Blanket Curing to Promote Early Strength Concrete, MLR-87-7, 1989

Fast Track concrete has proven to be successful in obtaining high early strengths. This benefit does not come without cost. Special Type III cement and insulating blankets to accelerate the cure add to its expense when compared to conventional paving. This research was intended to determine the benefit derived from the use of insulating blankets to accelerate strength gain in three concrete mixes using Type I cement. The goal was to determine mixes and curing procedures that would result in a range of opening times. This determination would allow the most economical design for a particular project by tailoring it to a specific time restraint. Three mixes of various cement content were tested in the field. Flexural beams were cast for each mix and tested at various ages. Two test sections were placed for each mix, one section being cured with the addition of insulating blankets and the other being cured with only conventional curing compound. Iowa Department of Transportation specifications require 500 psi flexural strength before a pavement can be opened to traffic. Concrete with Fast Track proportions (nominal 7 1/2 bag), Type I cement, and insulating blankets reached that strength in approximately 36 hr, a standard mix (nominal 6 1/2 bag) using the blankets in approximately 48 hr, and the Fast Track proportions with Type I cement without blankets in about 60 hr. The results showed a significant improvement in early strength gain with the use of insulating blankets.

Development of an Improved Agricultural-Based Deicing Product, TR-581, 2010

Snow and ice removal on public streets is a critical part of the work of departments of transportation in northern U.S. states, including Iowa. Iowa is also a state rich in agricultural resources, some of which undergo industrial processes that generate a number of byproducts, e.g., in converting corn to ethanol or soy to biodiesel. It would be desirable to find those that, with a minimum of additional processing, can be used as a deicing compound, either alone or in combination with products currently in use. The focus of this work is therefore to investigate by-products from agricultural processes that may be suitable for use as deicing applications. This topic has been investigated in the past by others, with many patented products described in the literature. An initial screening was carried out to assess the potential acceptability of selected commercial products, as well as a glycerol developed for this project. Based on the variety of parameters tested, the product combination that shows the greatest promise for future application consists of 80% glycerol with 20% NaCl.

Improving Subgrade Support Values with Longitudinal Drains, MLR-84-3, 1984

This report is a brief summary of research on the effect of longitudinal drains on subgrade support. The Iowa DOT began installing longitudinal subdrains at a depth of 24" in 1978. The trend in Iowa has been to deeper longitudinal drains with the present standard being 48" deep. A very limited amount of data would indicate that the deeper longitudinal drains are providing a greater benefit to the subgrade support value. The 24# deep drains of the Poweshiek Interstate 80 project yielded a spring subgrade support value of 165. The 30" deep drains on Pottawattamie Interstate 80 yielded a K value of 170 while the 48"deep drains on Cass County Interstate 80 yielded a K value of 210. This limited amount of data would indicate that the deeper drains provide greater benefit to improvement of the subgrade support values.

Recycling of Cass County I-80 Asphalt Concrete, Progress Report, HR-1011, 1977

Approximately 40,000 tons of slightly damaged asphalt concrete has been removed from Interstate 80 in Cass and stockpiled. Laboratory tests had indicated that this material had considerable value when upgraded with new aggregate and asphalt cement. This report documents the procedures used and results obtained on an experimental recycling project. It was demonstrated that present drum mixing-recycling equipment and procedures can be used to utilize this material with satisfactory results. Laboratory analyses of material components and mixtures were performed; these analyses indicate mixture can be produced that is uniform, stable, and very closely resembles mixture produced with all new material. Follow~up evaluations will be made to determine the effects of traffic and environment. Preliminary data indicate that plans should be made to incorporate the stockpiled material in projects near the stockpile site.

CIRAS News, Fall 2012, Vol. 48, no. 1

CIRAS is to enhance the performance of Iowa industry, and associated entities, through education and technology-based services. This newsletter holds information regarding these services.

CIRAS News, Winter 2012, Vol. 48, no. 2

CIRAS is to enhance the performance of Iowa industry, and associated entities, through education and technology-based services. This newsletter holds information regarding these services.

CIRAS News, Spring 2013, Vol. 48, no. 3

CIRAS is to enhance the performance of Iowa industry, and associated entities, through education and technology-based services. This newsletter holds information regarding these services.

CIRAS News, Summer 2013, Vol. 48, no. 4

CIRAS is to enhance the performance of Iowa industry, and associated entities, through education and technology-based services. This newsletter holds information regarding these services.

Water Summary Update, April 8, 2015, No. 48

A snapshot of water resource trends prepared by the Iowa DNR in collaboration with the Iowa Department of Agriculture and Land Stewardship, the U.S. Geological Survey, and The Iowa Homeland Security and Emergency Management Department.

Recycling of Asphalt Concrete From I-80 in Cass County, HR-1011, 1978

Approximately 40,000 tons of deteriorated asphalt concrete has been removed from Interstate 80 in Cass County and stockpiled. Laboratory tests indicate that this material has considerable value when upgraded with new aggregate and asphalt cement. This report documents the procedures used and results obtained on an experimental recycling project. It was demonstrated that present drum mixing-recycling equipment and procedures can be used to utilize this material with satisfactory results. Laboratory analyses of material components and mixtures were performed; these analyses indicate mixture can be produced that is uniform, stable, and very closely resembles mixture produced with all virgin material. A 1700 foot long test section was constructed on US 169 in Kossuth County wherein salvaged asphalt concrete from I-80 in Cass County was utilized. The salvaged mix was blended with virgin aggregate and recycled through a modified drum mixing plant, the reprocessed mixture was satisfactorily placed 1 1/2 inches thick as a resurfacing course on an old PCC pavement. An inspection of the test section was made in December of 1978 to evaluate the performance after one full year of service. There was no evidence of rutting or shoving from traffic. The surface does, however, have a very dry and somewhat ravelled appearance. This can be related to a low asphalt content in the mix and some temperature control problems which were difficult to get fully corrected on such a short project and with a short supply of readily available materials.

Polk County, Township 80 North Range 23 West

Des Moines River Plat Maps.

Polk County, Township 80 North Range 24 West

Des Moines River Plat Maps.

Polk County, Township 80 North Range 25 West

Des Moines River Plat Maps.

Dallas County, Township 80 North Range 26 West

Des Moines River Plat Maps.

Portland Cement Concrete Curing Compound Performance Phase I and Phase II, MLR-02-03, 2003

Testing the efficiency of Portland Cement Concrete (PCC) curing compounds is currently done following Test Method Iowa 901-D, May 2002. Concrete test specimens are prepared from mortar materials and are wet cured 5 hours before the curing compound is applied. All brands of curing compound submitted to the Iowa Department of Transportation are laboratory tested for comparative performance under the same test conditions. These conditions are different than field PCC paving conditions. Phase I tests followed Test Method Iowa 901-D, but modified the application amounts of the curing compound. Test results showed that the application of two coats of one-half thickness each increased efficiency compared to one full thickness coat. Phase II tests also used the modified application amounts, used a concrete mix (instead of a mortar mix) and applied curing compound a few minutes after molding. Measurements of losses, during spraying of the curing compound, were noted and were found to be significant. Test results showed that application amounts, testing techniques, concrete specimen mix design and spray losses do influence the curing compound efficiency. The significance of the spray losses indicates that the conventional test method being used (Iowa 901 D) should be revised.