Restoration of Fricitonal Characteristics on Older Portland Cement Concrete Pavement:Final Report for Iowa Highway Research Board Project HR-224, June 1986

Safety i s a very important aspect o f the highway program. The Iowa DOT initiated an inventory o f the friction values of all paved primary roadways i n 1969. This inventory, with an ASTM E-274 test unit, has continued to the present time. The t e s t i n g frequency varies based upon traffic volume and the previous friction value. Historically , the state o f Iowa constructed a substantial amount o f pcc pavement during the 1928-30 period t o "get Iowa out o f the mud". Some of that pavement has never been resurfaced and has been subjected to more than 50 years o f wear. The textured surface has been worn away and has subsequently polished. Even though some pavements from 15 t o 50 years old continue t o function structurally , because of the loss of friction , they do not provide the desired level o f safety to the driver. As a temporary measure, "Sl ippery -When -Wet " signs have been posted on many older pcc roads due to friction numbers below t h e desirable level. These signs warn the motorist of the current conditions. An economical method of restoring the high quality frictional properties i s needed.

Evaluation of Fly Ash Concrete Durability Containing Class II Durability Aggregates, July 1986

Fly ash was used in this evaluation study to replace 15% of the cement in Class C-3 concrete paving mixes. One Class "c" ash from Iowa approved sources was examined in each mix. Substitution rate was based on 1 to 1 basis, for each pound of cement removed 1.0 pound of ash was added. The freeze/thaw durability of the concrete studied was not adversely affected by the presence of fly ash. This study reveals that the durability of the concrete test specimens made with Class II durability aggregates was slightly increased in all cases by the substitution of cement with 15% Class "c" fly ash. In all cases durability factors either remained the same or slightly improved except for one case where the durability factor decreased from 36 to 34. The expansion decreased in all cases.

Evaluation of Fly Ash in lean Portland Cement Concrete Base "Econocrete", August 1986

Fly ash was used in this evaluation study to replace 30, 50 and 70 percent of the 400 1bs. of cement currently used in each cu. yd. of portland cement econocrete base paving mix. Two Class "c" ashes and one Class "F" ash from Iowa approved sources were examined in each mix. When Class "c" ashes were used, they were substituted on the basis of 1.0 pound for each pound of cement removed. When Class "F" ash was used, it was substituted on the basis of 1.25 pounds of ash for each pound of cement removed. Compressive strengths with and without fly ash were determined at 7, 28 and 56 days of age. In most cases, strengths were adequate. The freeze/thaw durability of the econocrete mixes studied was not adversely affected by the presence of fly ash. The tests along with erodibility and absorption tests have demonstrated the feasibility of producing econocrete with satisfactory mechanical properties even when relatively low quality and/or locally available aggregate is being used at no sacrifice to strength and/or durability.

Audit report on the City of Windsor Heights, Iowa for the year ended June 30, 2012

Audit report on the City of Windsor Heights, Iowa for the year ended June 30, 2012

Audit report on the City of Windsor Heights, Iowa for the year ended June 30, 2013

Audit report on the City of Windsor Heights, Iowa for the year ended June 30, 2013

The Economics of Reducing the County Road System: Three Case Studies in Iowa - Executive Summary, HR-242, 1986

This Executive Summary presents a brief summary of the main research report, "The Economics of Reducing the County Road System: Three Case Studies in Iowa" (DOT/OST/P-34/86-035). The case studies are described, as well as the analytic methodology and research findings.

