Freeze-Thaw Durability of Concretes with Infilling of Ettringite in Voids, Phase 2, MLR-94-9, 1997

Examination of field portland cement concrete cores, from Iowa pavements with premature deterioration, reveals extensive infilling of calcium sulfate aluminum (CSA) compound in their air voids. A previous study (Phase I) has shown some evidence of the correlation between freeze-thaw durability of concretes and ettringite infilling. To further verify the previous observation, a more extensive experimental program was conducted in this Phase 2 study. A total of 101 concrete mixes were examined. Seven cements, six fly ashes, two water reducers and three coarse aggregates were used in the concrete mixes. Specimens were under moist curing for up to 223 days before being subjected to the freeze-thaw cycling. An environmental treatment consisting of three consecutive wet [70 deg F (21 deg C) in distilled water]/dry [120 deg F (49 deg C) in oven] cycles was applied to some specimens. Immediately prior to the freeze-thaw cycling, most specimens were examined by a low-vacuum scanning electron microscope (SEM) for their microstructure. The results obtained further demonstrate the correlation between concrete freeze-thaw response and CSA compound infilling in the air voids. The extent of the infilling depends on the period of moist curing as well as the wet/dry treatment. The extent of the infilling also relates to materials used. Concrete mixes with extensive infilling are more vulnerable to the freeze-thaw attack. Based on the obtained results, material criteria on cements and fly ashes for mainline paving were proposed for minimizing potential infilling of CSA compound in concrete.

Floods of September 15-16, 1992, in the Thompson, Weldon, and Chariton River Basins, South-Central Iowa, HR-140, 1997

Water-surface-elevation profiles and peak discharges for the floods of September 15-16, 1992, in the Thompson, Weldon, and Chariton River Basins, south-central Iowa, are presented in this report. The profiles illustrate the 1992 floods along the Thompson, Weldon, Chariton, and South Fork Chariton Rivers and along Elk Creek in the south-central Iowa counties of Adair, Clarke, Decatur, Lucas, Madison, Ringgold, Union, and Wayne. Water-surface-elevation profiles for the floods of July 4, 1981, along the Chariton River in Lucas County and along the South Fork Chariton River in Wayne County also are included in the report for comparative purposes. The September 15-16, 1992, floods are the largest known peak discharges at gaging stations Thompson River at Davis City (station number 06898000) 57,000 cubic feet per second, Weldon River near Leon (station number 06898400) 76,200 cubic feet per second, Chariton River near Chariton (station number 06903400) 37,700 cubic feet per second, and South Fork Chariton River near Promise City (station number 06903700) 70,600 cubic feet per second. The peak discharges were, respectively, 1.7, 2.6, 1.4, and 2.1 times larger than calculated 100-year recurrence-interval discharges. The report provides information on flood stages and discharges and floodflow frequencies for streamflow-gaging stations in the Thompson, Weldon, and Chariton River Basins using flood information collected through 1995. Information on temporary bench marks and reference points established in the Thompson and Weldon River Basins during 1994-95, and in the Chariton River Basin during 1983-84 and 1994-95, also is included in the report. A flood history summarizes rainfall conditions and damages for floods that occurred during 1947, 1959, 1981, 1992, and 1993.

You are not alone...making an informed decision about your pregnancy, January 1997

When you are faced with a difficult decision, it’s not unusual to feel confused, frustrated, and perhaps a little frightened because you are not sure what to expect or where to turn for answers. The purpose of this handbook is to assist you in making an informed choice about your pregnancy.

Iowa Ag Review, August 1997, Vol. 3, no. 3

Iowa Ag Review is a quarterly newsletter published by the Center for Agricultural and Rural Development (CARD). This publication presents summarized results that emphasize the implications of ongoing agricultural policy analysis, analysis of the near-term agricultural situation, and discussion of agricultural policies currently under consideration.

New Method for Breaking High Strength Prestress Cable, MLR-97-6, 1997

A new method was developed for breaking high strength prestressed cable. The old method used an aluminum oxide grit packed into a special gripping jaw. The new method uses aluminum shims wrapped around the cable and then is gripped with a V-grip. The new method gives nearly 100% "good breaks" on the cable compared to approximately 10% good breaks with the old method. In addition, the new cable breaking method gives higher ultimate tensile strengths, is more reproducible, is quicker, cleaner and easier on equipment.

Leopold Center for Sustainable Agriculture, Annual Report 1997-1998

The Leopold Center was established by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. Its mandated missions are to identify impacts of agricultural practices, contribute to the development of profitable farming systems that conserve natural resources, and cooperate with Iowa State University Extension to inform the public of new findings.Information for this report was compiled by Leopold Center staff with the help of its researchers and educators who are committed to improving Iowa agriculture and the lives of Iowans.

Summary of FY 1998 Budget and Governor's Recommendations, January 1997

The purpose of this document is to provide the General Assembly with information related to FY General Fund estimated receipts and the Governor’s recommendations. This information provides an overall summary of the State budget and is intended to help the General Assembly take a proactive approach toward the budgeting process.

Summary of FY 1997 Budget and Governor's Recommendations, January 1996

The purpose of this document is to provide the General Assembly with information related to FY General Fund estimated receipts and the Governor’s recommendations. This information provides an overall summary of the State budget and is intended to help the General Assembly take a proactive approach toward the budgeting process.

1996-1997 University of Northern Iowa Annual Financial Report, November 18, 1997

Comprehensive Annual Financial Report For University of Northern Iowa.

1997-1998 University of Northern Iowa Annual Financial Report, November 13, 1998

Comprehensive Annual Financial Report For University of Northern Iowa.

Leopold Letter: A Newsletter of the Leopold Center for Sustainable Agriculture, Spring 1997

The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.

Leopold Letter: A Newsletter of the Leopold Center for Sustainable Agriculture, Summer 1997

The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.

Leopold Letter: A Newsletter of the Leopold Center for Sustainable Agriculture, Fall 1997

The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.

Leopold Letter: A Newsletter of the Leopold Center for Sustainable Agriculture, Winter 1997

The Leopold Center was created by the Iowa Legislature as part of the Iowa Groundwater Protection Act of 1987. The Leopold Center believes contribute to a healthy ways of thinking about markets for Iowa farmers, a better understanding of local ecosystems, public policies and economic practices, and partnerships with consumers.

Marsh rainbow arch bridges in Iowa, 1997

The Marsh Rainbow Arch Bridge is a patented bridge design by James Barney Marsh, a graduate of Iowa State College of Agriculture and Mechanic Arts (now Iowa State University). Around the turn of the 20th Century, reinforced concrete was introduced in Iowa as an important new bridge construction material. Marsh used the new technology to encased steel truss arches in concrete to produce a sturdy yet esthetic arch bridge. This booklet touches on the important aspects of Marsh's life, business and industrial contributions.