Prospects of Portland-Limestone Cement Usage in

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uniform blend with one or more of granulated blast-furnace slag, hydrated lime and ... production by installation new kilns. 2. ..... of cement manufacturing.

University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

Prospects of Portland-Limestone Cement Usage in Structural Concrete Ass. Prof. Dr. Alaa H. Al-Zuhairi College of Eng./University of Baghdad E-mail: [email protected]

Ass. Prof. Dr. Zena K. Abbas College of Eng./University of Baghdad E-mail: [email protected]

1. Introduction Consulting Engineering Bureau (CEB) has been authorized by LafargeHolcim/Iraq to prepare this technical report according to formal request dated June 28, 2016. One of the most effective and popular ways of reducing the ecological impact of Portland cement production in terms of CO2 emissions is the blending of Portland clinker with a substantial amount of pozzolans or supplementary cementitious materials [1]. Blended cement is defined as hydraulic cement consisting essentially of an intimate and uniform blend with one or more of granulated blast-furnace slag, hydrated lime and pozzolan, produced by intergrading or blending or by combination of intergrading and blending the Portland cement clinker with other materials, ACI 116R-00[2]. The most accepted and widely used materials in the production of blended cements are Portland cement clinker, and pozzolans. Other materials such as crushed limestone, finely ground silica sand, rice husk, and cement kiln dust, etc. are also used. In addition to these materials, small amounts of chemical admixtures activators may also be used to improve performance [3]. Generally, blended cements may offer a number of potential advantages can be summarized by [3]: Page 1 of 15

University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

1. Increasing plant capacity without increase the rate of clinker production by installation new kilns. 2. Reducing fuel consumption per one ton of cement product. 3. Reducing CO2 emissions per one ton of cement product. 4. Control of alkali-silica reactivity even with high alkali content in clinker. 5. Reducing cement kiln dust due to increase in alkali content of the clinker. 6. Improvement concrete permeability when Portland-limestone cement is used. 7. Lowering risk of thermal cracking occurrence. 8. And consequently, reducing the overall concrete cost.

2. Types of Blended Cements According to ASTM C595: 2012 [4], four basic classes of blended cement may be distinguished: 1.

Type IS - Portland blast-furnace slag cement which is

produced by blending Portland cement (usually Type I or II) and up to 95% by mass of granulated (quenched) blast-furnace slag. This type of cement may be used for general concrete construction when the specific properties of other types are not required. 2.

Type IP – Portland – pozzolan cement which may be also

used for general concrete construction. Portland-pozzolan cements contain up to 40% by mass of pozzolan in the blended cement. 3.

Type IL-Portland –limestone cement that contains between

5 and 15% by mass of fine limestone and may be used for general concrete construction. Page 2 of 15

University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

4. Type IT-Portland-ternary cement which consists of Portland cement (or clinker) and two additional ingredients: either slag and pozzolan, slag and limestone, pozzolan and limestone, or two different pozzolans. Ternary blended cements have a maximum pozzolan content of 40% by mass; a maximum limestone content of 15% by mass; and maximum total content of pozzolan, limestone, and slag of 70% by mass. The ASTM C 595:2012 [4] shows physical and chemical requirements of above mentioned blended cement types. 3. Practical Aspects of Blended Cement Usage Blended cement is a structurally sound building material when described to meet specific conditions with appropriate curing times and standards. Blends will vary depending on specific uses and weather conditions and are to be used in accordance with cement industry guidelines [5]. From practical point of view, using blending cement will not change the process of cement handling concrete production. Although with relatively high percentage of additives (blends), the setting time may need to be a bit longer. Ultimately, most blended cements would have a higher strength, and better resistant to chemicals like sulfate and seawater [5]. Portland-limestone cements is one of common cement types that specified by BS EN197-1:2011 standard .The standard specifies two types containing 6-20% and 21-35% limestone fines. Portland-limestone cements, containing up to 20% limestone fines were previously specified in the United Kingdom under the standard BS 7583:1992. The updated

