Introduction
Concrete is at the heart of many aspects of the construction industry. If you are building a residential home, commercial property, a bridge, or a roadway, concrete is a critical material to use.
However, before the concrete is poured, it must be tested, even if it is the highest grade of concrete. This is where the Concrete Slump Test comes into play. This is a simple yet very effective test that measures the workability or consistency of fresh concrete.
Table of Contents
Concrete that is too dry may lead to difficulty placing. Concrete that is too wet reduces the strength and typically leads to segregation. A Concrete Slump Test will allow site engineers to find the right balance, and take the guesswork out of every batch that is produced and used in construction.
In this guide, we will look at exactly what the test is, why it is important, how the test is carried out, and what the test results mean.
Finally, we will provide a brief description of positively charged admixtures (like Addage Plast PCE 811) and how modifications of test results and improved programmable capabilities can produce better-performing Concrete.
What Is a Concrete Slump Test?
A Concrete Slump Test is used to measure the consistency and workability of fresh concrete. In simple terms, it explains how easily the concrete can be mixed, transported, placed, and compacted.

This field test has been utilized since 1922, and it remains common because of its simplicity, economy, and speed.
The test is carried out with a cone-shaped mold (which is commonly referred to as a slump cone) that is filled with fresh concrete and then placed in three or four layers, with a steel rod used to tamp the concrete in each layer.
After the cone is removed, the concrete “slumps” or settles down by the weight itself. The distance between the top of the original cone and the height of the slumped concrete is recorded, therefore the “slump.”
The IS code that governs this test in India is IS 1199.
Reasons for Carrying Out a Slump Test
Quick Quality Check: Helps identify if the concrete mix is too dry or too wet.
Check for Uniformity: Indicates consistency between batches of concrete.
Early Detection of Potential Failures: Catch an improper mix before it is poured and cracks the concrete or has other structural weaknesses.
Types of Slump in Concrete
When the cone is lifted, the concrete can assume different shapes. These shapes can be used to distinguish the type of slump:
1. True Slump
The concrete settles evenly.
This indicates a well-mixed concrete mixture that is cohesive.
2. Shear Slump
There is a side slip of concrete.
This indicates a lack of cohesive properties of the concrete mixture, which can lead to segregation.
3. Collapse Slump
The concrete breaks down completely.
This indicates too much water leading to a weak, too-flowy mix.
4. Zero Slump
The concrete keeps its shape.
Usually, the case for very dry mix typically found in road pavements and precast elements.
How It Works?
The Concrete Slump Test works on a simple principle. When a cone of concrete is inverted and released, how it slumps in relationship to gravity indicates its consistency.
A consistent, well-compacted mix will slump moderately. A watery or weak mix will collapse and a stiff mix will barely slump at all.
This principle is very useful for construction crews to understand how concrete will perform once it is poured.
The Process
To test for concrete slump, we can break down the process as follows:
Gather Equipment:
Slump Cone: Made of steel, 200 mm base, 100 mm top, and 300 mm height.
Tamping Rod: steel rod with 16 mm diameter, 600 mm long rounded end rod.
Measuring Scale:
Base Plate: non-absorbent flat surface.
Preparation:
Clean the cone and make sure the base is a stable surface.
Filling the cone:
Fill in three lifts of concrete to roughly one third of the height.
Tamp each lift 25 times with the tamping rod.
Level the Top:
When full, strike off the top surface with the rod to obtain a level surface.
Remove the cone:
Lift the cone up vertically and slowly.
Measure slump:
Get the difference in height between the top of the cone and the height of the slumped concrete.
Apparatus Description
Slump cone: Can be steel, plastic, or polymer. The cone needs to be 12″ tall and can be 8″ or 4″ at the bottom.
Base plate: Can have feet and/or a holder.
Tamping rod: Steel, at least 24″ long and 5/8″ diameter.
Tape measure: A tape measure will be useful for getting exact height measurements.
IS Code
The test process is described in IS 1199:1959. It shows consistency and accuracy. It describes everything from specimen preparation to interpretation of results.
It is important to follow the standards when you are being inspected and/or performing a large job to ensure consistency from batch to batch.
Standards from Around the World
Each region has its own testing codes.
ASTM C143 / C143M – USA.
AASHTO T119 – State transportation standards in the USA.
BS EN 12350-2 – British and European standards.
IS 1199:1959 – Indian standard.
Interpreting Slump Test Results
The amount the concrete slumps tells you about its workability:
Slump Value | Workability |
0-25 mm | Very low |
25-50 mm | Low |
50-100 mm | Medium |
100-175 mm | High |
If you observe either a Shear Slump or Collapse Slump it is best to do another test, only a True Slump produces a reliable result.
Common Errors and Precautions
Clean down all equipment before the test:
- Perform the tests within 2 minutes of mixing.
- The base should be firm and not vibrating.
- Tamp uniformly and avoid any air pockets.
- Lift the cone without tilting or shaking.
Field Example: Collapse Slump
You are placing concrete for a structural beam. You perform a slump test, and when you lift the cone the mix completely collapses.
What does it mean?
- Too much water.
- It’s a weak mix.
- There will be a very high risk of segregation and failure.
What is the Action?
- Do not use this batch and notify the engineer.
- Change the mix by adding cement or reducing the water.
