Center for By-Products Utilization

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1 Center for By-Products Utilization CPI Ash as a Potential Source for Construction Materials By Tarun R. Naik and Rudolph N. Kraus Report No. CBU Rep-399 August 2000 Submitted to Consolidated Papers, Inc., Wisconsin Rapids, WI Department of Civil Engineering and Mechanics College of Engineering and Applied Science THE UNIVERSITY OF WISCONSIN - MILWAUKEE

2 CPI Ash as a Potential Source for Construction Materials A Report Submitted to Dr. F. Andrew Gilbert Consolidated Papers, Inc. August 2000

3 REP -399 CPI Ash as a Potential Source for Construction Materials by Tarun R. Naik, Ph.D., P.E. and Rudolph N. Kraus UWM Center for By-Products Utilization Department of Civil Engineering and Mechanics College of Engineering and Applied Science The University of Wisconsin - Milwaukee P.O. Box 784 Milwaukee WI 53201

4 Ph: (414) Fax: (414) Executive Summary TITLE: CPI Ash as a Potential Source for Construction Materials SOURCE: UWM-CBU Report No. CBU , REP-399, August 2000 BACKGROUND/PURPOSE: To conduct physical, chemical, mineralogical, and microstructural tests for determining properties of typical Consolidated Papers, Inc. (CPI) wood ashes (Biron #4 precipitator ash, Biron #4 bottom ash, Biron #4 boiler slag, Biron #5 boiler precipitator ash, Biron #5 mechanical hopper ash, Kraft P1-P2 "fine" ash, Kraft P1-P2 bottom ash, Niagara B21-B23 fly ash, and Niagara B24 bottom ash) for evaluating their potential options for beneficial reuse. The nine ash sources were selected based upon their diverse character (such as color, texture, and type of collection system/process etc.) in consultation with Dr. F. Andrew Gilbert, Consolidated Papers, Inc.. OBJECTIVE: The primary objective of this project was to recommend alternatives to the normal practice of landfilling by evaluating potential reuse/recycle applications for these materials, especially in cement-based construction materials. CONCLUSIONS: CPI s wood ashes have considerable potential for many applications. However, the performance of these ashes needs to be established for individual applications. The following are some of the high-volume applications that would require further evaluation. These applications would consume all of the wood ashes produced at Consolidated Papers. Flowable Materials have up to 1200 psi compressive strength, have flowing mud-type of consistency and fluidity, contain very little portland cement and a lot of water, and consist mostly of ash or similar materials. It is believed that concrete Bricks, Blocks, and Paving Stones could also be made with the wood ashes tested. Additionally the fly ash and precipitator ash should be useful for replacement of clay in clay bricks manufacturing. The test data collected also indicate that these wood ashes can be used as a partial replacement of aggregates and/or cement in -Strength Concrete. It is also concluded that there is a potential for high-value use of the fly ash and precipitator ash in manufacturing Blended Cements. Soil stabilization or site remediation is another significant potential use of the ashes. For example, for log-yard paving (Roller Compacted Concrete Pavement) these wood ashes can function as a soil stabilizing or strengthening medium as well as significantly improving the performance of log-yards and reducing cost of handling logs and minimizing waste of logs. The Biron #4 slag has a very significant potential to be utilized as an Architectural Aggregate in Concrete or as a Roofing Shingle Grit. Based upon the limited testing performed for the project, these applications have the potential to be a significant source of revenue. A further evaluation is very strongly recommended. Probability of success is excellent. RECOMMENDATIONS: Further evaluation is recommended, starting with lab-scale production and testing of wood ash use in the above applications. Cost/benefit analysis and marketing studies should be ii

5 undertaken; and a long-term evaluation program for these products should be started. This includes the development of wood ash specifications for high-potential, high-value, applications. iv

6 Table of Contents Item Page Executive Summary... iii List of Table v List of Figures... vi Section 1: Introduction... 1 Section 2: Tests of CPI Wood Fly Ashes...5 EXPERIMENTAL PROGRAM... 5 PHYSICAL PROPERTIES... 5 As-Received Moisture Content... 5 Particle Size Analysis... 6 Unit Weight... 8 Specific Gravity... 9 SSD Absorption ASTM C 618 TESTS Physical Properties per ASTM C Cement Activity Index Water Requirement Autoclave Expansion Chemical Properties per ASTM C CHEMICAL COMPOSITION ELEMENTAL ANALYSIS SCANNING ELECTRON MICROSCOPY (SEM) Section 3: Constructive Use Options for CPI Ashes...20 INTRODUCTION USES OF CPI WOOD FLY ASHES Section 4: Suggestions for Further Evaluations...22 FLOWABLE MATERIALS BRICKS, BLOCKS, AND PAVING STONES MEDIUM-STRENGTH CONCRETE DECORATIVE AGGREGATE - ROOFING SHINGLE GRIT BLENDED CEMENT ROLLER-COMPACTED CONCRETE PAVEMENT SOIL AMENDMENT WITH OR WITHOUT DREDGED MATERIALS...24 Section 5: References...96 APPENDIX 1: Modified ASTM C 422 for Particle Size Analysis...97 v

7 List of Tables Item Page Table 1: As-Received CPI Ash Moisture Content Table 2: Sieve Analysis of CPI Ash Table 3: Material Finer Than No. 200 Sieve by Washing Table 4: Materials Retained on No. 325 Sieve Table 5: Unit Weight and Voids Table 6 Specific Gravity Table 7: Specific Gravity Table 8: Absorption Table 9: Mortar Cube Compressive Strength Table 10: Strength Activity Index with Cement Table 11: Water Requirement Table 12: Autoclave Expansion or Contraction Table 13: Physical Tests Requirements of Coal Fly Ash per ASTM C Table 14: Chemical Analysis Table 15: Mineralogy of CPI Ash Table 16: Elemental Analysis Table 17: Potential Uses of the Biron #4 Wood Ashes Table 18: Potential Uses of the Biron #5 Wood Ashes Table 19: Potential Uses of the Kraft Wood Ashes Table 20: Potential Uses of the Niagara Wood Ashes vi

