Precast Concrete Panel Thickness for Epoxy-Coated Prestressing Strands, Volume 1, HR-353, 1994

This final report for Phase 1 of the research on epoxy-coated, prestressing strands in precast prestressed concrete (PC) panels has been published in two volumes. This volume, Volume 1--Technical Report, contains the problem description, literature review, and survey results; descriptions of the test specimens, experimental tests, and analytical models; discussions of the analytical and experimental results; summary, conclusions, and recommendations; list of references; and acknowledgment. Volume 2--Supplemental Report contains additional information in the form of summarized responses to the questionnaires; graphs showing the strand forces; figures showing the geometry of the specimens and concrete crack patterns that formed in the strand transfer length and strand development length specimens; and graphs of the concrete strains in the strand transfer length specimens, load-point deflections, and strand-slip measurements for the strand development length specimens.

An Investigation of Portland Cement Concrete Utilizing 70% Class V Aggregate and 30% Calcareous Coarse Aggregate, R-255, 1973

The main sources of coarse aggregate for secondary slip form paving in Southwest Iowa exhibit undesirable "D" cracking. "D" cracking is a discoloration of the concrete caused by fine, hairline cracks. These cracks are caused by the freezing and thawing of moisture inside the coarse aggregate. The cracks are often hour glass shaped, are parallel to each other, and occur along saw joints. The B-4, a typical secondary mix, utilizes 50% fine aggregate and 50% coarse aggregate. It has been proposed that a concrete mix with less coarse aggregate and more fine aggregate might impede this type of deterioration. The Nebraska Standard 47B Mix, a 70% fine aggregate, and 30% coarse aggregate mix, as used by Nebraska Department of Roads produces concrete with ultimate strengths in excess of 4500 psi but because of the higher cost of cement (it is a six bag per cubic yard mix) is not competitive with our present secondary mixes. The sands of Southwest Iowa generally have poorer mortar strengths than the average Iowa Sand. Class V Aggregate also found in Southwest Iowa has a coarser sand fraction, therefore it has a better mortar strength, but exhibits an acidic reaction and therefore must be·used with limestone. This illustrates the need to find a mix for use in Southwest Iowa that possesses adequate strength and satisfactory durability at a low cost. The purpose of this study is to determine a concrete mix with an acceptable cement content which will produce physical properties similar to that of our present secondary paving mixes.

An Evaluation of the Consolidation Monitoring Device, HR-1013, 1978

The Iowa Department of Transportation research project HR-1013 is the evaluation of a prototype continuous monitoring nuclear density unit. The Unit, the Consolidation Monitoring Device (CMD), mounts on the rear of a slip-form paver and measures the density of the concrete while still in the plastic state. The evaluation performed determined the usefulness, accuracy, precision and reproducibility of the unit. The CMD was calibrated and tested in the laboratory for one week before field evaluation. The field evaluation consisted of monitoring at least 5 miles of paving and then correlating the CMD data with two conventional density methods. The two supplemental methods were density measurement with a Troxler nuclear gauge and densities obtained from core samples.

Treating Iowa's Marginal Aggregates and Soils by Foamix Process, HR-212, 1980

Quality granular materials suitable for building all-weather roads are not uniformly distributed throughout the state of Iowa. For this reason the Iowa Highway Research Board has sponsored a number of research programs for the purpose of developing new and effective methods for making use of whatever materials are locally available. This need is ever more pressing today due to the decreasing availability of road funds and quality materials, and the increasing costs of energy and all types of binder materials. In the 1950s, Professor L. H. Csanyi of Iowa State University had demonstrated both in the laboratory and in the field, in Iowa and in a number of foreign countries, the effectiveness of preparing low cost mixes by stabilizing ungraded local aggregates such as gravel, sand and loess with asphalt cements using the foamed asphalt process. In this process controlled foam was produced by introducing saturated steam at about 40 psi into heated asphalt cement at about 25 psi through a specially designed and properly adjusted nozzle. The reduced viscosity and the increased volume and surface energy in the foamed asphalt allowed intimate coating and mixing of cold, wet aggregates or soils. Through the use of asphalt cements in a foamed state, materials normally considered unsuitable could be used in the preparation of mixes for stabilized bases and surfaces for low traffic road construction. By attaching the desired number of foam nozzles, the foamed asphalt can be used in conjunction with any type of mixing plant, either stationary or mobile, batch or continuous, central plant or in-place soil stabilization.

Summary of the opinions of the Attorney General, 2015

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2014

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2012

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2011

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2009

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2007

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2008

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2006

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2005

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2004

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.

Summary of the opinions of the Attorney General, 2003

Compiled biennially as Official opinions of the Attorney General in the Report of the Attorney General. Report year ends December 31. Slip opinions of the Attorney General.