kevin macdonald cont’din-Situ cont’d

in-Situ cont’dnorth dakota

inside this issue aet updateS

When detailed information about the strength and compressibility of soil and bedrock is required beyond just the “blow counts,” in-situ methods should be con-sidered. In-situ geotechnical testing can provide more geotechnical data than the Standard Penetration Test. These methods include the field vane shear test, borehole pressuremeter and dilatometer, the bore-hole shear test, and the cone penetration test.

Cone Penetration TestThe electronic Cone Penetration Test, or “CPT,” is a fast and economical way to supplement conventional soil borings. The cone penetrometer is a cylindrical

In 2010, AET’s Board of Directors’ primary concern was filling the sig-nificant void left in our organization following the untimely loss of one of our founders, Richard D. Stehly, P.E.

With only a handful of individuals in our industry who could match Richard’s credentials, experience, and credibility, it was not an easy task. We could not be more pleased to welcome Kevin MacDonald, P.E., PhD to our staff. We are certain that Richard would be in full agreement with our selection—especially since Kevin was his colleague.

Prior to joining AET, Kevin spent eleven years as the Vice President and Technical Director of Materials at Cemstone Concrete Products. Kevin has been instrumental in the new

device, 43.7 mm in diameter, attached to a series of rods which are hydraulically pushed into the ground (see photo at left). At the tip of the penetrometer is a steel cone which is connected internally to an electronic load cell. The “tip resis-tance” is measured as the pene-trometer is advanced into the ground. A second internal load cell is connected to the side of the pen-etrometer, which measures the “sleeve friction.” Most penetrome-ters in use today, such as AET’s, have a pore pressure element, typi-cally located just behind the cone, or on the “shoulder” of the pene-trometer. This element measures porewater pressures generated as the penetrometer is advanced into the ground. A penetrometer which incorporates the pore pressure pie-zometric element is known as a “piezocone,” and is designated as “CPTu.”

Cone Penetrometer HistoryThe mechanical cone penetrometer was first invented in the Netherlands in 1932, and was known as the “Dutch cone.” The first electronic cone penetrometers were intro-duced in the late 1940s, but these early penetrometers only measured tip resistance and sleeve friction. Modern-day piezocones came into use in the 1970s and 80s, but their use was relatively rare in the United States. It wasn’t until the 1990s

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A neWSleTTer for ClIenTS And BuSIneSS PArTnerS of AmerICAn engIneerIng TeSTIng, InC.

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In-SItu GeotechnIcal teStInG – Part 2 of 2 By GREGoRy R. REUTER, PE, PG – AET ST. PAUl

SPrIng 2012

a close-up of the piezocone penetrometer.

WelcomInG KevIn macdonald, Pe, Phd

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aet new hire kevin macdonald (at left) and terry Swor.

By TERRy SWoR, PG – CEo, ChAIRMAN

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when their use gained popularity in the U.S. The current ASTM designa-tion for CPT and CPTu testing is D5778-12 “Standard Test Method for Electronic Friction Cone and Piezocone Penetration Testing of Soils.”

Seismic GeophoneThe piezocone penetrometers that AET uses incorporate a seismic geo-phone, which allows for the measure-ment of the soil shear wave velocity. This provides data for the calculation of the soil modulus, used in soil set-tlement calculations, and also for determining the site seismic classifi-cation required by the International Building Code (IBC). Because the seismic piezocone (SCPTu) measures the soil shear wave velocity directly, a more accurate assessment of the site seismic classification can be made, when compared to generally more conservative estimates from conven-tional soil borings and Standard Penetration N-values.

AET operates two dedicated SCPTu rigs: a truck rig and a crawler-mount-ed rig, both of which provide 20 tons of reaction force for advancement of the piezocone penetrometer. The

penetrometer is pushed into the ground at a rate of 20 mm per second. The load cells and pore pressure element take readings every second; therefore, data on the subsurface soil profile is collected approximately every ¾ inch. SCPTu soundings can be performed to depths well over 100 feet. They provide a much more detailed assess-ment of the soil stratigraphy compared to a conventional soil boring which may collect samples only at about 2½- to 5-foot intervals. A conventional 100-foot deep soil boring may take a day to drill, whereas a 100-foot deep SCPTu sounding can be completed in about two hours.

SCPTu TestingThe results of the SCPTu test are pre-sented as a graph of data plotted against depth, as illustrated at the top of page 3. Shown are the cone tip resistance (qt), friction sleeve resis-tance (fs), porewater pressure (u2), and shear wave velocity (Vs). Also shown is the calculated “friction ratio” (Rf), which is simply the ratio of the sleeve friction to the cone tip resis-tance, expressed as a percent. The friction ratio is used, for example, to help further identify differing soil strata.

aet’s truck-mounted (at left) and crawler-mounted (at right) 20-ton, Scptu rigs.

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generation of concrete mixes used on many bridge structures under con-struction today. Renowned through-out the U.S. and Canada for his tech-nical innovation, he is a sought-after speaker on various aspects of con-crete technology.

Throughout the years, Kevin collabo-rated with Richard and AET on numerous projects. one such project will receive national recognition on March 22, 2012. The American Society of Civil Engineers will bestow Cemstone and AET with the presti-gious 2012 Charles J. Pankow Award for Innovation. The award recognizes the “New Sustainable Concrete Mix Design,” which proved to be an over-whelming success when used in the construction of AET’s NDT radiation vault. Kevin, Richard, and AET’s Dan Vruno teamed up to develop this cut-ting-edge and highly sustainable mix design.

like Richard, Kevin is committed to the industry and is actively involved in the American Concrete Institute (ACI). ACI will be hosting their national convention in the spring of 2013 in Minneapolis with Kevin as president of the Minnesota chapter of ACI and chair of the convention. When the ACI convention was held in the Twin Cities in 1993, Richard served in the exact same roles.