8 List of Figures Item Page Fig. 1: Particle Size Distribution of Biron #4 Precipitator Ash Fig. 2: Particle Size Distribution of Biron #4 Bottom Ash Fig. 3: Particle Size Distribution of Biron #4 Slag Fig. 4: Particle Size Distribution of Biron #5 Precipitator Ash Fig. 5: Particle Size Distribution of Biron #5 Mechanical Hopper Ash Fig. 6: Particle Size Distribution of Kraft P1-P2 "Fine" Ash Fig. 7: Particle Size Distribution of Kraft P1-P2 Bottom Ash Fig. 8: Particle Size Distribution of Niagara B21-B23 Fly Ash Fig. 9: Particle Size Distribution of Niagara B24 Bottom Ash Fig : SEM Photomicrographs of Biron #4 Precipitator Ash Figure 14 17: SEM Photomicrographs of Biron #4 Bottom Ash Figure 18 21: SEM Photomicrographs of Biron #4 Slag Figure 22 25: SEM Photomicrographs of Biron #5 Precipitator Ash Figure 26 29: SEM Photomicrographs of Biron #5 Mechanical Hopper Ash Figure 30 33: SEM Photomicrographs of Kraft P1-P2 "Fine" Ash Figure 34 37: SEM Photomicrographs of Kraft P1-P2 Bottom Ash Figure 38 41: SEM Photomicrographs of Niagara B21-B23 Fly Ash Figure 42 45: SEM Photomicrographs of Niagara B24 Bottom Ash vii

9 Section 1 INTRODUCTION The scope of this project was to determine physical, chemical, mineralogical, and microscopical properties of the Consolidated Papers, Inc. (CPI) wood and/or coal combustion products from daily operations. The main objective of this project is to recommend alternatives to the normal practice of landfilling by recommending potential reuse/recycling applications for these materials. Nine different types of wood and/or coal combustion products were used in this project: Biron #4 precipitator ash, Biron #4 bottom ash, Biron #4 slag, Biron #5 precipitator ash, Biron #5 mechanical hopper ash, Kraft P1-P2 "fine" ash (combined from P1 and P2 boilers), Kraft P1-P2 bottom ash (combined from P1 and P2 boilers), Niagara fly ash (combined from Boilers B21- B23), and Niagara bottom ash (Boiler B24). It has been established by previous projects at the UWM Center for By-Products Utilization (UWM-CBU) that properties of wood and/or coal combustion products (i.e. different types of ashes) can vary greatly from mill to mill depending upon the type and source of fuel, how the ash is collected, design and operation of the boiler, etc. Therefore, it is important to determine physical, chemical, and morphological properties of the ash for determining their appropriate use options. Before beginning any quantitative testing, the general physical appearance of the CPI materials were evaluated. The Biron #4 precipitator ash sample is dark-brown to black in color, had a fine gradation, and was dry. The Biron #4 bottom ash is light-brown in color, appeared to be a typical coal bottom ash type of material with gradation varying from a sand-like material with larger pieces up to 1-1/2". Biron #4 slag is a black glassy material with a coarse sand consistency (up to -1-

10 maximum size of 3/8-inch). Biron #5 precipitator ash is a very fine, dry, dark-gray ash. Biron #5 mechanical hopper ash is dry with a fine to coarse gradation, and color varies from gray to black. The Kraft P1-P2 "fine" ash is a black dry ash with a sand-like consistency, some agglomeration is present due to the fine material, and some large gray colored pieces are present. Kraft P1-P2 bottom ash is moist, light-brown to brown in color, has a typical coal bottom ash type of appearance, gradation varies from a fine sand to larger coarse pieces. The larger pieces of the Kraft P1-P2 bottom ash are heavy and agglomerated. The Niagara B21-B23 fly ash is a very fine, black, dry ash (appears to have a high carbon content). Niagara B24 bottom ash is black to darkgray in color, dry, and has some fine sand-like particles but has generally coarse gradation. The following background information on the source of the ash materials was obtained from Consolidated Papers, Inc. -2-

11 Background Information on the Biron Ash Source Biron Boiler #4 Biron Boiler #5 Make of Boiler B&W Combustion Engineering Type of Boiler Cyclone Stoker Traveling Grate Age of Boiler 43 yrs. 14 yrs. Aspen-Spruce-Balsam bark, Misc. Type of Fuel wood waste (pallets), Aspen saw Eastern coal, and #6 Oil dust, Western coal Maximum Size of Wood Fuel None None 132,840 tons coal 86,850 tons coal 17.7 x 10 6 BTU ton Amount of Fuel Used Per Year 23.8 x 10 6 BTU/ton 49,370 tons wood waste 8.4 x 10 6 BTU/ton Burning Temperature, Deg.F Not measured 1250 Type of Energy Steam Steam 1450 psi, 950 F 1450 psi, 950 F Amount of Energy 1.76 x BTU/yr 2.32 x BTU/yr Dry - Fly Ash Wet - Slag Dry - Fly Ash Dry - Mechanical Collector Ash Wet or Dry Ash Collection Amount of Slag/Bottom Ash 4,500 tons/yr - Slag 100,000 tons/yr - Bottom Ash Amount of Fly Ash (1) (2) (1) #4 Boiler Precipitator Ash = 4,000 tons/yr, #4 Boiler Hopper Fly Ash = 1,200 tons/yr (2) #5 Boiler Precipitator Ash = 3,000 tons/yr, #5 Boiler Mechanical Hopper Ash = 2,500 tons/yr Background Information on the Kraft Division Ash Source Kraft P-1 Kraft P-2 Make of Boiler Combustion Engineering Stoker Traveling Grate Type of Boiler Age of Boiler 34 yrs. 34 yrs. Type of Fuel Maximum Size of Wood Fuel Bark, wood, saw dust, and coal Combustion Engineering Stoker Traveling Grate Bark, wood, saw dust, and coal ~1" x 1" ~1" x 1" 89,000 t/yr coal 88,000 t/yr wood 97,000 t/yr coal Amount of Fuel Used waste 89,000 t/yr wood Per Year waste Burning Temperature, Deg.F Type of Energy Steam Steam Amount of Energy ~240 k#/hr ~250 k#/hr Dry - Fly Ash Wet - Bottom Ash Dry - FlyAsh Wet - Bottom Ash Wet or Dry Ash Collection Amount of Bottom Ash 800 tons/yr 900 tons/yr Amount of Fly Ash 7,400 tons/yr 7,800 tons/yr -3-

