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Building and Environment 42 (2007) 3060–3065

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Wet and dry cured compressive strength of concrete containing groundgranulated blast-furnace slag

Cengiz Duran Atis-�, Cahit Bilim

Engineering and Architecture Faculty, Civil Engineering Department, Cukurova University, 01330 Balcali-Adana, Turkey

Received 23 August 2005; received in revised form 13 July 2006; accepted 24 July 2006

Abstract

This paper reports a part of an ongoing laboratory investigation in which the compressive strength of ground granulated blast-furnace

slag (GGBFS) concrete studied under dry and wet curing conditions. In the study, a total of 45 concretes, including control normal

Portland cement (NPC) concrete and GGBFS concrete, were produced with three different water-cement ratios (0.3, 0.4, 0.5), three

different cement dosages (350, 400, 450 kg/m3) and four partial GGBFS replacement ratios (20%, 40%, 60%, 80%). A hyperplasticizer

was used in concrete at various quantities to provide and keep a constant workability. Twelve cubic samples produced from fresh

concrete were de-moulded after a day, then, six cubic samples were cured at 2272 1C with 65% relative humidity (RH), and the

remaining six cubic samples were cured at 2272 1C with 100%RH until the samples were used for compressive strength measurement at

28 days and three months. Three cubic samples were used for each age and curing conditions. The comparison was made on the basis of

compressive strength between GGBFS concrete and NPC concrete. GGBFS concretes were also compared within themselves. The

comparisons showed that compressive strength of GGBFS concrete cured at 65%RH was influenced more than that of NPC concrete. It

was found that the compressive strength of GGBFS concrete cured at 65%RH was, at average, 15% lower than that of GGBFS concrete

cured at 100%RH. The increase in the water-cementitious materials ratios makes the concrete more sensitive to dry curing condition.

The influence of dry curing conditions on GGBFS concrete was marked as the replacement ratio of GGBFS increased.

r 2006 Elsevier Ltd. All rights reserved.

Keywords: Concrete; Ground granulated blast-furnace slag; Curing; Compressive strength

1. Introduction

Granulated blast-furnace slag is defined as the glassygranular material formed when molten blast-furnaceslag is rapidly chilled as by immersion in water [1–3]. Fastcooling results with minimum crystallization and convertsthe molten slag into fine aggregate sized particles (smallerthan 4mm), composed of predominantly noncrystallinematerial [1].

Due to its high content of silica and alumina in anamorphous state, GGBFS shows pozzolanic behaviorsimilar to that of natural pozzolans, fly ash and silicafume [1]. Blast-furnace slags have been widely utilized asingredients in cement or concrete with potential hydrauli-

e front matter r 2006 Elsevier Ltd. All rights reserved.

ildenv.2006.07.027

ing author. Fax: +90 322 338 6126.

ess: cengiz@cukurova.edu.tr (C. Duran Atis-).

city from the point of view of effective use industrial by-products [4].Erdogan [1] reported that the use of granulated blast-

furnace slag as finely divided mineral admixture in NPCconcrete mixes was initiated in South Africa in 1953.The use of GGBFS in concrete increases the workability,

reduces bleeding of fresh concrete or mortar. It improvesstrength, reduces heat of hydration, reduces permeabilityand porosity, reduces the alkali–silica expansion [1,4–7].Regarding influence of curing conditions, Ramezanian-

pour and Malhotra [8] stated that ‘‘if the potential ofconcrete with regards to strength and durability is to befully realized, it is most essential that it be curedadequately. The curing becomes even more important ifthe concrete contains supplementary cementing materialssuch as fly ash, or ground, granulated blast-furnace slag orsilica fume, and is subjected to hot and dry environmentsimmediately after casting’’.

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Table 1

Chemical composition of cement and GGBFS (%)

Oxide SiO2 Al2O3 Fe2O3 CaO MgO SO3 K2O Na2O LOI

Cement 19.71 5.20 3.73 62.91 2.54 2.72 0.90 0.25 0.96

GGBFS 36.70 14.21 0.98 32.61 10.12 0.99 0.76 0.42 NA

Table 2

Mixed aggregate grading with standard limit [12]

Sieve size

(mm)

% Passed

TS 706

lower limit

TS 706

medium

limit

TS706 upper

limit

Mixed

aggregate

16 100 100 100 100.0

8 60 76 88 74.7

4 36 56 74 41.0

2 21 42 62 23.7

1 12 32 49 17.4

C. Duran Atis-, C. Bilim / Building and Environment 42 (2007) 3060–3065 3061

Since curing conditions influence the hydration andpozzolanic reaction, it is expected that curing conditionsinfluence the GGBFS concrete as influence the plain NPCconcrete.

