IMPLEMENTATION OF TECHNOLOGY FOR CONTROLLED LOW-STRENGTH MATERIALS USING ILLINOIS COAL
COMBUSTION PRODUCTS
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Title
IMPLEMENTATION OF TECHNOLOGY FOR CONTROLLED LOW-STRENGTH MATERIALS USING ILLINOIS COAL
COMBUSTION PRODUCTS
COMBUSTION PRODUCTS
ICCI Project ID
00-1/3.1B-5
Investigator
Naik
Institution
University of Wisconsin-Milwaukee
ICCI Abstract
Approximately 5.5 million tons of coal combustion products are generated each year from combustion of Illinois coal. About 3.0 million tons of these coal combustion products are produced in Illinois and the remaining 2.5 million tons are generated in other states (including Wisconsin) burning Illinois coal. A majority of these 5.5 million tons of ash products are landfilled. The overall utilization rate in the USA for all coal ashes was approximately 30% in 1999 (i.e., about 30 million tons). Illinois coal, when it is burned in conventional boilers, produces Class F, low-lime, fly ash. In general, utilization rate of Class F fly ash in U.S.A. is substantially lower relative to Class C, high-lime, fly ash. This is partly due to the perceived lower quality of Class F fly ash compared to Class C fly ash, and greater variation in its properties, especially for the fly ash generated from older power plants. Also, there is a significant lack of commercial products that use high-volumes of Class F fly ash; and, there is even a greater lack of use for clean coal ash. Due to shrinking landfill space, to solve environmental concerns, and due to increased public awareness and debate, it has become mandatory to find practical solutions to this "ash problem".
The objective of this project was to implement technology and development of markets for controlled low-strength material (CLSM) slurry for use in Illinois using Illinois coal ash as the main component, meeting Illinois regulations, for use by Illinois state agencies, and others, especially Illinois Department of Transportation (IDOT). Use of significant quantities of Illinois coal ash in CLSM slurry will result in reduced costs to users of Illinois coal. The CLSM mixtures developed for this project used a wet-collected Class F coal ash obtained from Pekin, IL. CLSM slurry may be used wherever a typical compacted backfill material is used such as for pavement sub-base, utility trenches, backfill around foundations, foundation base materials, etc. The Illinois Department of Transportation (IDOT) has developed and written specifications for use of CLSM slurry and general acceptance criteria. Some county highway departments already accept the IDOT specifications and allow CLSM use for backfilling utility trenches. Many potential Illinois users and producers of CLSM slurry have not been familiar with the many advantages of CLSM over traditional backfill materials. The existence of approved Illinois specifications on CLSM, and considerable existing literature on CLSM containing high-volumes of fly ash, indicate that CLSM slurry may not need additional research dollars. However, to meet the objectives of market development and to promote the use of Illinois coal ash and production technology of CLSM slurry, this project focused on bringing the technology to ready-mixed concrete plants with construction demonstrations and technology transfer workshops showcasing the use of Illinois coal ash in CLSM slurry. Two technology transfer workshops were held in Illinois, one in Rockford and the second in Peoria. The target audience for these implementations, workshops, and construction demonstrations were those that would produce, use, and specify CLSM, such as ready-mixed concrete plant operators, engineers, contractors, government engineers, etc.
The work for this project involved production-scale manufacturing, testing, and evaluation of selected mixtures under actual commercial production facilities, followed by technology transfer workshops and construction demonstrations. The results of the project were intended to establish mixture proportions and production technology for CLSM mixtures containing Illinois coal ash that meets IDOT specifications for many varied applications. In order to establish performance characteristics of CLSM prior to prototype-scale production, laboratory mixtures were produced. Two separate series of mixtures, Series 1 which used fine crushed sand (FCS) as the fine aggregate, and Series 2, which used standard concrete sand as the fine aggregate. Series 1 laboratory mixtures consisted of two groups of mixtures: Series 1A, which established preliminary performance data, and Series 1B, which had more extensive testing.
A total of six mixtures were produced for Series 1A mixtures. Fly ash content of the mixtures, expressed as a percentage of total fines (fly ash and crushed fine sand), varied from 100% (Mixture S1) to 0% (Mixture S6). Intermediate fly ash concentrations were established at 80%, 50%, 40%, and 27% for Mixtures S2, S3, S4, and S5, respectively. Compressive strength of all mixtures were tested at the age of 7, 28 and 182 days. All mixtures exhibited satisfactory levels of compressive strength (less than 100 psi at 28- days). Mixtures with lowest cement content produced the lowest strength.
