Center for By-Products Utilization CONCRETE WITH PAPER INDUSTRY FIBROUS RESIDUALS: MIXTURE PROPORTIONING By Yoon-moon Chun and Tarun R. Naik Report No. CBU-2003-28 REP-522 February 2005 Accepted for publication in ACI Materials Journal (Manuscript No.: 2004089). Department of Civil Engineering and Mechanics College of Engineering and Applied Science THE UNIVERSITY OF WISCONSIN – MILWAUKEE

1

Concrete with Paper Industry Fibrous Residuals: 1

Mixture Proportioning 2

by Yoon-moon Chun and Tarun R. Naik 3

4

UWM Center for By-Products Utilization 5

Department of Civil Engineering and Mechanics 6

College of Engineering and Applied Science 7

University of Wisconsin - Milwaukee 8

P.O. Box 784 9

Milwaukee, WI 53201-0784 10

(Shipping Address: 3200 North Cramer Street 11

Milwaukee, WI 53211) 12

13

Yoon-moon Chun is a postdoctoral fellow at the University of Wisconsin-Milwaukee - Center 14

for By-Products Utilization (UWM-CBU). His has conducted research on the use of coal fly ash, 15

coal bottom ash, and used foundry sand in concrete and masonry units, and the use of fibrous 16

residuals from pulp and paper mills in concrete. He has also been involved with research on 17

self-consolidating concrete and the use of shrinkage reducing admixtures in concrete. 18

19

Tarun R. Naik, FACI, is a Professor of Structural Engineering at the UWM and Director of the 20

UWM-CBU. He is a member of ACI’s Board Advisory Committee on Sustainable 21

Development; and ACI Committees 123, Research and Current Developments; 214, Evaluation 22

of Results of Tests Used to Determine the Strength of Concrete; and 232, Fly Ash and Natural 23

2

Pozzolans in Concrete. He was also Chair of the ASCE Technical Committee on Emerging 1

Materials (1995-2000). 2

3

ABSTRACT 4

A total of seven sources of fibrous residuals generated from pulp and paper mills were 5

characterized and included in the concrete. The inclusion of the residuals increased the water 6

demand, and decreased the density and compressive strength of the concrete. The inclusion of 7

high-range water-reducing admixture (HRWRA) did the opposite. The strength of the concrete 8

was proportional to the density of concrete with various combinations of residuals and HRWRA. 9

By keeping constant the combined volume of mixing water, residual, and HRWRA, concrete 10

mixtures containing up to 0.65% fibrous residuals (by mass of concrete) were produced equal in 11

slump, density, and strength to a reference concrete made without the residuals. HRWRA was 12

used in proportion to the amount of wood cellulose fibers. Later, the mixture proportions thus 13

established formed the basis for producing equivalent-strength concrete mixtures for the 14

comparison of the durability of concrete made with or without the fibrous residuals. 15

16

Keywords: compressive strength; concrete; factorial design; fiber reinforcement; mixture 17

proportioning; recycling; pulp-and-paper-mill wastewater-treatment residuals; wood cellulose 18

fibers. 19

20

3

INTRODUCTION 1

Pulp and paper mill wastewater treatment plant residuals (also called sludge) are the solid 2

residue removed from mill wastewater before the water is discharged into the environment or 3

reused in the mills. Residuals are removed via a two-step process of treating the wastewater1-5. 4

5

A primary residual is the solid removed from the primary clarifier. Primary clarification is 6

usually carried out by sedimentation and sometimes by dissolved air flotation. In the 7

sedimentation process, chemical additives are used to make non-settleable solids settleable 8

through flocculation. A primary residual consists mainly of wood cellulose fibers, papermaking 9

fillers (kaolinitic clay, calcium carbonate, and/or titanium dioxide), and water. In some cases, 10

ash generated by the mill and inert solids rejected during chemical recovery processes become 11

part of the primary residual. The water clarified by the primary treatment is passed on to the 12

secondary treatment. 13

14

The secondary treatment is usually a biological process in which micro-organisms convert 15

soluble organic matter to carbon dioxide and water while consuming oxygen. A secondary 16

residual is mainly microbial biomass (also called biosolids) grown during this process and 17

removed through clarification. Many times primary and secondary residuals are combined to 18

facilitate handling. In most cases, before the residuals are being used or disposed of, the excess 19

water contained in the residuals is removed by dewatering. 20

21

In 1995, the U.S. pulp and paper industry generated about 5.3 million metric tons (on oven-dry 22

basis) of mill wastewater treatment residuals, which is equivalent to about 15 million metric tons 23

4

of dewatered moist residuals. About half of this was disposed in landfills/lagoons, a quarter was 1

burned, one-eighth was applied on farmland/forest, one-sixteenth was reused/recycled in mills, 2

and the final one-sixteenth was used in other ways6. Due to the increasing cost of landfilling, 3

increasingly stringent environmental regulations, and potential long-term environmental 4

liabilities, the percentage of the residuals disposed in landfills has decreased considerably over 5

the past several decades2, 3, 6. However, a significant amount of residuals still need to be diverted 6

from landfilling. 7

8

Numerous projects have been conducted on the use of cellulose fibers as reinforcement in 9

pressed cement and/or mortar sheets. Cellulose fiber reinforced cement-based sheet composites 10

showed considerably higher flexural toughness than plain cement-based sheets7, 8. The use of 11

cellulose fibers reduced the extent of shrinkage cracking of mortar9 and improved the resistance 12

of cement-based composites to cycles of freezing and thawing10. Concrete containing processed 13

virgin cellulose fibers showed higher resistance to plastic-shrinkage cracking11 and drying-14

shrinkage cracking12 compared with control concrete without fibers. 15

16

Concrete is weak in tension (3 to 9 MPa). Wood cellulose fiber is strong in tension (300 to 900 17

