ASTM Standard Test Method C143: Slump of Hydraulic Cement Concrete

Updated on January 14, 2019
Lissa Clason profile image

Melissa has a bachelor's degree in geology, and is an ACI-certified field and lab technician at Froehling and Robertson.

To measure your slump, measure down from the height of your slump cone, using your tamping rod to provide a marker to measure from.
To measure your slump, measure down from the height of your slump cone, using your tamping rod to provide a marker to measure from.

Significance and Use of ASTM C143

Slump is a measure of the consistency of a sample of concrete, and tells you how fluid the concrete will be. It can help give an idea of workability, telling you how easy or hard it will be to place, and can help to predict strength.

You can also get a general idea of how much water is in the mix and if it is too wet or too dry for the project’s specifications. One gallon of added water per cubic yard equals 200 to 300 psi less strength, so knowing the slump of concrete when it's fluid is vital to knowing how strong and durable it will be once it solidifies. One gallon of water per cubic yard also equals about 1 more inch of slump (slump is measured by how far downwards the concrete sinks when the slump cone is raised and the concrete is no longer held in place).

The smaller the stone or gravel size in the batch, the more water will need to be added, as smaller stones have a greater surface area and have more areas for cement and water to bond to.

As air content in the concrete increases, so does the slump. Superplasticizer, a substance that makes concrete flow easier, may be added at times to increase the slump without adding water or air and compromising the concrete’s strength.

Please clean your slump cones, especially on the inside, or your test results will be thrown off by a change in volume.
Please clean your slump cones, especially on the inside, or your test results will be thrown off by a change in volume.

Equipment Needed for the Slump Test

  • Slump cone – Must have an average thickness of at least 0.06 inches for metal cones. Must have a base that is 8 inches in diameter and a top that is 4 inches in diameter. All diameters must be within 1/8 of these dimensions. The inside of the cone needs to be smooth and clean, and the cone must be free of dents and deformations.

  • Tamping rod – Must have a smooth hemispherical tip and must have a 5/8 inch diameter ± 1/16 inches. Must be at least 4 inches longer than the depth of the slump cone. The rod itself cannot be longer than 24 inches. The rod must be smooth and clean.
  • Scoop – Must be large enough to get a representative scoop of concrete and small enough to where you don’t spill any concrete on the ground as you are pouring concrete into the cone.
  • Ruler or measuring tape – Must have markings at the ¼ inch mark or smaller. Must be at least 12 inches long.
  • Slump plate – Must have a clean, level surface with no gouges, grooves or indentations. If it has clamps, they must be able to move freely and be fully released without moving the slump cone during the test. Must be larger than the diameter of the slump cone’s base.
  • Bucket of water and rag – for cleaning your equipment before and after the test.
  • Sampling receptacle – usually a wheelbarrow. Must be able to hold at least 1 cubic foot of concrete, and be able to be wheeled comfortably without spilling the sample.

Only take your feet off when you are ready to lift the slump cone and measure the slump.
Only take your feet off when you are ready to lift the slump cone and measure the slump.

ASTM C143 Procedure

  1. Sample the concrete, first checking with the crew to make sure all water has been added, according to ASTM C172, and mix it thoroughly. Set up your test area in a place that is free of debris and traffic, and make sure your slump plate is on the most level surface possible. Get a bucket of water and moisten the surface of the slump plate and the inside of the slump cone, to keep concrete from sticking to it.
  2. Put your slump cone on the plate and either clamp it down or stand on the foot pieces. If standing on it, do not step off until the cone is full and ready to be lifted.
  3. Fill your first layer to 2 and 5/8 inches (1/3 of the cone by volume), making sure it is even inside the cone.
  4. Rod the layer 25 times, making sure to cover all the surface area inside the cone, slightly angling the rod to get the edges. Here, unlike other tests, you do not tap the side of the cone, because that causes artificial subsidence and your slump will come out higher than it really is.
  5. Fill the second layer to 6 and 1/8 inches (2/3 of the cone by volume) making sure the concrete layer is even.
  6. Rod the layer 25 times, and this time make sure you penetrate the first layer by 1 inch. Again, do not tap the side of the cone.
  7. Fill the last layer up to the top, where the concrete is slightly overflowing.
  8. Rod the layer 25 times and penetrate the second layer by 1 inch. Remember to not tap the sides of the cone. This top layer needs to be kept full at all times, so add a bit of concrete if it starts to go below the rim of the cone.
  9. Strike off the excess concrete, and if you are standing on the cone keep it steady and do not get off yet. Clean around the rim of the cone, making sure it is full. (Optional: Place a penny in the center of the cone, so you can see where the center is displaced when you lift it.)
  10. Put your hands on the handles of the cone and push down while unclamping the cone or stepping off of it. Keep it steady.
  11. Lift the cone straight upwards with no sideways motion or twisting. The lifting process should take between 3 and 7 seconds, count if necessary.
  12. Flip the cone upside down next to the slumped concrete, and place your tamping rod on top of the cone and over the slumped concrete. Measure from the displaced center to the rod, and record the slump to the nearest quarter of an inch. The entire slump procedure needs to take place in 2.5 minutes.
  13. Clean your equipment and discard the used concrete. If the slump is out of spec, perform a second test to be certain, and then tell the site superintendent if both slumps were out of spec.

Common Errors Associated With The Slump Test

  • Placement of the slump plate on an uneven surface. Make sure the plate is level before putting concrete into your mold.
  • Pulling the slump cone up too fast or jerking the cone in a horizontal direction. Pull the cone straight up, smoothly and steadily.
  • Failure to measure to the displaced original center. The penny trick is very helpful when finding the center.
  • Equipment being out of spec or dirty. Slump cones and plates should be calibrated yearly, and cleaned after every test, especially on the inside surface of the cone and the surface of the plate.
  • Slumps taken on the first 1/4 or last 1/4 of the load cannot be used to reject concrete, as they are not the main characterization of the batch.
  • Using sampled material that has not been mixed up properly.
  • Starting the slump test too late when the concrete is beginning to harden.

How to Perform the Slump Test

ASTM C143 Quiz

view quiz statistics

© 2018 Melissa Clason


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)