Center for By-Products Utilization

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1 Center for By-Products Utilization USE OF FGD MATERIAL AND PONDED CLASS F CCPs IN READY-MIXED CONCRETE By Tarun R. Naik, Rudolph N. Kraus, Rafat Siddique, and Francois Botha Report No. CBU REP-518 June 2003 For Submission to Construction and Building Materials Journal. Department of Civil Engineering and Mechanics College of Engineering and Applied Science THE UNIVERSITY OF WISCONSIN - MILWAUKEE

2 Use of FGD Material and Ponded Class F CCPs in Ready-Mixed Concrete by Tarun R. Naik a, Rudolph N. Kraus b, Rafat Siddique c, and Francois Botha d a Director, b Assistant Director, c Research Associate UWM Center for By-Products Utilization, Department of Civil Engineering and Mechanics, College of Engineering and Applied Science, University of Wisconsin-Milwaukee, P.O. Box 784, Milwaukee, WI d Project Manager, Illinois Clean Coal Institute, 5776 Coal Drive, Suite 200, Carterville, IL Abstract This paper presents the results of experimental investigations carried out to study the effects of FGD material and ponded Class F CCPs (coarse Class F ash) on the properties of non-air-entrained and air-entrained concrete. A FGD material is defined as the ash derived from thermal power plants using clean-coal technologies such as SO 2 Control Systems, NO x Control Technology, Fluidized Bed Combustion, and Gasification Combined Cycle for reducing SO x and NO x. FGD material is generally obtained by combustion of high-sulfur coal. Ponded ash is usually a mixture of fly ash and bottom ash or boiler slag. Concrete was made and tested in laboratory as well as at a readymixed concrete plant. A total of nine concrete mixtures were produced: three non-airentrained concrete mixtures, three non-air-entrained concrete mixtures with HRWRA, and three air-entrained concrete mixtures. Percentage of FGD material varied from 22 to 45 % of the total cementitious (cement and FGD material) materials in non-air-entrained 1

3 concrete and 17 to 27 % in the air-entrained concrete. All concrete mixtures also contained ponded, coarse Class F ash, as a replacement of up to 6 % of aggregates. Control mixture of non-air-entrained concrete and non-air-entrained concrete with HRWRA were proportioned to attain 28-day compressive strength of 35 MPa. Control mixture of air-entrained concrete was proportioned to achieve compressive strength of 28 MPa at 28 days. Tests were performed for fresh concrete properties, and also for compressive strength, splitting tensile strength, flexural strength, and abrasion resistance. For air-entrained concrete mixtures, salt-scaling test was also conducted. Based on the tests results it was concluded that: (1) non-air-entrained concrete mixtures can successfully incorporate up to 22 % FGD material and a blend of 34 % FGD material and 6 % coarse Class F ash; (2) FGD material up to 45 % and 6 % of coarse Class F ash can also be used in non-air-entrained concrete mixtures using HRWRA for general concrete construction; and, (3) air-entrained concrete mixtures incorporating up to 17 % FGD material and blends of 27 % FGD material and 5% coarse Class F ash can also be used for general concrete construction. Keywords: Abrasion resistance; Coarse Class F ash; Compressive strength; Density; FGD material; Flexural strength; Salt-scaling; Splitting-tensile strength; Slump 2