Ramezanianpour and Malhotra [8] reported that drycuring at room temperature after demoulding resulted in38% drop for concrete containing 25% GGBFS, and 50%drop for concretes made with 25% fly ash, 50% GGBFS orhigh volume fly ash. They concluded that the concretesincorporating supplementary cementing materials are moresensitive to the lack of supply of moisture, and showsignificant loss of strength compared with the strengthobtained after moist curing.

Influence of curing conditions on plain concrete havebeen extensively studied and results have been established[9,10]. The aim of this research is to investigate andevaluate the influence of curing conditions for differentrelative humidity (RH) on compressive strength of GGBFSconcrete.

0.5 7 20 35 12.9

0.25 3 8 18 3.0

2. Properties of materials

2.1. Cement

The cement used was ASTM Type I normal Portlandcement (PC 42.5N/mm2) with a specific gravity of 3.16 g/cm3.Initial and final setting times of the cement were 230 hand 330 h, respectively. Its Blaine specific surface area was3250 cm2/g and its chemical composition is given in Table 1.

2.2. Ground granulated blast-furnace slag (GGBFS)

GGBFS was supplied from Iskenderun Iron–Steel Factoryin Turkey. Its chemical oxide composition is given in Table 1.The specific gravity of GGBFS was 2.81 g/cm3. The GGBFSwas ground granulated in Iskenderun Cement Factory tohave a Blaine specific surface area about 4250cm2/g.According to ASTM C 989 [11] hydraulic activity index,the GGBFS used was classified as a category 80 slag.

2.3. Aggregate and its grading

Dry and clean natural, river aggregate was used inconcrete mixture. The gravel was 16mm maximum nominalsize with 1.3% absorption value and its relative density atsaturated surface dry (SSD) condition was 2.70 g/cm3. Theabsorption value of the sand used was 1.8% and its relativedensity at SSD condition was 2.67 g/cm3.

The grading of the mixed aggregate was presented inTable 2 with the standard limit [12]. Table 2 shows theaggregate grading is suitable for concrete production.

2.4. Concrete mixture proportions

For each concrete of a cubic meter, approximateconcrete composition is given in Table 3. Mixture design

is made with according to absolute volume method givenby Turkish Standard TS802 [13]. At the beginning of themixture design, binder content (350, 400, 450 kg/m3) andwater–cement ratio (0.3, 0.4, 0.5) were chosen as constant,then, the volume of aggregate was determined for eachcontrol NPC concrete by assuming 2% air is trapped infresh concrete suggested by TS802. The volume ofaggregate was used to determine the aggregate weight.GGBFS concrete was produced by modifying NPC

concrete. The modification is made by replacing the cementwith GGBFS for a given ratio on mass basis. The increasein the paste volume due to inclusion of GGBFS wasconsidered. Then, the volume of aggregate for eachGGBFS concrete was compensated accordingly usingabsolute volume method. A carboxilic-type hyperplasticiz-ing (HP) admixture was used at various amounts tomaintain the workability of fresh concrete. The amount ofhyperplasticizer was given in Table 3.Measured unit weight of fresh concrete was in the range

of between 2350 and 2550 kg/m3, however, theoretical freshunit weight determined from mixture proportions was inthe range of between 2270 and 2500 kg/m3. Workabilityvalue of fresh concrete obtained from flow table was in theorder of 40–50 cm.Twelve cubic samples (with 150mm a side) produced

from fresh concrete were de-moulded after a day, then, sixcubic samples were cured at 2272 1C with 65%RH, and theremaining six cubic samples were cured at 2272 1C with100%RH until the samples were used for compressivestrength measurement at 28 days and three months. Threecubic samples were used for each age and curing conditions.Compressive strength measurements were carried out usingELE International ADR 3000 hydraulic press with acapacity of 3000kN, the loading rate was 0.3MPa/s.

