Slump Test for Fresh Concrete: Board Base for SCC

Slump Test for Fresh Concrete: Slump Board Base for Self-Consolidating Concrete Test

Self Consolidating Concrete (SCC) Testing - 36 x 36” J-Board for Self Consolidating Concrete (SCC) - 3/8” WHITE PVC

Structural elements with rebar require Self-Consolidating Concrete (SCC) mix designs to ensure voids and honeycombing free structures.

The J-Ring test along with the Slump-Flow test is one way to determine if SCC, defined as the ability of the concrete to flow under its own weight to fill all the spaces in the formwork. How well the concrete flows is critical in determining if a concrete batch is properly mixed for its intended use.

Depending on the method, the modified slump cone is placed either inverted or upright in the middle of the J-Ring and filled with fresh concrete in one lift.

The cone is then lifted straight up and the diameter of the circular flow of concrete is measured. After the cone is removed, the behavior of the concrete is observed to assess its workability and check for issues such as segregation.

Same test is then run without the J-Ring and the difference in the flow diameters is recorded as the passing ability. Additional measurements or visual classification may also be done at the end of the test.

Meets Test Methods: ASTMC 1611 ASTM C 1621. For laboratories needing a certified reference material for cement fineness testing, see the NIST 46H Portland Cement Fineness Standard, SRM (10/Pk) or Portland Cement for cement testing.

What is Concrete Slump Test

Concrete slump test is a simple process in the construction industry, used to measure the consistency and workability of freshly made concrete.

The concrete slump test measures the workability and consistency of concrete, assessing its flow and suitability for construction. This easy test can be done on site with minimal skills, making it practical for concrete testing.This test is to ensure the fresh concrete mix is right for its intended use.

The concrete slump test measures how fresh concrete flows, gives you valuable information on the mix’s workability. Measuring slump is a standard way to measure workability, using a slump cone and following ASTM C143 guidelines.

By doing this test, contractors can detect potential issues, such as an improperly mixed batch and make necessary adjustments to the concrete mix.

Accurate slump testing ensures the fresh concrete is properly mixed and has the right consistency, which is critical for achieving the ideal slump for the intended application and the desired strength and durability in construction projects.

Base Board

The base board is the foundation of the concrete slump test apparatus, designed to provide a stable and level surface for the cone. Made from durable materials like steel or plastic, the base board has a smooth flat surface to ensure accurate measurements during the concrete slump test.

Compact and lightweight for easy transport and storage, perfect for on site concrete testing. Has holes or clamps to secure the cone in place to prevent any movement that can affect the slump measurement.

The base board ensures the concrete slump test can be done accurately across different loads of concrete, maintaining consistency in the measurements.

Equipment Needed for Concrete Slump Test

To do a concrete slump test, several equipment are needed. The most important tool is the cone, a specialized device to measure the slump of the concrete.

The cone is filled in three layers, with each layer tamped using the tamping rod to ensure uniform compaction and consistency in the testing method.

Typically made of steel or plastic, the cone has a standard shape and size to ensure consistent results.

Along with the cone, a tamping rod is used to compact the concrete mixture and measure the slump accurately. A slump board is also necessary to support the cone and provide a stable, level surface for the test. Together, these tools ensure the concrete slump test is done accurately and efficiently, gives you reliable data on the concrete’s workability.

Water reducing admixtures can also be used in the mix to improve workability and influence slump without increasing water content.

Why Accuracy Matters

Accurate slump testing is to ensure the concrete mix is right for its intended use. High slump means the concrete is too wet and will result to a weak and porous final product.

Low slump means the concrete is too dry and difficult to pour and vibrate. Zero slump means the concrete is extremely stiff, has almost no workability and retains the shape of the mold, it may not be suitable for most applications.

Different slumps – true, shear or collapse – reflect varying levels of workability, cohesion and quality control and selecting the right slump range is important for specific applications.

By doing regular concrete slump test, contractors can ensure uniformity in the concrete mix, detect issues and adjust accordingly to achieve the desired strength, durability and workability.

