Fatigue Behavior of Air-Entrained Concrete, HR-183, 1977

When a material fails under a number of repeated loads, each smaller than the ultimate static strength, a fatigue failure is said to have taken place. Many studies have been made to characterize the fatigue behavior of various engineering materials. The results of some of these studies have proved invaluable in the evaluation and prediction of the fatigue strength of structural materials. Considerable time and effort has gone into the evaluation of the fatigue behavior of metals. These early studies were motivated by practical considerations: The first fatigue tests were performed on materials that had been observed to fail after repeated loading of a magnitude less than that required for failure under the application of a single load. Mine-hoist chains, railway axles, and steam engine parts were among the first structural components to be recognized as exhibiting fatigue behavior. Since concrete is usually subjected to static loading rather than cyclic loading, need for knowledge of the fatigue behavior of concrete has lagged behind that of metals. One notable exception to this, however, is in the area of highway and airfield pavement design. Due to the fact that the fatigue behavior of concrete must be understood in the design of pavements and reinforced concrete bridges, highway engineers have provided the motivation for concrete fatigue studies since the 1920's.

Fatigue Behavior of Air-Entrained Concrete: Phase II, HR-197, 1979

When a material fails under a number of repeated loads, each smaller than the ultimate static strength, a fatigue failure is said to have taken place. Many studies have been made to characterize the fatigue behavior of various engineering materials. The results of some of these studies have proved invaluable in the evaluation and prediction of the fatigue strength of structural materials. Considerable time and effort have gone into the evaluation of the fatigue behavior of metals. These early studies were motivated by practical considerations: the first fatigue tests were performed on materials that had been observed to fail after repeated loading of a magnitude less than that required for failure under the application of a single load. Mine-hoist chains (1829), railway axles (1852), and steam engine parts were among the first structural components to be recognized as exhibiting fatigue behavior. Since concrete is usually subjected to static loading rather than cyclic loading, need for knowledge of the fatigue behavior of concrete has lagged behind that of metals. One notable exception to this, however, is in the area of highway and airfield pavement design. Due to the fact that the fatigue behavior of concrete must be understood in the design of pavements and reinforced concrete bridges, highway engineers have provided the motivation for concrete fatigue studies since the 1920s.

2014 Iowa Commercial Air Service Retention and Expansion Committee - Plan

Senate File 2355 Sec. 19 (Iowa Code §328.13) created a commercial air service retention and expansion committee within the aviation office of the department of transportation. The membership of the committee consisted of the director or the director’s designee; the managers of each airport in Iowa with commercial air service; two members of the senate, one appointed by the majority leader of the senate and one appointed by the minority leader of the senate; and two members of the house of representatives, one appointed by the speaker of the house and one appointed by the minority leader of the house. The committee was to develop a plan by December 31, 2014 for the retention and expansion of passenger air service in Iowa. The committee is to meet as the committee deems necessary to assess progress in implementing the plan and, if necessary, to update the plan.

Concrete Pavement Mixture Design and Analysis (MDA): Evaluation of Foam Drainage Test to Measure Air Void Stability in Concrete

The stability of air bubbles in fresh concrete can have a profound influence of the potential durability of the system, because excessive losses during placement and consolidation can compromise the ability of the mixture to resist freezing and thawing. The stability of air void systems developed by some air entraining admixtures (AEAs) could be affected by the presence of some polycarboxylate-based water reducing admixtures (WRAs). The foam drainage test provides a means of measuring the potential stability of air bubbles in a paste. A barrier to acceptance of the test was that there was little investigation of the correlation with field performance. The work reported here was a limited exercise seeking to observe the stability of a range of currently available AEA/WRA combinations in the foam drainage test; then, to take the best and the worst and observe their stabilities on concrete mixtures in the lab. Based on the data collected, the foam drainage test appears to identify stable combinations of AEA and WRA.