12 Source Make of Boiler Background Information on the Niagara Ash Niagara Boiler B21 Combustion Engineering Pulverized General, Dry Bottom Niagara Boiler B22 Combustion Engineering Pulverized General, Dry Bottom Niagara Boiler B23 Combustion Engineering Pulverized General, Dry Bottom Type of Boiler Age of Boiler 61 yrs. 61 yrs. 61 yrs. 39 yrs. Type of Fuel Coal, wood waste Coal, wood waste Coal Coal Maximum Size of Wood Niagara Boiler B24 Babcock & Wilcox Spreader Stoker Fuel Not Available Not Available Not Available Not Available 13,170 tons coal 19,790 tons 21,760 tons coal Amount of Fuel Used wood waste 19,790 tons 27,360 tons Per Year wood waste coal 16,980 tons coal Burning Temperature, Deg.F Not Available Not Available Not Available Not Available Type of Energy Steam Steam Steam Steam 360,324,000 lb steam 515,110,000 lb steam 536,887,000 lb steam 329,031,000 lb steam Amount of Energy Wet or Dry Ash Collection Dry-Fly Ash Dry-Fly Ash Dry-Fly Ash Dry-Fly Ash Amount of Bottom Ash Not Available Not Available Not Available (1) Amount of Fly Ash (1) (1) (1) Not Available (1) Total Fly Ash from Boiler B21, B22 and B23 = 7120 tons/yr, Total Bottom Ash from Boiler B24 = 2380 tons/yr -4-

13 Section 2 Tests of CPI Wood and/or Coal Combustion Products EXPERIMENTAL PROGRAM A test program was designed to measure physical, chemical, mineralogical, and microscopical properties of the ashes from CPI boilers. Wood and/or coal combustion products were received from the following CPI mills: Biron, Kraft Division, and Niagra. Five types of ash were received from the Biron mill: Boiler #4 precipitator ash, Boiler #4 bottom ash, Boiler #4 Slag, Boiler #5 precipitator ash, and Boiler #5 mechanical hopper ash. Two types of ash were received from the Kraft Division: "fine ash" and bottom ash. These ash materials were obtained from a combination of units P1 and P2. Finally, two types of ash were obtained from the Niagara mill: fly ash combined from boilers B21-B23 and bottom ash from boiler B24. In order to measure properties of these ash products, the following experiments were carried out. PHYSICAL PROPERTIES As-Received Moisture Content As-received moisture content (MC) of the ashes was determined in accordance with the ASTM Test Designation C 311. Table 1 provides the test data. The results show that the Kraft P1-P2 "fine" ash had a very high (78.9% ) MC, while the Biron #4 bottom ash, Kraft P1-P2 bottom ash, Niagara B21-B23 fly ash, and Niagara B24 bottom ash had a mid-range MC (20.0%, 17.7%, 27.9%, and 12.2%, respectively). The remaining materials, Biron #4 precipitator ash, Biron #4 slag, Biron #5 precipitator ash, and Biron #5 mechanical hopper ash had low moisture contents (0.1%, 3.3%, -5-

14 0.3%, and 0.2%, respectively). There are some significant negative attributes of these ashes with very high end to mid-range MC: (1) moisture/water content leads to cost of shipping water along with the ash to the potential user of the ash. This, of course, increases the cost to the user in obtaining the ash for beneficial reuse. (2) If the moisture content is not within control, then the variation leads to quality control problems for the user. (3) The water content is a critical parameter for manufacturing cement-based products. Therefore, if the user is planning to use the ash in cement-based materials, then the water content must be controlled in a narrow range to control the quality of such products. (4) Wetting the ash with or soaking it in water destroys any cementitious ability of the ash. (5) A typical manufacturer of cement-based materials is equipped very well to handle dry or relatively dry materials. Therefore, wet or variable moisture content ash would make it harder for CPI to market these ashes for reuse/recycle purposes to such manufacturers. Particle Size Analysis Ash samples were first oven-dried at 210 F ± 10 F and then were tested for gradation using standard sieve sizes (3/4" through #100), as reported in Table 2, in accordance with ASTM Test Designation C 136. Ash samples were also tested in accordance with ASTM Test Designation C117 to determine the amount of material finer than No. 200 sieve by washing as reported in Table 3. Three ash samples, Biron #4 precipitator ash, Biron #5 precipitator ash, and Niagara B21-23 fly ash were not evaluated using ASTM C 136 and C 117 due to the fact that these sources of the ash were too fine to conduct these tests. Ash samples were further tested for materials passing No. 325 sieve by washing under pressure in accordance with ASTM Test Designation C 430. Bottom ash and slag samples were too coarse for this test. Results are reported in Table

