Posts Tagged ‘aggregates’

Dependence on Aggregates as Building Blocks of Our Infrastructure

Posted on: September 4th, 2015 by Microtrac

Dependence on Aggregates as Building Blocks of Our Infrastructure.

Highways, bridges, airport runways, dams, and railway beds are all integral components of a country’s infrastructure. Their quality and long term endurance are dependent on the quality and strength of the crushed stone aggregates and natural and manufactured sand that get combined in the particle blends used to produce cement and asphalt concretes for their construction. Coarse Aggregate is crushed stone, usually granite, limestone, gravel and slag, between 90 and 4.75 millimeters in sieve sizes. Fine Aggregate is natural, manufactured, or combination sand, between 9.5 millimeters and 75 microns in sieve sizes.

End users of these construction materials are generally regulatory agencies like departments of transportation, airport and railway authorities. These groups issue specifications to their suppliers based very closely on the various standard tests which have been written for large regions globally, many ASTM and AASHTO standards for the US, British standards for Europe, Indian standards for India, etc.

These test standards vary from one to another, but are very similar. They include various types of tests, but one of the major groups of tests are for measuring the geometric (or morphological) parameters of the particles in the aggregate blends. These various geometric parameters correlate to physical properties of the end construction, like load-bearing strength, degree of internal frictional strength, wear rate,  and bonding/binding strength with the cement or asphalt matrix. Until just recently, the only ways to make these measurements were manually, by screening samples of aggregate products into different size classes to calculate their size distributions, and then running

a myriad of manual tests on samples of the different size fractions using: hand-held gauges to measure various sizes of individual particles like length, width and thickness, a series of rod screens; measuring water-filled void spaces in large containers; abrading samples and measuring the % of the abraded fines; and more. These are very manpower intensive and can take up to days to complete, which leads some suppliers to make them only once a week on a collected sample. There is now, however, an automated 3-Dimensional Dynamic Image Analyzer which can make all these measurements on a large representative sample of particles in one sample run. Achieving all these results in under an hour, without operator subjectivity, rather than up to a day, and with concern about operator error, is a huge savings in time and expense. And this much time savings contributes greatly to improved productivity, fewer unscheduled plant shut-downs and less time to reach process equilibrium upon start-up.

Meanwhile, additional research is underway to make other either improved or additional measurements, like particle surface area, particle surface roughness or texture, angularity, and three-dimensional volumes. All these parameters too can be measured on the 3-D image analyzer.

Particle Length, Width and Thickness (all three major axis size dimensions) need to be measured to then calculate some of the important geometric parameters for aggregate as ASTM requires, the 3 Flat, Elongated, and Flat & Elongated particles parameters. The 3-D mode is also required for measuring the British Standard’s Flakiness Index results. Results of both these standard tests give numbers which correlate with the load-bearing strength of the final road bed. The 3-D mode is patented by, and available only in Microtrac’s line of PartAn3D Dynamic Image Analysis Instruments; in both on-line process and in lab bench top Models for R&D and QC labs. Microtrac has more than 40 on-line PartAn line instruments installed and operating globally, and many more lab models.

To read more technical detailed descriptions on this subject check our Application Note by clicking here

Or you can watch our on-demand webinar that details our proprietary analysis.

Interested in seeing if the PartAn is right for your?  Request a complimentary sample analysis by clicking here.

Sorry sieves and calipers, you’re just not good enough anymore

Posted on: April 27th, 2015 by Microtrac

Sorry sieves and calipers, you’re just not good enough anymore.

A big pile of rocks like the one pictured below.  That’s several tons of aggregates.

AggregatePile

Believe it or not, the rocks need to meet certain size and morphology specifications based on their application.  To ensure the product is compliant, the quality department will use primitive tools such as sieves and calipers, tasks that are labor intensive and error prone.

Here are the following problems associated with using sieves and calipers to measure size and morphology of large quantities of materials:

  • Time consuming – load the bucket from the line, carry the bucket to the production line, run through the stack, take the stack apart, manually calculate, record, repeat. – How long do you think that takes?
  • Error prone – one man’s elongated is another man’s perfect.  Not to mention that data discrepancies that occur shift to shift from manual data entry.
  • Small, unrepresentative sampling – based on the time it takes for one person/small team to use sieves and calipers, do you think its realistic for them to be able to measure several tons of materials before it ships to a customer? Exactly what I thought.

