An increasing number of integral and semi-integral abutment bridges are being built in Minnesota. A standard E8 expansion joint consisting of a 4.5 in (114 mm) piece of foam filler placed in a 4 in (102 mm) wide opening is typically provided at the joint between the approach panel and pavement. This joint has not performed well often failing within a year of service. This research project was primarily a synthesis study of other states' practices for the expansion joint. A detailed study of the following agencies' practices was conducted: Wisconsin, South Dakota, Iowa, Michigan, Ohio, Kansas, and Ontario, Canada. There were substantial differences between all of the practices and none easily adaptable to Minnesota. For instance, Minnesota, unlike the other states studied, does not permit deck drains on its bridges for environmental reasons. Most of the agencies seemed satisfied with their current practices. Four out of the seven agencies used strip seals in one form or another. Only one (Iowa) still uses the same foam filler as Minnesota, although others had in the past. The Iowa detail involves doweled bars across the joint and a different approach slab detail. In order to measure the actual movement at the joints, sensors were installed on several bridges and recorded displacement and temperature for a period of one to two years.
Conservation and reuse of resources is a necessity in achieving sustainability across the globe. In recent years, construction and demolition debris including bricks has appeared in stockpiles around Minnesota. The objective of this research project was to investigate the possibility of putting the brick to beneficial use as aggregates for base courses in pavements. This would help to conserve natural stone aggregate and also recycle the brick instead of dumping it as waste in a landfill. In addition, contractors could save money by being able to reuse locally available material. MnDOT is already quite progressive in its use of recycled materials and allows the use of recycled concrete aggregates, recycled asphalt pavement, and recycled glass in base and surface courses. Based on current literature review, Minnesota may become a pioneer in the use of recycled brick aggregate as well. There are many different types of clay bricks including structural bricks (both commercial and residential), pavers, and refractory bricks. The structural bricks and pavers will also vary from region to region. The bricks used in Minnesota are of the highest quality available because they have to meet severe weathering requirements. Structural brick accounts for the largest amount of brick manufactured. In this project, samples of various types of bricks were tested. The main tests conducted were the Los Angeles Rattler to assess abrasion properties and the magnesium sulfate soundness to evaluate freeze-thaw durability. In addition, basic engineering properties such as specific gravity and absorption were determined.
The need to consider sustainability in design dictates that materials should be recycled and reused whenever possible. The Minnesota Department of Transportation (MnDOT) is quite progressive in allowing the use of recycled aggregates in new construction. While the use of recycled concrete aggregate (RCA) in the base course of new pavements is quite common in Minnesota and many other states; it is rarely used in the concrete pavement itself. In fact; Minnesota was one of the few states to build multiple trial projects and has one of the largest number of concrete pavements constructed using the RCA in the concrete itself. The performance of those pavements; most of which are still in service; has never been formally evaluated against similar conventional concrete pavements. This prompted the current research study. Additional objectives were to assess the current state of practice across the nation; conduct experimental investigations using RCA in concrete; assess the sustainability and in particular the economics of using RCA in concrete; and finally to provide some recommendations for guidelines on using RCA in concrete. It has been shown by the authors and other researchers that it is possible to create strong and durable concrete mixtures using RCA as coarse aggregate in volume replacement levels of natural coarse aggregate up to 100%.