4 1. Introduction Approximately 107 million tonnes of coal-combustion products (62 million tonnes of fly ash, 17 million tonnes of bottom ash, 2.3 million tonnes of boiler slag, and 26 million tonnes of flue gas desulfurization (FGD) material) were generated in USA in the year The overall utilization rate in the USA for all coal ashes was approximately 32% in the year Although a great deal of research has been conducted on utilization of Class F fly ash in concrete and concrete products [1-8], relatively very little work has been conducted in developing products containing FGD material compared to conventional coal ash. Utilization of FGD material is much lower than Class F fly ash. With increasing federal regulations on power plant emissions, finding use for FGD material (vs. Class F fly ash) is becoming a more important issue since the quantity of FGD material will increase. Finding practical solutions to this "ash problem" is essential due to shrinking landfill space, environmental concerns, and increased public awareness. Recent research studies [9-15] have shown various potential applications for FGD material. The UWM Center for By-Products Utilization (UWM-CBU) has conducted a number of projects on high-volume uses of both Class F and Class C fly ashes in cementitious products for the last two decades. UWM-CBU has also worked on concrete using FGD material since the late 1980 s. Naik and Kraus [15] have reported promising results for concrete and cast-concrete products utilizing FGD material and FGD material blended with Class F fly ash from Illinois. 3

5 2. Experimental procedure 2.1 Materials Type I portland cement (ASTM C 150) was used in this work. A source of FGD material and an ASTM Class F fly ash from a wet-collection process was used for the current investigation [13,14]. The as-received moisture content of the Class F fly ash was approximately 29 %. The fine aggregate for concrete was natural sand. The coarse aggregate for concrete mixtures was natural gravel with a 19 mm maximum size. A normal water-reducing admixture (ASTM C 494, Type A) was used in both non-airentrained and air-entrained concrete mixtures, and a high-range water-reducing admixture (HRWRA) (ASTM C 494, Type F) was used in the HRWRA concrete mixtures. An air-entraining admixture (ASTM C 260) was used in air-entrained concrete mixtures. 2.2 Mixture proportions A total of nine concrete mixtures were produced: three non-air-entrained concrete mixtures, three non-air-entrained concrete mixtures with HRWRA, and three airentrained concrete mixtures. Mixture proportions of non-air-entrained concrete are given in Table 1. There was one control concrete mixture, and two concrete mixtures with 22 % and 34 % by mass of FGD material of the total cementitious (cement and FGD material) materials. Third mixture also contained the coarse Class F fly ash, 6 % (by mass) of ash plus sand plus coarse aggregates. Mixture proportions of non-air-entrained HRWRA concrete are given in Table 1. There was one control concrete mixture and the remaining two contained 35 % and 45 % of FGD material by mass of the total 4

6 cementitious (cement and FGD material) materials. The third mixture also contained 6 % coarse Class F ash as a replacement of fine and coarse aggregates. Mixture proportions of air-entrained concrete are given in Table 1. First mixture was control concrete mixture, and the remaining two were proportioned to contain FGD material at cement replacements of 17 % and 27 % of total cementitious (cement and FGD material) materials. Third mixture also incorporated 5% of the coarse Class F ash as a replacement of fine and coarse aggregates. Non-air-entrained concrete mixtures recorded slump in the range of mm, and density between 2208 and 2368 kg/m 3. Non-air-entrained HRWRA concrete mixtures had slump of mm, and density between 2220 and 2365 kg/m 3. The air-entrained concrete mixtures recorded slump of mm, and density between 2211 and 2387 kg/m Manufacturing of concrete mixtures The required amount of the fly ash was manually weighed and loaded into the ready-mixed concrete truck prior to the addition of the other concrete ingredients in the truck. All the other ingredients were automatically batched and mixed at the ready-mixed concrete plant. Additional water and/or HRWRA were added to the mixture as needed for achieving the desired level of workability. Whenever any additional water and/or HRWRA were added, the concrete mixture was mixed at a high-mixing speed for an additional minimum three minutes. After all the materials were added to the truck, they were mixed at the maximum mixing speed for 70 revolutions. Transportation time to a typical job site was then simulated by mixing at transit speed. The concrete was transported to a nearby facility of the plant for fresh concrete properties measurements 5