MPa)13. Therefore, the use of wood cellulose fibers in concrete can improve the properties of 18

concrete. Pulp and paper mill fibrous residuals could become an economical source of wood 19

fibers for microfiber reinforcement of concrete. To the pulp and paper industry, the use of the 20

residuals in concrete could become an economical alternative to landfilling, burning, or other use 21

options. 22

23

5

Very few investigations have been conducted on the use of fibrous residuals from pulp and paper 1

mills in concrete. In an early laboratory investigation, some concrete mixtures containing 2

fibrous residuals showed higher compressive and splitting-tensile strengths than the control 3

concrete made without the residuals14. (The maximum size of the coarse aggregate used in the 4

concrete mixtures was 9.5 mm.) Overall, a strong correlation was observed between the density 5

and the strength of concrete containing the residuals. In another research project15 (which 6

involved concrete mixtures containing coarse aggregate with a maximum size of 19 mm), the 28-7

day compressive, splitting-tensile, and flexural strengths of most of the concrete mixtures 8

containing the residuals were in the ranges of 51 to 67%, 66 to 73%, and 44 to 63% of the 9

corresponding strengths of the control concrete made without the residuals. One of the concrete 10

mixtures containing the fibrous residuals showed virtually zero strength even at 28 days. 11

Initially, it was suspected that there might have been certain papermaking chemicals present in 12

the fibrous residuals, which might have hindered the strength development of concrete. But an 13

analysis conducted later16, 17 of the concrete mixture proportions and the strength test results 14

showed that the significantly lower strength was due to the use of excessive quantities of 15

HRWRA in the concrete mixtures containing the residuals, and the consequent delay in the 16

setting, hardening, and strength development of the concrete. 17

18

Subsequently, an extensive three-year research project16, 17 was conducted on the use of fibrous 19

residuals in concrete. Through a series of preliminary mixture proportioning and testing, 20

concrete mixture proportions were established for each of the various sources of fibrous 21

residuals used in the project, for producing a residual-containing concrete mixture that was 22

equivalent in slump and compressive strength to a reference concrete made without the residuals. 23

6

This manuscript reports the approaches used to achieve this, and the test results from the initial 1

stage of the project. 2

3

In the main stage of the project, by using the mixture proportions thus established in the initial 4

stage, concrete mixtures were produced for the evaluation of the time of setting and the 5

durability of concrete incorporating the fibrous residuals. The test results and the findings from 6

the main stage of the project are available elsewhere16, 17. 7

RESEARCH SIGNIFICANCE 8

Currently, most of the fibrous residuals generated from pulp and paper mills in the U.S. are 9

disposed of in landfills or burned, incurring increasingly higher disposal cost and potential long-10

term environmental liabilities to pulp and paper mills. This research was conducted to 11

characterize various sources of fibrous residuals from pulp and paper mills, to investigate the 12

influence of the residuals on the strength of concrete, and to develop mixture proportions for 13

concrete containing the residuals. This research demonstrated the potential of the use of the 14

fibrous residuals as an economical source of cellulose fibers for microfiber reinforcement of 15

concrete. 16

MATERIALS 17

Cement, fine and coarse aggregates, and chemical admixtures 18

Type I portland cement used in this research had 340 m2/kg fineness by air permeability test, 19

3.13 specific gravity, and 1.7% loss on ignition. Oxides composition of the cement showed 20

21.9% SiO2, 4.9% Al2O3, 3.0% Fe2O3, 64.1% CaO, 2.4% MgO, 0% TiO2, 0.5% K2O, 0.1% 21

Na2O, and 1.4% SO3. The cement met the requirements of ASTM C 150. 22

7

1

Fine aggregate (sand) used in this research had 1800 kg/m3 bulk density, 2.73 specific gravity, 2

1.3% absorption, and 2.88 fineness modulus. Crushed stone with a 19-mm maximum size was 3

used as coarse aggregate in this research. The coarse aggregate had 1570 kg/m3 bulk density, 4

2.67 specific gravity, and 0.4% absorption. The sand and the coarse aggregate met the 5

requirements of ASTM C 33. 6

7

The HRWRA used in this research was a carboxylated polyether liquid admixture meeting the 8

requirements of ASTM C 494 for Type F (HRWRA). The addition rate of this HRWRA 9

recommended by its manufacturer ranged from 0.195 to 0.650 L/100 kg of cement, or 0.7 to 2.3 10

L for 360 kg of cement. The HRWRA was composed of 2-propenoic acid homopolymer 11

reaction product with polyalkoxyalkylamine (Chemical Abstracts Service Registry No. 179733-12

16-5) (35% by mass) and water (65%). 13

Fibrous Residuals 14

A total of seven sources of pulp and paper mill fibrous residuals were used representing a wide 15

variation in the type of wood fibers and processes. The types, physical properties, loss on 16

ignition (LOI), and wood fiber contents of the residuals are presented in Table 1. The mineral 17

composition and main elements of the residuals are presented in Tables 2 and 3, respectively. 18

The concentration of cadmium in pulp and paper mill wastewater treatment residuals is well 19

below the most restrictive concentrations specified for land applied municipal sewage treatment 20

biosolids18. Scanning electron micrographs (SEM) of oven-dry samples of Residuals C1, C2, I, 21

S, WG, and WV are shown in Fig. 1. 22

8

Deflocculation (or “Repulping”) of Residuals 1

Due to dewatering, as-received moist residuals contained fibrous clumps that consisted of wood 2

fibers, clay (in Residuals C1, C2, I, S, & WV), and other particulates (in Residuals C2, I, S, WG, 3

