(Slag Cement) on the Drying Shrinkage of Concrete

The Effect of Ground, Granulated Blast Furnace Slag (Slag Cement) on the Drying Shrinkage of Concrete – A Critical Review of the Literature R. Doug Hooton*, Kyle Stanish**, and Jan Prusinski*** *Professor, University of Toronto, Dept. of Civil Engineering, Toronto, Ontario, Canada, M5S 1A4 (fax: 416 978 7046, [email protected]) ** Former PhD student, University of Toronto, Post-Doctoral Fellow, University of Capetown, Dept. of Civil Engineering, Private Bag, Rondebosch 7700,South Africa. (fax 011-27-21-650-3782, [email protected]) ***Executive Director, Slag Cement Association, 14090 Southwest Freeway, suite 300, Sugar Land Texas, USA, 77478, (fax: 281-340-8551, [email protected]) ACI Fellow, Doug Hooton is a Professor of Civil Engineering at the University of Toronto. He is a member of ACI Committee 233 on Slag Cement, ASTM C09.27 on Ground Slag, and Chairs the CSA subcommittee on Supplementary Cementing Materials. Kyle Stanish is a post-doctoral fellow at the University of Capetown, South Africa. He obtained his PhD from the University of Toronto. ACI Member, Jan Prusinski is Executive Director of the Slag Cement Association. He was formerly with the Portland Cement Association. He is is a member of ACI Committee 233 on Slag Cement and other ACI Committees.

Abstract This report details the results of a critical review of the literature on the effect of ground, granulated, blast-furnace slag and slag-blended cements on the drying shrinkage of concrete. Drying shrinkage values from the literature were collected, and concretes containing slag were compared to otherwise identical concretes that did not contain slag.

Overall, while

individual data may indicate a higher drying shrinkage, on average, the drying shrinkage for concretes containing slag cement was on average only 2.9% higher than concretes without slag. From examination of the data it was determined that the only parameter of the mix design that had a significant influence on the drying shrinkage was the total aggregate volume. Any increase in drying shrinkage of the slag concrete was typically reduced with increasing aggregate content. The level of slag replacement and the w/cm of the concrete mixture were not found to affect the

Presented at Eighth CANMET/ACI Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete

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relative drying shrinkage, at least over the typical range used for concrete mix designs. The relative values of the drying shrinkage was also unaffected by whether slag was added as a separate ingredient or if pre-blended slag cement was used. The aggregate content of concrete made with slag was often lower than a comparable concrete made without slag due to the slag’s lower density relative to Portland cement and when slag was used as a replacement on an equal mass basis. A correction for this makes shrinkage of slag concretes the same as for Portland cement concretes. In addition, the increase in relative shrinkage of slag-containing concretes may, in some cases, also be partially due to the reduced gypsum content of the cementitious mixture, although this is unclear and needs further investigation. Although the data is limited, the restrained shrinkage cracking of concrete containing slag appears to be less than that of concrete without slag. Cracking was delayed to later ages and resulted in smaller total crack widths. The effect of the inclusion of slag on restrained cracking needs to be further investigated. Keywords: Concrete, Slag Cement, Drying Shrinkage, Review

Background on Drying Shrinkage The amount of shrinkage strain that a concrete experiences is controlled by both its environment (ie. Temperature and relative humidity) and by the properties of the concrete. As well, the rate of shrinkage will be influenced by the size of the element, with elements of smaller cross-section drying and shrinking faster. While some general points are raised here, the ACI 209 committee report gives a more comprehensive coverage [1].