15 The size distributions of samples having a significant percentage of particles passing #100 sieve (Biron #4 precipitator ash, Biron #5 precipitator ash, Biron #5 mechanical hopper ash, Niagara B21-B23 fly ash, and Niagara B24 bottom ash) were also analyzed in accordance with ASTM C 422 (hydrometer analysis). The complete size distribution of all of the ashes are shown in Fig. 1 to Fig. 9. Table 2 particle size analysis data show that the Biron #4 bottom ash, Biron #4 slag and Kraft P1- P2 bottom ash generally were coarse materials with only 16% to 21% passing through the No. 16 sieve. Furthermore, these materials had less than 4% of the total materials passing No. 200 sieve when washed with water (Table 3). These test data indicate that these three sources of ash may be acceptable as a substitute for sand replacement in ready-mixed concrete and/or as both coarse and fine aggregates replacements in dry-cast concrete products such as bricks, blocks, and paving stones because of its generally coarse gradation. Furthermore, these materials are not fine enough; i.e., too coarse, to be used for cement replacement in concrete. Table 4 data show that the Biron #4 precipitator ash, Biron #5 mechanical hopper ash, and Kraft P1-P2 "fine" ash had a considerable amount of material retained on the No. 325 sieve (53%, 76%, and 93%, respectively). The Biron #5 precipitator ash and Niagara B21-B23 fly ash were considerably finer with about 10% and 31%, respectively, retained on the No. 325 sieve. ASTM C 618 for coal fly ash classifies a value of maximum 34% retained on the No. 325 sieve as satisfactory for use in concrete. Based upon this criterion for pulverized coal fly ash, the CPI Biron #5 precipitator ash and Niagara B21-B23 fly ash met this requirement of ASTM C 618. These results indicate that the Biron #5 precipitator ash and Niagara B21-B23 fly ash may be quite suitable as a cement replacement in concrete and also for CLSM-type of flowable slurry products. -7-

16 The coarser materials (Biron #4 precipitator fly ash, Biron #5 mechanical hopper ash, and Kraft P1-P2 "fine" ash) maybe more suitable for use in CLSM, but may be too coarse as produced to be used as a cement replacement in concrete. Test data for particle size analysis in accordance with the modified ASTM C 422 are presented in Figs. 1, 4, 5, 8, and 9. Appendix 1 provides the details of this modified ASTM test. These figures show that the gradation of the Biron #4 precipitator ash, Biron #5 mechanical hopper ash, and Niagara B21-B23 fly ash (Figs. 1, 5, and 8, respectively) is reasonably uniform while over 80% of the particles of Biron #5 precipitator ash (Fig. 4) fall between 8-15 microns. Unit Weight Unit weight (i.e., bulk density) of the ash was determined in accordance with the ASTM Test Designation C 29. Table 5 provides the test results. The results show that the fine ash materials (Biron #4 precipitator ash, Biron #5 precipitator ash, Kraft P1-P2 "fine" ash, and Niagara B21-B23 fly ash) had similar density values, approximately lb/ft³. Bulk density of Biron #4 bottom ash, Biron #4 slag, Biron #5 mechanical hopper ash, Kraft P1-P2 bottom ash, and Niagara B24 bottom ash was 60, 93, 48, 61, and 44 lb/ft³, respectively. This is consistent with the gradation of the slag and bottom ash, which showed a significant amount of coarser fractions of the ash materials. These data indicate that these materials (except the Biron #4 slag) may be suitable for replacing regular, normal-weight, sand and/or coarse aggregates in making semi-lightweight or lightweight CLSM and/or concrete. Such lightweight construction materials are well suited for insulating fill for roofs and walls, as well as sound and/or ground vibration barriers. Typical manufactured lightweight sand costs over $50 per ton and light weight coarse aggregates costs about $45 per ton. Bulk density value is also necessary for calculations for establishing and modifying -8-

17 cement-based construction materials mixture proportioning. Percentage of voids in Table 5 indicate amount of free space available for packing of other materials in making cement-based materials. The higher the percent voids, the higher the amount of other materials necessary for making cement-based materials. Specific Gravity Specific gravity tests for the fine ash materials (Biron #4 precipitator ash, Biron #5 precipitator ash, Biron #5 mechanical hopper ash (passing No. 100 sieve), and Niagara B21-B23 fly ash were conducted in accordance with the ASTM Test Designation C 188, Table 6. Results show that the specific gravity values for the Biron #4 precipitator ash and Niagara B21-B23 fly ash are similar, approximately 2.15 (ranges between 2.13 and 2.21). This is a similar order of magnitude as a typical coal fly ash, though these two ashes have a lower specific gravity value than typical Class F coal fly ash (specific gravity approximately 2.50), and significantly lower than typical Class C fly ash (specific gravity approximately 2.60). The value of specific gravity for the Biron #5 precipitator ash is This is consistent with specific gravity of typical Class F coal ash. It is also noted from Table 6 that the specific gravity for samples passing #100 sieve is slightly higher than that tested for as received samples. This may be due to the fact that the coarse fractions of the ashes contain higher amounts of carbon than the finer fractions. Specific gravity value is necessary for determining relative substitution rate for fly ash versus amount of cement or sand replaced in a mixture; and, also for calculations for establishing and modifying cement-based construction materials mixture proportions. Specific gravity tests for the Biron #4 bottom ash, Biron #4 slag, Biron #5 mechanical hopper ash (as received), Kraft P1-P2 "fine" ash, Kraft P1-P2 bottom ash, and Niagara B24 bottom ash were -9-

18 carried out in accordance with ASTM Test Designation C 128. Test results are shown in Table 7. The Biron #5 mechanical hopper ash, Kraft P1-P2 "fine" ash and Niagara B24 bottom ash had an average apparent specific gravity of 1.84, 1.85 and 2.03, respectively. This is considerably lower than that for typical aggregates used in concrete, which is around Therefore, these sources of ash should be useful as semi-lightweight and/or lightweight aggregates. Specific gravity of Biron #4 slag, 2.67, is consistent with that of a typical concrete aggregate and may have applications as a decorative aggregate in concrete. The remaining materials, Biron #4 bottom ash and Kraft P1-P2 bottom ash have specific gravities slightly lower than a typical aggregate ( ). These may be useful for reducing the weight of the construction materials made from these ash materials. SSD Absorption For the coarser ashes (Biron #4 bottom ash, Biron #4 slag, Biron #5 mechanical hopper ash, Kraft P1-P2 "fine" ash, Kraft P1-P2 bottom ash, and Niagara B24 bottom ash) saturated surface dry (SSD) moisture absorption tests in accordance with the ASTM Test Designation C 128 were conducted. Results are shown in Table 8. These ash materials, with the exception of Biron #4 slag, had SSD absorption values that were considerably higher than that for typical sand or coarse aggregate used in concrete, which is typically less than 2%. The Kraft P1-P2 bottom ash had an absorption of over 50%. The SSD absorption value is an indication of the porosity of the aggregates. Typical lightweight aggregates used in concrete generally have very high absorption values and must be pre-soaked in order to manufacture consistent quality workable concrete. SSD moisture absorption value is also required for calculations for establishing and modifying cementbased construction materials mixture proportioning. er absorption materials may lead to better curing of the cement-based materials after they are cast; and, therefore, better quality for such materials. -10-

