Evaluating Properties of Blended Cements for Concrete Pavements, December 2003

The addition of supplementary cementitious materials (SCMs), such as fly ash (FA) and slag, generally improves concrete workability, durability, and long-term strength. New trends in sustainable development of concrete infrastructure and in environmental regulations on waste disposal are spurring use of SCMs in concrete. However, use of SCM concrete is sometimes limited due to a lack of understanding about material behaviors and lack of proper specifications for its construction practice. It is believed that SCM concrete performance varies significantly with the source and proportion of the cementitious materials. SCM concrete often displays slower hydration, accompanied by slower setting and lower early-age strength, especially under cold weather conditions. The present research was conducted to have a better understanding of SCM concrete behaviors under different weather conditions. In addition to the study of the effect of SCM content on concrete set time using cementitious materials from different sources/manufacturers, further research may be needed to investigate the effects of SCM combinations on concrete flowability, air stability, cracking resistance, and durability.

State of Iowa HIV and AIDS Surveillance Report,June 2005

This quarter, we saw 17 HIV diagnoses, half the number of persons diagnosed in the first quarter of the year. For the two quarters, there were 50 diagnoses, keeping pace with last year’s number of diagnoses. Nineteen of the 50 (38%) received concurrent AIDS diagnoses. Of concern this year is the high number of persons reported without a risk. Over 40% of new cases were initially reported without a risk. Most of these cases are being investigated by disease prevention specialists. History shows us that a good proportion of these cases will be assigned to a risk category in the coming months as more is learned about their risks and the risks of their partners. Note that only 17% of cases diagnosed in 2004 remain without a known risk. There were 36 AIDS diagnoses in the first two quarters of 2005, just a bit ahead of what we saw last year. Fifteen of these were persons who had been diagnosed with HIV at least one year (fifteen years for two persons), and the rest received concurrent HIV and AIDS diagnoses.

2002 Iowa Youth Survey State of Iowa Results, April 2003

The 2002 Iowa Youth Survey (IYS) State of Iowa report was designed to help state-level planners identify youth development-related needs, develop relevant programs, and assess the outcomes of those programs. These data can help us better understand our youth and their needs. They can help us assess the strengths and weaknesses of our schools, families and communities from the young person’s perspective. In addition, the data in this report help the state obtain funds for a wide variety of programs. At every step in the process – from needs identification, to program development and implementation, to program assessment – the 2002 IYS data will provide a valuable resource. The state report can also help Iowa’s schools, area education agencies and counties assess their relative strengths and weaknesses. The grades 6, 8, and 11, as well as male and female percentages reported in each of these reports can be compared with the respective state report percentages. The higher the proportion of students in each of these columns that completed a usable IYS questionnaire, the more likely the comparisons with the state report percentages will be unbiased. Such comparisons should be considered exploratory, but for the most part are likely to prove useful.

2005 Iowa Youth Survey State of Iowa Results, Revised December 2006

The 2005 Iowa Youth Survey (IYS) State of Iowa report was designed to help state-level planners identify youth development-related needs, develop relevant programs, and assess the outcomes of those programs. These data can help you better understand our youth and their needs. They can also help you assess the strengths and weaknesses of our schools, families, and communities from the young person’s perspective. In addition, the data in this report help the state obtain funds for a wide variety of programs. At every step of the process–from needs identification, to program development and implementation, to program assessment–the 2005 IYS data will prove to be a valuable resource. The state report can also help Iowa’s schools, area education agencies, and counties assess their relative strengths and weaknesses. The grades 6, 8, and 11, as well as male and female percentages reported in district-level, AEA-level, county-level, and other 2005 IYS reports can be compared with the respective state report percentages. The higher the proportion of students in each of these columns that completed usable IYS questionnaires, the more likely the comparisons with the state report percentages will be unbiased. Such comparisons should be considered exploratory, but for the most part are likely to be useful.

Performance of Randomly Oriented, Fiber-Reinforced Roadway Soils, HR-211, 1982

Several primary techniques have been developed through which soil aggregate road material properties may be improved. Such techniques basically involve a mechanism of creating a continuous matrix system of soil and/or aggregate particles, interlocked through the use of some additive such as portland cement, lime, or bituminous products. Details by which soils are stabilized vary greatly, but they are dependent on the type of stabilizing agent and nature of the soil, though the overall approach to stabilization has the common feature that improvement is achieved by some mechanism(s) forcing individual particles to adhere to one another. This process creates a more rigid material, most often capable of resisting the influx of water during freezing, loss of strength due to high moisture content and particle dispersion during thawing, and loss of strength due to migration of fines and/or water by capillarity and pumping. The study reported herein, took a new and relatively different approach to strengthening of soils, i.e., improvement of roadway soils and/or soil-aggregate materials by structural reinforcement with randomly oriented fibers. The purpose of the study was to conduct a laboratory and field investigation into the potential of improving (a) soil-aggregate surfaced and subgrade materials, including those that are frost-prone and/or highly moisture susceptible, and (b) localized base course materials, by uniting such materials through fibrous reinforcement. The envisioned objective of the project was the development of a simple construction technique(s) that could be (a) applied on a selective basis to specific areas having a history of poor performance, or (b) used for improvement of potential base materials prior to surfacing. Little background information on such purpose and objective was available. Though the envisioned process had similarities to fibrous reinforced concrete, and to fibrous reinforced resin composites, the process was devoid of a cementitious binder matrix and thus highly dependent on the cohesive and frictional interlocking processes of a soil and/or aggregate with the fibrous reinforcement; a condition not unlike the introduction of reinforcing bars into a concrete sand/aggregate mixture without benefit of portland cement. Thus the study was also directed to answering some fundamental questions: (1) would the technique work; (2) what type or types of fibers are effective; (3) are workable fibers commercially available; and (4) can such fibers be effectively incorporated with conventional construction equipment, and employed in practical field applications? The approach to obtaining answers to these questions, was guided by the philosophy that an understanding of basic fundamentals was essential to developing a body of engineering knowledge, that would serve as the basis for eventual development of design procedures with fibrous products for the applications previously noted.