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University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

standard designates factory made Portland-limestone cements by CEMII /A-L (or A-LL) and CEM II /B-L (or B-LL) where, - CEM II /A-L (or A-LL) for product that contains (6-20)% limestone. - CEM II /B-L (or B-LL) for product that contains (21-35)% limestone. The suffixes (L) and (LL) indicate the total organic content. Unfortunately, in spite of producing and application of some types of Portland blended cement in construction industry, Iraqi standard no. 5 does not comprise or cover any type of these cements. This is may be attributed to long updating time interval for this standard that exceeded thirty years. However, the standard now is under updating process to be convenient for modern cement industry in Iraq. 4. Lime Stone Rocks Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of mineral calcite. It is most commonly formed in clear, warm, shallow marine waters. It is usually an organic sedimentary rock that is formed from the accumulation of shell, coral, algal and fecal debris. It can also be a chemical sedimentary rock formed by the precipitation of calcium carbonate from lake or ocean water [9]. The calcium carbonate content of limestone gives it a property that is often used in rock identification; it effervesces in contact with a cold solution of 5% hydrochloric acid. Limestone is a rock with an enormous diversity of uses. Mainly, limestone is principal partner with clay shell in any process of cement production. Page 4 of 15

University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

BS EN197-1:2011[8] specifies limestone that shall meet the following requirements: a) The calcium carbonate (CaCO3) content calculated from the calcium oxide content shall be at least 75 % by mass. b) The clay content, determined by the methylene blue test in accordance with EN 933-9, shall not exceed 1.20 g/100 g. c) The total organic carbon (TOC) content, when tested in accordance with BS EN 13639:1999, shall conform to the following criteria: - shall not exceed 0.20 % by mass for CEM II/A-LL or CEM II/B-LL - shall not exceed 0.50 % by mass for CEM II/A-L or CEM II/B-L. Huge deposits of good quality limestone are found in the western desert in Iraq [10] as shown in figure (1). This is one of the reasons that should encourage the investors of cement industry in Iraq to produce the Portland limestone cement. 5. Effect of Cement Replacement by Limestone Powder on its Performance : It has been observed that limestone filler sometime has a positive effect on strength and strength development. The phenomenon is referred to "filler effect" and may be considered the influent of the strength enhancement. The mechanisms that stand behind this effect are recently interpreted but they are mostly considered to be of a physical nature that is by filling the voids between grains of cement clinker. Goldman and Bentur1993 [11] suggested that a fine filler, with particle size smaller than 0.073 µm, even though inert, would increase the strength of

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University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

concrete. This increase may be attributed by the densification of transition zone between the paste and the aggregate becomes denser. Al-Taai, 2009 [12] observed that concrete produced from limestone-ordinary Portland cement generally shows improvement the workability properties which are particularly useful in unformed surfaces. Limestone filler is often considered as an inert material. However, it may have a chemical nature effect [13].Among other things it implies increasing the rate of reaction of the C3S. The chemical activity of limestone filler when used in cement and concrete is also sustained by some more recent studies. Bonavetti et al 2003[14] indicated an increased degree of hydration in cement pastes due to the presence of limestone filler. Tsivilis et al, 2002 [15] found an increased amount of CH and of non – evaporable water in limestone cement paste, which would imply an improved hydration of the alite. Bonavetti et al 2003[14] proposed that limestone powder substitution for cement makes perfect sense in these lower w/c concretes, saving money and energy and reducing carbon dioxide emissions. Abdul Hakeem et al 2009 [16] studied the effect of replacement cement by limestone powder (5, 10 ,15 ,20 ,25 ,30 ) % and found that the replacement of cement by limestone powder resulted in an increase of splitting tensile strength by 14% at an optimum ratio of cement replacement at 15%. Erdoğdu [21] prepared blended cements with 5, 10, 20, and 30% limestone replacement ratios, and reported that consistency water demand decreases with the increasing limestone replacement. Page 6 of 15

University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

In concrete, limestone powder has been used as filler for concrete production for many years. It has been found to increase workability and early strength, as well as to reduce the required compaction energy. The increased strength is found particularly when the powder is finer than the Portland cement particles [17]. Some researchers reported that increasing limestone contents decreased the consistency water requirement [18], [19] and [20]. For example, İnan Sezer [20] showed that consistency water demand decreases when limestone and clinker are grinded together. The mechanical properties using Portland –limestone cement (10) % replacement of cement compared to reference mix for compressive strength with percentage increases is (20, 11 and 5) % at (7, 28 and, 90) days respectively[22] as shown in figure (2). 6. Effect of External Sulfate Attack on Portland –Limestone Cement ACI 318R-14 [23] classifies the external sulfate attack by the Exposure Category S that is applies to concrete in contact with soil or water containing deleterious amounts of water soluble sulfate ions. For all other exposures, ACI 318R-14 does not give any restriction regarding the type of cement used against them. Exposure category S is subdivided into four exposure classes as presented in Table (1): (a) Exposure Class S0 is assigned for conditions where the watersoluble sulfate concentration in contact with concrete is low and injurious sulfate attack is not a concern.