7 and for casting test specimens. 2.4 Specimen preparation and testing Test specimens were prepared for compressive strength, splitting-tensile strength, flexural strength, and abrasion resistance for non-air-entrained, non-air-entrained with HRWRA, and air-entrained concrete mixtures. For air-entrained concrete mixtures, test specimens were also made for salt-scaling resistance. Compressive strength (ASTM C 39), splitting-tensile strength (ASTM C 496), flexural strength (ASTM C 78), and saltscaling resistance using 4 % CaCl 2 (ASTM C 672) tests were conducted. 3. Results and discussion 3.1 Compressive strength Compressive strength test results data for non-air-entrained concrete mixtures are shown in Fig. 1. The compressive strength of Control concrete mixture was 34.5 MPa at the age of 28 days. Compressive strength at the age of 28 days ranged from 24.8 to 36.6 MPa, and increased to 32.4 to 44.1 MPa at the age of 182 days. The compressive strength decreased with increase in FGD material content. The rate of compressive strength gain was approximately the same for all of the mixtures (N1, N2, and N3). The pozzolanic effect of the FGD material did not significantly increase the compressive strength of the mixtures through the age of 182 days. However the compressive strengths achieved by all test mixtures, were suitable for most construction applications. Water-to-cementitious materials ratio should be decreased for Mixture N3 in order to increase the strength to the desired level. 6

8 The compressive strength test results for the non-air-entrained HRWRA concrete mixtures are shown in Fig. 2. The compressive strength of Control concrete mixture was 36.6 MPa at 28 days. Compressive strength of the mixtures ranged from 24.1 to 36.4 MPa at the age of 28 days to a range of 36.6 to 51.3 MPa at the age of 182 days. Similar to the non-air-entrained concrete mixtures, compressive strength of the non-air-entrained HRWRA concrete mixtures decreased as the amount of CCPs increased in the mixture. This is primarily attributed to higher W/Cm for Mixtures NS2 and NS3 containing CCPs. The rate of increase of all three mixtures were approximately the same between the ages of 28 and 182 days, which indicates that the pozzolanic contribution was not significant after 28 days. Compressive strengths achieved by the non-air-entrained HRWRA concrete mixtures between the ages of 28 days and 182 days are again suitable for most concrete construction applications. The compressive strength results for air-entrained concrete mixtures are shown in Fig. 3. Control mixture A1, attained the compressive strength of 31.3 MPa at the age of 28 days, and 38 MPa at the age of 182 days. Mixture A2, containing 17 % FGD material exhibited higher compressive strength than Control mixture (38.2 MPa at 28 days and 51.8 MPa at 182 days). The higher compressive strength is attributed to the lower air content of this mixture compared to the Control mixture. Mixture A3, containing 20 % FGD material and 5 % coarse Class F ash had compressive strength that was lower than Mixture A1, 22.1 MPa at 28 days and 31.5 MPa at the age of 182 days, but achieved strength that were again acceptable for many concrete applications. 3.2 Splitting-tensile strength The splitting-tensile strength data for the non-air-entrained concrete mixtures are 7

9 shown in Fig. 4. Splitting-tensile strength of the concrete mixtures decreased with increase in fly ash content. Splitting-tensile strength of the mixtures containing ash at the ages of 7 and 28 days were initially lower than the Control mixture; however, at the age of 182 days, these mixtures met or exceeded the strength of Control mixture. Mixture N1 (no ash) achieved strengths of 2.5, 3.0, 3.3, and 3.5 MPa at the ages of 7, 28, 91, and 182 days, respectively. Splitting-tensile strength at the age of 7 days of Mixture N2 (22 % FGD material) was 1.9 MPa, but at 182 days it obtained strength of 4.2 MPa, which exceeded that of Control mixture. The splitting-tensile strength results for the non-air-entrained HRWRA concrete mixtures are shown in Fig. 5. The splitting-tensile strength of Control mixture, NS1, was much higher than the mixtures containing ash at the age of 7 days. Beyond the age of 7 days, the rate of increase of splitting-tensile strength was much greater for the mixtures containing ash. Splitting-tensile strength of mixture NS2 (35 % FGD material) was within 10 % of the strength of Control mixture at the age of 91 and 182 days. This is a significant improvement from the results from the 7-day test age, which were only 43 % of the strength of Control mixture. The splitting-tensile strength data for the air-entrained concrete mixtures are shown in Fig. 6. The general trend was similar to that for the non-air-entrained concrete mixtures through the age of 28 days. Splitting-tensile strength of Mixture A2 (containing 17% FGD material) was higher than Control mixture without fly ash. This again is attributed to lower air content and higher density of Mixture A2 as compared with Control mixture A1. 8