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Table 3

Approximate concrete composition for a cubic meter

Mixture PC (kg/m3) GGBFS (kg/m3) W (lt/m3) HP (kg/m3) Aggregate (kg/m3)

CP 350-0.3-00 350 0 105 12.25 2030

GS 350-0.3-20 280 70 105 11.55 2025

GS 350-0.3-40 210 140 105 8.75 2015

GS 350-0.3-60 140 210 105 7.00 2010

GS 350-0.3-80 70 280 105 5.60 2000

CP 350-0.4-00 350 0 140 5.25 1940

GS 350-0.4-20 280 70 140 4.20 1930

GS 350-0.4-40 210 140 140 3.50 1925

GS 350-0.4-60 140 210 140 1.75 1915

GS 350-0.4-80 70 280 140 2.80 1910

CP 350-0.5-00 350 0 175 0.70 1845

GS 350-0.5-20 280 70 175 0 1840

GS 350-0.5-40 210 140 175 0 1830

GS 350-0.5-60 140 210 175 0 1825

GS 350-0.5-80 70 280 175 0 1815

CP 400-0.3-00 400 0 120 16.00 1950

GS 400-0.3-20 320 80 120 14.00 1940

GS 400-0.3-40 240 160 120 9.60 1935

GS 400-0.3-60 160 240 120 6.00 1925

GS 400-0.3-80 80 320 120 4.80 1915

CP 400-0.4-00 400 0 160 6.00 1845

GS 400-0.4-20 320 80 160 4.00 1835

GS 400-0.4-40 240 160 160 4.00 1825

GS 400-0.4-60 160 240 160 2.40 1820

GS 400-0.4-80 80 320 160 3.60 1810

CP 400-0.5-00 400 0 200 0.40 1735

GS 400-0.5-20 320 80 200 0 1730

GS 400-0.5-40 240 160 200 0 1720

GS 400-0.5-60 160 240 200 0 1710

GS 400-0.5-80 80 320 200 0 1705

CP 450-0.3-00 450 0 135 18.00 1865

GS 450-0.3-20 360 90 135 14.40 1860

GS 450-0.3-40 270 180 135 11.70 1850

GS 450-0.3-60 180 270 135 9.00 1840

GS 450-0.3-80 90 360 135 8.10 1830

CP 450-0.4-00 450 0 180 4.50 1750

GS 450-0.4-20 360 90 180 3.60 1740

GS 450-0.4-40 270 180 180 2.25 1730

GS 450-0.4-60 180 270 180 2.25 1720

GS 450-0.4-80 90 360 180 1.35 1710

CP 450-0.5-00 450 0 225 0 1630

GS 450-0.5-20 360 90 225 0 1620

GS 450-0.5-40 270 180 225 0 1610

GS 450-0.5-60 180 270 225 0 1600

GS 450-0.5-80 90 360 225 0 1590

C. Duran Atis-, C. Bilim / Building and Environment 42 (2007) 3060–30653062

3. Results and discussion

Average compressive strength of control and GGBFSconcrete at 28 days and 3 months were illustrated inTable 4 for dry and wet curing conditions separately. Thecompressive strength values at three months are given inthe parenthesis. The ratios of compressive strengthobtained from dry curing to wet curing were presented inTable 5. The relative differences between compressivestrength of dry curing and wet curing were determined andgiven in Table 5.

In general, Table 4 shows that, wet cured compressivestrength of GGBFS is higher than that of control NPCconcrete for 20% and 40% replacement ratios at 28 daysand three months. Compressive strength of GGBFS isfound to be equivalent to that of control NPC concrete for60% replacement ratio. However, compressive strength ofGGBFS is found to be satisfactory when compared tocontrol NPC concrete for 80% replacement ratio. Table 4also shows that, for dry curing conditions, compressivestrength of GGBFS concrete is found to be equivalent tothat of control NPC concrete for 20% and 40% replacement

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Table 4

Compressive strength of concrete at 28 days and three months (MPa)