& WV). These clumps may be considered as weaker spots in concrete compared with well-4

dispersed individual fibers and particles. Also, in order for the fibers to function as fibers in 5

concrete, they must be separated into well-dispersed individual fibers before they can be used to 6

strengthen concrete. 7

8

Therefore, all seven sources of residuals were deflocculated, or “repulped”, into separated wood 9

cellulose fibers and particulates before they were introduced into concrete mixtures. The 10

“pulper” used for this purpose in the concrete laboratory at the University of Wisconsin-11

Milwaukee consisted of a 19-liter plastic bucket and a high-speed mixer with a spinning rotor 12

positioned above the bottom of the bucket. Mechanical repulping was performed by immersing 13

a source of residual in room-temperature water in the bucket and subjecting the mixture of water 14

and fibrous residual to a high-speed rotation by the rotor blades for no less than 20 minutes. 15

Residuals C1, C2, WG, and BR deflocculated readily upon mechanical repulping. However, it 16

took a higher mixing speed and a longer mixing time to deflocculate Residuals I, S, and WV. 17

The reason for this was attributed to a relatively high degree dewatering of I, S, and WV 18

residuals at the time they were generated at mill wastewater treatment plants. Later, it was 19

shown that the properties of concrete improved in proportion to the ease of repulping the 20

residuals into individual fibers and particles19. 21

9

CONCRETE MIXING AND SPECIMEN PREPARATION 1

Mixing was done in accordance with ASTM C 192 using a revolving-drum tilting mixer. First, 2

coarse aggregate and some of the mixing water (or a mixture of water and “repulped” residuals) 3

were added into the mixer. Then the mixer was started and, after it turned a few revolutions, it 4

was stopped. Next, sand was added, and the mixer was started and stopped again after it turned 5

a few more revolutions. Finally, cement, the rest of the mixing water (or the mixture of water 6

and residuals), and HRWRA were added. 7

8

After all of the ingredients were in the mixer, the fresh concrete was mixed for three minutes 9

followed by a 3-minute rest, followed by additional two minutes of final mixing. When 10

necessary, either water or HRWRA was incrementally added during the mixing process to 11

modify the concrete mixture to achieve the desired slump. 12

13

The properties of freshly mixed concrete were determined, and test specimens were cast for the 14

evaluation of strength of concrete. Specimens were demolded 24 ± 8 hours after casting, and 15

stored in lime-saturated water at 23 ± 2°C until the time of the test. 16

MIXTURE PROPORTIONS, TEST RESULTS, AND DISCUSSIONS 17

Compressive strength as influenced by fibrous-residuals and HRWRA 18

contents (Modeling of compressive strength) 19

The influence of fibrous-residuals and HRWRA contents on compressive strength of concrete 20

was evaluated by using the two-level factorial design of experiments20. Test setup for the 21

experiments is presented in Table 4. Residuals C1, C2, WG, and WV were used for the 22

10

experiments. Mixture proportions and fresh properties of concrete are given in Tables 5 and 6. 1

As-received residuals content in concrete was approximately in the ranges of 0.27 to 0.80% for 2

C1, 0.22 to 0.68% for C2, 0.25 to 0.75% for WG, and 0.15 to 0.46% for WV concrete mixtures 3

by mass. 4

5

For a given combination of residuals and HRWRA contents, the amount of mixing water was 6

adjusted to achieve a target slump of 75 ± 25 mm. The variation in the amount of mixing water 7

affected the water-cement ratio (w/c), density, and, ultimately, compressive strength of concrete. 8

For most mixtures, the actual slump was in the range of 70 to 140 mm. Overall, the average 9

value of the actual slump was about 100 mm. For each concrete mixture, compressive strength 10

was determined at 3, 7, and 28 days by testing two 100 × 200 mm cylinders at each test age. The 11

results are presented in Tables 7 and 8. 12

13

All the mixtures, except for Mixture WG-4, showed similar patterns of strength development 14

over age. Mixture WG-4 showed a lower strength and a lower rate of strength gain compared 15

with Mixtures C1-4, C2-4, and WV-4. Although w/c of WG-4 was lower and density of WG-4 16

was higher when compared with WG-1 and WG-2 (Table 6), the compressive strength of WG-4 17

was lower than that of WG-1 at the ages of 3, 7, and 28 days, and became lower than that of 18

WG-2 at 28 days (Table 8). The reason for this is not yet understood. Other similar concrete 19

mixtures that were produced later in the project, using Residual WG and HRWRA, did not show 20

the erratic behavior of Mixture WG-4. 21

22

11

The 28-day compressive strength of concrete is shown in perspective in Fig. 2 to present the 1

influence of residuals and HRWRA contents on compressive strength. In addition, empirical 2

models were built for the description/prediction of w/c, air content, density, and the 28-day 3

compressive strength of concrete. Averages and coefficients for the models are shown in Table 4

9. The values of the average and three coefficients for each model were determined by 5

multiplying the 1 × 4 matrix of response (w/c, air content, density, or the 28-day strength in 6

Table 5, 6, 7, or 8 corresponding to the test setup, Table 4), by the 4 × 4 matrix shown in Table 7

