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Tim Ruelke, P.E., Director, Office of Materials

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Did You Know?

By Matt Bluman, Manager of Training and Safety

Posted: April 2011Header-Did-You-Know

Some tips, tricks and interesting facts to make life in the testing laboratory just a little bit easier.

soil-paper

Formerly just a quick shortcut, but now added to the standard for determining the moisture content of soil (ASTM D 2216), detecting remaining moisture in a hot sample can be done by placing a strip of paper over the material.  If the strip of paper curls, the sample still contains moisture.

 


Sodium hexametaphosphate is commonly used in the particle size analysis of soils (AASHTO T88 and ASTM D 422). However, did you know that since it is a dispersing agent, it works great in cleaning clogged fine-mesh test sieves? Try soaking your No. 200 wash sieve in your expired or unused sodium hexametaphosphate solution to remove unwanted soil or aggregate particles.


eyepieceWe receive many questions regarding the magnifying eyepiece that our staff carries in their assessment kits.   These devices are sometimes called optical comparators, jeweler’s loupes, watchmaker’s loupes, or Hastings lenses.  The eyepieces that assessors carry have 7x enlargement, a range of 0 to 20 mm, and are readable to the nearest 0.1 mm.   We use them to visually inspect sieves, penetration needles, and other smaller pieces of equipment during an assessment.

 

The small glass pycnometers used for Specific Gravity of Asphalt Cement (AASHTO T 228 or ASTM D 70) are called Hubbard bottles or Hubbard-Carmick bottles. The straight-walled pycnometers are the Hubbard variety, and the conical-shaped ones are the Hubbard-Carmick type. A simple search in your favorite search engine will bring up many online stores that sell this glassware.

 

vinegar-bottle


Prompt washing of slump cones, unit weight measures, air meters, and scoops is always the best way to keep them clean and free of debris. However, if your field equipment does get encrusted with cured concrete, soak it in a bucket of vinegar for a week or two for easy cleaning.   Remember never to soak anything with a rubber gasket in vinegar, as the acidity could cause the rubber to break down.

 

 

 

Do you have your own tips and tricks that you'd like to see included in a future edition of "Did You Know?" Send your suggestions to Matt Bluman.

Special thanks to Kevin Kelly, Cement and Concrete Reference Laboratory (CCRL).

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