Mixture Wet cured Dry cured

Name W/C 0.3 0.4 0.5 0.3 0.4 0.5

CP-350-00 75.8 (83.9) 63.9 (71.3) 53.6 (61.5) 72.4 (80.2) 63.9 (65.6) 52.3 (57.6)

GS-350-20 81.4 (86.8) 65.8 (73.7) 57.0 (65.4) 73.3 (83.8) 60.4 (68.6) 50.6 (54.1)

GS-350-40 81.0 (87.8) 67.2 (76.3) 55.9 (65.9) 72.0 (82.0) 57.6 (67.2) 46.5 (53.0)

GS-350-60 73.3 (81.2) 61.8 (74.0) 45.1 (58.3) 57.2 (62.2) 52.6 (61.0) 40.4 (42.9)

GS-350-80 62.7 (70.6) 50.4 (58.9) 29.9 (38.1) 50.2 (57.1) 42.7 (49.2) 26.9 (27.6)

CP-400-00 80.7 (85.2) 63.9 (67.9) 51.4 (56.8) 73.1 (78.1) 65.6 (67.1) 36.9 (41.4)

GS-400-20 81.4 (90.1) 66.0 (72.4) 52.6 (61.4) 69.6 (82.3) 63.1 (69.2) 37.5 (39.4)

GS-400-40 82.0 (88.3) 66.9 (77.9) 51.6 (57.9) 66.5 (79.4) 61.6 (69.9) 35.4 (37.2)

GS-400-60 77.8 (79.0) 61.1 (75.1) 40.1 (49.6) 68.2 (74.9) 59.0 (66.3) 30.5 (37.7)

GS-400-80 67.7 (76.2) 53.1 (56.8) 25.3 (31.6) 54.4 (57.5) 47.2 (51.9) 19.7 (22.1)

CP-450-00 80.3 (85.7) 64.3 (71.0) 48.7 (50.5) 75.0 (84.2) 68.2 (70.2) 41.7 (45.3)

GS-450-20 81.8 (90.1) 73.5 (82.3) 50.4 (56.2) 73.2 (85.4) 69.1 (73.6) 36.3 (38.9)

GS-450-40 83.8 (91.4) 66.4 (81.0) 49.3 (53.4) 76.4 (87.2) 61.7 (71.9) 35.1 (36.6)

GS-450-60 80.6 (92.5) 61.8 (73.4) 39.5 (49.1) 58.2 (70.0) 54.2 (61.6) 28.3 (30.2)

GS-450-80 66.3 (77.4) 46.8 (54.6) 27.7 (35.0) 56.0 (62.1) 42.6 (44.6) 17.6 (18.3)

Table 5

Compressive strength ratio (dry/wet) and relative difference between dry and wet curing ((wet–dry)/wet) for 28 days and three months

Mixture Dry/wet Relative Difference ((Wet–dry)/wet)

Name W/C 0.3 0.4 0.5 0.3 0.4 0.5

CP-350-00 0.96 (0.96) 1.00 (0.92) 0.98 (0.94) 0.04 (0.04) 0.00 (0.08) 0.02 (0.06)

GS-350-20 0.90 (0.97) 0.92 (0.93) 0.89 (0.83) 0.10 (0.03) 0.08 (0.07) 0.11 (0.17)

GS-350-40 0.89 (0.93) 0.86 (0.88) 0.83 (0.80) 0.11 (0.07) 0.14 (0.12) 0.17 (0.20)

GS-350-60 0.78 (0.77) 0.85 (0.82) 0.90 (0.74) 0.22 (0.23) 0.15 (0.18) 0.10 (0.26)

GS-350-80 0.80 (0.81) 0.85 (0.84) 0.90 (0.72) 0.20 (0.19) 0.15 (0.16) 0.10 (0.28)

CP-400-00 0.91 (0.92) 1.03 (0.99) 0.72 (0.73) 0.09 (0.08) �0.03 (0.01) 0.28 (0.27)

GS-400-20 0.86 (0.91) 0.96 (0.96) 0.71 (0.64) 0.14 (0.09) 0.04 (0.04) 0.29 (0.36)

GS-400-40 0.81 (0.90) 0.92 (0.90) 0.69 (0.64) 0.19 (0.10) 0.08 (0.10) 0.31 (0.36)