1020. 8

9

Overall, due to the increase in water demand for maintaining the actual slump at about 100 mm, 10

the addition of pulp and paper mill fibrous residuals in concrete resulted in an increase in w/c, a 11

negligible increase in air content, a decrease in fresh concrete density, and a decrease in 12

compressive strength. The addition of HRWRA resulted in decreases in w/c and air content and 13

increases in fresh concrete density and compressive strength. It then follows that with proper 14

combination of residuals and HRWRA contents, the strength of residual-containing concrete 15

mixtures can be made equivalent to that of a reference concrete containing no residuals. The 16

models also showed that the strength of concrete containing the residuals is proportional to the 17

density of concrete and inversely proportional to the w/c of concrete. 18

Equivalent strength of concrete containing Residual C1, C2, WG, or WV 19

A series of concrete mixtures containing C1, C2, WG, and WV residuals were made at as-20

received residuals contents of 0.35 and 0.65% by mass of concrete. A Reference concrete (Ref. 21

1) without residuals was also made for comparison. The objective was to produce concrete 22

mixtures comparable in slump and compressive strength regardless of residuals contents. To 23

12

achieve this objective, the amount of mixing water in concrete containing the fibrous residual 1

was reduced by the combined volume of residual and HRWRA that was added to concrete. As 2

planned, this led to: (1) a constant combined volume of mixing water, fibrous residual, and 3

HRWRA; (2) a constant combined volume of cement, sand, and coarse aggregate; (3) almost 4

uniform density of concrete; and, ultimately, (4) almost uniform strength of concrete. The 5

amount of HRWRA increased in an approximate proportion to the amount of wood cellulose 6

fibers in concrete in order to achieve a target slump of 75 ± 25 mm. At a later stage in the 7

project, it was shown that approximately 0.5 L of the HRWRA used in this research needs to be 8

added for 1 kg (oven-dry basis) of wood cellulose fibers (contributed by fibrous residuals) added 9

in concrete. Therefore, the amount of HRWRA required (in L) could have been predicted as: 10

5.0100

×

+ MCFCR (1)

where: 11

R = amount of as-received residual, kg; 12

FC = fiber content of residual, % of oven-dry mass of residual; and, 13

MC = moisture content of residual, % of oven-dry mass of residual. 14

15

To accommodate the addition of residual and HRWRA, the amount of mixing water was reduced 16

by the following amount (in kg): 17

HSG

R

AR

+ (2)

where: 18

R = amount of as-received residual, kg; 19

SGAR = specific gravity of as-received residual; and, 20

13

H = amount of liquid HRWRA, kg. 1

2

For example, suppose there exists a fibrous residual, which possesses the average properties of 3

the residuals (FC = 57%, MC = 153%, SGAR = 1.24 as shown in Table 1). To add 15 kg of the 4

as-received residual in 1 m3 of concrete, the amount of HRWRA required will be approximately 5

15 × 57 / (100 + 153) × 0.5 = 1.7 L ≈ 1.7 kg, using Equation (1). Then, using Equation (2), the 6

amount of mixing water to be reduced is approximately 15 / 1.24 + 1.7 = 13.8 kg (or about 10% 7

reduction of mixing water). 8

9

Mixture proportions and fresh properties of concrete mixtures made with Residuals C1, C2, WG, 10

and WV are presented in Table 11. Actual slump of concrete mixtures was approximately in the 11

range of 50 to 150 mm. Average w/c was about 0.43. The w/c slightly decreased as the amount 12

of fibrous residuals increased, maybe due to the increased dosage of HRWRA. As planned, the 13

density of concrete was relatively uniform, Table 11. 14

15

The compressive strength of the concrete was determined at 3, 7, and 28 days by testing three 16

100 × 200 mm cylinders at each test age. Regardless of residuals content, the compressive 17

strength of concrete was almost uniform for all the mixtures (Table 12). (This was a proof that 18

the fibrous residuals from pulp and paper mills can be used in concrete.) Average 28-day 19

compressive strength was about 49.3 MPa. The compressive strength of C2-35, C2-65, WG-35, 20

and WV-35 concrete mixtures was slightly higher than that of the Reference concrete (Ref. 1) 21

made without residuals. Mixture proportions for Ref. 1, C1-65, C2-65, WG-65, and WV-65 22

14

mixtures formed the basis of the mixture proportions used later for the evaluation of the 1

durability of concrete mixtures containing Residuals C1, C2, WG, and WV. 2

Equivalent strength of concrete containing Residual BR, I, or S 3

A series of concrete mixtures were made using Residuals I, S, and BR at as-received residuals 4

contents of 0, 0.35, and 0.65% by mass of concrete. Mixture proportions and fresh properties of 5

concrete are presented in Table 13. Segregation of fresh concrete was observed for BR-65 6

mixtures containing an excessive amount of HRWRA (4.66 L/m3 of concrete). Slump of 7

concrete ranged from 57 to 114 mm. Air content ranged from 1.9 to 2.5%. As intended, the 8

density of concrete was relatively uniform, Table 13. Test results for compressive strength of 9

concrete are presented in Table 14. The equivalent compressive strength of concrete was 10

achieved for as-received I or S residual content of up to 0.65% and for as-received BR residual 11

content of up to 0.35%. A reduction in the compressive strength of concrete was observed for 12

Mixture BR-65, which showed segregation while it was fresh. Mixture proportions for BR-35, I-13

65, and S-65 concrete were later used for the evaluation of the durability of concrete mixtures 14

containing Residuals BR, I, and S. 15

CONCLUSIONS 16

Several series of concrete mixtures were produced to establish mixture proportions for concrete 17

mixtures containing fibrous residuals generated from pulp and paper mills. Based on the data 18

presented, the following conclusions can be drawn: 19

1. The addition of a fibrous residual itself increases the water demand for achieving a given 20

level of slump, lowers the density, and reduces the compressive strength of concrete. 21

