The Role of Magnesium in Concrete Deterioration, HR-355, 1994

Concretes with service lives of less than 15 years and those with lives greater than 40 years were studied with petrographic microscope, scanning electron microscope, and electron microprobe to determine why these two groups of concrete exhibit such different degrees of durability under highway conditions. Coarse aggregate used in both types of concrete were from dolomite rock, but investigation revealed that dolomite aggregate in the two groups of concretes were much different in several respects. The poorly-performing aggregate is fine-grained, has numerous euhedral and subhedral dolomite rhombohedra, and has relatively high porosity. Aggregate from durable concrete is coarse-grained, with tightly interlocked crystal fabric, anhedral dolomite boundaries, and low porosity. Aggregate in short service life concrete was found to have undergone pervasive chemical reactions with the cement which produced reaction rims on the boundaries of coarse aggregate particles and in the cement region adjacent to aggregate boundaries. Textural and porosity differences are believed to be chiefly responsible for different service lives of the two groups of concrete. The basic reaction that has occurred in the short service life concretes between coarse aggregate and cement is an alkali-dolomite reaction. In the reaction dolomite from the aggregate reacts with hydroxide ions from the cement to free magnesium ions and carbonate ions, and the magnesium ions precipitate as brucite, Mg(OH)2. Simultaneously with this reaction, a second reaction occurs in which product carbonate ions react with portlandite from the cement to form calcite and hydroxide ions. Crystal growth pressures of newly formed brucite and calcite together with other processes, e.g. hydration state changes of magnesium chloride hydrates, lead to expansion of the concretes with resultant rapid deterioration. According to this model, magnesium from any source, either from reacting dolomite or from magnesium road deicers, has a major role in highway concrete deterioration. Consequently, magnesium deicers should be used with caution, and long-term testing of the effects of magnesium deicers on highway concrete should be implemented to determine their effects on durability.

Welcoming New Iowans; A Guide for Christians and Churches, 2002

Immigrant and refugee newcomers have an important role in Iowa. These newcomers have revitalized many Iowa communities, workplaces and faith-based institutions. The arrival of immigrants and refugees poses challenges as well as rewards; understanding and addressing these issues is vital to welcoming and accommodating new Iowans and assuring their part in the long-term economic and social health of our state. This handbook represents a unique collaboration between the University of Northern Iowa (UNI) and Ecumenical Ministries of Iowa (EMI). The goal of this collaboration is to create a guidebook for Iowans to learn more about Iowa’s growing immigrant and refugee population and discover ways to welcome these newcomers and accommodate them in our communities and churches. The unique nature of this joint publication between a public university and Christian churches acknowledges that both institutions have a stake in accommodating immigrants in Iowa. UNI and all institutions of higher education need to support population growth to assure future enrollments. Churches and many other community institutions need immigrants and other newcomers to help maintain their viability. Universities and churches also need healthy local economies. Newcomers can provide much needed skills and labor to make this happen. In short, His collaboration recognizes that making immigration in Iowa work has important long-term implications for us all. This book was written and compiled by two university faculty members, but it is not an official university endorsement of Christianity as the only religion practiced and accepted by Iowans, and no university funds were used to print or distribute this handbook. This handbook is written for Iowa’s Christian community and is based on the Biblical mandate to welcome newcomers, but we acknowledge Iowa’s other religious groups and their role in accommodating newcomers as well. We readily acknowledge that other faith-based organizations also welcome newcomers and have a stake in making immigration a positive experience. In order to accommodate the perspectives and needs of these groups, the UNI New Iowans Program is planning to develop similar handbooks for Iowa’s Jewish and Muslim communities. This handbook includes a number of resource lists for individuals, newcomers, churches and others. Of course, as soon as these lists are printed, they may become out-of-date. In order to obtain the most up-to-date information, please visit the UNI New Iowans Web site: www.bcs.uni.edu/idm/newiowans/ The UNI New Iowans website also makes this handbook available in a PDF format.

Watching Corn Grow: A Hedonic Study of the Iowa Landscape, april 2007

Landscape amenities can be scarce in places with large areas of open space. Intensely farmed areas with high levels of monocropping and livestock production are akin to developed open space areas and do not provide many services in terms of landscape amenities. Open space in the form of farmland is plentiful, but parks and their services are in short supply. This issue is of particular importance for public policy because it is closely linked to the impact of externalities caused by agricultural activities and to the indirect effects of land use dynamics. This study looks at the impact of landscape amenities on rural residential property values in five counties in North Central Iowa using a hedonic pricing model based on geographic information systems. The effect of cropland, pasture, forest, and developed land as land uses surrounding the property is considered, as well as the impact of proximity to recreational areas. The study also includes the effect of other disamenities, such as livestock facilities and quarries, which can be considered part of the developed open space and are a common feature of the Iowa landscape.