http://www.fhwa.dot.gov/advancedresearch/pubs/10051/10051.pdf
We have many times documented for you the now undeniable performance benefits that can be achieved when Coal Ash is used as a fine aggregate, an ingredient in Portland-type Cement Concrete, "PCC", mix; that is, as a substitute for traditional materials that must, at significant cost and environmental disruption, otherwise be mined, quarried and processed.
One example would include our report of:
West Virginia Coal Association | Coal Ash Concrete More Durable, Resists Chemical Attack | Research & Development; concerning: "United States Patent 5,772,752 - Sulfate and Acid Resistant Concrete and Mortar; 1998; Assignee: New Jersey Institute of Technology; Abstract: The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction and other applications, which hardenable mixtures demonstrate significant levels of acid and sulfate resistance. Government Interests: The research leading to the present invention was conducted with Government support under Contract No. DE-FG22-90PC90299 awarded by the Department of Energy. The Government has certain rights in this invention".
So great is the performance enhancement imparted to Concrete that incorporates Coal Ash, that, as seen in:
West Virginia Coal Association | Coal Ash in Concrete Saves $100 Billion | Research & Development; concerning: "The Economic Impacts of Prohibiting Coal Fly Ash Use in Transportation Infrastructure Construction; 2011; American Road & Transportation Builders Association; Fly Ash: A High-Return 'Green' Building Material; Replacing a portion of the cement with fly ash creates a cementitious material that, when used as an input with aggregates, water and other compounds, produces a concrete mix that is well-suited to road, airport runway and bridge construction. Fly ash concrete has a number of very significant, well-documented benefits that make it a mixture of choice for many state and local transportation departments and transportation engineers. It is more durable, yet less expensive than other traditional portland cement blends. Despite the many established benefits of fly ash as a construction material and its widespread utilization, new proposed disposal regulations may limit or eliminate its availability. This study was conducted to forecast the potential economic impacts of the loss of fly ash availability in just one U.S. construction market - transportation infrastructure. Our analysis has found that such an action would increase the average annual cost of building roads, runways and bridges (in the US; and, over) 20 years, the additional cost would be $104.6 billion";
a group of professionals dedicated to the promulgation of best practices in the construction and repair of our transportation infrastructure estimates that the use of Coal Ash in Concrete, as applied to transportation infrastructure alone, will, if regulations don't prevent it, save our nation over $100 billion in the coming few decades.
So obvious and well-established, in fact, are the benefits of using Coal Ash in Concrete, and in other, related, aspects of road building and maintenance, that our Federal Highways Administration, as seen in:
West Virginia Coal Association | Federal Highway Administration Recommends Fly Ash Concrete | Research & Development; "'Infrastructure Materials Group: Fly Ash'; In addition to economic and ecological benefits, the use of fly ash in concrete improves its workability, reduces segregation, bleeding, heat evolution and permeability, inhibits alkali-aggregate reaction, and enhances sulfate resistance. FHWA has been encouraging the use of fly ash in concrete"; and, in:
West Virginia Coal Association | FHWA Instructs on the Use of Coal Ash in Road Construction | Research & Development; "'Fly Ash Facts for Highway Engineers'; Course No: T06-003; Sponsoring Agency: Federal Highway Administration; Coal fly ash is a coal combustion product that has numerous applications in highway construction. Since the first edition of Fly Ash Facts for Highway Engineers in 1986, the use of fly ash in highway construction has increased and new applications have been developed.This document provides basic technical information about the various uses of fly ash in highway construction";
actively promotes the use of Coal Ash in multiple aspects of "highway construction".
And, herein, from the Federal Highways Administration's Exploratory Advanced Research Group:
Exploratory Advanced Research-Home page;
in a recent publication issued just May 3 of this year, our United States Government, through the FHWA, states flatly and plainly that the benefits of using Coal Ash both as a reactive aggregate in and as a partial, even near-total, replacement for Portland-type Cement, in the making of Portland-type Cement Concrete, are so great and so indisputable that they are going to actively promote using even more of it.
Comment follows excerpts from the initial link in this dispatch to:
"Benefits of High Volume Fly Ash:
New Concrete Mixtures Provide Financial, Environmental and Performance Gains
Exploratory Advanced Research . . . Next Generation Transportation Solutions
High volume fly ash (HVFA) concrete mixtures offer many benefits, including reduced cost, reduced energy content, enhanced environmental sustainability, and improved long-term performance.
The aim of "Greatly Increased Use of Fly Ash in Hydraulic Cement Concrete (HCC) for Pavement Layers and Transportation Structures," an Exploratory Advanced Research (EAR) Program project, is to identify innovative methods to overcome existing barriers to use, and work towards the increased use of HVFA in pavements and transportation structures. The 24-month project, part of a Federal Highway Administration (FHWA) initiative, is being conducted by Purdue University in partnership with Auburn University, the National Institute of Standards and Technology, and the National Ready Mixed Concrete Association.