19 ASTM C 618 TESTS Physical Properties per ASTM C 618 ASTM C 618 provides standard specifications for coal fly ash for use in concrete. There is no other similar test standards available for wood ashes. Therefore, to judge the suitability of the CPI wood ash resource for potential use as a mineral admixture in cement-based materials, physical tests were performed as described below in accordance with the ASTM Test Designation C 618. The following physical properties of the CPI ash were determined: (1) Cement Activity Index; (2) Water Requirement; and, (3) Autoclave Expansion. Cement Activity Index Cement activity index tests for four fine ash materials (Biron #4 precipitator ash, Biron #5 precipitator ash, Biron #5 mechanical hopper ash, and Niagara B21-B23 fly ash) were performed in accordance with the ASTM Test Designation C 311/C 109. Two-inch mortar cubes were made in a prescribed manner using a mixture of cement, sand, and water, without any wood ash (Control Mixture). Compressive strength tests were conducted at the age of 3, 7, and 28 days. Actual strength test results, in psi, are reported in Table 9 for these test specimens made from the Control Mixture. Additional test mixtures were prepared using 80% cement and 20% CPI ash, by weight (instead of cement only without CPI ashes as in the Control Mixture). Four different mixtures were made with the four fine CPI ashes being evaluated in this study. Cube compressive strength test results, in psi, for these CPI ashes are also reported in Table

20 Comparison of the four CPI ash mixtures cube compressive strengths, with the Control Mixture, is reported in Table 10. These results are designated as Strength Activity Index with Cement. In this comparison, the Control Mixture was assigned a value of 100, at each age, and all other cube compressive strength values were scaled from this reference datum. The Biron #5 precipitator ash and Niagara B21-B23 fly ash samples pass the ASTM C 618 requirement for Cement Activity Index of Class N, C, and F fly ash (75% at either 7- or 28-day test age). Overall, the Activity Index with Cement test results of these two CPI ashes show that they are suitable for making medium strength (say up to 5,000 psi compressive strength) concrete and CLSM (which by the ACI Committee 229 Definition has up to 1,200 psi compressive strength). The cube compressive strength test results, Table 9, for the Biron #4 precipitator ash and Biron #5 mechanical hopper ash mixtures were lower than that for the Control Mixture without fly ash. The Activity Index with Cement data, Table 10, for these ashes were 54% to 58% (lower than 75% required for coal ash by ASTM C 618) for the compressive strength, compared with the Control Mixture without the CPI ash. However, the actual test data, Table 9, show that sufficient compressive strength can be achieved with the Biron #4 precipitator ash and Biron #5 mechanical hopper ash even though these ash mixtures did not perform as well as the no ash Control Mixture. Based upon the cube compressive strength data, overall, it can be concluded that the Biron #4 precipitator ash and Biron #5 mechanical hopper ash are suitable for making CLSM, including making slightly lower strength (say up to 4,000 psi compressive strength) concrete for base course and/or sub-base course for pavement of highways, roadways, and airfields; driveways; parking lots; and other similar construction applications. These ash sources can also be considered quite satisfactory for housing construction where typically a compressive strength of 3,000 psi concrete at the age of 28 days, is used. These two ash resources can also be used for in-house concrete -12-

21 construction needs of the CPI mills. In summary, ASTM C 618 classifies a value at 7-day or 28-day age of 75 or above for the Activity Index with Cement for coal fly ash as passing. Based upon this criterion only, the Biron #5 precipitator ash and Niagara B21-B23 fly ash pass and the Biron #4 precipitator ash and Biron #5 mechanical hopper ash do not pass either the 7 or 28 day requirement. Water Requirement Water requirement tests for the Biron #4 precipitator ash, Biron #5 precipitator ash, Biron #5 mechanical hopper ash, and Niagara B21-B23 fly ash were performed in accordance with the ASTM Test Designation C 311. This test determines the relative amount of water that may be required for mixture proportioning of cement-based construction materials. It is well established that the lower the water required for a desired value of workability for the cement-based material, the higher the overall quality of the product. Test data for water requirement for the CPI ashes are reported in Table 11. The results show that the average value for water requirement for the four CPI ashes tested were higher than the maximum desirable value for water requirement. ASTM C 618 specifies a maximum value of 105 or 115, depending upon the type of ash, as an acceptable value for water requirement. For coal fly ash the acceptable value is 105, while that for volcanic ash it is 115. It is concluded that these CPI ashes may perform satisfactorily in cement-based construction materials, even though the water required for a desired amount of workability probably would be somewhat higher. This would lead to a slightly higher amount of cement to compensate for the potential negative effects of the higher water content in the mixture. This negative effect of higher water required could also be overcome by judicious use of chemical admixtures which would be more cost-effective. -13-

22 Autoclave Expansion Autoclave expansion tests for the Biron #4 precipitator ash, Biron #5 precipitator ash, Niagara B21-B23 fly ash, and Niagara B24 bottom ash (material passing No. 20 sieve) were performed in accordance with the ASTM Test Designation C 311/C 151. Test specimens in the shape of bars were cast using cement paste containing these CPI ashes. The test specimens were then subjected to a high-temperature steam bath at approximately 295 psi pressure in a boiler (a pressure cooker meeting the requirements of the ASTM). The test results, given in Table 12, show that the expansion was negligible. The range of expansion values recorded for the CPI ash samples tested were well below the acceptable maximum limit of expansion/contraction of 0.8%, as specified by ASTM C 618 for coal fly ash. Therefore, all CPI ashes tested are acceptable in terms of long-term soundness/durability from the viewpoint of undesirable autoclave expansion. Table 13 shows physical properties requirements for coal fly ash per ASTM Test C 618. Chemical Properties per ASTM C 618 Chemical analysis tests were conducted to determine oxides present in the nine sources of the CPI ash. X-ray fluorescence (XRF) technique was used to detect the presence of silicon dioxide (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3), calcium oxide (CaO), magnesium oxide (MgO), titanium oxide (TiO2), potassium oxide (K2O), and sodium oxide (Na2O). In this method, ignited samples were fused in a 4:1 ratio with lithium carbonate-lithium tetraborate flux and cast into pellets in platinum molds. The XRF technique for measuring sulfate (SO3) involves grinding the ash sample and manufacturing a compressed pellet with boric acid. A double dilution method using a 4:1 and a 10:1 ratio with boric acid was used to correct for matrix effects. These buttons -14-