GS-400-60 0.88 (0.95) 0.97 (0.88) 0.76 (0.76) 0.12 (0.05) 0.03 (0.12) 0.24 (0.24)

GS-400-80 0.80 (0.75) 0.89 (0.91) 0.78 (0.70) 0.20 (0.25) 0.11 (0.09) 0.22 (0.30)

CP-450-00 0.93 (0.98) 1.06 (0.99) 0.86 (0.90) 0.07 (0.02) �0.06 (0.01) 0.14 (0.10)

GS-450-20 0.89 (0.95) 0.94 (0.89) 0.72 (0.69) 0.11 (0.05) 0.06 (0.11) 0.28 (0.31)

GS-450-40 0.91 (0.95) 0.93 (0.89) 0.71 (0.69) 0.09 (0.05) 0.07 (0.11) 0.29 (0.31)

GS-450-60 0.72 (0.76) 0.88 (0.84) 0.72 (0.62) 0.28 (0.24) 0.12 (0.16) 0.28 (0.38)

GS-450-80 0.84 (0.80) 0.91 (0.82) 0.64 (0.52) 0.16 (0.20) 0.09 (0.18) 0.36 (0.48)

C. Duran Atis-, C. Bilim / Building and Environment 42 (2007) 3060–3065 3063

ratio at 28 days and three months. Compressive strength ofGGBFS is found to be satisfactory when compared tocontrol NPC concrete for 60% replacement ratio. However,concrete containing 80% GGBFS developed lower strengththan that of control NPC concrete.

Furthermore, it can be seen from the table thatcompressive strength of each concrete decreases as a resultof increase in water–cementitious material ratio. It can alsobe seen from the table that compressive strength obtainedat three months were higher than that of compressivestrength obtained at 28 days for all concrete mixture.

When a closer examination made at the relativedifference column of Table 5, it can be seen that most of

the compressive strength of concrete made with 0.3 and 0.5water-binder ratios were influenced by dry curing condi-tions more than that of concrete made with 0.4 water-binder ratio. Therefore, it may be concluded that anoptimum water-binder ratio, for which the influence ofcuring conditions becomes minimum, exist for a concretemixture.This is explained in the following. A water-binder ratio,

which is higher than the optimum value, results higherporosity and larger capillary porous, thus, permitting free-water evaporate rapidly, resulting higher loss in strengthfor a concrete when compared to concrete made withoptimum water-binder ratio.

ARTICLE IN PRESSC. Duran Atis-, C. Bilim / Building and Environment 42 (2007) 3060–30653064

Water content of a concrete made with water-binderratio lower than the optimum value may become critical,because, a concrete needs certain amount of mixing waterfor hydration of its cementitious material content. There-fore, loss of water from a concrete made with low water-binder ratio results in a larger reduction in the compressivestrength of concrete when compared to concrete made withoptimum water-binder ratio.

When the difference between dry and wet curingconditions in terms of compressive strength was comparedbetween control and GGBFS concrete, in general, it can beconcluded that dry curing conditions influenced GGBFSconcrete more than that of control NPC concrete.

Most of the concrete compressive strength indicated thatthe more the GGBFS content in concrete is the more thereduction in compressive strength due to dry curingcondition (see Table 5). Furthermore, it can be observedfrom Table 5 that there is a weak evidence indicating thatthe increase in the binder content make the concrete moresensitive to dry curing conditions for both NPC andGGBFS concrete.

A statistical analysis was carried out to establish a linearrelationship between compressive strengths obtained fromdry curing and wet curing. A linear best-fit relationship wasestablished for control NPC and GGBFS concreteseparately. The relationships established were presentedin Fig. 1, which shows that there is a strong linear relationbetween compressive strengths of dry and wet curedsamples regardless whether the concrete made with orwithout GGBFS.

The comparison made between the relationship estab-lished for control and GGBFS concrete shows that, drycuring resulted in a 6% average reduction in compressivestrength for control NPC concrete, and 15% averagereduction in compressive strength for GGBFS concretecompared to wet curing compressive strength. It also showsthat GGBFS concrete was influenced more than that ofNPC concrete.

y = 0.94 x, R2 = 0.87, Control Concrete (circles)

y = 0.85 x, R2 = 0.89, GGBFS Concrete (dots)

10

20

30

40

50

60

70

80

90

20 30 40 50 60 70 80 90 100

Wet Cured-Compressive Strength (MPa)

Dry

Cur

ed-C

ompr

essi

ve S

tren

gth

(MP

a)

Fig. 1. The relation between dry and wet cured concrete compressive

strength.