2

In concrete, drying shrinkage, in most cases, only takes place in the paste fraction and is restrained by the aggregate fraction. Therefore the amount of restraint will be related to both the volume fraction and the elastic modulus of the aggregates. As well, the stiffness or elastic modulus of the paste fraction will rise as w/cm is reduced. So for a given environment, the three primary concrete materials factors affecting drying shrinkage (and creep) are the volume of aggregate (1 - paste volume) elastic modulus of aggregate, and the w/cm of the paste. For a given paste content, the influence of different cementing materials on shrinkage will generally be small, and only in as much as they influence the development of the elastic modulus of the paste (during the drying period) and the volume of fraction of the paste. However, a cementitious binder that is deficient in gypsum will tend to have higher drying shrinkage [2]. If slag cement, when added as a separate component to a concrete mixture, does not contain gypsum then the total cementitious binder may become sufficiently deficient in gypsum to increase drying shrinkage. The degree of hydration has an influence on the drying shrinkage of a concrete in a similar manner that the aggregate has an influence. The shrinkage occurs primarily in the hydrated CSH structure. Any unhydrated cement grains will also act to restrain the shrinkage that is occurring. More shrinkage can thus be expected to occur with a more completely hydrated concrete [2]. Cement containing a larger portion of coarse particles, particularly the fraction over 75 µm, will have a larger number of particles that undergo little hydration [2]. These particles will act to provide some restraint to drying shrinkage. The fineness of the cement does not otherwise affect the amount of shrinkage [3].


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The driving force for drying shrinkage is the relative humidity of the air surrounding the concrete. In standard tests such as ASTM C 157, this is standardized at 50% relative humidity and tests are conducted at 23°C.

In most reported literature, concretes are typically kept

saturated until 7 days of age before being exposed to drying, since this is typically the maximum moisture curing that concretes in service will see.

Literature Review In the study by Hogan and Meusel [31], which was cited in the original state-of-the-art report published by ACI Committee 233 R – Ground Granulated Blast-Furnace Slag as a Cementitious Constituent in Concrete [4], slag appeared to increase drying shrinkage significantly, but on closer inspection it was found that for the 0.38 w/cm concrete control mixture had a lower unit water content and a lower cementitious content and hence lower paste fraction (by up to 7.6%, or 23L/m3) than all the slag mixtures. In the 1995 ACI C233 R document, the recommendation that the incorporation of ground slag in concrete may lead to an increase in drying shrinkage of the concrete was based solely on this single reference. Given the increased paste volume of the slag mixtures in this study, at least part of the higher drying shrinkage observed can be explained. For this reason, other references were sought for the 2003 revision on the ACI 233 document, but only a few were found at that time [32]. One of the purposes of this review was to examine a wider range of literature on drying shrinkage in order to determine whether new data needs to be generated prior to the next revision of the ACI 233 document. To examine the influence of GGBFS on the drying shrinkage of concrete, the data from sixteen studies reported in the literature was collected and summarized [5-20, 31] in Table 1. It Presented at Eighth CANMET/ACI Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete

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should be stated that, in several cases, the information was estimated from the graphs contained in the referenced papers, where tabular data was not provided. In all cases, the shrinkage of concrete containing slag cement, either as a separate admixture or in the form of blended cement, was compared to a similar concrete that did not contain slag cement. The parameter studied was the relative shrinkage value of the slag cement concrete as a ratio to the Portland cement control concrete. Data excluded: In cases (all the data from [21] and some of the data from [10]) where the reference concrete also contained silica fume (the slag cement concrete contained both slag and silica fume), the shrinkage data was not included in the summary. In some literature, mortars rather than concretes were examined [22-24], and these results are not included here. In one case, no Portland reference cement concrete was included, making determination of relative shrinkage impossible [25]. Use of ultrafine slag with Blaine fineness of 800 m2/kg [26] was also not included, even though it resulted in a reduction in shrinkage. In one reference, data presented was repeated from elsewhere (data in [26] is the same as in [5]). The concretes studied had w/cm ratios ranging from 0.60 to 0.26 and slag contents ranging from 20% to 80%. The volumetric aggregate content of the mixtures was not generally reported. However, for most of the references there was sufficient information to estimate values. Since the aggregate densities were not normally reported, the volumetric aggregate contents were estimated from the volumetric contents of the other components. This approach was taken, as the properties of the cementitious materials and water are more uniform and easier to estimate with a fair degree of confidence. A portland cement density of 3150 kg/m3, a slag density of 2900 kg/m3, a silica fume density of 2200 kg/m3, and a water density of 1000 kg/m3 were used unless other values were provided. The air content was also assumed, although it was


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provided in a few cases. The calculated volumetric aggregate contents ranged from 50% to 73%, for those references where it was possible to estimate these values. The drying time that the concretes were exposed to ranged from 10 days to 490 days. The curing time prior to drying ranged from 3 to 28 days, but was most commonly 7 days. The most common drying exposure environment was 50% relative humidity at 20 or 23oC, but relative humidities of 65% were used in a few studies. Data from 62 slag concrete mixtures taken from 16 references is compiled in Table 1. As much information as possible about experimental variables was collected: aggregate size, curing conditions, drying conditions, shrinkage specimen type and size, cementitious materials content, w/cm, % slag, % Al2O3 in the slag, and slag Blaine. Drying shrinkage values after 28, 56, 114, and 365 (or 448 days, 64 weeks) days were tabulated where available.