- In other words, there may be significant structural problems later- and this simple test can save all that trouble.
Now let’s talk about the role Addage Plast PCE 811 will play in the slump tests.
Addage Plast PCE 811 is a high-range water-reducing admixture for concrete. One of the most important roles it plays is to provide the concrete with the proper workability without adding too much water to the mix.
Here are specifics on how it works:
Increase the slump without adding more water: It maintains the concrete’s high workability while keeping the strength at a high level.
Prevent segregation: It keeps the mix uniform.
Reduce the water-cement ratio: It increases the strength and durability.
Using additives like Addage Plast PCE 811 makes it easier to meet slump specifications without compromising the integrity of the structure.

Conclusion
The Concrete Slump Test is a reliable, inexpensive method of measuring concrete workability. It gives immediate information to know how your specific concrete mix will work and can help prevent expensive errors. When you know what the result of this test is, you can make better decisions on stance.
Adding chemical admixtures to your concrete mix such as Addage Plast PCE 811 – in addition to its industry-leading performance – gives flexibility and quality control for all your concrete applications.
This is critical to completing whatever you are building whether it be a house, a bridge, or a road.
Are you ready for the next pour? Make sure you slump-test it first!
Concrete Slump Test FAQs
1. What is the normal Slump test?
The normal slump test is the standard method that can be used in the field to check the workability and consistency of freshly mixed concrete.
It consists of filling a metallic cone, called a slump cone, with fresh concrete in three uniform layers, making sure to tamp each layer in accordance with ASTM C 143-15, and then lifting the cone to observe how far the concrete slumps, or settles. The allowed difference in height measurement is the slump value that indicates the workability of the concrete itself.
In general construction applications such as beams, columns, and slabs, a slump of 75 mm to 100 mm would typically be considered ‘normal’ or in terms of slump, ideal. However, the slump required will vary by the application and method of placement.
2. What are the 3 types of Slump?
When performing the slump test three types of slump were observed and each provides us with some useful information about the density of concrete mix, these are:
True Slump: This is when the concrete settles straight down and remains even on a vertical plane when the cone is lifted. This is an indication that we have a cohesive uniform mix and is the most preferred type of slump in most applications.
Shear Slump: Shear slump occurs when part of the concrete shears off and slips on a horizontal plane. This is an indication that we have poor cohesion in the mix and the possibility of segregation. In some cases, it may be usable based on site conditions, but generally, this is not an ideal slump.
Collapse Slump: The whole sample of concrete completely flattens or spreads out when the cone is lifted and this indicates that the mix is simply too wet and therefore too fluid to retain any structure. I would recommend that a collapse slump be regarded as a “danger” on a construction site.
3. What is Slump height?
Slump height is a measure in millimeters of the vertical distance between the height of the concrete in the slump cone prior to removal and the point at which the highest point of the concrete was measured after removal of the cone.
For example, if the original height of the cone is 300 mm and after removal, the top of the concrete sits at 220 mm then the overall slump height would be 80 mm. This measurement allows us to evaluate how workable/stiff the mix is. A greater height of slump means greater workability (or wetter concrete) and a smaller slump means a drier, more stiff mix.
4. What is a high Slump value?
A high slump (very workable) concrete mix is typically 100 mm to 175 mm depending on the project type. It is very workable and can be easily poured into its position and spread. High-slump concrete mixes are preferred for projects where concrete must work its way easily into complicated molds or heavily reinforced areas.
However, if the slump is very high, it might indicate that there is too much water in the mix. The addition of excessive water will decrease the strength of the concrete and may increase the potential for cracking, segregation of the cement and aggregates, or other defects and surface issues. In addition, admixtures such as Addage Plast PCE 811 may be used to maintain appropriate workability without excess water.
5. What is a high concrete Slump value?
A slump value of 100 mm to 175 mm is considered a high slump value. The greater the slump value, the more workable concrete is (easier to pour and spread). High-slump concrete is needed on jobs requiring the concrete to flow easily into forms with complex shapes or in thick heavily reinforced areas.
One major consideration when using high-slump concrete is that very high slump values (greater than 175mm) may indicate too much water in the mix. This can lead to a reduction in concrete strength and increase the potential for cracking segregation, and surface defects. If there is a need to maintain workability without a corresponding increase in water in the mix, an admixture like Addage Plast PCE 811 could be utilized.
6. What is concrete workability?
Workability describes the capacity of fresh concrete to be mixed, transported, placed, and compacted in a manner that retains the homogeneity of the mixture. Workability is one of the most important properties of concrete because it defines how easily concrete can be handled and ultimately impacts the quality of the final construction.
Concrete workability can be impacted by several variables:
1. Water content
2. Mix proportions
3. Shape and size of the aggregate
4. Temperature and humidity conditions
Use of chemical admixtures like Addage Plast PCE 811 that improve flow without additional water.
The slump test is the most common way to measure workability, giving site engineers a quick and reliable way to check whether the mix is suitable for the job.
Sandip Agrawal, Polymer Engineer and MD of Sakshi Chem Sciences Pvt. Ltd., leads innovation in construction chemicals, shuttering oils, and industrial lubricants. With expertise in polymer science and eco-friendly solutions, he drives R&D and sustainable advancements, ensuring high-performance products for India and global markets.