It was stated in another study [14], in which the influenceof dry and wet curing on compressive strength of concretecontaining silica fume was presented, that in order tounderstand why concrete containing pozzolan was influ-enced more than that of NPC, it should be looked at thedefinition of a pozzolan. A pozzolan is defined as ‘‘asilicous or silicous and aluminous material which in itselfpossesses little or no cementitious value but which will, infinely divided form and in the presence of moisture,chemically react with calcium hydroxide at ordinarytemperature to form compounds possessing cementitiousproperties’’ [2,3]. From this definition, it is understood thata pozzolan needs a moist environment with calcium-hydroxide to show its binding property. Calcium hydroxide(portlandit) is available in the system due to chemicalreaction of C2S and C3S which are main compound ofNPC. When the available water in the medium begins toevaporate, it will prevent pozzolan to show its bindingproperty, thus, dry curing conditions would influence theconcrete made with pozzolan more than that of concretemade without pozzolan.

4. Conclusions

From the laboratory investigation, following conclusionswere made.

1.

Dry curing conditions influenced GGBFS concrete morethan that of control NPC concrete.

2.

The increase in the water-binder materials ratios makesthe concrete more sensitive to dry curing condition.

3.

The influence of dry curing conditions on GGBFSconcrete was marked as the replacement ratio ofGGBFS increased

4.

A linear relationship exists between dry and wet curingconditions for concrete made with and without GGBFS.

Acknowledgment

The authors would like to thank C- ukurova UniversityScientific Research Projects Directorate (Project number:MMF 2004 D16).

References

[1] Erdogan TY. Concrete. Ankara: Metu Press; 2003 (in Turkish).

[2] ASTM C-125. Standard terminology relating to concrete and

concrete aggregates, Annual book of ASTM Standards. 1994.

[3] ACI Committee 116, 116R-90, Cement and concrete terminology,

ACI manual of concrete practice, 1994.

[4] Sakai K, Watanabe H, Suzuki M, Hamazaki K. Properties of

granulated blast-furnace slag cement concrete, Proceedings of fourth

international conference on fly ash, silica fume, slag, and natural

pozzolans in concrete. Istanbul, Turkey: American Concrete Institute

Publication, ACI-SP132; 1992. p. 1367–383.

[5] Bijen J. Benefits of slag and fly ash. Construction and Building

Materials 1996;10(5):309–14.

ARTICLE IN PRESSC. Duran Atis-, C. Bilim / Building and Environment 42 (2007) 3060–3065 3065

[6] Park CK, Noh MH, Park TH. Rheological properties of cementitious

materials containing mineral admixtures. Cement and Concrete

Research 2005;35(5):842–9.

[7] Aldea CM, Young F, Wang K, Shah SP. Effects of curing on

properties of concrete using slag replacement. Cement and Concrete

Research 2000;30(3):465–72.

[8] Ramezanianpour AA, Malhotra VM. Effect of curing on the

compressive strength, resistance to chloride-ion penetration and

porosity of concretes incorporating slag, fly ash or silica fume.

Cement and Concrete Composites 1995;17(2):125–33.

[9] Neville AM. Properties of concrete, 4th ed. London: Longman

Group UK Limited Press; 1995.

[10] Mehta PK. Concrete: structure, properties, and materials. Englewood

Cliffs, NJ: Prentice-Hall; 1986.

[11] ASTM C-989. Standard specification for ground granulated blast

furnace slag for use in concrete and mortars, Annual book of ASTM

Standards. 1994.

[12] TSI. TS 706-Aggregate for concretes. Ankara, 1980 (in Turkish).

[13] TSI. TS802-Design of concrete mixture. Ankara, 1985, (in

Turkish).

[14] Atis CD, Ozcan F, Kilic A, Karahan O, Bilim C, Severcan

MH. Influence of dry and wet curing conditions on compressive

strength of silica fume concrete. Building and Environment

2005;40(12):1678–83.