23 were used to measure x-ray fluorescence intensities for the desired element, in accordance with standard practice for cementitious materials, by using an automated Philips PW1410 x-ray spectrometer. The percentages of each element were derived from the measured intensities through a standardized computer program based on a procedure outlined for low-dilution fusion. This is a standard practice for detecting oxides in cementitious compounds, including coal fly ash. Tests are reported in Table 14. Loss on ignition (LOI), moisture content, and available alkali (Na2O equivalent) for the pre-dried CPI ashes were also determined. These test results are also reported in Table 14. According to the oxide analysis data, the Biron #4 precipitator ash, Biron #5 precipitator ash, Biron #5 mechanical hopper ash, Kraft P1-P2 "fine" ash, and Niagara B21-B23 fly ash do not meet Class C or F coal fly ash requirements due to one or more of the following: high LOI, high available alkali content, and high sulfate contents. The calcium oxide content for the Biron #4 bottom ash, Biron #5 precipitator ash, Biron #5 mechanical hopper ash, Kraft P1-P2 "fine" ash, and Kraft P1-P2 bottom ash is judged to be very good because the calcium oxide values are above 10 percent. Furthermore, the magnesium oxide values are judged to be quite low enough for all CPI ash samples to minimize the soundness/durability related problems created due to a high MgO value, which is accepted to be greater than five percent. In general all oxides present, except the available alkali (Na2O equivalent, LOI, and the sulfate content), were within limits specified in the ASTM C 618 for coal fly ash. Available alkali was higher than that specified in ASTM for the Biron #5 precipitator ash and Kraft P1-P2 "fine" ash. Maximum amount of available alkali for coal fly ash is limited to 1.5% in accordance with the ASTM C 618. The actual values were 7.2 and 1.9% for the Biron #5-15-

24 precipitator ash and the Kraft P1-P2 "fine" ash, respectively. Available alkali of the remaining CPI ashes tested were less than 1.5 percent. Bottom ash and slag samples typically had the lowest available alkali values, approximately percent. The presence of high amount of alkali may lead to desirable early hydration reaction products in coal fly ash, natural pozzolans, ground granulated blast-furnace slag, silica fume, and/or metakaoline types of reactive-powder additives used in making cement-based construction materials. Available alkali may also impact cementbased construction materials negatively (developing ASR, alkali silica reaction) if it contains freesilica-based compounds in coarse or fine aggregates used for making such construction materials. Furthermore, higher amounts of available alkali may also lead to chemical combination with sulfates and leaching of such sulfate-based white compounds ( precipitates ) on the surface of concrete (called efflorescence) creating undesirable, randomly distributed, white coloring on the concrete surface. Loss on ignition (LOI) for many CPI ashes is higher (approximately 20 to 40%) than that permitted (maximum 6%) by ASTM C 618 for coal fly ash, with the exception of Biron #4 bottom ash, Biron #4 slag, and Kraft P1-P2 bottom ash. Under certain circumstances, up to 12% maximum LOI is permitted by ASTM C 618. Recent research at the UWM Center for By- Products Utilization show that high-loi coal ash can be effectively used for CLSM as well as roller compacted concrete pavements. Currents practice in Wisconsin and elsewhere also show that high-loi coal fly ash should generally perform satisfactorily for CLSM. -LOI ashes affect the use of air-entering agent used in concrete to make the concrete resistant to a freezing and thawing environment. In general, therefore, the CPI ashes may be used for CLSM and concrete, no-fines concrete, roller compacted concrete pavements, dry-cast concrete products, etc. These types of construction materials do not require the use of air-entraining agent for freezing and thawing -16-

25 resistance of concrete. CHEMICAL COMPOSITION The mineral analysis, (i.e., chemical composition) for the CPI ashes were conducted by using the X-ray diffraction (XRD) method. The results are shown in Table 15. A typical coal fly ash contains approximately 80% glass (amorphous) phase. Since the glass contents of fly ash contributes to its potential pozzolanic reactivity, a higher amount of glass phase is preferred when a fly ash is used as cementitious materials. As can be expected, the Biron #4 slag contained the highest amounts of glass phase (100%). Biron #4 precipitator ash, Biron #5 mechanical hopper ash, Kraft P1-P2 "fine" ash, and Niagara B24 bottom ash had glass phases that range from 72-79% while glass phases of the Biron #4 bottom ash, Biron #5 precipitator ash, Kraft P1-P2 bottom ash, and Niagara B21-B23 fly ash ranged from percent. ELEMENTAL ANALYSIS All CPI ash samples were analyzed for total chemical make-up by the Instrumental Neutron Activation Analysis (INAA). Knowledge of total elemental concentration is necessary because it provides an insight into the possibility of leaching potential characteristics of the material tested. Leaching of trace metals is known to be highly dependent upon the temperature of the combustion in the boiler and how these trace elements are converted to chemical compounds. A high concentration of undesirable elements does not necessarily mean that these undesirable elements will leach. Tests for leachate characteristics of construction materials, such as TCLP, must be performed in order to conduct the environmental assessment of the materials proposed to be used and the product (e.g., cement-based materials) to be made from it. The results for the elemental analysis performed are reported in Table

