinding technology and quality when grinding composite cements, Zement Kalk Gips (English version) 5 (1993) 141–144. [4] S. Tsivilis, G. Kakali, T. Alamanou, A comparative study of intergrinding and separate grinding of cement raw mix, Zement Kalk Gips 4 (1991) 74–78. [5] C. Hosten, C. Avsar, Grindability of mixtures of clinker and trass, Cem. Concr. Res. 28 (1998) 1519–1524. [6] H. Kaplan, H. Binici, Trass and trass cement, Cem. World 1 (1996) 23–30 (in Turkish). [7] G. Kelling, S. Kapur, N. Sakarya, E. Akca, C. Karaman, B. Sakarya, et al., Basaltic Tephra: potential new resource for ceramic industry, Br. Ceram. Trans. 99 (2000) 129–136. [8] S. Lee, H. Kim, E. Sakai, M. Daimon, The effect of particle size distribution of fly–ash–cement system on the fluidity of cement pastes, Cem. Concr. Res. 33 (2003) 763–768. [9] P. Rosin, E. Rammler, Regularities in the distribution of cement particles, J. Inst. Fuel 7 (1993) 29–33. [10] K. Djamarani, I. Clark, Characterization of particle size based on fine and coarse fractions, Powder Technol. 93 (1997) 101–108. [11] F.T. Olorunsogo, Particle size distribution of GBFS and blending characteristics of slag cement mortars, Cem. Concr. Res. 28 (6) (1998) 907–919.

147

[12] S. Grzeszczyk, G. Lipowski, Effect of content and particle size distribution of high calcium fly ash on the rheological properties of cement pastes, Cem. Concr. Res. 27 (6) (1997) 907–916. [13] ASTM C 204, Standard Test Method for Finenesses of Hydraulic Cement by Air Permeability Apparatus, 1996. [14] EN 196-1, European Standards, 1997. [15] EN TS 12142, Cement-composite, Turkish Standard, Turkey 1997. (in Turkish). [16] M.A. Tasdemir, A. Ozbek, E. Altay, Blaine specific surface area effect of GBFS on—the properties and microstructure of concrete, World Cem. 14 (2000) (2000) 19–36 (in Turkish). [17] H. Binici, O. Aksogan, Sulfate resistance of plain and blended cement, Cem. Concr. Compos. 28 (2006) 39–46. [18] M.I. Sanchez de Rojas, J. Rivera, M. Firas, Influence of the microsilica state on pozzolanic reaction rate, Cem. Concr. Res. 29 (1999) 945–949. [19] K. Erdogdu, M. Tokyay, P. Türker, Comparison of intergrinding and separate grinding for the production of natural pozzolan and GBFSincorporated blended cements, Cem. Concr. Res. 29 (1999) 743–746. [20] L. Beixing, L. Wenguan, H. Zhen, Composite Portland cement with a larger amount of industrial wastes, Cem. Concr. Res. 32 (2002) 1341–1344. [21] P.K. Mehta, Concrete, Structure, Properties and Materials, Prentice-Hall, New Jersey, 1986. [22] N. Bouzoubaa, M.H. Zhang, A. Bilodeau, V.M. Malhotra, Laboratoryproduced high volume fly ash blended cements; physical properties and compressive strength of materials, Cem. Concr. Res. 28 (1998) 1555–1569.