Air Content and Permeability of PCC Pavements: 1909 to 2006, MLR-05-02, 2007

Portland cement concrete pavements have given excellent service history for Iowa. Many of these pavements placed during the 1920’s and 1930’s are still in service today. Many factors go in to achieve a long term durable concrete pavement. Probably the most important is the durability of the aggregate. Until the 1930’s, pit run gravel was the most predominant aggregate used. Many of these gravels provided long term performance and their durability is dependent upon the carbonate fraction of the gravel. Later, limestone (calcium carbonate) and dolomite (calcium, magnesium carbonate) sources were mined across Iowa. The durability of these carbonate aggregates is largely dependent upon the pore system which can cause freeze thaw problems known as D-cracking, which was a problem with some sources during the 1960’s. Also, some of these carbonate aggregates are also susceptible to deterioration from deicing salts. Geologists have identified the major components that affect the durability of these carbonate aggregates and sources are tested to ensure long term performance in Portland cement concrete. Air entrainment was originally put in concrete to improve scaling resistance. It is well known that air entrainment is required to provide freeze thaw protection in concrete pavements today. In Iowa, air entrainment was not introduced in concrete pavements until 1952. This research investigates properties that made older concrete pavements durable without air entrainment.

Plastic Air Content versus Hardened Air Content by High Pressure Air Meter, MLR-99-03, 2001

Plastic air content is typically tested by the pressure method, ASTM C138. Loss of air content through the paver has been shown to exceed 2 percent at times. Research has shown that early deterioration of pavements in Iowa may be directly or indirectly related to low or inadequate air content. Hardened air content is typically checked using the linear traverse method, ASTM C457. The linear traverse method is very time consuming and could not be used on a production scale. A quick and effective method of testing in place air content is needed. Research has shown a high degree of correlation with the high-pressure method of determining air content of hardened concrete versus plastic air content in laboratory conditions. This research indicated that air contents are more variable when comparing core results to plastic air content, although the overall average for the air content was comparable. Perhaps, the location of the plastic air content test, obtained from construction records, versus location of the cores was not as accurate as needed.

Investigation into Freezing-Thawing Durability of Low-Permeability Concrete with and without Air Entraining Agent, 2009

The aim of the present study is to investigate the effect of low-permeability concrete, made with reduced water‐to‐binder ratios (w/b) and/or supplementary cementitious materials (SCMs), on the need for air entrainment to achieve freezing‐thawing (F‐T) durability. In the present study, concrete mixes were made with different types of cement (Types I and IP), with or without fly ash replacement (15%), with different water‐to‐binder ratios (w/b =0.25, 0.35, 0.45 and 0.55), and with or without air entraining agent (AEA). All concrete mixtures were controlled to have a similar slump by using different dosages of superplasticizer. The rapid chloride permeability and F-T durability of the concrete samples were determined according to ASTM C1202 and ASTM C666A, respectively. The air void structure of the concrete was studied using the Air Void Analyzer, RapidAir, and porosity tests (ASTM C642). In addition, the general concrete properties, such as slump, air content, unit weight, and 28‐day compressive strength, were evaluated. The results indicate that all concrete mixes with proper air entrainment (ASTM C231 air content ≥ 6%) showed good F‐T resistance (durability factor ≥85%). All concrete mixes without AEA showed poor F‐T resistance (durability factor < 40%), except for one mix that had very low permeability and high strength. This was the concrete made with Type IP cement and with a w/b of 0.25, which had a permeability of 520 coulombs and a compressive strength of 12,760 psi (88 MPa). There were clear relationships between the F‐T durability and hardened concrete properties of non–air entrained concrete. However, such relationships did not exist in concrete with AEA. For concrete with AEA, good F‐T durability was associated with an air void spacing factor ≤ 0.28 mm (by AVA) or ≤ 0.22 mm (by RapidAir).

Letter health consultation : Air emissions from American Packaging Corporation, Story City, Iowa (2009)

A health consultation is a verbal or written response from ATSDR or ATSDR’s Cooperative Agreement Partners to a specific request for information about health risks related to a specific site, a chemical release, or the presence of hazardous material. In order to prevent or mitigate exposures, a consultation may lead to specific actions, such as restricting use of or replacing water supplies; intensifying environmental sampling; restricting site access; or removing the contaminated material. In addition, consultations may recommend additional public health actions, such as conducting health surveillance activities to evaluate exposure or trends in adverse health outcomes; conducting biological indicators of exposure studies to assess exposure; and providing health education for health care providers and community members. This concludes the health consultation process for this site, unless additional information is obtained by ATSDR or ATSDR’s Cooperative Agreement Partner which, in the Agency’s opinion, indicates a need to revise or append the conclusions previously issued.

