ENHANCING STRENGTH AND DURABILITY OF CONCRETE USING RESIDUALS AND - - PowerPoint PPT Presentation

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ENHANCING STRENGTH AND DURABILITY OF CONCRETE USING RESIDUALS AND REJECT FIBERS FROM PULP AND PAPER MILLS

by Tarun R. Naik

Presented at the Workshop and Construction Demonstration for Use of Residuals and Reject Fibers from Pulp and Paper Industry in Concrete and CLSM Brookfield and New Berlin, WI, August 28, 2008

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Micro-fibers from Pulp and Paper Mill Wastewater Treatment Residuals

• Solid residue removed from mill wastewater

before the water is discharged or reused.

• Removed via a two-step (gravity/primary

and biological/secondary).

• Usually, dewatered before disposal or

beneficial use.

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Clarified Water Mill Wastewater

Primary Clarifier Dewatering

Primary Residual Secondary Residual

Secondary Clarifier

Dewatered Residual Recovered Water

Paper Mill Wastewater Treatment Process

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Pulp and Paper Mill Residual Solids in Concrete

• Approximately 60 % of the residual solids

generated in the USA is either landfilled

• r burned.
• Because of cellulose fibers in the residual

solids, the residual solids could become an economical source of fibers for use in concrete.

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Scanning electron micrograph of Residual S

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100 200 300 400 500 600 700 A spect R at i

• ,

L / D T ensi l e S t rengt h (M P a) M odul us

• f

E l ast i ci t y (G P a) S t eel C arbon W ood C el l ul

• se

Properties of Micro-fibers

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Pulp and Paper Mill Residual Solids in Concrete

• There have been very few investigations.
• Best performance of concrete seems to be

achieved if the residual solids were collected prior to chemical conditioning and solidification.

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As-received fibrous residual C1

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CONCRETE PROJECT 1

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Characterization of the Residuals

Seven sources of residual solids from various types of mills were selected.

– Primary and/or combined (primary + secondary) residuals – Virgin-fiber and recycled-fiber residuals

• Physical and chemical properties

determined.

• Effects of dispersants on sludge to separate

fibers established.

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Characteristics of Residuals

65.9 (43.6-99.6) LOI at 590°C (%)* 57 (35-94) Wood Fiber (%)* 1.27 (0.85-1.68)

• Avg. Fiber Length, LL (mm)

1.83 (1.56-2.17) Specific Gravity 153 (84-230) Moisture Content (%)* 5 Virgin, 1 Recycled, 1 Mixed Fiber Origin 6 Primary, 1 Fiber reclaim Type of Residual * % of oven-dry mass.

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Strength and Durability of Concrete Containing Residual Fibers

Mixture Proportions

–Residual content of 0.65 to 1.5%. –Initial and final setting times evaluated. –Air-entraining admixture (AEA) was not used. –HRWRA was used to adjust slump.

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Mixture Proportions (per m3) and Fresh Properties

1.8 1.3 2.3 1.9 1.7 1.8 1.6 2.8 1.6 Air Content (%) 75 90 125 75 125 180 150 90 115 Slump (mm) 0.44 0.42 0.41 0.43 0.44 0.45 0.43 0.41 0.43 W/Cm 1030 1050 1040 1050 1030 1020 1030 1030 1050 19-mm Coarse Aggregate (kg) 841 855 847 852 841 836 848 837 856 Sand (kg) 2400 359 2.2 15.6 WG 2410 361 3.4 15.7 WV 2420 367 0.8 Ref2 2410 365 1.5 8.5 BR 2410 2440 2420 2390 2430 Unit Wt. (kg/m3) 363 368 363 360 368 Cement (kg) 5.5 3.5 3.0 1.8 0.8 HRWRA (L) 15.7 16.0 15.7 15.6 Residuals (kg) S I C2 C1 Ref1 Mixture

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10 20 30 40 50 60 20 40 60 80 100

A ge (days) C om pressi ve Strength (M P a)

R ef . 1 C 1 C 2 W G W V

Compressive strength of concrete (ASTM C 39)

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Compressive strength of concrete (ASTM C 39)

(cont’d)

10 20 30 40 50 60 20 40 60 80 100

A ge (days) C om p ressi ve S tren gth (M P a)

R ef. 2 B R I S

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Length change of concrete due to curing in water and drying in air

• 0.