10 3.3 Flexural strength For non-air-entrained concrete mixtures (Fig. 7), the rate of strength gain for mixtures containing fly ash (Mixture N2 and N3) were lower than Control mixture without fly ash (Mixture N1). Generally fly ash mixtures achieved lower compressive strength than Control mixture N1 at the early age of 7 days. The difference between the fly ash mixtures and Control mixture decreased significantly beyond the age of 7 days whereas at later ages the flexural strength of Mixture N2 (22 % FGD material) exceeded the control mixture. The flexural strength results of the non-air-entrained HRWRA concrete mixtures are shown in Fig. 8. In general, flexural strength of concrete mixtures increased with age and decreased with increasing fly ash content, although at later ages the differences were small. At 28 days, the concrete mixtures containing fly ash (Mixtures NS2 and NS3) achieved strengths within 20 % of Control mixture (Mixture NS1). This margin further decreased at the 56 days age; and Mixtures NS2 and NS3 achieved flexural strengths within 10 % of Control mixture. The 28 and 56 days flexural strength was a dramatic improvement from the strength achieved the age of 4 days. The flexural strength data for air-entrained concrete mixtures are shown in Fig. 9. Flexural strengths obtained for these mixtures at the age of 28 days ranged from 3.3 to 4.5 MPa, and from 4.8 to 5.6 MPa at the age of 91 days. The strength achieved for Control mixture (Mixture A1), 4.2 MPa at the age of 28 days and 4.9 MPa at 91 days, was exceeded by the mixture containing 17 % clean-coal fly ash (Mixture A2). This trend agrees with the compressive and splitting-tensile strengths of the mixture and again 9

11 may be attributed to the lower air content. Mixture A3, containing 27 % FGD material and 5 % coarse Class F ash attained a flexural strength of 3.3 MPa at 28 days, and 4.8 MPa at 91 days. This is lower than Control mixture, but is considerably higher than the early age strength of 1.7 MPa obtained at 4 days. The rate of strength gain for this mixture, through the 91 days, is the highest of the three mixtures tested. 3.4 Abrasion resistance The maximum depth of abrasion of the non-air-entrained concrete mixtures is given in Fig. 10. The depth of wear data for Control mixture without ash was approximately 1.3 mm after 60 minutes of abrasion. Mixtures containing ash performed significantly better than Control mixture. Depth of wear for Mixture N2 (22% FGD material) was 0.5 mm whereas it was 0.6 mm for Mixture N3 (34 % FGD material, 6 % coarse Class ash). This improvement in abrasion resistance was expected since concrete made with fly ash have a less porous structure [2,6]. Test data for the non-air-entrained HRWRA concrete mixtures show that the depth of wear for all mixtures was less than 0.55 mm after 60 minutes of abrasion (Fig. 11). Air-entrained concrete mixtures (Fig. 12) also exhibited low abrasion values, less than a 0.7 mm depth of wear after 60 minutes of abrasion. Concrete exhibiting less than 2 mm depth of wear after 60 minutes of abrasion is considered to have adequate resistance to abrasion (per ASTM C 944 procedure). In general, all types of concrete mixtures with FGD material and coarse Class F ash were considered to have an excellent resistance to abrasion, and in fact out-performed Control mixtures without fly ash. 10