15

2. By adding HRWRA at a proper dosage, the slump, w/c, density, and strength of concrete 1

containing the fibrous residual can be made equivalent to those of a reference concrete made 2

without the residuals. In general, the dosage of HRWRA increased in proportion to the 3

amount of wood cellulose fibers in concrete. 4

3. By keeping the combined volume of mixing water, fibrous residual, and HRWRA constant, 5

concrete mixtures incorporating up to 0.65% fibrous residuals (by mass of concrete) were 6

produced equal in density and strength to a reference concrete. Later, the mixture 7

proportions thus established formed the basis for producing large batches of equivalent-8

strength concrete mixtures used for the comparison of the durability of concrete made with or 9

without the fibrous residuals. 10

ACKNOWLEDGMENTS 11

The writers would like to express their deep gratitude to the U.S. Department of Energy - 12

Agenda 2020 Program; National Council of the Paper Industry for Air and Stream Improvement 13

(NCASI), Research Triangle Park, N.C.; Weyerhaeuser Company, Federal Way, Wash.; and 14

Stora Enso North America Company, Wisconsin Rapids, Wis. for providing major funding for 15

this project. 16

17

The UWM Center for By-Products Utilization was established in 1988 with a generous grant 18

from the Dairyland Power Cooperative, La Crosse, Wis.; Madison Gas and Electric Company, 19

Madison, Wis.; National Minerals Corporation, St. Paul, Minn.; Northern States Power 20

Company, Eau Claire, Wis.; We Energies, Milwaukee, Wis.; Wisconsin Power and Light 21

Company, Madison, Wis.; and, Wisconsin Public Service Corporation, Green Bay, Wis. Their 22

16

financial support and additional grant and support from Manitowoc Public Utilities, Manitowoc, 1

Wis. are gratefully acknowledged. 2

REFERENCES 3

1. Smook, G. A., “Handbook for Pulp and Paper Technologists,” 2nd Edition, Angus Wilde 4

Publications, Bellingham, Wash., June 1992, 419 pp. 5

2. Unwin, J., “Why Bury It When You Can Use It?: NCASI’s Support of the Industry’s Efforts 6

to Find Beneficial Uses for Solid Wastes,” Proceedings, 2000 NCASI National Meeting, 7

National Council of the Paper Industry for Air and Stream Improvement (NCASI), Research 8

Triangle Park, N.C., 2000, pp. 57-74. 9

3. “Solid Waste Management and Disposal Practices in the U.S. Paper Industry,” Technical 10

Bulletin No. 641, National Council of the Paper Industry for Air and Stream Improvement 11

(NCASI), New York, N.Y., 1992, 27 pp. 12

4. Scott, G., and Smith, A., “Sludge Characteristics and Disposal Alternatives for Recycled 13

Fiber Plants,” Proceedings, 1995 Recycling Symposium, Technical Association of the Pulp 14

and Paper Industry (TAPPI), Atlanta, Ga., 1995, pp. 239-249. 15

5. “Alternative Management of Pulp and Paper Industry Solid Wastes,” Technical Bulletin No. 16

655, National Council of the Paper Industry for Air and Stream Improvement (NCASI), New 17

York, N.Y., 1993, 44 pp. 18

6. “Solid Waste Management Practices in the U.S. Paper Industry - 1995,” Technical Bulletin 19

No. 793, National Council of the Paper Industry for Air and Stream Improvement (NCASI), 20

Research Triangle Park, N.C., 1999, 26 pp. 21

17

7. Vinson, K. D., and Daniel, J. I., “Specialty Cellulose Fibers for Cement Reinforcement,” 1

Thin Section Fiber Reinforced Concrete and Ferrocement, SP-124, American Concrete 2

Institute, Detroit, Mich., 1990, pp. 1-18. 3

8. Soroushian, P.; Marikunte, S.; and Won, J., “Statistical Evaluation of Mechanical and 4

Physical Properties of Cellulose Fiber Reinforced Cement Composites,” ACI Materials 5

Journal, V. 92, No. 2, Mar.-Apr. 1995, pp. 172-180. 6

9. Sarigaphuti, M.; Shah, S. P.; and Vinson, K. D., “Shrinkage Cracking and Durability 7

Characteristics of Cellulose Fiber Reinforced Concrete,” ACI Materials Journal, V. 90, No. 8

4, Jul.-Aug. 1993, pp. 309-318. 9

10. Soroushian, P.; Marikunte, S.; and Won, J., “Wood Fiber Reinforced Cement Composites 10

Under Wetting-Drying and Freezing-Thawing Cycles,” Journal of Materials in Civil 11

Engineering, V. 6, No. 4, Nov. 1994, pp. 595-611. 12

11. Soroushian, P. and Ravanbakhsh, S., “Control of Plastic Shrinkage Cracking with Specialty 13

Cellulose Fibers,” ACI Materials Journal, V. 94, No. 4, Jul.-Aug. 1998, pp. 429-435. 14

12. Soroushian, P. and Ravanbakhsh, S., “High-Early-Strength Concrete: Mixture Proportioning 15

with Processed Cellulose Fibers for Durability,” ACI Materials Journal, V. 96, No. 5, Sep.-16

Oct. 1999, pp. 593-599. 17

13. “Fiber Reinforced Concrete,” Portland Cement Association, Skokie, Ill., 1991, p. 3. 18

14. Naik, T. R.; Friberg, T. S.; Chun, Y., “Use of Pulp and Paper Mill Residual Solids in 19

Production of Cellucrete,” Cement and Concrete Research, V. 34, No. 7, Jul. 2004, pp. 1229-20

1234. 21

18

15. Naik, T. R. and Kraus, R. N., “Development of Concrete Utilizing Paper Mill Residual 1

Solids,” Report No. CBU-1998-13, UWM Center for By-Products Utilization, Department of 2

Civil Engineering and Mechanics, University of Wisconsin-Milwaukee, 1998, 34 pp. 3