06

• 0.

05

• 0.

04

• 0.

03

• 0.

02

• 0.

01 0. 00 0. 01 0. 02 50 100 150 200 250

A ge (days) L ength C hange (% )

R ef. 2 B R I S

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Resistance of Concrete to De-icing Chemicals (ASTM C 672)

1 2 3 4 5 6 10 20 30 40 50 60 70 Salt Scaling Cycle Scaling Rating R BR I S

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Change in Dynamic Modulus of Elasticity of Concrete Due to Freezing and Thawing (ASTM C 666 A)

20 40 60 80 100 50 100 150 200 250 300 350 Freezing and Thawing Cycle Relative Dynamic Modulus of Elasticity (%) R BR I S

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Residual Flexural Strength (ASTM C 1339)

• Concrete containing residuals showed

slightly improved residual-strength than concrete without residuals.

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Electrical Indication of Chloride Ion Penetrability Into Concrete (ASTM C 1202)

1000 2000 3000 4000 5000 6000 Ref. 1 C1 C2 WG WV Ref. 2 BR I S Mixture Name Charge Passed (Coulombs)

Very Low Negligible High Moderate

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Abrasion test

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0. 0. 5 1. 1. 5 2. 2. 5 3. R ef. 1 C 1 C 2 W G W V R ef. 2 B R I S

M i xture N am e M ass L oss A fter S i x M i nutes

• f

A brasi

• n

(g)

Mass loss of concrete due to abrasion

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Construction Demonstration (2004)

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CONCLUSIONS

When compared to a reference concrete containing no residuals, concrete containing residuals exhibited:

• Slightly lower compressive strength
• higher average residual-strength
• Equivalent drying-shrinkage
• Improved resistance to freezing and thawing
• Equivalent or lower chloride-ion penetration

resistance and abrasion resistance.

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CONCRETE PROJECT 2 (for WI-DNR)

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Mixture Proportions and Fresh Properties of Prototype Concrete Mixtures - Project 2

Mixture Designation 1 2 3 4 5 Fibrous Residual Source (None) BR BR C1 C1 Cement (lb/yd3), C 563 593 575 519 522 Class C Fly Ash (lb/yd3) 95 93 102 88 94 Fine Aggregate, SSD (lb/yd3) 1340 1355 1340 1255 1235 Coarse Aggregate (3/4-in. max.), SSD (lb/yd3) 1695 1715 1715 1615 1565 Fibrous Residual, as-received (lb/yd3), FR 14 20 24 38 Water (lb/yd3), W 275 282 275 236 286 Air Entraining Admixture (oz/yd3) 5 W/C 0.42 0.41 0.41 0.39 0.46 Slump (in.) 3-1/4 3-3/4 3 3-3/4 4-1/2 Air Content (%) 5.8 2.2 2.6 9.2 9.3 Density (lb/ft3) 147.0 150.3 149.2 138.5 138.6

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Compressive Strength of Prototype Concrete – Project 2

1000 2000 3000 4000 5000 6000 7000 8000 1 10 100 1000 Age (days) Compressive Strength (psi) 10 20 30 40 50

(MPa)

1 2 3 4 5

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Splitting Tensile Strength of Prototype Concrete – Project 2

100 200 300 400 500 600 700 20 40 60 80 100 Age (days) Splitting Tensile Strength (psi) 1 2 3 4 (MPa)

1 2 3 4 5

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Resistance of Prototype Concrete to Cycles of Freezing and Thawing – Project 2

40 50 60 70 80 90 100 30 60 90 120 150 180 210 240 270 300 Freezing and Thawing Cycles Relative Dynamic Modulus of Elasticity (%) 1 2 3 4 5

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• When tested for resistance to freezing and

thawing, concrete made with wood fibers showed generally similar performance as air-entrained concrete made without fibers.