12 3.5 Salt-scaling resistance Resistance to scaling of the air-entrained concrete mixtures exposed to deicing chemicals is given in Fig. 13. Per ASTM C 672, the concrete surface was exposed to a 4% solution of calcium chloride. The test results are given as a visual rating of the concrete surface that is evaluated after every five cycles of freezing and thawing. The visual rating ranges from 0, which indicates no surface scaling to 5 for a surface exhibiting severe scaling with coarse aggregate visible over the entire surface. The surface of Control mixture without ash (Mixture A1) had slight to moderate scaling from 15 to 50 cycles. Mixtures containing fly ash were less resistant to scaling than Control mixture [6]. Mixture A2 (17 % FGD material) exhibited moderate to severe scaling starting at 15 cycles and continued through 50 cycles. Mixture A3 (27 % clean coal ash, 5 % coarse Class F ash) performed the worst of the three mixtures, with the surface exhibiting severe scaling after only five cycles. The relatively poor performance of both mixtures containing ash is attributed to the low air content of the mixtures compared to Control mixture. 4. Conclusions Based on strength and durability testing conducted, the following conclusions are made: 1. Non-air-entrained concrete incorporating up to 22 % FGD material by mass of cementitious materials showed either equivalent or higher compressive, splittingtensile, flexural strengths, and abrasion resistance when compared with Control concrete made without ash. 2. Non-air-entrained concrete incorporating 34 % FGD material and 6 % coarse 11

13 Class F ash showed lower compressive strength; but either equivalent of higher splitting-tensile strength and flexural strength, and higher abrasion resistance when compared with Control mixture. 3. Non-air-entrained concrete with HRWRA incorporating 45 % FGD material and 6 % coarse Class F ash showed almost equivalent compressive strengths, lower splitting-tensile strength, and higher flexural and abrasion resistance when compared with Control mixture. 4. Air-entrained concrete mixtures result indicated that although strength of the mixtures incorporating up to 17 % FGD material and blends of 27 % FGD material and 5 % coarse Class F ash can be used for typical construction, durability results from this project are not yet definitive. Air contents of the mixtures containing ash were lower than Control mixture without ash. Therefore, salt-scaling resistance of the mixtures without ash were negatively influenced compared with Control mixture. Additional testing is recommended for improving these mixtures required for freezing and thawing environment. Acknowledgements The authors wish to express their deep sense of gratitude for the grants made possible by the Illinois Department of Commerce and Community Affairs through the Office of Coal Development and Marketing and Illinois Clean Coal Institute. Authors also like to acknowledge their full appreciation for the support and guidance extended by Dr. Francois Botha, Project Manager, ICCI. Authors also wish to thank members of the UWM-CBU laboratory staff and students for their help and cooperation. 12

14 The UWM Center for By-Products Utilization was established in 1988 with a generous grant from Dairyland Power Cooperative, Lacrosse, Wisconsin; Madison Gas and Electric Company, Madison, Wisconsin; National Minerals Corporation, St. Paul, Minnesota; Northern States Power Company, Eau Claire, Wisconsin; We Energies, Milwaukee, Wisconsin; Wisconsin Power and Light Company, Madison, Wisconsin; and Wisconsin Public Service Corporation, Green Bay, Wisconsin. Their financial support and support from Manitowoc Public Utilities, Manitowoc, Wisconsin are gratefully acknowledged. Notice to Journalists and Publishers: If you borrow information from any part of this report, you must include a statement about the State of Illinois' support of the project. References [1] ACI 226 Committee. Use of fly ash in concrete. ACI Materials Journal 1987; 84 (5): [2] Naik TR, Singh SS. Effects of temperature and type F fly ash on compressive strength and abrasion resistance of concrete. Proceedings of the Second CANMET/ACI International Conference on Durability of Concrete, Montreal, Canada, (Ed. V. M. Malhotra) 1991: [3] Berry EE, Hemmings RT, Langley WS, Carette GG. Beneficiated fly ash: hydration, microstructure, and strength development in portland cement systems. Proceedings of the Third International Conference on the Use of Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete, Trondheim, Norway, ACI Special Publication SP :