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University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

(b) Exposure Classes S1, S2, and S3 are assigned for structural concrete members in direct contact with soluble sulfates in soil or water. The severity of exposure increases from Exposure Class S1 to S3 based on the more critical value of measured water-soluble sulfate concentration in soil or the concentration of dissolved sulfate in water. Seawater exposure is classified as Exposure Class S1. Table (1) Sulfate Exposure category according to ACI 318R-14 [23] Class S0 S1 S2 S3

Water-soluble sulfate (SO4 2–) Dissolved sulfate (SO4 2–) in in soil, percent by mass water, ppm 2– 2– SO4 < 0.10 SO4 < 150 2– 0.10 ≤ SO4 < 0.20 150 ≤ SO42– < 1500 or seawater 0.20 ≤ SO4 2– < 2.0 1500 ≤ SO42– < 10.000 SO4 2– > 2.0 SO42– >10,000

The requirements for concrete exposure class S0 are: 1. Maximum w/cm : N/A 2. Minimum f'c, : 17 MPa 3. According to ASTM C150, ASTM C595 and ASTM C1157: No type restriction.

That’s mean Portland –limestone cement can be used in concrete constructions except for exposure classes: S1, S2 and S3. According to EN BS 206-1:2000 the chemical attack from natural soil and ground water are presented in Table (2):

Table 2 — Limiting values for exposure classes for chemical attack from natural soil and ground water Class

Soil (SO4 2–), mg/kg total

Ground water (SO4 2–), mg/l

XA1

≥ 2 000 and ≤ 3 000c

≥ 200 and ≤ 600 Page 8 of 15

University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete XA2

>3000 and ≤ 12000

> 600 and ≤ 3000

XA3

>12000 and≤ 24000

>3000 and ≤ 6000

The Portland –limestone cement can be used in concrete construction except for exposure classes: XA2 and XA3. 7. Economic and Environmental aspects of Blended Cement Industry With the extensive use of cement in concrete, there have been some environmental concerns in terms of damage caused by the extraction of raw materials and CO2 emission during cement manufacture. This has brought pressures to reduce the cement consumption in industry. At the same time, more requirements are needed for the enhancement of concrete durability to sustain the changing environment which is apparently different from old days [9]. Cement replacement materials have been introduced as substitutes for cement in concrete. Several types of materials are in common use; some of which are by-products from other industrial processes, and hence their use may have economic advent ages. However, the main reason for their use is that they can give a variety of useful enhancements or modifications to the concrete properties [9]. As concrete still yet the most commonly used as construction material, there was need to study the effect of cement production on the environment. The major problem is concentrated in CO2 emission of cement manufacturing. Studies indicate that about (40%) of CO2 emission of cement producing is related to the burning of fossil fuels to acquire and process cement raw material to make clinker. Page 9 of 15

University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

The remain (60%) of CO2 emission may be shared by the calcination process of limestone during the formation of cement main components. Reducing CO2 emission and energy growling may be effectively treated by replacement of a part of cement clinker by animate material such as limestone powder i.e. producing Portland – limestone cement. In world, there is a general trend to increase the use of Portland – limestone cement upon the ordinary Portland cement as shown in figure (3). 8. Conclusions 1. The Portland –limestone cement can be used in structural concrete construction for concrete exposed to all exposure classes except classes S1, S2 and S3 according to ACI 318R:214 and classes XA2 and XA3 according to EN BS 206-1:2000 2. Save in energy and decrease in CO2 emission may be achieved by using blended cement rather than ordinary Portland cement. Portland –limestone cement usage in Iraq has a Feature since it represent the most economist product among the types of blended cement.

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University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

Figure (1): Mineral resources and industrial rocks in the western desert of Iraq. [11].