Results The average relative shrinkage ratios (slag cement concrete shrinkage/Portland cement concrete shrinkage) were 1.052 after 28 days (n=57), 1.030 after 56 days (n=41), 1.010 after 114 days (n=33), and 1.067 after one year (n=35) where individual data was available. When the average ratios obtained by Kleiger and Isberner [11], were added, the average relative shrinkage ratios reduced to 1.023 after 28 days (n=62), 1.029 after 56 days (n=46), 1.009 after 114 days (n=38), and 1.055 after one year (n=45). Therefore, the slag concretes on average increased drying shrinkage by 0.9 to 5.5% relative to the respective Portland cement mixtures. If a weighted average of all samples and ages is used, the value is a 2.9% higher shrinkage. However, as noted earlier, due to the lower relative density (specific gravity) of slag cement


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(approximately 2.90) relative to Portland cement (3.15), in all of this data, the slag mixtures had slightly higher paste contents. Corrections for the amount of aggregate can be made using the technique proposed by Addis, [3]. The shrinkage of the paste is related to the shrinkage of the concrete by the equation: S c = S p (1 − Va ) n

(1)

where: Sc is the shrinkage if the concrete, Sp is the shrinkage of the paste, Va is the volumetric aggregate content, and n is a constant. Values of n have been reported between 1.2 and 1.7 [3], but a value of 1.7 was used for the following example. For a 400 kg/m3 mixture with 50% slag and w/cm = 0.50, this would result in a 1.5% higher paste volume in the concrete. Using Equation 1, the shrinkage would be expected to be 2.6% higher. Therefore, effectively all of the 2.9% higher slag shrinkage could be accounted for, if values were recalculated on a constant paste volume basis. Some individual observations are made below. Effect of Slag Content: The effect of the slag content on drying shrinkage was examined. Figure 1 shows the relative drying shrinkage versus slag content for the set of data gathered here. No dependence of the relative value of drying shrinkage upon the slag content was detectable, at least between the range of 20% and 80%. This covers the range in slag content that would be expected for the usual use of slag as a mineral admixture. This is different from the trend reported by Fulton et al. [27], where the increase in shrinkage was found to depend upon the slag content, varying between approximately a 15% increase at 30% slag content to approximately a 50% increase at 70% slag content. However, it confirms the data of Ryan et al [18] as shown in Figure 2.


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Effect of Drying Time: It has been suggested by some researchers [3, 28] that the relative response to drying shrinkage of concrete containing slag cement to concrete without it is time-dependent. Concretes containing slag were said to shrink faster – leading to a much higher shrinkage at early drying times, but this ratio is reduced after longer periods of drying as the concrete without slag ‘catches up’. From all the data compiled in this study, the relative drying shrinkage as a function of drying time shows no trend for times ranging from 28 to 490 days. However, it should be noted that there are more data points at earlier ages than at later ages. This is understandable, as data was taken at multiple ages from a study, but not all studies lasted the same duration. Effect of W/CM: To investigate if the w/cm of the concrete had an effect on the relative shrinkage, Figure 3 was constructed. No trend is apparent in this data. While more spread is apparent in the region of higher w/cm, this is primarily because there is more data at these values. Effect of Gypsum Content: As shown in Table 1, the paper by Cook et al [9] (also cited in [29]) demonstrated the beneficial effect on drying shrinkage of adding gypsum to slag cements. Simply using 35% slag cement diluted the already low value from the Portland cement fraction, and resulted in much higher shrinkage. When SO3 contents in the blended mixture were raised to at least 3.0%, the shrinkage at one year became essentially the same as the Portland cement mixture. This is also reflected in the later paper by Ryan et al [18], where blends were made with 3.0% SO3 and shrinkage was generally unaffected at slag contents from 0 to 75% (see Figure 2). As suggested by Hawkins [30], optimization of gypsum likely becomes more critical with slags having Al2O3 contents above 10%. ASTM C989 allows the addition of gypsum to separately ground slag as long as the SO3 content does not exceed 4.0%.