15 [4] Mehta P K, Pozzolanic and cementitious by-products and mineral admixtures for concrete - a critical review. Proceedings of the First International Symposium on the Use of Fly Ash, Silica Fume, and other minerals in Concrete, Montebellow, Canada, ACI Special Publication No. SP : [5] Naik TR, Ramme BW. High early strength fly ash concrete for precast/prestressed products. PCI Journal 1990; 35 (6): [6] Naik TR, Ramme BW, Tews JH. Pavement construction with high volume Class C and Class F fly ash concrete. ACI Materials Journal 1995; 92 (2): [7] Naik TR, Sivasundaram V, Singh SS. Use of high-volume Class F fly ash for structural grade concrete. Transportation Record No. 1301, TRB, National Research Council, Washington D. C. 1991: [8] Naik TR, Singh SS. Fly ash generation and utilization - an overview. Published in the book titled "Recent Trend in Fly Ash Utilization", Ministry of Environment and Forests Management, Government of India (Ed. R. K. Suri and A. B. Harapanahalli) 1993: [9] Naik, TR, Patel VM, Peiper LA. Clean-coal by-products utilization in roadway, embankments, and backfills. Report, CBU , UWM Center for By-Products Utilization, University of Wisconsin-Milwaukee 1991: 35 pp. [10] Rick RD, Hilton R G, Smith CL. Utilization of flue gas desulfurization sludge. Proceedings of the EPRI-EPA 1990 SO 2 Control Symposium, Session 3B: By- Products Utilization 1990; Vol. 1. [11] Henzel D S. Commercial utilization of so 2 removal wastes in the application of new advanced control technology. Proceedings of the EPRI-EPA 1990 SO 2 Control 14

16 Symposium, Session 3B: By-Products Utilization 1990; Vol.1. [12] Naik TR, Kolbeck HJ, Singh SS, Kraus RN. Low-cost high-performance materials using Illinois coal combustion by-products - phase II. Report, CBU , UWM Center for By-Products Utilization, University of Wisconsin-Milwaukee 1997: 30 pp. [13] Naik TR, Banerjee DD, Kraus RN, Singh SS. Characterization and application of class f fly ash and clean coal ash for cement-based materials. Proceedings of the Twelfth ACAA International Symposium, Orlando, Florida, January [14] Naik TR, Banerjee DD, Kraus RK, Singh SS. Use of Class F fly ash and clean-coal ash blends for cast-concrete products. Proceedings of the Twelfth ACAA International Symposium, Orlando, Florida, January [15] Naik TR, Kraus RN. Low-cost, high-performance materials using Illinois coalcombustion by-products. Report No. CBU , UWM Center for By-Products Utilization, University of Wisconsin-Milwaukee, Milwaukee 2000: 29 pp. 15

17 Table 1 Concrete mixture proportions Non-air-entrained mixtures Non-air-entrained mixtures with HRWRA Air-entrained mixtures Mixture number N1 N2 N3 NS1 NS2 NS3 A1 A2 A3 FGD material (% of Cement and FGD material) Coarse Class F ash (% of total fine and coarse aggregates) Cement (kg/m 3 ), C FGD material (kg/m 3 ), A Water (kg/m 3 ), W W/Cm* SSD coarse Class F ash (kg/m 3 ), A SSD fine aggregate (kg/m 3 ) SSD 19 mm aggregate (kg/m 3 ) Water reducing admixture (L/m 3 ) HRWRA (L/m 3 ) Air-entraining admixture Air temperature ( C) Slump (mm) Air content (%) Density (kg/m 3 ) * W/Cm = W/(C+A1)

18 Compressive strength (MPa) Mixture N1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture N2, 22 % FGD Material, 0 % (of agg.) Class F Ash Mixture N3, 34 % FGD Material, 6 % (of agg.) Class F Ash Age (days) Fig. 1. Compressive strength of non-air-entrained concrete