I know what you are thinking…. It sucks to have that job.  You’re also probably thinking its 2015… there has to be a better way to measure the size and shape of aggregates.

You’re absolutely right… There is a faster, more accurate method to measure the size distribution and morphology parameters of aggregates.

Introducing 3D Dynamic Image Analysis, a non-contact, optical technology that uses high-speed, high-resolution cameras to take multiple pictures of each particle’s orientation (length, width, and thickness) as it falls through a sensing zone.  Proprietary software processes the images of the materials, then various size and shape information is calculated and displayed in a user friendly format.

3D-Dynamic-Image-Analysis

PartAn Measurement Schematic

 

PartAn3D-Size-Distribution

3D size distribution data

Microtrac, the global pioneer of particle characterization solutions since 1974 has been at the forefront of Dynamic Image Analysis with the release of the PartAn in 1987 – the first commercially available DIA.  As camera and computer technology evolves so do the PartAn’s capabilities.

The PartAn3D is ideal for helping solve the aggregate industries biggest quality control problems and also can be used as a reliable alternative to sieves and calipers.  Join us on April 30 at 11am EST for a free webinar that will demonstrate the advantages of using Dynamic Image Analysis to accurately measure size and morphology of aggregates.

The webinar will explain the following advantages:

Ability to accurately characterize coarse and fines (pictured below)

Screen Shot 2015-04-21 at 10.59.49 AM Screen Shot 2015-04-21 at 10.59.10 AM 

No fooling the PartA3D –Each particle is measured in one fast analysis, where as with sieves, elongated particles could easily slip through the screens.

Accuracy – Sieves can only measure equivalent spherical diameter, however the PartAn3D measures length, width, and thickness in one measurement, providing superior analysis capability.

Speed and Efficiency – Users can sample and measure more frequently, which enables users to measure more product and ensure tight specifications are being met.  Rather than running sieves and calipers all day, the user can now focus on other important quality tasks.

Eliminates data discrepancies – The PartAn3D removes the human error element from the equation which will gives the quality control department more accurate data sets.

See process variations in real time – By sampling and measuring with an enhanced tool, quality departments will be able to see process swings in real time, enabling immediate corrective action to be taken, which ultimately leads to increased production efficiency and higher quality products.

Sign up today by clicking the registration link below.  Ample time for Q&A with imaging technical specialists will be available after the presentation.

https://attendee.gotowebinar.com/register/6436478761435880450

We look forward to seeing you on Thursday.

Need an introduction to 3D Dynamic Analysis?  Check out this archived webinar to learn more about our proprietary measurement capability.

Fast and reliable alternative to sieve analysis – free webinar

Posted on: September 24th, 2014 by Microtrac

Fast and reliable alternative to sieve analysis – free webinar.

Sieve analysis, a crude, but effective method to measure the particle size distribution of a material.  Although widely accepted, there are more efficient ways to size your particulate.

Microtrac, the global pioneer of particle characterization solutions would like to invite you to a webinar that showcases a fast, accurate, and reliable sieve analysis alternative.  The webinar will be held on 9/25/14 and begins at 11am EST.

Dynamic Image Analysis (DIA) is an optical measurement that has been around for 25 years, but recently started gaining popularity in the material science community as a sieve alternative.  DIA’s use high-speed, high-resolution cameras to take multiple images of the particles as they pass through a sensing zone, while software algorithms track and analyze various morphological parameters of the material.

The PartAn 3D is the only 3D DIA instrument on the market that has the ability to measure particles in 3D, which allows a user to quickly identify out of spec product.  In addition to 3D, the PartAn 3D measures 31 morphological parameters including 15 size parameters, sphericity, aspect ratio, concavity, density, transparency, and compactness (to name a few) in one fast analysis.

The presentation will highlight sieve shortcomings and offer a solution to the following:

  • operator error
  • lack of robust reporting capability
  • worn screens
  • length of time to measure sample
  • inability to track each particle

Additionally, we will also demonstrates the PartAn 3D’s sieves correlation capabilities.

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