Learn how to be an AASHTO lab 24/7

"“…if you do everything that the AASHTO accreditation requires you to do, if you execute all of the requirements of [AASHTO re:source], you will have a well-run laboratory."

Florida Department of Transportation

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

55+ years of experience
PSP participants
samples shipped per year
laboratory assessments per year
accredited labs

  • Calibrating Thermometers: The Science Behind Meaningful Temperature Measurement, Part 1: Introduction

    ​I've said it myself: without calibration, we have no confidence in the measurements that we take. And if a measurement isn’t meaningful, why even bother? Nevertheless, if you’ve read my previous articles, "The Anatomy of a Liquid-in-Glass Thermometer" and "Let’s Get Digital," you know that, up to this point, I have (intentionally) avoided the subject of thermometer calibration. So, if calibration is such an important subject, why have I been avoiding it for so long? The answer is simple: I’ve been procrastinating.
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  • Under Pressure

    We experience pressure every day. Feeling the wind on your face, drinking through a straw, even sitting in your chair all give you sensations of pressure. So why can pressure be such a confusing concept to apply to laboratory testing? There are several factors. Pressure is measured in several different units – kilopascals, millimeters of mercury, pounds per square inch, and many others. Pressure can also be measured from several different perspectives, depending on the kind of equipment used. In addition, laboratory work may require the application of either a partial vacuum (also called negative pressure), or a positive pressure. Finally, there are terms for specific kinds of pressure (residual, partial, barometric, etc.) used in laboratory testing that can add to the confusion.
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  • The Road to Developing an Effective Quality Management System (QMS): Part 1 - Why Bother?

    Ease up on those brakes! Developing an effective QMS does require precious time and resources, but the benefits will far outweigh the work involved when the procedures and processes are followed and continually improved. An organization can benefit from developing and implementing an effective QMS in many ways. Here are some of the best:
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  • New Tools for Specifiers: the Missing Piece of the Accreditation Puzzle

    A specifier is any entity that requires laboratory testing to be performed by an agency that participates in one or more of AASHTO re:source’s programs. Specifiers can include departments of transportation, local municipalities, or even corporate offices that manage several branch laboratories. Some of AASHTO re:source’s current specifiers include the Federal Aviation Administration (FAA), the California Division of the State Architect (DSA), and the United States Army Corps of Engineers (USACE). Being a specifier can be challenging, and requires constant review of ever-changing laboratory information, such as proficiency sample ratings or accreditation status. In the past, tracking information for one hundred, ten, or even three laboratories was a daunting task.
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  • Let’s Get Digital: A Guide to Unraveling the Tangled World of Digital Thermometers

    Purchasing a digital thermometer for your laboratory can be a difficult task. There are numerous choices available, with prices ranging from just a few bucks to thousands of dollars. So, which one of these devices is right for you? How can you keep costs low without compromising quality? What is the difference between an RTD and a PRT, and which one works best? And what the heck is a thermistor, anyway?
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  • Did You Know?

    Some tips, tricks and interesting facts to make life in the testing laboratory just a little bit easier.
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  • A Very Boring Article: (New Requirements for Superpave Gyratory Compactor Molds)

    AASHTO T 312, Preparing and Determining the Density of Hot Mix Asphalt (HMA) Specimens by Means of the Superpave Gyratory Compactor, was modified in 2011 to include some new requirements for specimen molds. One of the major changes includes new diameter tolerances. New molds must still be manufactured to have a tolerance of 149.90 to 150.00 mm. However, in-service molds are allowed to have a diameter from 149.90 to 150.20 mm. In addition, a detailed procedure for measuring the inside diameter of the molds using a three-point bore gauge has been added and can be found in Annex A of T 312 (2011 version).
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  • The Anatomy of a Liquid-in-Glass Thermometer

    ​Some of my fondest memories from childhood are of working in the kitchen with my mother—canning tomatoes, making candy apples, and baking bread. I still remember how my mother taught me to carefully check the candy thermometer as we made the caramel coating, and how I learned to set the oven to just the right temperature so that the bread would rise and bake correctly. I never thought about it as a child, but temperature measurement played an important role in all of the cooking and baking projects that my mother and I shared.
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  • Seven Steps for a "Perfect" On-Site Assessment

    We all realize that having a perfect on-site assessment is no small accomplishment. However, there are some rather simple steps your laboratory can take to ensure that the assessment runs smoothly and relatively error-free. The staff at AASHTO re:source understands what a special event the on-site assessment is for each of our customers, and that it can be an overwhelming process. The goal of this article is to give you a few pointers on preparing for your on-site assessment. Following these steps will help you get the most out of the assessment process and ensure that it runs as smoothly as possible.
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  • Pycnometers, Calibrations, and Insulated Containers: A Guide to Understanding ASTM D 854, Soil Specific Gravity

    When planning an assessment for a laboratory that will be running ASTM D 854, many thoughts race through my mind. For example, does the technician know that there are significant differences between AASHTO T 100 and ASTM D 854? Have the calibrations been performed correctly? Or, is all of the right equipment available? ASTM D 854 can be a difficult test, and many people are not familiar with the intricacies involved with running it. In this article I will talk through the portions of the test that seem to cause the most confusion, explain reasons behind certain steps, and also offer helpful tips and suggestions.
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  • Metrology Musings: Uncertainty? There’s An App For That.

