Geotextiles are frequently used for subgrade improvement under roadways. Caltrans has released a document titled "Guide for Designing Subgrade Enhancing Geotextiles". This 18-page document covers what situations can be improved using geotextiles and includes a flowchart for guidance on when to apply them and for what purposes. From Geosynthetics magazine. (Image by Caltrans)
This post contains a summary of geotechnical, materials testing, geosynthetic and related testing standards that were updated by ASTM during the month of September. This month there were not as many updates as the last couple, but a few that caught my eye are a new standard for measuring geosynthetic-soil resilient interface shear stiffness, a revision to the standard practice for laboratories testing concrete and concrete aggregates for use in construction and criteria for laboratory evaluation and a revision to the standard for measuring slump flow of self-consolidating concrete.
The site for the new Harrison County Hospital, approximately 25-miles west of Louisville, Kentucky had 15 sinkholes formed by limestone dissolution, a geomorphologic process referred to as Karst topography. There were a number of geotechnical engineering and geological engineering challenges associated with the characterization, excavation, backfilling, foundation engineering and other mitigation measures as described by Peggy Hagerty Duffy, P.E. in her article entitled “Karst and Complications” in the August 2008 issue of Civil Engineering Magazine (Duffy, 2008b).
Mitigation measures for the sinkholes included use of graded filters with geotextiles, careful inspection of rock socket foundations along with pilot holes and careful geotechnical inspection throughout the construction process. One particularly interesting aspect of the project is that several of the sinkholes were used as drainage facilities to receive surface water runoff. Read on for a summary of this interesting article. (Photo of sinkhole in Karst Topography being used as a drainage feature, from Duffy (2008b), Civil Engineering Magazine)
Tenax is a well known name in the geosynthetics industry. Recently a new company, Syntec, acquired portions of Tenax. From GeosyntheticsMagazine.com: According to a press release distributed Oct. 13, Syntec acquired the assets related to […]