Obstacles to HVFA Use: Many producers and transportation agencies aim to increase the use of fly ash in the transportation infrastructure - however, several barriers exist to implementing new mixtures. A particular concern of many practitioners is the difficulty of predicting strength gain in full-scale structures. The project addresses this problem through the use of temperature management software and the development of a database with analytical prediction tools. In addition, agencies and contractors worry about potential incompatibilities between the fly ash, admixtures, and cement. To overcome this, the project team is developing screening procedures to identify the influence and properties of residual carbon on the rate of admixture absorption. Once all challenges are overcome, innovative strategies such as fly ash treatment, timing and rate of admixture addition, and prescreening of components for optimal performance can be implemented to improve the response of the overall system.
Moving Forward: The conventional approach to using fly ash has relied on the establishment of strict limits on the maximum amount of fly ash and the times of year that fly ash can be used in construction. Conventional applications also have set limits on the composition of the fly ash to enable the fly-ash-cement system to be treated the same way conventional portland cement has been treated in concrete. This project moves in a new direction by proposing innovative solutions to the use of fly ash in mixture proportioning. Fly ash is not used on a prescription basis, but on a performance basis - so that more fly ash can be used in concrete, and less will go to a landfill. New design methodologies are needed to predict strength, and new strategies to overcome issues associated with HVFA use. One example of innovation is the team's work with new internal curing technologies, with the intention of efficiently supplying water for hydration directly inside the concrete after placement. Another area of innovation is the use of low temperature calorimetry to determine the length of curing needed to ensure that concrete can ultimately be exposed to stresses brought on by freezing and thawing.
Concrete Solutions: The project kicked off with a literature review and consideration of the commercial, specification, and quality assurance impacts associated with the use of HVFA. The research and innovation phase of the project was designed to resolve identified issues by probing in new directions. Areas examined include investigating material compatibility, predicting property development, managing temperature and strength development, controlling internal and external curing, reducing early-age cracking, and improving freezing and scaling durability. In addition, carefully controlled large-scale test sections were prepared to evaluate the proposed solutions identified in each project phase. This form of large-scale testing is unique due to the ability to carefully establish and monitor the environment in which the HVFA concrete is placed while monitoring test structures.
Concrete Of The Future: 'The impact of this project on the materials used in the Nation's transportation systems and highway programs is expected to be significant,' says Richard Meininger at FHWA. 'Entirely new concepts are being put forward here that really get to the heart of the critical issues currently limiting the amounts and sources of fly ash used in construction,' continues Meininger. 'The implementation of the technologies being developed is expected to guide the concrete mixture designs and proportions of the future, ultimately offering pavements and other concrete structures with a smaller carbon footprint and lower embodied energy while also showing the improved long-time performance possible with fly ash.'"
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As encouraging as it might be for us to consider that Fly Ash can be used in some, unspecified herein, "high volume" in a concrete mix, a concrete mix that cures into a final product that offers so "many benefits, including reduced cost, reduced energy content, enhanced environmental sustainability, and improved long-term performance", keep in mind the fine portion of a concrete mix is only a part of the total.
A coarse aggregate, too, is most often added, a coarse aggregate that imparts additional, desired properties to the mix.
And, as seen, for only one example, in our report of:
West Virginia Coal Association | Wyoming Converts Coal Ash to Construction Aggregates | Research & Development; concerning: "United States Patent 6,334,895 - Producing Manufactured Materials from Coal Combustion Ash; 2002; Assignee: The University of Wyoming Research Corporation; Abstract: This invention discloses a system for cold bond processing of combustion ash which enhances various characteristics of the resulting cured consolidated combustion ash materials. Specifically, the invention relates to processing techniques which enhances both density and strength of the of the consolidated combustion ash materials. The invention also relates to processing techniques which control various chemical reactions which assure that certain types of minerals are formed in the proper amounts which results in a cured consolidated combustion ash material which has greater dimensional stability and enhanced resistance to degradation. Embodiments for both normal weight and light weight combustion ash aggregates are disclosed which meet various ASTM and AASHTO (American Association of State Highway and Transportation Officials) specifications";
"both normal weight and light weight" coarse concrete aggregates can be formed from Coal Ash, as well.
Our recent past has been marked by contention over what to do with our solid Coal Combustion Products; especially Fly Ash.
Maybe it's time we put those past disagreements to rest. As herein explained by one branch of the United States Government, we can bury them, forever and securely entomb them, along with our Coal Ash, in the high-performance:
"Concrete of the Future".