19 Compressive strength (MPa) Mixture NS1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture NS2, 35 % FGD Material, 0 % (of agg.) Class F Ash Mixture NS3, 45 % FGD Material, 6 % (of agg.) Class F Ash Age (days) Fig. 2. Compressive strength of non-air entrained with HRWRA concrete 18

20 Compressive strength (MPa) Mixture A1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture A2, 17 % FGD Material, 0 % (of agg.) Class F Ash Mixture A3, 27 % FGD Material, 5 % (of agg.) Class F Ash Age (days) Fig. 3. Compressive strength of air-entrained concrete 19

21 Splitting-tensile strength (MPa) Mixture N1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture N2, 22 % FGD Material, 0 % (of agg.) Class F Ash Mixture N3, 34 % FGD Material, 6 % (of agg.) Class F Ash Age (days) Fig. 4. Splitting-tensile strength of non-air-entrained concrete 20

22 Splitting-tensile Strength (MPa) Mixture NS1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture NS2, 35 % FGD Material, 0 % (of agg.) Class F Ash Mixture NS3, 45 % FGD Material, 6 % (of agg.) Class F Ash Age (days) Fig. 5. Splitting-tensile strength of non-air-entrained with HRWRA concrete 21

23 Splitting-tensile strength (MPa) Mixture A1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture A2, 17 % FGD Material, 0 % (of agg.) Class F Ash Mixture A3, 27 % FGD Material, 5 % (of agg.) Class F Ash Age (days) Fig. 6. Splitting-tensile strength of air entrained concrete 22

24 Flexural strength (MPa) Mixture N1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture N2, 22 % FGD Material, 0 % (of agg.) Class F Ash Mixture N3, 34 % FGD Material, 6 % (of agg.)class F Ash Age (days) Fig. 7. Flexural strength of non-air-entrained concrete 23

25 Flexural strength (MPa) Mixture NS1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture NS2, 35 % FGD Material, 0 % (of agg.) Class F Ash Mixture NS3, 45 % FGD Material, 6 % (of agg.) Class F Ash Age (days) Fig. 8. Flexural strength of non-air-entrained with HRWRA concrete 24

26 Flexural strength (MPa) Mixture A1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture A2, 17 % FGD Material, 0 % (of agg.) Class F Ash Mixture A3, 27 % FGD Material, 5 % (of agg.) Class F Ash Age (days) Fig. 9. Flexural strength of air-entrained concrete 25

27 Depth of wear (mm) Mixture N1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture N2, 22 % FGD Material, 0 % (of agg.) Class F Ash Mixture N3, 34 % FGD Material, 6 % (of agg.) Class F Ash Abrasion time (Minutes) Fig. 10. Abrasion resistance of non-air-entrained concrete at 182 days 26

28 Depth of wear (mm) Mixture NS1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture NS2, 35 % FGD Material, 0 % (of agg.) Class F Ash Mixture NS3, 45 % FGD Material, 6 % (of agg.) Class F Ash Abrasion time (Minutes) Fig. 11. Abrasion resistance of non-air-entrained with HRWRA concrete at 182 days 27

29 Depth of wear (mm) Mixture A1, Control, 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture A2, 17 % FGD Material, 0 % (of agg.) Class F Ash Mixture A3, 27 % FGD Material, 5 % (of agg.) Class F Ash Abrasion time (Minutes) Fig. 12. Abrasion resistance of air-entrained concrete at 182 days 28

30 Visual rating Mixture A1, Control 0 % FGD Material, 0 % (of agg.) Class F Ash Mixture A2, 17 % FGD Material, 0 % (of agg.) Class F Ash Mixture A3, 27 % FGD Material, 5 % (of agg.) Class F Ash Cycles Fig. 13. Resistance to salt-scaling of air-entrained concrete 29