Accurate slump testing ensures the concrete mix is balanced which is critical to meet the standards and ensure the structure’s longevity.

Using the Base Board

To use the base board with cone, place the cone on the base board and secure it using the holes or clamps provided. Fill the cone with freshly mixed concrete, make sure it’s evenly distributed.

Use a tamping rod to compact the concrete and remove excess concrete and any air pockets that can affect the test. Once the cone is filled and compacted, lift it up vertically to allow the concrete to settle. Measure the distance it settled, that’s the “slump”.

If the concrete completely collapses after the cone is lifted, it means excessive water content and poor mix quality.

This slump value is an indicator of the workability of the concrete, therefore the ease with which it can be poured and compacted, you can adjust the concrete mix accordingly to achieve the desired consistency.

Preparation and Procedure for Slump Testing

Preparation is key to getting accurate and consistent results in any slump test. Before you start, gather all the testing equipment including slump cone, base plate, steel rod and tape.

Make sure the testing area is flat, level and free from vibrations as an uneven or unstable surface can affect the result. Use a freshly concrete sample that represents the batch being tested.

Fill the slump cone in three equal layers, tamp each layer 25 times with the steel rod to remove air pockets and ensure uniform compaction.

After the final layer is added and tamped, lift the cone vertically in a steady motion, do not rotate. Measure the slump from the top of the cone to the highest point of the slumped concrete to the nearest 5mm.

Following the exact specifications and procedure in ASTM C143 is crucial for reliable and repeatable results in concrete slump testing.

Factors Affecting Slump Results

Several variables can affect the slump test result, so it’s important to control as many as possible to get accurate slump values. The design including the proportion of cement, aggregate and water plays a big role – excess water in the mix will result to higher slump, while a drier mix will result to lower slump.

The type and size of aggregate also affects the test, larger aggregates yield lower slump values. Environmental conditions such as temperature and humidity can affect how the concrete settles during testing.

The condition and calibration of the testing equipment and strict adherence to the correct testing procedure is also vital.

Any deviation such as improper tamping or not using the correct number of layers can lead to inaccurate results. Being aware of these factors will ensure that the slump test will give you a true reflection of the concrete’s workability.

Interpreting Slump Test ResultsInterpreting Slump Test Results

Understanding the result of a slump test is key to evaluating the quality and workability of a concrete mix. A true slump is indicated by a uniform, even subsidence of the concrete, means the mix is well-proportioned and workable.

If the concrete shears off or slips sideways, resulting to shear slump, or if the concrete collapses completely, known as collapse slump, this means there’s an issue with the mix – too much water or poor aggregate distribution.

The slump value should be within the specified range for the intended application; higher than specified slump means the mix is too wet, lower value means the mix is too dry or stiff.

Only true slump is valid for most applications so if shear or collapse slump occurs, the test should be repeated with a fresh sample. Careful interpretation of slump test results will ensure the concrete will perform as required in the finished structure.

Applications and Uses of Slump Testing

Slump testing is a basic quality control method used in the construction industry to check the workability and consistency of concrete.

It’s more important when using ready mixed concrete as it provides immediate feedback if the sample meets project specifications.

Tests are done when constructing pavements, building foundations and installing structural elements where the right consistency is critical for durability and performance.

The test is also useful in monitoring the quality of concrete and cement tests delivered to the job site, to ensure each batch is good for its intended use.

By doing tests regularly, contractors and engineers can detect variations in the concrete mix, make necessary adjustments and maintain high standards throughout the construction process.

Base Board Maintenance and Care

Base board maintenance is important to ensure accuracy and reliability of every test. After each use, the base board should be thoroughly cleaned and dried to remove any residual concrete or moisture that can affect future tests.

Regularly inspect the base board for signs of wear, damage or warping and address any issues promptly by repairing or replacing the board as needed. Proper storage is also important – keep the base board in a dry, secure location to prevent exposure to the elements or accidental damage.

By following these simple maintenance steps, you can extend the life of your testing equipment and get precise and reliable results every time.