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Restrained Drying Shrinkage In addition to the amount of free shrinkage that is developed, the amount of cracking induced by restraining drying shrinkage is also important. This is controlled not only by the amount of drying shrinkage that will occur, but by the stiffness of the concrete, its tensile strength, and the creep that it will experience in the same time frame as the drying shrinkage occurs [2]. When concrete is restrained from shrinking, strain-induced stress develops. The amount of stress developed for a given shrinkage depends upon the stiffness of the concrete, with stiffer concretes developing greater stress. When the stress that develops is greater than the tensile strength of the concrete, the concrete will crack. At the same time as the drying shrinkage is occurring and the tensile stress is developing, however, creep is acting to relieve the stresses. Thus, a stiff concrete with a low tensile strength that also experiences little creep will have the greatest tendency to crack under a restrained drying shrinkage situation. Changing the composition of the concrete in any manner influencing the stiffness, tensile strength or creep of the concrete will thus have an influence on the restrained drying shrinkage cracking that will occur. Li et al., [31] examined concretes containing slag. They compared a concrete containing 50% slag to one without, both at a w/cm of 0.39. Both of these specimens had similar free drying shrinkages. They were also tested under restrained shrinkage conditions in a ring-type specimen. This consisted of a 35 mm thick, 140 mm high concrete ring cast around the outside of a 25 mm thick steel ring with an outer diameter of 305 mm. The specimens, after initial curing, were exposed to a 40% rh, drying environment at 20°C. The onset time of the cracks was noted, and the total crack widths determined at the outside surface of the concrete ring, taking as the crack width the average of the width at one-quarter, one-half Presented at Eighth CANMET/ACI Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete

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and three-quarters of the ring height. Their results, [31] are reproduced here as Figure 4. The onset of cracking was later and the ultimate total crack width was lower for the concrete containing slag. Even with greater shrinkage for concrete containing slag (even though this was not the case in this instance), this figure indicates that there may be less cracking. To fully substantiate this claim, these tests need to be reproduced with a wider range of concretes.

Conclusions and Recommendations A review of the literature resulted in the following conclusions relevant to the drying shrinkage of concrete containing ground, granulated, blast-furnace slag (slag cement): 1.

The drying shrinkage of concrete containing slag is approximately 3% higher than a similar concrete not containing slag. When corrected to a constant paste content, this increase reduces to about 1.5%. This is true independent of the slag content and water-cement ratio of the concrete mixture over the typical range in concrete. Such a small difference is not significant.

While some references state that the relative increase in drying shrinkage of concretes containing concrete decreases with drying time, no evidence of this could be established from the overall set of data available in the literature. 2.

Part of the small increase in drying shrinkage is due to the reduced aggregate content of the concretes containing slag.

There is also a smaller increase in drying shrinkage for

concretes containing a higher aggregate content. 3.

The data related to the effect of gypsum on shrinkage is limited but indicates that optimizing gypsum contents of the entire cementitious binder will reduce drying shrinkage. The influence of optimizing gypsum needs further investigation.


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4.

There did not appear to be a difference in relative drying shrinkage between concretes made with blended cement and those made with slag added separately at the time of mixing. It would be useful to examine concretes made from the same source materials with the slag added either separately or as a pre-blended cement, and with the gypsum content either unadjusted or adjusted to the same value. Both the amount of shrinkage and the tendency to crack under restraint should be examined.

5.

The cracking due to restrained drying shrinkage of concrete containing slag is less than that for concrete without slag, at least for the one reference available. To draw a more definite conclusion, further investigation needs to be undertaken.

Acknowledgements Figures and rapport was received from the Slag Cement Association.

References 1.

ACI 209R-92, 1992, Prediction of Creep, Shrinkage, and Temperature Effects in Concrete Structures, American Concrete Institute, 47 pp.