Based upon the results of Series 1A, five Series 1B mixtures were produced. Similar to the Series 1A mixtures, ash content of the mixtures varied from 100% (Mixture A1) to 0% (Mixture A5). Target values for ash content of mixtures were 67% for Mixture A2, 50% for Mixture A3, and 33% for Mixture A4. Flow of the mixtures was maintained at about ten inches. Water requirement of the mixtures decreased with increased fine crushed sand content, 919 lb/yd3 for Mixture A1 (100% ash) to 518 lb/yd3 for Mixture A5 (0% ash). As expected, density of the CLSM also increased as the amount of fine crushed sand increased: 90 lb/ft3 to 134 lb/ft3 for Mixtures A1 to A5. Compressive strength of the mixtures were determined at the ages of 3, 7, 28, 56, 91 and 130 days. Initially, at the age of 3 days compressive strength of mixtures varied between 20-35 psi. Compressive strength of the mixtures typically increased at later ages. Dynamic cone penetrometer (DCP) values, for all mixtures were one inch/blow or less at the age of 24 hours. IDOT CLSM specifications indicate that 1.5-in/blow or less as adequate to support construction loading.
The second series of laboratory CLSM mixtures, Series 2, consisted of mixtures using standard concrete sand in combination with Illinois coal ash. Similar to Series 1 mixtures, the ash content of the mixtures was varied from 100% to 0% (ash content expressed as a percentage of total fines, ash and fine aggregate). A total of five mixtures were produced for Series 2. Mixture L1, 100% Illinois coal ash, was taken as the same mixture from Series 1, Mixture A1. Fly ash concentrations of Mixtures L1 to L6 was 100%, 81%, 60%, 40%, 20% and 4% respectively. Compressive strength of the mixtures were determined at the ages of 3, 7, 28, 56, and 91 days. Compressive strength of all mixtures was satisfactory for CLSM applications when the material may be excavated in the future (less than 100 psi at the age of 28 days). Mixtures L5 and L6 achieved the lowest strength, 10 to 15 psi at 56 and 91 days. Although low, a 10 psi unconfined compressive strength is equivalent to 1,440 lb/ft2 for soil backfill. Typically this level of strength is acceptable for many backfill applications. Water permeability of the mixtures for Series 2 were slightly higher than Series 1 mixtures.
Prototype-scale production of CLSM was manufactured at the facilities of Meyer Material Company and Rockford Sand and Gravel, Inc. (Series F1), Rockford, IL, and at United Ready-Mix, Inc. (Series F2), Peoria, IL. Production at Meyer Material Co., and Rockford Sand and Gravel Inc., consisted of eight CLSM mixtures using a combination of Illinois coal ash and fine crushed sand as the fine aggregate. The purpose of the prototype production at these facilities was to familiarize the producers with the handling of Illinois coal ash for CLSM and to obtain test data from these production mixtures. The first series of prototype production mixtures, Series F1, consisted of five mixtures, 1 to 5, containing 100%, 64%, 47%, 23%, and 0% fly ash, respectively. Since several of the Series F1 mixtures fell outside of the expected range of laboratory mixtures, three additional prototype-scale mixtures were produced, Series F1A. Series F1A Mixtures 6, 7, and 8 contained 68%, 51%, and 33% fly ash, respectively. Approximately three cubic yards were produced for each prototype-scale mixture. Compressive strength of Series F1A mixtures was determined at the age of 7, 28, and 160 days. Compressive strength of Mixtures 6 and 7 were approximately the same: 25 to 30 psi at the age of 7 days, 50 psi at 28 days, and 90 to 100 psi at 160 days. Both of these CLSM mixtures are considered excavatable. Mixture 8, 33% fly ash and 67% fine crushed sand, attained a slightly higher compressive strength compared with Mixtures 6 and 7.
CLSM produced at the facilities of United Ready-Mix, Peoria, IL used coal ash and standard concrete sand as the fine aggregate. These CLSM mixtures, Series F2, consisted of six mixtures, Mixtures F1 to F6, which contained 100%, 83%, 50%, 43%, 20%, and 4% coal ash, respectively (expressed as percentage of total fines in the mixture, fly ash and standard concrete sand, Table 19). Compressive strength of Series F2 mixtures was measured at the ages of 8, 28, and 100 days. Compressive strength of Series F2 CLSM mixtures typically increased as the amount of fly ash was increased in the mixture. A significant increase was obtained at all test ages, particularly at the age of 100 days.
The CLSM test mixtures manufactured in Rockford and Peoria generated the necessary experimental and production data to optimize CLSM mixture proportions for commercial production. Two construction demonstration/technology transfer workshops were held in Illinois. In order to promote the use of CLSM using Illinois coal ash, two different geographic locations were selected in Illinois. One field demonstration was held in Rockford, IL, in cooperation with the Rockford Blacktop Construction Co., and a second demonstration and technology transfer workshop was held in Peoria, with cooperation from the City of Peoria. Also, as a part of these workshops, handout materials were developed for CLSM products, construction methods and technologies, for commercial and government use. In conjunction with these field demonstrations, a one-day workshop (in Rockford and Peoria) was held to introduce engineers, area contractors, ready-mixed concrete suppliers, environmental agencies, local and state government personnel, and other potential users to the benefits of CLSM slurry with Illinois coal ash.