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CONCRETE PROJECT 3 Using High-Carbon Materials

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Background and Objectives

• This testing work was conducted to evaluate the

use of high-carbon fly ash and carbon in non-air entrained concrete.

• Fibrous residual from pulp and paper mill was

used to improve the durability of the concrete to freezing and thawing.

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Background and Objectives (cont’d)

• This new technology would also lead to reduced

amount of high-carbon fly ash and pulp mill residual solids going to landfills.

• It is believed that the improvement in concrete

durability can be achieved without depending on specialty chemical air-entraining admixture, even when high-carbon fly ash is used in such concrete mixtures.

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MIXTURES – Group 1

• Fibrous residual contents: Approximately 0.25,

0.5, and 0.75% by mass of concrete.

• Presque Isle activated carbon: 25% of the sum
• f cement and Presque Isle activated carbon.
• Valley high-carbon fly ash: 14% of the sum of

cement and Valley high-carbon fly ash.

• Tests: Compressive strength, flexural strength,

chloride-ion penetrability, and resistance to freezing and thawing.

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MIXTURES – Group 2

• Fibrous residual contents: Approximately 0,

0.3, 0.6, and 0.9% by mass of concrete.

• Presque Isle activated carbon: 25% of the sum
• f cement and Presque Isle activated carbon.
• Valley high-carbon fly ash: 14% of the sum of

cement and Valley high-carbon fly ash.

• Tests: Compressive strength, and resistance to

freezing and thawing.

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Mixture Proportions and Fresh Properties of Group 2 Concrete Mixtures Made with Presque Isle Activated Carbon

Mixture Designation Ref-2 P-11 P-12 P-13 P-14 Fibrous Residual, BR (mass % of concrete) 0.07 0.29 0.59 0.88 Cement, C (lb/yd3) 588 440 439 435 430 Presque Isle Activated Carbon, P (lb/yd3) 144 144 143 141 Water, W (lb/yd3) 255 248 254 248 263 Sand, SSD (lb/yd3) 1481 1486 1473 1458 1435 Crushed Stone, 3/4-in. max., SSD (lb/yd3) 1799 1789 1785 1770 1750 Fibrous Residual, BR (lb/yd3) 3 12 24 36 ADVA 190 HRWRA (fl. oz./yd3) 24 94 128 103 164 W/C 0.43 0.56 0.58 0.57 0.61 Slump (in.) 2.75 2.5 6.25 1.25 2 Air Content (%) 1.2 1.3 0.9 1.3 1.0 Density (lb/ft3) 153 152 152 151 150

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Compressive Strength of Group 2 Concrete Mixtures Made with Presque Isle Activated Carbon (psi)

Age (days) Ref-2 P-11 P-12 P-13 P-14 7 6440 7350 7220 6370 5700 28 6890 8500 7550 7540 7060

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50 60 70 80 90 100 31 59 90 120 150 Freezing and Thawing Cycles Relative Dynamic Modulus of Elasticity (%) Ref-2 P-11 P-12 P-13 P-14

Resistance of Group 2 Concrete Mixtures Made with Presque Isle Activated Carbon to Cycles of Freezing and Thawing

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• Based on the test results obtained so far,

concrete made with high-carbon materials and fibrous residual from pulp and paper mill, showed high resistance to freezing and thawing.