26 SCANNING ELECTRON MICROSCOPY (SEM) A scanning electron microscope available at the University of Wisconsin-Milwaukee was employed for this part of the investigation. SEM pictures (photomicrographs) for the nine CPI ashes were obtained, Figures 10 through 45. These SEM pictures are an important part of understanding the character and morphology of the particles of the product being evaluated for considering their constructive use options. For example, studying the morphology allows judgment to be made regarding the physical and/or mechanical bond that might be possible for the wood ash in creating new cement-based construction materials. Also, it allows an opportunity to study the contours of the particles and how they may help in mixing and manufacturing these cement-based materials. The particle morphology helps in understanding the level of completeness of combustion and microstructure of burned, partially burned, or unburned particles. This evaluation of level of combustion, and particle size and distribution, also help in judging the water demand that may be placed upon for making cement-based materials. All nine CPI ash SEM micrographs can be observed to be composed of heterogeneous mixture of particles of varying size. Some glass-type material is present, particularly in the Biron #4 slag and other Biron #4 ashes. Partially hydrated, unhydrated, and hydrated compounds of calcium are also present. Unlike coal fly ash particles, these CPI ash particles are not all spherical in shape. Also, all of these CPI ash particles are not observed to be solid but some of them are cellular in form. These cellular particles are mostly unburned or partially burned wood or bark particles. -18-

27 Section 3 Constructive Use Options for CPI Ashes INTRODUCTION A number of uses of coal combustion products (CCP) in construction materials already exist [1]. However, these applications depend upon physical, chemical, mineralogical, and surface properties of such by-products. The same is true for the CPI ashes. The following sections deal with potential uses of the CPI ashes analyzed in this investigation. USES OF CPI WOOD ASHES The size distribution of some CPI ash products is similar to that of conventional coal ash products. In general, however, CPI fly ashes are not as fine as typical coal fly ash. Furthermore, the CPI ashes are irregular in shape versus spherical shape for coal fly ash. This means that when CPI ashes are added in mortar or concrete then workability of fresh mortar or concrete may not be helped as much as that typical with the use of coal fly ash. In fact, some porous particles of unburned or partially burned wood or coal (charcoal) may absorb the water added in mortar or concrete and further reduce the workability of the mixture. Some of the CPI ashes have high LOI (i.e., unburned or partially burned wood). This investigation revealed that the CPI ash samples generally did not conform to all parts of the -19-

28 ASTM C 618 Class F or C requirements for coal fly ash for applications in cement-based composites. ASTM C 618 also gives standard specifications for natural pozzolans, which is a volcanic ash. There are no wood ash ASTM standards available. Therefore, the CPI ashes cannot be compared to such standard specifications. However, the CPI fly ashes are still expected to be suitable for use in normal strength (up to 5,000 psi) concrete. The CPI ashes are also very suitable for CLSM and grouting applications. In some applications in which conventional coal fly ashes are used, the CPI ash cannot be used. However, the CPI ashes probably can be used effectively for many more applications after it is beneficiated; for example, after sieving coarser fractions and/or removing undesirable charcoal particles and thus reducing LOI. For more useful applications, with or without beneficiating CPI ashes, further study would be needed to develop optimum use options. A list of potential uses of the CPI ashes presented in Tables

29 Section 4 Suggestions for Further Evaluations As indicated in Section 3, the CPI ashes have considerable potential for many applications. However, the performance of these CPI ashes needs to be proven for individual applications. The following are some of the potential high-volume applications that would require further proof for various uses.. It is anticipated that these applications can consume most of the ash products produced by CPI. FLOWABLE MATERIALS Large amounts of CPI ashes can be utilized in manufacture of flowable fill (a.k.a. manufactured dirt) material. This is defined by ACI Committee 229 as Controlled -Strength Material (CLSM). The compressive strength of CLSM can be very little (10 psi) up to 1200 psi. This material can be used for foundations, bridge abutments, buildings, retaining walls, utility trenches, etc. as backfill; as embankment, grouts, abandoned tunnel and mine filling for stabilization of such cavities, etc. See Tables for more details. CLSM can be manufactured with large amounts of CPI ash, low amount of cement and/or lime, and high water-to-cementitious materials ratio to produce the flowable fill. An evaluation study is highly (very strongly) recommended in order to produce CLSM for various applications with this material for approval by local environmental agencies, such as Wisconsin Department of Natural Resources. Probability of success is excellent. -21-

30 BRICKS, BLOCKS, AND PAVING STONES The CPI ashes have potential for applications in numerous masonry products such as bricks, blocks, and paving stones. Additionally, these ashes can be utilized as a replacement of clay in manufacture of clay bricks. However, in order to meet the ASTM requirements for strength and durability, testing and evaluation work is necessary. The results of such testing would be used in developing specifications for the CPI ash in the manufacture of masonry products. Lab evaluation is strongly recommended. Probability of success is very high. MEDIUM-STRENGTH CONCRETE The CPI ashes can be used as a partial replacement of sand and/or cement in concrete. This is a very broad conclusion from the work conducted as a part of this test evaluation. Test results show that these wood ashes did not meet all ASTM C 618 coal ash requirements for concrete products applications. However, the ASTM C 618 is written exclusively for coal fly ash (and natural/volcanic ash) materials. Future ASTM standards, therefore, may evolve which could be satisfied by the CPI ashes. In order to determine the effects of optimum inclusion of the these ashes on concrete strength and durability properties, lab study is very strongly recommended. Probability of success is very high. DECORATIVE AGGREGATE - ROOFING SHINGLE GRIT The CPI Biron #4 slag has a very significant potential to be utilized as an architectural aggregate in concrete or as a roofing shingle grit. Based upon the limited testing performed for the project, these applications have the potential to be a significant source of revenue. A further evaluation is very strongly recommended. Probability of success is excellent. -22-