2.

Neville, A., Properties of Concrete, 4th Edition, Longman Scientific & Technical, London, 1995.

3.

Addis, B.J. ed., Fulton’s Concrete Technology, 7th Edition, South Africa Portland Cement Institute, Midrand, South Africa, 1994.

4.

233R-95, 1995, published in ACI Manual of Concrete Practice, Part 1, 2001.

5. Brooks, J.J, Wainwright, P.J., and Boukendakji, M., “Influence of Slag Type and Replacement Level on Strength, Elasticity, Shrinkage, and Creep of Concrete,” ACI SP


11

132: Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Proceedings Fourth International Conference, Istanbul, Turkey, 1992, pp.1325- 41. 6.

Chan, Y.W., liu, C.Y., and Lu, Y.S., “Effects of Slag and Fly Ash on the Autogenous Shrinkage of High Performance concrete”, Autogenous Shrinkage of Concrete, ed. E. Tazawa, E&FN Spon, London, 1999, pp.221-228.

7.

Chern, J.-C., and Chan, Y.-W., “Deformations of Concrete Made with Blast-Furnace Slag Cement and Ordinary Portland Cement,” ACI Materials Journal, Vol. 86, No. 4, 1989,pp. 372-382.

8.

Chojnacki, B., “Partial Replacement of Portland Cement with Pelletized Slag”, Ontario Ministry of Transportation and Communications, Report IR56, 1975, 14pp.

9.

Cook, D.J., Hinczak, I., and Duggan, R., “Volume Changes in Portland-Blast Furnace Slag Cement Concrete,” ACI SP-91, Second International Conference on the Use of Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Madrid, Spain –Volume of Supplementary Papers, 1986, pp. 1-14.

10. Khatri, R.P., Sirivivatnanon, V., and Gross, W., 1995, “Effect of Different Supplementary Cementitious Materials on Mechanical Properties of High Performance Concrete,” Cement and Concrete Research, Vol. 25, No. 1, pp. 209-220. 11.

Kleiger, P. and Isberner, A.W., “Laboratory Studies of Blended Cements—Portland BlastFurnace Slag Cements”, Journal of the PCA Research and Development Laboratories, Vol. 9, No. 3, 1967, pp.2-22.

12.

Lankard, D. “Evaluation of Concretes for Bridge Deck Applications”, Lankard Materials Laboratory Inc. Columbus, Ohio, Report No. I-2930-1 to Ohio Department of Transportation, Dec. 1992.


12

13. Lankard, D., “ Factors Affecting Drying Shrinkage Strain in Concretes Intended for Use in Industrial Floors”, Lankard Materials Laboratory Inc. Columbus, Ohio, Final Report to Scioto-Darby Concrete, No. 2150-2-3, Nov. 1995. 14.

Luther, M., Personal Communication, Data from CTL Report to Holcim (US) Inc. 1999.

15.

Malhotra, V.M., “Mechanical Properties and Freezing and Thawing Durability of Concrete Incorporating A Ground Granulated Blast-Furnace Slag”, Proceedings, International Workshop on Granulated Blast-Furnace Slag in Concrete, Toronto, 1987, pp.231-274.

16.

Ozyildirim, C. and Walker, H. “Evaluation of Hydraulic Cement Concretes Containing Slag Added at the Mixer”, Virginia Highway and Transportation Research Council, Final Report, 1985.

17.

Ravindrarajah, R.S., Mercer, C.M. and Toth, J., “Moisture-Induced Volume Changes in High-Strength Concrete”, ACI SP-149, High Performance Concrete, 1995, pp.475-490.

18.

Ryan, W.G., Hinczak, I. And Cook, D.J., “Engineering Properties of Slag Concretes in Australia, Evolution Over Twenty Years”, Supplemental Paper Volume, Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Third International Conference, Trondheim, Norway, pp. 667-681.

19.

Tazawa, E., Yonekura, A., and Tanaka, S., “Drying Shrinkage and Creep of Concrete Containing Granulated Blast Furnace Slag,” ACI SP-114 Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete: Proceedings Third International Conference, Trondheim, Norway, 1989, pp. 1325-43.