16. Chun, Y, “Investigation on the Use of Pulp and Paper Mill Residual Solids in Producing 4

Durable Concrete,” Ph.D. Dissertation, University of Wisconsin-Milwaukee, Dec. 2002, 256 5

pp. 6

17. Naik, T. R.; Chun, Y.; and Kraus, R. N., “Use of Residual Solids from Pulp and Paper Mills 7

for Enhancing Strength and Durability of Ready-Mixed Concrete,” Final Scientific/Technical 8

Report Submitted to the US Department of Energy for the Project DE-FC07-00ID13867, 9

Available at <www.osti.gov/servlets/purl/815132-VCYzJS/native/>, Oct. 2003, 300 pp. 10

18. “A Summary of Available Data on the Chemical Composition of Forest Products Industry 11

Solid Wastes,” Special Report No. 99-04, National Council of the Paper Industry for Air and 12

Stream Improvement (NCASI), Research Triangle Park, N.C., Oct. 1999, 54 pp. 13

19. Chun, Y. and Naik, T. R., “Repulping Fibrous Residuals from Pulp and Paper Mills for 14

Recycling in Concrete,” TAPPI Journal, Vol. 3, No. 12, Dec. 2004, pp. 7-10. 15

20. DeVor, R. E.; Chang, T.; and Sutherland, J. W., “Statistical Quality Design and Control,” 16

Prentice Hall, Upper Saddle River, N.J., 1992, Chapters 15-18, pp. 503-673. 17

18

19

TABLES AND FIGURES 1

List of Tables: 2

Table 1—Types, physical properties, loss on ignition (LOI), and wood fiber contents of residuals 3

Table 2—Mineralogical composition of residuals by powder diffraction analysis 4

Table 3—Main elements in residuals by instrumental neutron activation analysis 5

Table 4—Test setup for two-level factorial design of experiments for modeling 6

Table 5—Mixture proportions and fresh properties of C1 and C2 concrete for modeling 7

Table 6—Mixture proportions and fresh properties of WG and WV concrete for modeling 8

Table 7—Compressive strength of C1 and C2 concrete for modeling (MPa) 9

Table 8—Compressive strength of WG and WV concrete for modeling (MPa) 10

Table 9—Averages and coefficients for 22 models of responses 11

Table 10—Matrix for the calculation of the average and coefficients for a 22 model of response 12

Table 11—Mixture proportions and fresh properties of Ref. 1, C1, C2, WG, and WV concrete 13

Table 12—Compressive strength of Ref. 1, C1, C2, WG, and WV concrete 14

Table 13—Mixture proportions and fresh properties of Ref. 2, I, S, and BR concrete 15

Table 14—Compressive strength of Ref. 2, I, S, and BR concrete (MPa) 16

List of Figures: 17

Fig. 1—Scanning electron micrographs of residuals. 18

Fig. 2—28-day compressive strength of concrete as influenced by wood-fiber and HRWRA 19

contents. 20

21

20

1 Table 1—Types, physical properties, loss on ignition (LOI), and wood fiber contents of 2

residuals 3

Resid-ual Type

Fiber source

Moisture content,

%*

Specific gravity†

(as-received)

Specific gravity† (oven-dry)

Bulk density (as-received),

kg/m3

Avg. fiber

length, mm

LOI at 590°C,

%*

Wood fiber,%*

C1 Primary Virgin 185 1.18 1.77 1080 1.22 54.9 43 C2 Primary Virgin 220 1.15 1.69 1000 1.20 73.1 64 I Primary Recycled 95 1.35 2.04 830 0.85 49.7 40e

S Primary

80% recycled,

20% virgin

84 1.37 2.00 660 1.11 57.9 49e

WG Primary Virgin 116 1.33 2.17 750 1.51 43.6 35 WV Primary Virgin 142 1.19 1.62 570 1.68 82.3 77

BR Fiber reclaim Virgin 230 1.12 1.56 450 1.34K 99.6 94e

Avg. — — 153 1.24 1.83 760 1.27 65.9 57 *% of oven-dry (105°C) mass. 4

†Tests were performed on as-received moist samples. 5

‡Length-weighted average fiber length, ∑∑==

=N

iii

N

iiiL lnlnL

11

2 . 6

KUsing Kajaani FS-100. The rest determined by using a fiber quality analyzer. 7

eEstimated as 1.083 LOI – 14.1. The rest determined by infrared analysis. 8

9 10

21

1 Table 2—Mineralogical composition of residuals by powder diffraction analysis 2

Residuals Minerals, mass % C1 C2 I S WG WV Calcite (CaCO3) 15 51 36 63 21

Kaolinite* (Al2Si2O5(OH)4) 52 14 16 7 2 Magnesite (MgCO3) 7

Quartz (SiO2) 5 1 2 3 Talc (Mg3Si4O10(OH)2) < 1 3

*Kaolin-type clay. 3 4 5 6

Table 3—Main elements in residuals by instrumental neutron activation analysis 7

Residuals Element, ppm C1 C2 I S WG WV Avg. Rank

Aluminum (Al) 56,300 22,900 31,600 21,900 < 1,760 9,320 < 24,000 1 Cadmium (Cd) 1,770 1,860 1,870 1,130 1,700 2,830 1,860 7 Calcium (Ca) < 515 < 3,660 21,000 17,200 33,000 7,860 < 13,900 2 Chlorine (Cl) 243 810 733 341 < 173 179 < 413 9

Iron (Fe) 2,070 4,010 969 2,740 2,650 9,080 3,580 4 Magnesium (Mg) 3,440 3,390 2,820 4,520 2,080 1,120 2,900 5 Manganese (Mn) 274 2,090 242 394 7,640 3,010 2,270 6

