Monday Morning Eye Opener, December 07, 2015

Weekly Newsletter from the Northwest District Office for libraries containing programs, activities, classes for the upcoming week.

Iowa 58 Viking Road Corridor from U.S. 20 to Greenhill Road in Cedar Falls, Iowa, NHSX-U-58-1(91)--8S-07, 2015

The Proposed Action consists of the improvement of Iowa Highway 58 (IA 58) from U.S. Highway 20 (U.S. 20) north to Greenhill Road in Cedar Falls (Black Hawk County, Iowa). The improvement would include limiting at-grade access to IA 58 by adding one or more interchanges to the corridor which would be located at Viking Road, Greenhill Road, and reconfiguring the U.S. 20 interchange (Figure 1). In order to construct these interchanges and associated ramps, the pavement of IA 58 would be reconstructed. In a couple of locations, the alignment of IA 58 would be shifted.

Cement Stabilization of Embankment Materials, 2015

Embankment subgrade soils in Iowa are generally rated as fair to poor as construction materials. These soils can exhibit low bearing strength, high volumetric instability, and freeze/thaw or wet/dry durability problems. Cement stabilization offers opportunities to improve these soils conditions. The objective of this study was to develop relationships between soil index properties, unconfined compressive strength and cement content. To achieve this objective, a laboratory study was conducted on 28 granular and non-granular materials obtained from 9 active construction sites in Iowa. The materials consisted of glacial till, loess, and alluvium sand. Type I/II portland cement was used for stabilization. Stabilized and unstabilized specimens were prepared using Iowa State University 2 in. by 2 in. compaction apparatus. Specimens were prepared, cured, and tested for unconfined compressive strength (UCS) with and without vacuum saturation. Percent fines content (F200), AASHTO group index (GI), and Atterberg limits were tested before and after stabilization. The results were analyzed using multi-variate statistical analysis to assess influence of the various soil index properties on post-stabilization material properties. Results indicated that F200, liquid limit, plasticity index, and GI of the materials generally decreased with increasing cement content. The UCS of the stabilized specimens increased with increasing cement content, as expected. The average saturated UCS of the unstabilized materials varied between 0 and 57 psi. The average saturated UCS of stabilized materials varied between 44 and 287 psi at 4% cement content, 108 and 528 psi at t 8% cement content, and 162 and 709 psi at 12% cement content. The UCS of the vacuum saturated specimens was on average 1.5 times lower than that of the unsaturated specimens. Multi-variate statistical regression models are provided in this report to predict F200, plasticity index, GI, and UCS after treatment, as a function of cement content and soil index properties.

Iowa AgriNews, March 7, 2016, Vol. 16, no. 07

Crop and livestock summaries for the state of Iowa, produced by the Iowa Department of Agriculture. Previously Agri-News