In his new position at AET, Kevin will serve as Principal Engineer and Vice President of AET’s Materials Technology. Kevin will assist the Concrete Technology Group and American Petrographic Services in continuing to provide the latest in concrete technology to AET’s clients.

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SCPTu testing can be carried out in a wide range of soil conditions, from clays to sands, and from very soft to dense soils. Cone penetration testing is particularly useful in profiling peat and swamp deposits, which are com-mon in the Upper Midwest. The results of SCPTu testing can be used for cal-culating bearing capacity and settle-ment of spread footing foundations and embankments and to estimate the capacity and settlement of deep foun-dation elements, such as driven piles.

Although the cone penetrometer does not collect soil samples, correlations have been developed to take the data obtained from the penetration test and define a soil behavior type which links the CPTu mechanical response to traditional soil descriptions. AET does, however, have a soil sampler that can be pushed using the SCPTu rig to obtain a small, one-inch diame-ter soil sample if needed. Correlations are also made for estimating geotech-nical properties of the soil, such as friction angle, undrained shear strength, unit weight, and relative density.

The piezocone test can also be paused during advancement and the rate of porewater pressure dissipation in the soil can be measured by the piezomet-ric element located on the shoulder of the penetrometer. The results can be

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typical seismic piezocone results: cone tip resistance (qt), friction sleeve resistance (fs), porewater pressure (u2), shear wave velocity (vs), and “friction ratio”(rf).

used for correlation to time rate of consolidation and permeability, which are helpful in evaluating the settle-ment and consolidation characteristics of clay and fine-grained soil deposits.

AET introduced the first commercial-ly available SCPTu rig in Minnesota, and is a leader in seismic piezocone testing and analysis in the Upper Midwest. Please contact us to discuss how piezocone analysis can benefit your project.

About the author: Gregory Reuter, PE, PG is a principal geotechnical engineer and engineering geologist for AET and works at the St. Paul office. If you have any questions, he can be contacted at greuter@amengtest.com.

aet engineering technician performing a piezocone sounding.

By WIllIAM holDER, PE – AET RAPID CITy / DICKINSoN

WorKInG In north daKota

In 2011, AET headed west to open offices in Dickinson and Williston, North Dakota. Since then, AET’s geotechnical and materials staff have provided solutions on a diverse range of oil well pad construction projects.

like any new frontier, working in North Dakota has its own special challenges. After North Dakota’s wet spring in 2011, muddy and deterio-rated roads made it nearly impossible for oil companies to access their well pads. To facilitate all-weather access, AET engineered cement-stabilized well pads and access roads.

Also challenging is the high sulfate concentration of some North Dakota soils. These soils can “attack” and deteriorate building foundations and other concrete structures. With this in mind, it’s important to measure soil sulfate concentrations on every proj-ect and incorporate the appropriate concrete mix design in order to pro-tect against sulfate attack.

have questions about working in North Dakota? Bill h older can be reached at wholder@amengtest.com or (605) 786-8799.

the north dakota oil boom has provided new opportunities within the a/e/c industry.

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©2012 by AET

Published four times a year by AET for our clients

and business partners. Comments? Contact:

Libbie Krussow – Marketing Coordinator

lkrussow@amengtest.com or (651) 659-1327

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PRESoRTED STANDARD

US PoSTAGE PAID EAU ClAIRE WIPERMIT No. 366

american engineering testing, Inc.550 cleveland avenue northSaint Paul, mn 55114

return ServIce reQueStedAnjie Flowers – hR Mgr. / St. PaulDavid Jozwiak – CMT I / WausauRoger McFee – NDT II / Baton RougeRichard hampton – CMT II / WausauShirley lieberman – Administrative

Assistant / St. Paulla Zhao – Engineer / St. PaulKevin MacDonald – V.P. / St. Paul

new employees dec. 2011 – mar. 2012 employee Spotlight – Anjie flowers, Jd

Anjie Flowers recently joined AET as human Resources Manager in AET’s St. Paul office. Anjie holds a master’s

degree in organizational Management and human Resources. She earned her law degree from hamline University School of law in December 2011. An-jie’s10 years of professional business experience includes human resources positions in business corporations and higher education.

Certifications

on the moveChuck Bisek, a senior envi-ronmental scientist in AET’s St. Paul office, was recently appointed to oversee the devel-opment of AET’s environmen-

tal operations in western North Dakota. Chuck will be moving from St. Paul to Dickinson, North Dakota in mid-April and can be reached at (701) 483-4288.

look for us at These Tradeshows4/11-13 – MN Airports – Rochester, MN4/17-18 – SME – Duluth, MN5/2-3 – WI AIA – Madison, WI5/22-24 – Petroleum Conf. – Bismarck, ND6/20-22 – MN Cities – Duluth, MN

Kris Bordak received her certification in MnDoT Grading & Base II.

leRoy Callais received certification from the ICC as a Special Inspector of Structural Masonry.

Greg Reuter and Jay Brekke recently tested and achieved “Advanced” level on the Dynamic Measurement and Analysis Proficiency Test given by Pile Dynamics, Inc. and the Pile Driving Contractors Association.

Daniel lakadawala – NDT II / PalatkaJames Meyer – Engineer / St. PaulMarilyn hein – CMT I / WausauRyan Keske – CMT II / Chippewa Falls

Welcome Back!

AET won both the 2011 ACEC Grand and People’s Choice awards for Beacon Bluff! Also Gail Cederberg won the 2011 Member of the y ear award from Minnesota Environmental Initiative, con-grats Gail!

Awards