31 BLENDED CEMENT The highest market value use of the CPI ashes is in the production of blended cements. Blended cement material is typically composed of portland cement, coal fly ash, and/or other cementitious or pozzolonic materials, and chemicals. The CPI ashes have significant available alkali content (above the maximum allowed by ASTM C 618, Table 14). The high alkali content, however, would be a desirable characteristic for activating chemical reactions for cementing-ability of blended cements for various applications. Further evaluation is very strongly recommended. Probability of success is very high. ROLLER-COMPACTED CONCRETE PAVEMENT The CPI ashes can be used for Roller-Compacted Concrete Pavement (RCCP) for improving the performance and use of log-yards in all types of Wisconsin weather. Log-yards pavings using CPI ashes would be a very important application. RCCP popularity is increasing in Wisconsin. Lab evaluation is very strongly recommended for future applications. Probability of success is very high. SOIL AMENDMENT WITH OR WITHOUT DREDGED MATERIALS Wisconsin dredges a significant tonnage of dredged materials from the Great Lakes and the Mississippi River to keep the navigation channels open. The CPI ashes would be an excellent additive to dredged materials to make manufactured topsoil for use in tree farms, sod farms, potting soil, pulp-mill new growth woods/plantations, etc. These ashes will act as a desiccant, deodorizer, and chemical activators for dredged materials. The resulting manufactured topsoil can be used as a fertilizer, and to decrease subsurface porosity and -23-

32 improve infiltration characteristics of soils. Further lab study is very strongly recommended. Probability of success is very high. -24-

33 CONSOLIDATED PAPERS, INC. ASH CHARACTERIZATION Biron #4 Precipitator Ash, Bottom Ash and Slag. Biron #5 Precipitator Ash and Mechanical Hopper Ash. Kraft P1 and P2 "Fine" Ash and Bottom Ash. Niagara B21-B23 Fly Ash. Niagara B24 Bottom Ash. -25-

34 Table 1: As-Received CPI Ash Moisture Content Moisture Content, % Ash Source* Biron #4 Precipitator Ash Biron #4 Bottom Ash Biron #4 Slag Biron #5 Precipitator Ash Biron #5 Mechanical Hopper Ash Kraft P1-P2 "Fine" Ash Kraft P1-P2 Bottom Ash Niagara B21-B23 Fly Ash Niagara B24 Bottom Ash Actual** Average * All samples were received in August ** Moisture content, as-received, % = (as-received sample wt. - dry sample wt.) * 100 dry sample weight -26-

35 CONSOLIDATED PAPERS, INC. ASH PARTICLE SIZE ANALYSIS -27-

36 Table 2: Sieve Analysis of CPI Ash (As-Received Samples) (Tests conducted per ASTM C 136) Biron #4 Precipitator Ash Sieve Size % Passing* 3/4" (19.1-mm) NA*** 1/2" (12.7-mm) NA*** 3/8" (9.5-mm) NA*** #4 (4.75-mm) NA*** #8 (2.36 mm) NA*** #16 (1.18 mm) NA*** #30 (600 μm**) NA*** #50 (300 μm**) NA*** #100 (150 μm**) NA*** Biron #4 Bottom Ash Sieve Size % Passing* ASTM C 33 % Passing for sand 3/8" (9.5-mm) #4 (4.75-mm) to 100 #8 (2.36 mm) to 100 #16 (1.18 mm) to 85 #30 (600 μm**) to 60 #50 (300 μm**) to 30 #100 (150 μm**) to 10 * Values reported for % passing are the average of two tests. ** 1.0 μm = 10-6 m = mm *** NA = Test is not applicable, material very fine, see Fig

37 Table 2 (Continued): Sieve Analysis of CPI Ash (As-Received Samples) (Tests conducted per ASTM C 136) Biron #4 Slag Sieve Size % Passing* ASTM C 33 % Passing for sand 3/8" (9.5-mm) #4 (4.75-mm) to 100 #8 (2.36 mm) to 100 #16 (1.18 mm) to 85 #30 (600 μm**) to 60 #50 (300 μm**) to 30 #100 (150 μm**) to 10 Biron #5 Precipitator Ash Sieve Size % Passing* 3/8" (9.5-mm) NA*** #4 (4.75-mm) NA*** #8 (2.36 mm) NA*** #16 (1.18 mm) NA*** #30 (600 μm**) NA*** #50 (300 μm**) NA*** #100 (150 μm**) NA*** * Values reported for % passing are the average of two tests. ** 1.0 μm = 10-6 m = mm ***NA = Test not applicable, material very fine, see Fig

38 Table 2 (Continued): Sieve Analysis of CPI Ash (As-Received Samples) (Tests conducted per ASTM C 136) Biron #5 Mechanical Hopper Ash Sieve Size % Passing* ASTM C 33 % Passing for sand 3/8" (9.5-mm) #4 (4.75-mm) to 100 #8 (2.36 mm) to 100 #16 (1.18 mm) to 85 #30 (600 μm**) to 60 #50 (300 μm**) to 30 #100 (150 μm**) to 10 Kraft P1-P2 "Fine" Ash Sieve Size % Passing* ASTM C 33 % Passing for sand 3/8" (9.5-mm) #4 (4.75-mm) to 100 #8 (2.36 mm) to 100 #16 (1.18 mm) to 85 #30 (600 μm**) to 60 #50 (300 μm**) to 30 #100 (150 μm**) to 10 * Values reported for % passing are the average of two tests. ** 1.0 μm = 10-6 m = mm -30-

39 Table 2 (Continued): Sieve Analysis of CPI Ash (As-Received Samples) (Tests conducted per ASTM C 136) Kraft P1-P2 Bottom Ash Sieve Size % Passing* ASTM C 33 % Passing for sand 1/2" (12.7-mm) /8" (9.5-mm) #4 (4.75-mm) to 100 #8 (2.36 mm) to 100 #16 (1.18 mm) to 85 #30 (600 μm**) to 60 #50 (300 μm**) to 30 #100 (150 μm**) to 10 Niagara B21-B23 Fly Ash Sieve Size % Passing* 3/4" (19.1-mm) NA*** 1/2" (12.7-mm) NA*** 3/8" (9.5-mm) NA*** #4 (4.75-mm) NA*** #8 (2.36 mm) NA*** #16 (1.18 mm) NA*** #30 (600 μm**) NA*** #50 (300 μm**) NA*** #100 (150 μm**) NA*** * Values reported for % passing are the average of two tests. ** 1.0 μm = 10-6 m = mm -31-