The Economics of Reducing the County Road System: Three Case Studies in Iowa, HR-242, 1986

This research project looked at the economic benefits and costs associated with alternative strategies for abandoning low volume rural highways and bridges. Three test counties in Iowa were studied, each 100 square miles in size: Hamilton County having a high agricultural tax base and a high percentage of paved roads and few bridges; Shelby County having a relatively low agricultural tax base, hilly terrain and a low percentage of paved road and many bridges; and Linn County having a high agricultural tax base, a high percentage of paved roads and a large number of non-farm households. A questionnaire survey was undertaken to develop estimates of farm and household travel patterns. Benefits and costs associated with the abandonment of various segments of rural highway and bridge mileages in each county were calculated. "Benefits" calculated were reduced future reconstruction and maintenance costs, whereas "costs" were the added cost of travel resulting from the reduced mileage. Some of the findings suggest limited cost savings from abandonment of county roads with no property access in areas with large non-farm rural population; relatively high cost savings from the abandonment of roads with no property access in areas with small rural population; and the largest savings from the conversion of public dead-end gravel roads with property or residence accesses to private drives.

Floods of 1986 and 1990 in the Raccoon River Basin, West-Central Iowa, HR-140, 1992

Water-surface-elevation profiles and peak discharges for the floods of 1973 and 1979 are compared to those of 1986 and 1990 in the Raccoon River basin, west-central Iowa. The profiles illustrate the 1979 and 1986 floods on the Raccoon, South Raccoon, and Middle Raccoon Rivers, the 1973 and 1986 floods on Walnut Creek, and the 1986 flood on Willow Creek and Mosquito Creek. The 1986 flood is the largest on record at U.S. Geological Survey streamflowgaging stations on the Middle Raccoon River tributary at Carroll, Middle Raccoon River near Bayard, Middle Raccoon River at Panora, and Walnut Creek at Des Moines. The 1990 flood discharge is the largest on record at U.S. Geological Survey crest-stage gaging stations on Hardin Creek near Farlin and on East Fork Hardin Creek near Churdan. The flood history given in this report describes rainfall conditions for floods that occurred during 1986 and 1990. Discharge for the 1990 flood on East Fork Hardin Creek near Churdan was 1.01 times larger than the 100-year recurrence-interval discharge.

Taxonomic study of the isopod crustaceans from the Spanish expedition 'Antartida 1986-11' in the Scotia Sea, South Atlantic

This paper summarizes the results of a taxonomic study of the isopods collected during the 'Antártida 1986-11' expedition. A total of 123 specimens were studied, of which 99 were in the adult or juvenile phases and 24 were in the postmanca phase. The specimens were attributed to 11 species, 9 genera, 5 families and 4 suborders. The most abundant species were Glyptonotus antarcticus and Ceratoserolis trilobitoides. Several records are reported for the first time from the archipelagos of the Scotia Arc.

An Evaluation of the Troxler 3241-B Nuclear Asphalt Gauge, MLR-85-11, 1986

The Troxler 3241-B Asphalt Content Gauge is intended for rapidly determining the bitumen content of bituminous paving mixtures. A 300 Millicurie Americuium 241: Beryllium source emitts neutrons which are affected by the hydrogen in the mix. The affected neutrons are detected by Helium 3 detectors, counted and computed into a percentage bitumen of the asphalt mix. The current methods of determining the bitumen content of bituminous paving mixtures requires the use of potentially hazardous chemicals and several hours of testing time. When extracted aggregates are not needed, determination of the bitumen content of a paving mixture by the nuclear method may be easier, quicker and potentially safer. The objective of the project is to study the accuracy of the Troxler 3241-B Nuclear Asphalt Content Gauge in measuring the asphalt cement (AC) content of asphalt concrete mixtures produced with different asphalt cements and different aggregates.

Structural Analysis and Overlay Design of Pavements Using the Road Rater, MLR-84-3, 1986

In recent years the Iowa DOT has shifted emphasis from the construction of new roads to the maintenance and preservation of existing highways. A need has developed for analyzing pavements structurally to select the correct rehabilitation strategy and to properly design a pavement overlay if necessary. This need has been fulfilled by Road Rater testing which has been used successfully on all types of pavements to evaluate pavement and subgrade conditions and to design asphaltic concrete overlays. The Iowa Road Rater Design Method has been simplified so that it may be easily understood and used by the widely diverse groups of individuals which may be involved in pavement restoration and management. Road Rater analysis techniques have worked well to date and have been verified by pavement coring, soils sampling and testing, and pavement removal by block sampling. Void detection testing has also been performed experimentally in Iowa, and results indicate that the Road Rater can be used to locate pavement voids and that Road Rater analysis techniques are reasonably accurate. The success of Road Rater research and development has made deflection test data one of the most important pavement management inputs.