20. Wannamaker, D., Evaluation of Alternative Concrete for Water Retaining Structures, M.Eng. Thesis, Department of Civil Engineering, University of Toronto, 1996.


13

21.

Haque, M.N., “Strength Development and Drying Shrinkage of High-strength Concrete,” Cement and Concrete Composites, Vol. 18, 1996, pp. 333-42.

22.

Kanna, V., Olson, R.A., and Jennings, H.M., “Effect of Shrinkage and Moisture Content on the Physical Characteristics of Blended Cement Mortars,” Cement and Concrete Research, Vol. 28, No. 10, 1998, pp. 1467-77.

23. Dubovoy, V.S., Gebler, S.H., Kleiger, P., and Whiting, D.A., “Effects of Ground Granulated Blast-Furnace Slags on Some Properties of Pastes, Mortars, and Concretes,” Blended Cements, ASTM STP 897, G. Frohnsdorff, Ed., American Society for Testing and Materials, Philadelphia, 1986, pp. 29-48. 24.

Nagataki, S. and Wu, C., “A Study of the Properties of Portland Cement Incorporating Silica Fume and Blast Furnace Slag,” ACI SP-153: Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Proceedings Fifth International Conference, Milwaukee, Wisconsin, USA, 1995, pp. 1051-68.

25.

Sakai, K. Wannabe, H., Suzuki, M., and Hamazaki, K., “Properties of Granulated BlastFurnace Slag Cement Concrete”, ACI SP 132: Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete, Proceedings Fourth International Conference, Istanbul, Turkey, 1992, pp.1367- 1383.

26.

Brooks, J.J., “How Admixtures Affect Shrinkage and Creep”, Concrete International, Vol. 21, No. 4, April 1999, pp.35-38.

26. Jianyong, L., and Yan, Y., “A Study on Creep and Drying Shrinkage of High Performance Concrete,” Cement and Concrete Research, Vol. 31, 2001, pp. 1203-6.


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27.

Fulton, F.S., Van Aardt, J.H.P., and Visser, S., 1974, The Properties of Portland Cements Containing Milled Granulated Blastfurnace Slag, The Portland Cement Institute, Johannesburg, South Africa.

28.

Alexander, M.G., “Deformation Properties of Blended Cement Concretes Containing Blastfurnace Slag and Condensed Silica Fume,” Advances in Cement Research, Vol. 6, No. 22, 1994, pp. 73-81.

29.

Brooks, J.J. and Neville, A., Creep and Shrinkage of Concrete as Affected by Admixtures and Cement Replacement Materials”, ACI SP 135:Proceedings, Creep and Shrinkage of Concrete: Effect of Materials and Environment , 1992, pp.19-36.

30.

Hawkins, P., “Experience with Slag, a) Slow cooled Slag Addition to Kiln System, b) Gound Granulated Blast-furnace Slag as a Mineral Admixture”, Proceedings, Symposium on Slag, Bulk Materials International, Atlantic City, May 2000, 5pp.

30.

Li, Z., Qi, M., Li, Z, and Ma, B., “Crack Width of High-Performance Concrete due to Restrained Shrinkage,” Journal of Materials in Civil Engineering, Vol. 11, No. 3, 1999, pp. 214-23.

31.

Hogan, F.J., and Meusel, J.W., 1981, “Evaluation for Durability and Strength Development of a Ground Granulated Blast Furnace Slag,” Cement, Concrete and Aggregates, Vol. 3, No.1, pp. 40-52.

32.

Slag Cement in Concrete and Mortar: ACI Report 233R-03, 2003, published in ACI Manual of Concrete Practice, Part 1, 2004.


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List of Tables Table 1. Summary of Slag Relative Shrinkage Data from Literature

List of Figures: Figure 1. Effect of Slag Cement Replacement Level on Relative Shrinkage (data from Table 2) Figure 2. Effect of Slag Content on Relative Shrinkage at Various Ages (after [18]) Figure 3. Effect of w/cm on relative drying shrinkage Figure 4. Drying Shrinkage Crack Widths as a Function of Drying Time – With and Without Slag [30].


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Table 1. Summary of Slag Relative Shrinkage Data from Literature Ref.