The objective of this project was to implement technology and development of markets for controlled low-strength material (CLSM) slurry for use in Illinois using Illinois coal ash as the main component, meeting Illinois regulations, for use by Illinois state agencies, and others, especially Illinois Department of Transportation (IDOT). Use of significant quantities of Illinois coal ash in CLSM slurry will result in reduced costs to users of Illinois coal. The CLSM mixtures developed for this project used a wet-collected Class F coal ash obtained from Pekin, IL. CLSM slurry may be used wherever a typical compacted backfill material is used such as for pavement sub-base, utility trenches, backfill around foundations, foundation base materials, etc. The Illinois Department of Transportation (IDOT) has developed and written specifications for use of CLSM slurry and general acceptance criteria. Some county highway departments already accept the IDOT specifications and allow CLSM use for backfilling utility trenches. Many potential Illinois users and producers of CLSM slurry have not been familiar with the many advantages of CLSM over traditional backfill materials. The existence of approved Illinois specifications on CLSM, and considerable existing literature on CLSM containing high-volumes of fly ash, indicate that CLSM slurry may not need additional research dollars. However, to meet the objectives of market development and to promote the use of Illinois coal ash and production technology of CLSM slurry, this project focused on bringing the technology to ready-mixed concrete plants with construction demonstrations and technology transfer workshops showcasing the use of Illinois coal ash in CLSM slurry. Two technology transfer workshops were held in Illinois, one in Rockford and the second in Peoria. The target audience for these implementations, workshops, and construction demonstrations were those that would produce, use, and specify CLSM, such as ready-mixed concrete plant operators, engineers, contractors, government engineers, etc.
The work for this project involved production-scale manufacturing, testing, and evaluation of selected mixtures under actual commercial production facilities, followed by technology transfer workshops and construction demonstrations. The results of the project were intended to establish mixture proportions and production technology for CLSM mixtures containing Illinois coal ash that meets IDOT specifications for many varied applications. In order to establish performance characteristics of CLSM prior to prototype-scale production, laboratory mixtures were produced. Two separate series of mixtures, Series 1 which used fine crushed sand (FCS) as the fine aggregate, and Series 2, which used standard concrete sand as the fine aggregate. Series 1 laboratory mixtures consisted of two groups of mixtures: Series 1A, which established preliminary performance data, and Series 1B, which had more extensive testing.
A total of six mixtures were produced for Series 1A mixtures. Fly ash content of the mixtures, expressed as a percentage of total fines (fly ash and crushed fine sand), varied from 100% (Mixture S1) to 0% (Mixture S6). Intermediate fly ash concentrations were established at 80%, 50%, 40%, and 27% for Mixtures S2, S3, S4, and S5, respectively. Compressive strength of all mixtures were tested at the age of 7, 28 and 182 days. All mixtures exhibited satisfactory levels of compressive strength (less than 100 psi at 28- days). Mixtures with lowest cement content produced the lowest strength.
Based upon the results of Series 1A, five Series 1B mixtures were produced. Similar to the Series 1A mixtures, ash content of the mixtures varied from 100% (Mixture A1) to 0% (Mixture A5). Target values for ash content of mixtures were 67% for Mixture A2, 50% for Mixture A3, and 33% for Mixture A4. Flow of the mixtures was maintained at about ten inches. Water requirement of the mixtures decreased with increased fine crushed sand content, 919 lb/yd3 for Mixture A1 (100% ash) to 518 lb/yd3 for Mixture A5 (0% ash). As expected, density of the CLSM also increased as the amount of fine crushed sand increased: 90 lb/ft3 to 134 lb/ft3 for Mixtures A1 to A5. Compressive strength of the mixtures were determined at the ages of 3, 7, 28, 56, 91 and 130 days. Initially, at the age of 3 days compressive strength of mixtures varied between 20-35 psi. Compressive strength of the mixtures typically increased at later ages. Dynamic cone penetrometer (DCP) values, for all mixtures were one inch/blow or less at the age of 24 hours. IDOT CLSM specifications indicate that 1.5-in/blow or less as adequate to support construction loading.