Effects of Special Aggregate on Bridge Deck Overlay Frictional Properties, HR-205, 1986

The Iowa DOT has been using the "Iowa Method" thin bonded low-slump dense Portland Cement Concrete (PCC) bridge deck overlay for rehabilitation of delaminated decks since 1963. In time, continued use of studded tires will wear away the transverse grooved texture. The objective of this research was to evaluate the benefit of incorporating a hard durable aggregate into a dense PCC overlay to provide frictional property longevity. The project included three overlays on I-35 near Ankeny. The texture and friction properties of two overlays, one constructed with crushed granite and the other with crushed quartzite coarse aggregate, were compared to an overlay constructed with locally available crushed limestone. There were no construction problems resulting from the use of crushed granite or quartzite. There was no significant frictional property benefit from the crushed granite or crushed quartzite through six years.

Detection of Concrete Delamination by Infrared Thermography, HR-244, 1986

Iowa has approximately 1000 bridges that have been overlaid with a nominal 2" of portland cement concrete. A Delamtect survey of a sampling of the older overlaid bridges indicated delaminations in several of them. Eventually these bridges as well as those that have not received an overlay must be programmed for rehabilitation. Prior to rehabilitation the areas which are delaminated must be identified. There are currently two standard methods of determining delaminated areas in bridge decks; sounding with a metal object or a chain drag and sounding with an electro-mechanical sounding system (Delamtect). Sounding with a metal object or chain drag is time consuming and the accuracy is dependent on the ear of the operator and may be affected by traffic noise. The Delamtect requires less field time but the graphical traces require that data reduction be done in the office. A recently developed method of detecting delamination is infrared thermography. This method is based on the temperature difference between sound and delaminated concrete. A contract was negotiated with Donohue and Associates, Inc. of Sheboygan, Wisconsin, to survey 18 p.c. concrete overlaid bridge decks in Iowa using the infrared thermography method of detecting delaminations.

Development of a Conductometric Test for Frost Resistance of Concrete, HR-272, Phase II, 1986

The purpose of this report is to describe the major research activities during the period of February 1, 1985 - October 30, 1986 for the Iowa Highway Research Board under the research contract entitled "Development of a Conductometric Test for Frost Resistance of Concrete." The objective of this research, as stated in the project proposal, is to develop a test method which can be reasonably rapidly performed in the laboratory and in the field to predict the behavior of concrete subjected to the action of alternate freezing and thawing with a high degree of certainty. In the work plan of the proposal it was stated that the early part of the first year would be devoted to construction of testing equipment and preparation of specimens and the remainder of the year would be devoted to the testing of specimens. It was also stated that the second and third years would be devoted to performance and refinements of tests, data analysis, preparation of suggested specifications, and performance of tests covering variables which need to be studied such as types of aggregates, fly ash replacements and other admixtures. The objective of this report is to describe the progress made during the first 20 months of this project and assess the significance of the results obtained thus far and the expected significance of the results obtainable during the third year of the project.

Field Evaluation of Bonded Concrete Overlays, HR-288, 1986

A field program of strain and deflection measurements was conducted by the Construction Technology Laboratories (CTL) for the Iowa Department of Transportation. The objective of the field measurement program was to obtain information on bonded concrete resurfaced pavements that can be used as a data base for verifying bonded resurfacing thickness design procedures. Data gathered during the investigation included a visual condition survey, engineering properties of the original and resurfacing concrete, load related strain and deflection measurements, and temperature related curl (deflection) measurements. Resurfacing is basically the addition of a surface layer to extend the life of an existing pavement. Portland cement concrete has been used to resurface existing pavements since about 1913.