Health consultation : Sub-Slab Gas and Air Sampling Data Alcoa – Davenport Works CERCLIS No. IAD005270160 Riverdale, Scott County, Iowa (2005)

The U.S. Environmental Protection Agency (EPA), the Alcoa – Davenport Works Facility (Alcoa), and concerned citizens and community leaders of Riverdale, Iowa requested the Iowa Department of Public Health (IDPH) Hazardous Waste Site Health Assessment Program to evaluate the health impacts of exposures to volatile organic vapors detected within residences located immediately to the west of the Alcoa property. This health consultation addresses inhalation exposure to individuals that may have occupied the currently vacant residences in which the air sampling was completed.

The Effect of Deicing Salt on Aggregate Durability, Progress Report HR-266, 1985

The Iowa DOT has been using rapid freezing in air and thawing in water to evaluate coarse aggregate durability in concrete since 1962. Earlier research had shown that the aggregate pore system was a major factor in susceptibility to D-cracking rapid deterioration. There are cases were service records show rapid deterioration of concrete containing certain aggregates on heavily salted primary roads and relatively good performance with the same aggregate in secondary pavements with limited use of deicing salt. A five-cycle salt treatment of the coarse aggregate prior to durability testing has yielded durability factors that correlate with aggregate service records on heavily salted primary pavements. X-ray fluorescence analyses have shown that sulfur contents correlate well with aggregate durabilities with higher sulfur contents producing poor durability. Trial additives that affect the salt treatment durabilities would indicate that one factor in the rapid deterioration mechanism is an adverse chemical reaction. The objective· of the current research is to develop a simple method of determining aggregate susceptibility to salt related deterioration. This method of evaluation includes analyses of both the pore system and chemical composition.

Air Formed Arch Culvert Construction: Crawford County, Construction Reports, HR-314, 1991

Iowa's secondary roads contain nearly 15,000 bridges which are less than 40 feet (12 m) in length. Many of these bridges were built several decades ago and need to be replaced. Box culvert construction has proven to be an adequate bridge replacement technique. Recently a new bridge replacement alternative, called the Air-0-Form method, has emerged which has several potential advantages over box culvert construction. This new technique uses inflated balloons as the interior form in the construction of an arch culvert. The objective of research project HR-314 was to construct an air formed arch culvert to determine the applicability of the Air-O-Form technique as a county bridge replacement alternative.

Effect of a Noise Wall on Snow Accumulation and Air Quality, 1985

A noise wall was investigated to assess its effect on snow accumulation and air quality. Wind tunnel studies were undertaken to evaluate (a) possible snow accumulations and (b) the dispersion of particulate concentrations (dust, smoke, and lead particles) and carbon monoxide. Full-scale monitoring of particulate concentrations and carbon monoxide was performed both before and after the noise wall was constructed. The wind tunnel experiments for snow accumulation were conducted on a model wall located in a flat, unobstructed area. A separated flow zone existed upwind of the wall and snow immediately began to accumulate over most of the separated zone. Having the noise wall in an aerodynamically rough area, such as in an urban area as this one was, substantially decreased the amount of snow collected, compared with in the wind tunnel studies, because of turbulence reducing the separation zone. The snow accumulation has not been significantly greater with the noise wall in place than it was before construction and has proven to be of no concern to date. Monitoring for particulate concentrations has shown that the noise wall has had a beneficial effect because the amount of material collected was reduced. With the noise wall in place, monitoring for carbon monoxide has indicated that (a) for equivalent emissions under conditions of high atmospheric stability and low wind speeds, the carbon monoxide levels would be lower; and (b) under conditions of low atmospheric stability and high wind speeds, the carbon monoxide levels would be higher than expected without the wall in place.

Health consultation : Review of on-site air monitoring data during the removal action at Le Mars coal gas site, Le Mars coal gas plant Le Mars, Plymouth County, Iowa EPA facility ID: IA0001032556 (2005)

The Iowa Department of Public Health (IDPH), Hazardous Waste Site Health Assessment Program was asked by the US Environmental Protection Agency (EPA) to review a round of air sampling data. The air data was collected and analyzed during a removal action at the Le Mars Coal Gas Site in Le Mars, Iowa. EPA asked IDPH to determine from the air data if additional monitoring is necessary throughout the removal action to protect nearby residents from exposure.