The second series of laboratory CLSM mixtures, Series 2, consisted of mixtures using standard concrete sand in combination with Illinois coal ash. Similar to Series 1 mixtures, the ash content of the mixtures was varied from 100% to 0% (ash content expressed as a percentage of total fines, ash and fine aggregate). A total of five mixtures were produced for Series 2. Mixture L1, 100% Illinois coal ash, was taken as the same mixture from Series 1, Mixture A1. Fly ash concentrations of Mixtures L1 to L6 was 100%, 81%, 60%, 40%, 20% and 4% respectively. Compressive strength of the mixtures were determined at the ages of 3, 7, 28, 56, and 91 days. Compressive strength of all mixtures was satisfactory for CLSM applications when the material may be excavated in the future (less than 100 psi at the age of 28 days). Mixtures L5 and L6 achieved the lowest strength, 10 to 15 psi at 56 and 91 days. Although low, a 10 psi unconfined compressive strength is equivalent to 1,440 lb/ft2 for soil backfill. Typically this level of strength is acceptable for many backfill applications. Water permeability of the mixtures for Series 2 were slightly higher than Series 1 mixtures.
Prototype-scale production of CLSM was manufactured at the facilities of Meyer Material Company and Rockford Sand and Gravel, Inc. (Series F1), Rockford, IL, and at United Ready-Mix, Inc. (Series F2), Peoria, IL. Production at Meyer Material Co., and Rockford Sand and Gravel Inc., consisted of eight CLSM mixtures using a combination of Illinois coal ash and fine crushed sand as the fine aggregate. The purpose of the prototype production at these facilities was to familiarize the producers with the handling of Illinois coal ash for CLSM and to obtain test data from these production mixtures. The first series of prototype production mixtures, Series F1, consisted of five mixtures, 1 to 5, containing 100%, 64%, 47%, 23%, and 0% fly ash, respectively. Since several of the Series F1 mixtures fell outside of the expected range of laboratory mixtures, three additional prototype-scale mixtures were produced, Series F1A. Series F1A Mixtures 6, 7, and 8 contained 68%, 51%, and 33% fly ash, respectively. Approximately three cubic yards were produced for each prototype-scale mixture. Compressive strength of Series F1A mixtures was determined at the age of 7, 28, and 160 days. Compressive strength of Mixtures 6 and 7 were approximately the same: 25 to 30 psi at the age of 7 days, 50 psi at 28 days, and 90 to 100 psi at 160 days. Both of these CLSM mixtures are considered excavatable. Mixture 8, 33% fly ash and 67% fine crushed sand, attained a slightly higher compressive strength compared with Mixtures 6 and 7.
CLSM produced at the facilities of United Ready-Mix, Peoria, IL used coal ash and standard concrete sand as the fine aggregate. These CLSM mixtures, Series F2, consisted of six mixtures, Mixtures F1 to F6, which contained 100%, 83%, 50%, 43%, 20%, and 4% coal ash, respectively (expressed as percentage of total fines in the mixture, fly ash and standard concrete sand, Table 19). Compressive strength of Series F2 mixtures was measured at the ages of 8, 28, and 100 days. Compressive strength of Series F2 CLSM mixtures typically increased as the amount of fly ash was increased in the mixture. A significant increase was obtained at all test ages, particularly at the age of 100 days.
The CLSM test mixtures manufactured in Rockford and Peoria generated the necessary experimental and production data to optimize CLSM mixture proportions for commercial production. Two construction demonstration/technology transfer workshops were held in Illinois. In order to promote the use of CLSM using Illinois coal ash, two different geographic locations were selected in Illinois. One field demonstration was held in Rockford, IL, in cooperation with the Rockford Blacktop Construction Co., and a second demonstration and technology transfer workshop was held in Peoria, with cooperation from the City of Peoria. Also, as a part of these workshops, handout materials were developed for CLSM products, construction methods and technologies, for commercial and government use. In conjunction with these field demonstrations, a one-day workshop (in Rockford and Peoria) was held to introduce engineers, area contractors, ready-mixed concrete suppliers, environmental agencies, local and state government personnel, and other potential users to the benefits of CLSM slurry with Illinois coal ash.
Start Date
11/1/2000
End Date
10/31/2001
Year Funded
2000
Citation
Naik, T.R., "What is Flowable Slurry (a.k.a. CLSM), Engineering Properties and Mixture Proportions of Flowable Slurry Made with Coal Ash, Sand, Used Foundry Sand, Wood Ash, Crushed Glass, On-Site Excavated Materials, etc.," UWM Center for By-Products Utilization Workshop and Field Demonstration of Use of Flowable Slurry Containing Coal Ash, Fine Crushed Sand and Other Recyclable Products, June 20, 2001, Rockford, IL.
Collection
Citation
“IMPLEMENTATION OF TECHNOLOGY FOR CONTROLLED LOW-STRENGTH MATERIALS USING ILLINOIS COAL
COMBUSTION PRODUCTS,” ICCI Reports, accessed May 20, 2024, https://isgswikis.web.illinois.edu/icci_reports/items/show/29.
COMBUSTION PRODUCTS,” ICCI Reports, accessed May 20, 2024, https://isgswikis.web.illinois.edu/icci_reports/items/show/29.