Posted in Geotechnical Engineering

An Overview of Compaction Equipment, from DM 7

Below are some charts for selecting compaction equipment for a given project and soil condition, from NAVFAC DM 7.02

You can order NAVFAC DM 7.02–and 7.01–for this and more valuable information by clicking here.

Posted in Academic Issues, Civil Engineering

Yes, Civil Engineers, Things Move —

A salutary reminder from Y. Ryabov’s An Elementary Survey of Celestial Mechanics: There is of course no sense in asking why the planets rotate or why they have motion in general. Everything in the universe, from the smallest dust particle to colossal cosmic bodies, is in constant motion. There is no such thing as matter […]

Yes, Civil Engineers, Things Move —
Posted in Academic Issues, Geotechnical Engineering

Ohio DOT’s Rendition of the AASHTO Classification System

With the Unified soil classification system, there are many ways of diagramming it. One of those was presented in the last post. With the AASHTO system, there’s generally only one, as shown in the Soils and Foundations Reference Manual. For classification this is pretty much it, but it’s not very informative when it comes to getting a “feel” for what these classifications mean.

Below is a chart from the Ohio Department of Transportation (about the only DOT I know of which uses the AASHTO system for just about everything they do) which describes each AASHTO classification in words and attempts to describe the type of soil for each type in the system.

AASHTO Soil Classification System as Described by the Ohio Department of Transportation
Posted in Geotechnical Engineering, Soil Mechanics, Academic Issues

Unified Soil Classification, from NAVFAC DM 7

In the course of teaching my Soil Mechanics class, I’ve tried numerous different charts and methods for teaching the Unified system of soil classification. Probably the most success I’ve had is with the one from NAVFAC DM 7, and it’s below. (I’ve included the plasticity chart for completeness.)

An example of how this works is here.

NAVFAC DM 7 remains a popular reference book for geotechnical engineers, and ordering information is here.