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Flowable Slurry Made With Class C Fly Ash and Paper Industry Fibrous Residuals

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As-received fibrous residual WR

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FLOWABLE SLURRY PROJECT 1

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Mixture Proportions and Fresh CLSM Properties

0.47 0.62 0.50 0.62 0.36 0.39 W/Cm 444 445 456 522 645 496 Water (kg/m3) 1.8 3.0 3.1

• n. a.

1.2 0.8 Air content (%) 275 235 230 380 415 335 Flow (mm) 190 285 181 167 Fibrous residual (kg/m3) Sand, SSD (kg/m3) 1540 877 27 WR FA- WR-2 1440 692 21 C1 FA- C1 1590 923 29 C1 FA- C1-2 1530 2440 1780 Density (kg/m3) 811 1612 1213 Class C fly ash (kg/m3) 25 179 75 Cement (kg/m3) WR (None) (None) Fibrous residual FA- WR FA- Ref-2 FA- Ref Mixture designation

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Mixture Proportions and Fresh Properties of Ash Slurry

• The fly ash slurry mixtures FA-Ref and FA-Ref-2

made without fibrous residuals were not easy to handle — fast-setting and agglomerated while mixing.

• Fly ash slurries containing fibrous residuals were

easy to produce and handle.

• The fly ash slurry mixtures made with fibrous

residuals remained workable while specimens were being cast.

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Compressive Strength of Ash Slurry

• The fly ash slurry mixtures containing fibrous

residuals (Mixtures FA-WR, FA-WR-2, FA-C1, and FA-C1-2) maintained a controlled low long- term strength (0.14 to 0.99 MPa at 91 days and 0.55 to 1.44 MPa at 182 days).

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CONCLUSIONS

• Fibrous residuals improved workability of fly ash
• slurry. Easier (less time-consuming) to

thoroughly mix the ingredients.

• Fibrous residuals prevented rapid setting of the

fly ash slurry mixtures made with Class C fly ash and kept the fresh ash slurry mixtures workable while they were being placed.

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CONCLUSIONS (cont’d)

• Fibrous residuals helped the fly ash and sand

slurry mixtures to set at an early age and maintain a low long-term strength, allowing for future excavation.

• Use of fibrous residuals, especially C1, was

helpful in reducing the hydraulic conductivity of sand flowable slurry.

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FLOWABLE SLURRY PROJECT 2

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Mixture Proportions and Fresh Properties of Prototype Flowable Slurry Mixtures

Mixture Designation 6 7 8 9 10 Fibrous Residual Source (None) WR WR C1 C1 Cement (lb/yd3) 67 43 40 38 35 Class C Fly Ash (lb/yd3) 694 665 590 568 534 Fine Aggregate, SSD (lb/yd3) 2375 2275 2083 2070 2025 Fibrous Residual, as-received (lb/yd3) 64 89 95 123 Water (lb/yd3) 368 393 561 434 480 Air Entraining Admixture (oz/yd3) 2.6 3” x 6” cylinder flow (in.) 10 9-1/2 8 9-3/4 9-1/2 Air Content (%) 7.8 0.3 0.5 9.4 9.6 Density (lb/ft3) 129.8 127.5 124.6 118.6 118.4

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Compressive Strength of Prototype Flowable Slurry Mixtures (psi)

Age (days) 6 7 8 9 10 3 17 5 4 7 170 2 7 5 13 440 10 5 11 8 28 750 21 11 19 14 91 1860 83 21 103 16 182 1940 140 130 160 20 357 1430 260 180 230 16

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• Use of fibrous residuals from pulp and paper mill

helped to maintain a controlled low-strength of flowable slurry.

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More information at

<www.cbu.uwm.edu>.

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Thank you very much for your interest.

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Spaceship Earth – La Bella Terra

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Aabhar Tamaro, Afcharisto Poly, Arigatou Gozaimasu, Grazie Molte, Maraming Salamat, Merci Beaucoup, Muchas Gracias, Muito Obrigado, Dziekuje, Salamat, Shukriya, Spasibo, Thank you, Toda Raba.