Sodium (Na) 434 982 1,800 723 2,050 2,010 1,330 8 Titanium (Ti) 6,300 1,970 15,500 3,230 < 1,060 < 984 < 4,840 3

8 9

22

1 Table 4—Test setup for two-level factorial design of experiments for modeling 2

Mixture name X*-1 X*-2 X*-3 X*-4Wood fiber content

(WFC)†, kg/100 kg of cement

0.34 1.02 0.34 1.02

HRWRA content (HC), L/100 kg of cement 0.2 0.2 0.6 0.6

*X: Designation of fibrous residual. 3

†: On oven-dry basis. 4 5 6 7

Table 5—Mixture proportions and fresh properties of C1 and C2 concrete for modeling 8

Mixture name C1-1 C1-2 C1-3 C1-4 C2-1 C2-2 C2-3 C2-4Residuals, as-received, mass

% of conc. 0.27 0.79 0.27 0.81 0.22 0.67 0.23 0.68

Wood fibers from residuals*, kg/m3 0.95 2.82 1.00 2.94 1.06 3.12 1.12 3.26

Residuals, as-received, kg/m3 6.3 18.7 6.6 19.5 5.3 15.6 5.6 16.3

HRWRA, L/m3 0.72 0.70 2.26 2.19 0.71 0.70 2.25 2.18 Cement, kg/m3 358 350 376 365 357 348 375 364

Sand, SSD, kg/m3 832 812 867 848 826 805 867 843 Coarse agg., 19-mm max.,

SSD, kg/m3 1020 995 1070 1040 1010 991 1070 1040

Water, kg/m3 163 178 139 148 166 181 135 147 Water/cement, w/c 0.46 0.51 0.37 0.41 0.47 0.52 0.36 0.40

Slump, mm 83 70 165 102 76 57 152 76 Air content, % 3.8 3.7 2.1 2.8 3.7 3.2 2.3 2.6 Density, kg/m3 2380 2350 2460 2420 2370 2340 2450 2410

*Throughout the project, as-received moist fibrous residuals were used. The quantities of the 9

fibers shown are on oven-dry basis. 10

11 12

23

1 Table 6—Mixture proportions and fresh properties of WG and WV concrete for modeling 2

Mixture name WG-1 WG-2 WG-3 WG-4 WV-1 WV-2 WV-3 WV-4Residuals, as-received, mass

% of conc. 0.25 0.74 0.25 0.76 0.15 0.45 0.16 0.46

Wood fibers from residuals, kg/m3 0.97 2.83 1.00 2.98 1.14 3.34 1.19 3.48

Residuals, as-received, kg/m3 6.0 17.5 6.2 18.4 3.6 10.6 3.8 11.0

HRWRA, L/m3 0.72 0.70 2.25 2.20 0.71 0.70 2.23 2.17 Cement, kg/m3 362 349 375 367 356 348 372 363

Sand, SSD, kg/m3 835 804 865 847 827 808 863 842 Coarse agg., 19-mm max.,

SSD, kg/m3 1030 991 1070 1040 1010 990 1060 1030

Water, kg/m3 174 192 137 154 166 187 132 152 Water/cement, w/c 0.48 0.55 0.37 0.42 0.47 0.54 0.35 0.42

Slump, mm 76 127 140 114 70 64 102 70 Air content, % 2.6 3.1 2.2 1.8 3.7 3.6 2.5 3.1 Density, kg/m3 2410 2350 2450 2430 2370 2340 2430 2400

3 4 5

Table 7—Compressive strength of C1 and C2 concrete for modeling (MPa) 6

Age, days C1-1 C1-2 C1-3 C1-4 C2-1 C2-2 C2-3 C2-4

3 28.9 23.5 44.3 37.4 30.7 24.5 40.5 34.6 7 34.9 31.0 50.2 44.5 37.5 30.9 46.6 40.5 28 40.8 37.2 59.0 51.6 44.3 39.0 55.9 48.5

7 8

24

1 Table 8—Compressive strength of WG and WV concrete for modeling (MPa) 2

Age, days

WG-1

WG-2

WG-3

WG-4

WV-1

WV-2

WV-3

WV-4

3 27.7 23.0 38.9 27.5 28.6 22.7 42.3 35.7 7 35.1 30.1 42.0 32.3 35.4 28.5 48.0 41.3 28 43.2 38.4 50.7 37.1 40.9 35.4 54.5 49.3

3 4 5

Table 9—Averages and coefficients for 22 models of responses 6

y w/c Air content, % Density, kg/m3 28-d. comp. str., MPab’s 0b 1b 2b 12b 0b 1b 2b 12b 0b 1b 2b 12b 0b 1b 2b 12bC1 0.43 0.02 -0.05 0.00 3.1 0.2 -0.7 0.2 2400 -16 37 -4 47.2 -2.8 8.1 -1.0C2 0.44 0.02 -0.06 0.00 3.0 0.0 -0.5 0.2 2390 -17 36 -3 46.9 -3.2 5.3 -0.5WG 0.45 0.03 -0.06 0.00 2.4 0.0 -0.4 -0.2 2410 -17 31 8 42.4 -4.6 1.6 -2.2WV 0.44 0.03 -0.06 0.00 3.2 0.1 -0.4 0.2 2390 -13 30 -2 45.0 -2.7 6.9 0.1 Avg. 0.44 0.03 -0.06 0.00 2.9 0.1 -0.5 0.1 2400 -16 34 0 45.4 -3.3 5.5 -0.9