    My smartphone is really smart. Really. It can serve as a phone, a camera, a computer, a radio, and a global positioning system (GPS). I also can choose from over 300,000 apps to download onto my phone, all designed to make my life fun and easy. Really. Want to Facebook your friends? There’s an app for that. Need help with your taxes? There’s an app for that…oops, you're too late for that. Want to transform your phone into a baby monitor? There’s an app for that. Looking for a great example of measurement uncertainty? There’s even an app for that.
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  • Getting the Most Out of the Proficiency Sample Program: A Guide to Our Online Features and Tools

    Samples, data, ratings…Oh My! It can be a challenge to keep everything straight when enrolled in the AASHTO re:source Proficiency Sample Program (PSP). If your laboratory is already registered at www.AASHTOresource.org, you know how it can help you keep track of everything PSP-related. This article will cover some of the features on our website that will make participation in the Proficiency Sample Program a bit more manageable.
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  • Get to the Root of the Problem: Root Cause Analysis (RCA) Explained

    Ever get tired of those pesky dandelions in your otherwise lush yard? The weeds are the obvious problem, but have you ever thought about the underlying, or “root,” cause? That might not be so obvious. In reality, there are usually multiple “roots” to most problems, even in the construction materials testing (CMT) industry.
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  • Did You Know?

    Some tips, tricks and interesting facts to make life in the testing laboratory just a little bit easier.​
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  • The Importance of Asphalt Content Ignition Furnace Correction Factors

    Thanks to new technology, many of our materials testing procedures are becoming more automated. It only makes sense that advancements in computing, measurement science, and electronics have had a positive effect on laboratory testing. Testing machines with a "set it and forget it" operation allow us to perform more testing with less staff in a shorter amount of time. These advancements certainly make life in a testing laboratory easier and, in many cases, the benefits directly correlate to cost savings. However, some testing equipment has become so easy to use that we tend to trust the data obtained without question.
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  • Quality Corner: ISO/IEC 17025 Accreditation

    Did you know that AASHTO re:source offers on-site assessments and AASHTO offers accreditation for International Standard ISO/IEC 17025? You may have at least heard of this standard by now, but maybe you don't know much about it. The title of the standard is "General Requirements for the Competence of Testing and Calibration Laboratories." But how does that differ from AASHTO R 18, "Establishing and Implementing a Quality Management System for Construction Materials Testing Laboratories," which is the basis for accreditation through the AASHTO Accreditation Program (AAP)? How can a laboratory become accredited for ISO/IEC 17025? What are the benefits? Let's take a closer look.
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  • Proficiency Sample Ratings: Being Average Has Never Been So Good

    So you opened up your email notification to see that the latest AASHTO re:source proficiency sample ratings were just posted, you log into the website to view your ratings (Figure 1), and you see ratings of **, -5, -3, 5,4. You think to yourself, "I know that 4 and 5 are good, but what about the negative numbers? Those are below 3, so they must be bad... and what are the stars for? I doubt they're like the stars that my elementary school teacher used to give me... and what is this repeatability rating?"
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  • Metrology Musings: Calibration vs. Standardization

    I promised in the inaugural article of Metrology Musings that I'd discuss metrology topics such as calibration, traceability, and measurement uncertainty. Let's use these terms to compare and contrast the two most common, and most commonly misunderstood concepts: calibration and standardization. These terms are prevalent in many testing standards, as well as in AASHTO R 18, Establishing and Implementing a Quality Management System for Construction Materials Testing Laboratories, so it's important to understand the implications of each.
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  • Is Water More Than Just H2O?

    Many common test procedures require special kinds of water, such as tap, distilled, deionized, or deaired. What are the differences among these types of water? Why is it so important to make sure we are using the correct type of water for the correct test?
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  • A Day in the Life of an Assessor

    RING! RING! RING! - The hotel wake-up call abruptly starts my morning routine. In a familiar hotel room, but unfamiliar city, I groggily roll out of bed. So starts another day as an AASHTO re:source Laboratory Assessor on the road. I have to remind myself where I am - I'm just outside of Chicago today. Luckily I got in early enough yesterday to get settled in and this morning is starting off pretty well. Before I head to the laboratory, I grab a quick bite to eat.
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