70

Comperssive s trength (MPa)

60 50 40

7days

30

28days

20

90days

10 0 M ref

ML10

ML20

Figure (2): Compressive strength of concrete using Portland-limestone cement [22]

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University of Baghdad Consulting Engineering Bureau

Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

Figure (3): Percentage of various EN197-1 cement types used in Europe between 1999 and 200 (Hooton et al. 2007, quoting Cembureau data.). References 1. Habert, G., Billard, C., Rossi, P., Roussel, N., “Cement production technology improvement compared to factor for objectives”. Cement and Concrete Research (2009).40, 820 – 826. 2. ACI 116R, "Cement and Concrete Terminology", (2000). 3. Tarun R, Naik “Development of manufacturing technology for lowcost, highperformance, blended cements in Wisconsin” part 1, CBU2004-15, REP-562, January, (2005). 4. ACI Education Bulletin E3-13 “Cementitious Material for concrete “developed by ACI committee E-701. 5. Berkeley Energy Commission “Blended Cement”, Technical report, Dec. 17, (2002), http:// www.ci.berkeley.ca.us/energy.

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Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

6. Abdul Hakeem H., Rana A., Zena M., "Influence of Limestone Powder as Partial Replacement of Cement on Concrete and the Effect of High Temperature on It”,Civ. Energy. Dept. / Mosul University, (2009). 7. British Standards Institution.BS 7583: 1996,"Specification for Portland limestone cement". 8. British Standards Institution. BS EN 197-1: Part 1: "Composition, specifications and conformity criteria for common cements", (2011) pp.11. 9.

Geology

Science

and

Earth

Information,

http://geology.com/rocks/limestone.shtml. 10. Iraqi Bull. Geol. Min., “Geology of Iraqi Western Desert“(2007), Special Issue, p.147. 11. Goldman A., Bentur A., "The influence of micro filler on enhancement of concrete strength" Cem. Conc. Res. 23 (1993) pp. 962972. 12. Al-Taai, S. R., “Some Properties of Blended Cement Produced from local Material", M.Sc. Thesis, University of Mustansriyah ,(December2009) p.84,. 13. Taylor, H.F.W., "Cement Chemistry" second edition, Thomas Telford publishing, (1997). pp. 459. 14. Bonavetti, V. Donza, H., Menedez, G. Cabrera, O., Irassar, E. F., "limestone filler in cement in low W/C concrete: A rational use of energy" Cem. Conc. Res.33 (2003) pp. 865 – 871.

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Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

15. Tsivilis, S., Chaniotakis, E., Kakali, G., Batis, G., "An analysis of the properties of Portland limestone cement and concrete" Cem. Conc. Comp. 24 (2002) pp. 871-378. 16. Abdul Hakeem H., Rana A., Zena M., "Influence of Limestone Powder as Partial Replacement of Cement on Concrete and the Effect of High Temperature on It”,Civ. Energy. Dept. / Mosul University, (2009). 17. Opoczky, L., "progress of the particle size distribution during the intergrinding of a clinker- limestone mixture", ZementKalk- Gips, No.2, pp. E54-57, (1993). 18. Tsivilis, S., Chaniotakis, E., Badogiannis, E., Pahoulas, G., Ilias, A., "A Study on the Parameters Affecting the Properties of Portland Limestone Cements". Cement and Concrete Composites, 21, 107-116, (1999). 19. Voglis, N., Kakali, G., Chaniotakis, E., Tsivilis, S., "PortlandLimestone Cements their Properties and Hydration Compared to Those of Other Composite Cements" Cement and Concrete Composites, 27, 191–196, (2005). 20. İnan Sezer, G.," Effects of Limestone and Clinker Properties on the Properties of Limestone Blended Cement". PhD Thesis, Ege University, Institute of Applied Sciences, İzmir, 2007, (in Turkish).all, Inc., Newjersy, (1986), pp.450- 491. 21. Erdoğdu, K., Hydration," Properties of Limestone İncorporated Cementitious Systems", PhD. Thesis, METU, Civil Engineering Department, Ankara, (2000).

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Technical Report Prospects of Portland-Limestone Cement

Usage in Structural Concrete

22. Abbas, Z.K. and Al-Obaidi, A.A ," Some Mechanical Properties of Concrete by using Manufactured Blended Cement with Grinded Local Rocks",Vol.22, No.3, (2016),pp.1-21. 23. ACI 318, "Building Code Requirements for Structural Concrete", (2014).pp. 315-324 24. MCC Research Committee, "Literature Review Portland-Limestone cement", (2013), pp.1-15.

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