Ozyildirum & Walker, 1985 [16] Ozyildirum & Walker, 1985 [16] Lankard, 1995 [13] Ryan et al, 1989 [18]

Malhotra, 1987 [15] Malhotra, 1987 [15] Malhotra, 1987 [15] Cooke et al, 1986 [9]

Type

w/cm

[cm] kg/m3

Concrete

0.45

377

Concrete

0.48

349

Concrete 20 mm Agg. Concrete

0.50 0.50

327 297

0.58

340

Concrete 20 mm Agg. Concrete 20 mm Agg. Concrete 20 mm Agg. Concrete 20mm gravel

0.45

200, 253, 334 200, 253, 334 200, 253, 334 340

0.55

0.70

0.59

% slag

50 40 50 65 40 40 35 45 60 75 25 50 75 25 50 75 25 50 75 35-1.6% 35-2.5% 35-3.0% 35-3.8%

Slag Al2O3 (%)

Drying Conditions Age (d)

Temp {°C)

rh (%)

Time (d)

-

28

23

50

365

-

28

23

50

365

-

7

23

1418% (typ.)

7

28

50

8.8

7

23

50

8.8

7

23

8.8

7

23

50

224

14.1

7

28

50

91


50

50

365

365

224

224

17

Relative Shrinkage to PC Control 28d 56d 114d 365d

Comments / Specimens

75 x 75 x 300 mm prisms

0.62

-

0.64

0.71

1.00 1.03 0.97 0.83 1.23

0.86 0.97

0.92 1.00 1.11 0.94 1.02


0.76 0.59 0.62 0.83 0.66 0.53 0.76 0.69 0.59 1.51 1.27 1.14 1.14

1.20 1.11 0.93 1.31 0.93 0.77 0.64 1.01 0.82 0.76 0.96 0.86 0.72 -

1.08 1.08 1.19 0.95 1.10 (90d) 0.81 0.71 0.79 0.81 0.82 0.97 0.87 1.01 0.95 1.28 1.13 1.03 0.97

0.96 0.95 0.98 0.91 -

75 x 75 x 300 mm prisms %SO3 of slag controlled at 3.0% 76 x 102 x 390 mm prisms Slag Blaine 600 76 x 102 x 390 mm prisms Slag Blaine 600 76 x 102 x 390 mm prisms Slag Blaine 600 75x75x285mm prisms SO3 contents noted Cement SO3=2.3%

75x 75 x 300 mm prisms


Type/ (Vpaste )

w/cm

Concrete

0.42

312

Concrete

0.62

312

Concrete 25mm limestone

0.51

378

Lankard 1992 [12]

Concrete 20mm

-

-

~20 Type IS Blended ~20 Type IS Blended 4.5 36 68 Blended 40

Ravindrarajah et al 1995 [17] Chojnacki, 1975 [8]

Concrete

0.30 0.30 0.48 0.38

500 500 307 414

35% Blended 25% 25%

0.32

550

0 40 60 0 40 60 0 40 60

Klieger & Isberner, 1967 [11] Klieger & Isberner, 1967 [11] Chern & Chan, 1989 [7]

[cm] kg/m

% slag

3

Chan et al, 1999 [6]

Concrete 20 mm limestone Concrete (0.44)


Concrete (0.41)

0.32

520


Concrete (0.38)

0.32

493

Slag Al2O3 (%) ~12

Drying Conditions Age Temp rh (%) Time (d) (d) {°C) 28 23 50 365

Relative Shrinkage 28d 56d 114d 365d

~12

28

23

50

365

13.8

7

23

50

365

1.17 1.13 1.08

-

-

0.981.03 (5) 1.001.04 (5) 1.13 1.26 1.32

28

23

50

56

0.60

0.82

-

-

3 460 3 3

20 20 23 23

65 65 50 50

465 500 84 84

1.26 1.02 0.89

1.04 0.88

1.04 0.60 -

1.04 -

14.0

7

23

50

28

14.0

7

23

50

28

14.0

7

23

50

28

1.30 1.15 1.38 1.15 1.37 1.37

-

-

-

11.3


18

0.81.0 (5) -

0.91.05 (5) -

0.971.04 (5) -

Comments / Specimens 150 x 300 mm cylinders

75x75x300mm prisms

150 x 300 mm cylinders Blended cements 75 x 75 x 300 mm prisms

75 x 75 x 300 mm prisms 75 x 75 x 300 mm prisms Slag Blaine = 427 100 x 300 cylinders max. agg (gravel) Slag Blaine = 427 100 x 300 cylinders max. agg (gravel) Slag Blaine = 427 100 x 300 cylinders max. agg (gravel)


