Development of a Rational Characterization Method for Iowa Fly Ash, HR-286, 1988

This research project was conducted in an attempt to determine the cause of paste strength variability in Iowa fly ashes and to develop test methods to more adequately reflect fly ash physical and chemical characteristics. An extensive three year sampling and testing program was developed and initiated which incorporated fly ash from several Iowa power plants. Power plant design and operating data were collected. The variability was directly linked to power plant maintenance schedules and to sodium carbonate coal pretreatment. Fly ash physical and chemical properties can change drastically immediately before and after a maintenance outage. The concentrations of sulfate bearing minerals in the fly ash increases sharply during shutdown. Chemical, mineralogical, and physical testing indicated that the sodium, sulfate bearing minerals, lime and tricalcium aluminate contents of the fly ashes play important roles in the development of hydration reaction products in fly ash pastes. The weak pastes always contained ettringite as the major reaction product. The strong pastes contained straetlingite and monosulfoaluminate as the major reaction products along with minor amounts of ettringite. Recommendations for testing procedure changes and suggested interim test methods are presented.

Development of a Rational Characterization Method for Iowa Fly Ash, HR-286, Annual Progress Report 1, 1986

The following report summarizes research activities on the project for the period December 1, 1985 through November 31, 1986. Research efforts for the first year have proceeded basically as outlined in the project proposal.

Development of a Rational Characterization Method for Iowa Fly Ash, HR-286, Annual Progress Report 2, 1987

The following report summarizes research activities on the project for the period December 1, 1986 to November 30, 1987. Research efforts for the second year deviated slightly from those described in the project proposal. By the end of the second year of testing, it was possible to begin evaluating how power plant operating conditions influenced the chemical and physical properties of fly ash obtained from one of the monitored power plants (Ottumwa Generating Station, OGS). Hence, several of the tasks initially assigned to the third year of the project (specifically tasks D, E, and F) were initiated during the second year of the project. Manpower constraints were balanced by delaying full scale implementation of the quantitative X-ray diffraction and differential thermal analysis tasks until the beginning of the third year of the project. Such changes should have little bearing on the outcome of the overall project.

U.S. Farm Policy and the Variability of Commodity Prices and Farm Revenues, February 2000

A dynamic, three-commodity rational-expectations storage model is used to compare the impact of the Federal Agricultural Improvement and Reform (FAIR) Act of 1996 with a freemarket policy and with the agricultural policies that preceded the FAIR Act. Results support the hypothesis that the changes made when FAIR was enacted did not lead to permanent significant increases in the volatility of farm prices or revenues. An important finding is that the main economic impacts of the Pre-FAIR scenario, relative to the free-market regime were to transfer income to farmers and to substitute government storage for private storage in a way that did little to support prices or to stabilize farm incomes.