Note: The model is represented as 211222110 xxbxbxbby +++= , where y is response; 0b is 7

average; 1b , 2b , 12b are coefficients of variable 1 (wood fiber content), variable 2 (HRWRA 8

content), and interaction of variables 1 and 2; and, 1x , 2x are variables 1 and 2 in coded value 9

(range: –1 to 1). Using Table 4, x1 = [WFC – 0.5(1.02 + 0.34)] / [0.5(1.02 – 0.34)]; and, x2 = 10

[HC – 0.5(0.6 + 0.2)] / [0.5(0.6 – 0.2)]. 11

12 13

25

1 Table 10—Matrix for the calculation of the average and coefficients for a 22 model of 2

response 3

0b 1b 2b 12b +1 –1 –1 +1 +1 +1 –1 –1 +1 –1 +1 –1 4

1

+1 +1 +1 +1 4 5 6

Table 11—Mixture proportions and fresh properties of Ref. 1, C1, C2, WG, and WV 7

concrete 8

Mixture name Ref. 1 C1-35 C1-65 C2-35 C2-65WG-35

WG-65

WV-35

WV-65

Residuals, as-received, mass % of conc. 0 0.35 0.65 0.35 0.65 0.35 0.65 0.35 0.64

Wood fibers from residuals, kg/m3 0 1.26 2.32 1.66 3.08 1.35 2.50 2.60 4.86

Residuals, as-received, kg/m3 0 8.3 15.3 8.3 15.4 8.4 15.4 8.2 15.4

HRWRA, L/m3 0.80 1.45 2.04 1.57 2.50 1.70 2.27 1.96 3.35Cement, kg/m3 364 361 359 360 362 362 362 357 361

Sand, SSD, kg/m3 850 843 839 842 845 845 845 833 842 Coarse agg., 19-mm max.,

SSD, kg/m3 1020 1020 1010 1010 1020 1020 1020 1000 1010

Water, kg/m3 165 156 150 156 151 157 152 153 152 Water/cement, w/c 0.45 0.43 0.42 0.43 0.42 0.43 0.42 0.43 0.42

Slump, mm 114 89 102 89 102 152 140 89 51 Air content, % 1.8 2.8 3.2 2.5 2.3 2.0 1.9 3.2 2.8 Density, kg/m3 2400 2380 2380 2380 2390 2390 2390 2360 2390

9 10

26

1 Table 12—Compressive strength of Ref. 1, C1, C2, WG, and WV concrete (MPa) 2

Age, days

Ref. 1

C1-35

C1-65

C2-35

C2-65

WG-35

WG-65

WV-35

WV-65

3 33.3 35.1 34.3 34.1 35.2 36.2 33.3 35.7 30.6 7 39.5 40.7 39.3 39.7 41.2 43.1 39.9 43.5 37.3 28 48.7 48.1 48.1 50.7 50.1 51.4 47.8 51.8 47.3

3 4 5

Table 13—Mixture proportions and fresh properties of Ref. 2, I, S, and BR concrete 6

Mixture Name Ref. 2 I-35 I-65 S-35 S-65 BR-35 BR-65Residuals, as-received,

mass % of conc. 0 0.35 0.64 0.35 0.64 0.35 0.64

Wood fibers from residuals, kg/m3 0 1.73 3.17 2.24 4.09 2.37 4.44

Residuals, as-received, kg/m3 0 8.5 15.5 8.5 15.5 8.3 15.6

HRWRA, L/m3 0.82 1.69 3.45 2.26 5.50 1.45 4.66 Cement, kg/m3 366 366 364 366 362 361 366

Sand, SSD, kg/m3 854 855 849 854 846 842 855 Coarse agg., 19-mm max.,

SSD, kg/m3 1030 1040 1030 1030 1020 1020 1030

Water, kg/m3 162 156 150 157 152 152 150 Water/cement, w/c 0.44 0.43 0.41 0.43 0.42 0.42 0.41

Slump, mm 108 70 95 114 64 89 57 Air content, % 1.9 2.1 1.9 2.0 2.0 2.5 1.9 Density, kg/m3 2420 2420 2410 2420 2400 2380 2420

7 8

27

1 Table 14—Compressive strength of Ref. 2, I, S, and BR concrete (MPa) 2

Age, days

Ref. 2 I-35 I-65 S-35 S-65

BR-35

BR-65

3 34.0 39.7 35.0 35.7 29.7 39.8 22.37 38.9 44.8 41.4 40.5 35.2 44.8 27.728 45.3 53.2 48.8 47.2 42.2 51.3 33.7

3 4

28

1

Fig. 1—Scanning electron micrographs of residuals. 2

3 4

29

1

0.34

1.020.2

0.6354045505560

28-day Comp.

Strength(MPa)

Wood Fibers(kg/100 kg cem.)

HRWRA(L/100

kg cem.)

55-6050-5545-5040-4535-40

(MPa)

C1

0.34

1.020.2

0.6354045505560

28-day Comp.

Strength (MPa)

Wood Fibers(kg/100 kg cem.)

HRWRA (L/100

kg cem.)

55-6050-5545-5040-4535-40

(MPa)

C2

0.34

1.020.2

0.6354045505560

28-day Comp.

Strength (MPa)

Wood Fibers(kg/100 kg cem.)

HRWRA (L/100

kg cem.)

55-6050-5545-5040-4535-40

(MPa)

WG

0.34

1.020.2

0.6354045505560

28-day Comp.

Strength (MPa)

Wood Fibers(kg/100 kg cem.)

HRWRA(L/100

kg cem.)

55-6050-5545-5040-4535-40

(MPa)

WV

Fig. 2—28-day compressive strength of concrete as influenced by wood-fiber and HRWRA 2

contents. 3

4 [Note to the Editor: The figure is to be printed in black and white.] 5