Luther, 1999 [14]

Khatri et al, 1995 [10] Brooks et al, 1992 [5] Brooks et al, 1992 [5] Brooks et al, 1992 [6] Brooks et al, 1992 [5] Hogan and Meusel, 1981 [3] Hogan and Meusel, 1981 [3] Tazawa et al 1989 [18]

Type

w/cm

[cm] kg/m3

% slag


0.45 0.45

293 293

0.45 0.35

293 diff PC 420

19 23 blended 34 blended 65 Blended

0.43

437

0.43

437

0.43

437

Concrete 20mm gravel Concrete 10 mm quartzite Concrete 10 mm quartzite Concrete 10 mm quartzite Concrete 10 mm quartzite Concrete 20mm gravel Concrete 20mm gravel Concrete 20mm Agg.

30 50 70 30 50 70 50

Slag Al2O3 (%) -

Drying Conditions Age Temp rh (%) Time (d) (d) {°C) 231 50 23 7 231 50 23 7

437

50

0.55

430 430 449 288

0.51

370

40 50 65 40 50 65 35 55


23

50

231

0.76

0.71

0.65

13.4

7

23

50

365

1.26

1.34

-

1.36

75x75x285mm prisms

10.8

14

20

65

70

14

20

65

70

12.9

14

20

65

70

1.25 1.09 1.21 1.16 1.16 1.13 1.12

-

1.07 0.96 1.02 1.01 1.00 0.98 0.91

75 x 265 mm cylinders

12.9

1.37 1.18 1.34 1.26 1.29 1.23 1.30

15.2

14

20

65

70

1.31 1.13

1.16 1.08

-

0.98 1.02

10.2

7

23

50

448

10.2

7

23

50

448

1.16 1.24 1.22 1.07 1.41 1.39 1.14

1.20 1.16 1.14 1.48 1.48 1.36

14.4

7

~23

~50

300

1.26 1.23 1.21 0.92 1.46 1.38 1.03 0.95 0.74

0.99 1.19 1.19 1.20 1.52 1.57 1.59 0.79 0.80 (300d)

70 0.38

Comments / Specimens

7

70 0.43

Relative Shrinkage 28d 56d 114d 365d/ 448d 0.97 0.97 0.88 1.08 1.00 0.97


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75 x 265 mm cylinders 75 x 265 mm cylinders 75 x 265 mm cylinders Slag Blaine 550 Control cm = 425kg/m3 Slag Blaine 550

Slag Blaine 441 100x100x400mm prisms


Wannamak er, 1996 [19]

Type


w/cm

0.38

[cm] kg/m3

% slag

25

Slag Al2O3 (%)

Age (d) 7

Drying Conditions Temp rh (%) Time (d) {°C) 23 50 182


20

Relative Shrinkage 56d 114d 365d/ 448d 0.79 0.79 0.93 28d

Comments / Specimens 75x75x300mm prisms

2.5

Relative Strain

2.0 1.5 1.03 1.0 0.5 0.0 0.2

0.25

0.3

0.35

0.4

0.45

0.5

0.55

0.6

w/cm

Figure 1. The effect of Slag Cement Replacement Level on Relative Shrinkage (data from Table 2)

Figure 2. Effect of Slag Content on Relative Shrinkage at Various Ages (after [18])


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2.5

Relative Strain

2.0

1.5 1.03 1.0

0.5

0.0 10

30

50

70

90

Slag Content [%]

Figure 3. Effect of w/cm on relative drying shrinkage

0.8 0.7 Crack Width (mm)

0 % Slag

0.6 0.5 0.4 0.3

50 % Slag

0.2 0.1 0 0

20

40 Age (day)

60

80

Figure 4. Drying Shrinkage Crack Widths as a Function of Drying Time – With and Without Slag [31]. Presented at Eighth CANMET/ACI Eighth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete

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