by Slump Cone Test of Concrete – Procedure, Types, Formula, IS Code, Calculator & FAQs
The slump cone test is the most widely used field test to assess the workability and consistency of fresh concrete before placement. By performing this simple test on-site, engineers can quickly assess whether a concrete mix can be transported, placed, compacted, and finished without segregation or excessive bleeding.
Because the test is quick, economical and easy to perform, it is routinely used in RCC works such as:
• Foundations and footings
• Columns and beams
• Slabs and roof systems
• Retaining walls
• Pavements and industrial floors
In India, the slump test is standardised by IS 1199 (Part 2): 2018, which specifies the method for determining the consistency of fresh concrete and workability of concrete.
Workability is the most important property of freshly mixed concrete. Workability can be defined as the ease or difficulty with which the concrete can be mixed, transported, placed and compacted. The workability of concrete in the field can be measured by using the slump cone test.
What Is Slump in Concrete?
In concrete technology, slump is the vertical settlement (drop in height) of freshly mixed concrete when a standard slump cone mould is filled, compacted and then lifted vertically.
Once the cone is removed, the concrete subsides. The amount of subsidence is the slump value, and it indicates the workability of the mix:
• Higher slump → More workable, more flowable concrete
• Lower slump → Stiffer, less workable concrete
• Excessively high slump → Risk of segregation, bleeding and loss of strength
Important: The slump test does not measure compressive strength. It only provides an indication of workability and consistency.
Objectives of the Slump Cone Test
The main objectives of the slump cone test of concrete are:
• To determine the workability of fresh concrete on site
• To check uniformity and consistency between different batches
• To verify the water–cement ratio and its control during production
• To help detect improper or inadequate mixing
• To support quality control before placement of concrete
• To reduce the chances of honeycombing, segregation and poor compaction
For site engineers and quality control teams, the slump test is a quick decision‑making tool before concrete is accepted for placement.
Relevant IS Codes for Slump and Concrete Workability
Some important Indian Standard codes related to slump and concrete testing are:
• IS 1199 (Part 2): 2018 – Method of determination of slump of fresh concrete
• IS 456: 2000 – Code of practice for plain and reinforced concrete
• IS 10262 – Guidelines for concrete mix design
• IS 516 – Methods of tests for strength of concrete
These standards together guide mix design, workability control and strength testing in Indian construction projects.
Slump Cone Test Apparatus
The slump test requires only a few standard pieces of equipment, making it ideal for field use.
1. Slump Cone (Standard Mould)
The standard slump cone is a frustum of a cone made of metal, with the following dimensions as per IS 1199:
• Height: 300 mm
• Top (smaller) diameter: 100 mm
• Bottom (larger) diameter: 200 mm
The cone is usually equipped with handles, footpieces, or clamps to hold it firmly in position during filling and compaction.
2. Additional Equipment
• Tamping rod – 16 mm diameter, 600 mm long, with rounded ends
• Base plate – Rigid, non‑absorbent surface or metal plate
• Measuring scale or steel ruler – To measure slump in millimetres
• Scoop – For placing concrete into the cone
• Fresh concrete sample – Taken in accordance with relevant standards
Standard Slump Cone Dimensions
• Height of cone: 300 mm
• Top diameter: 100 mm
• Bottom diameter: 200 mm
• Tamping rod diameter: 16 mm
• Tamping rod length: 600 mm
These dimensions are critical for obtaining comparable and repeatable test results.
Slump Cone Test Procedure (Step‑by‑Step)
Follow this standard slump cone test procedure for accurate and reliable results on site:
Step 1 – Preparation of Equipment
Clean the slump cone and base plate, remove any old concrete, and place the cone on a level, smooth, non‑absorbent surface.
Step 2 – Filling the Cone
Fill the cone with fresh concrete in three or four approximately equal layers (depending on practice), ensuring no large voids remain.
Step 3 – Compacting Each Layer
Compact each layer using the tamping rod, applying 25 strokes uniformly over the cross‑section. Drive the rod through the upper layer into the layer below to ensure proper compaction.
Step 4 – Levelling the Top Surface
After the top layer is compacted, strike off the excess concrete with a tamping rod or a trowel until the top surface is flush with the cone.
Step 5 – Lifting the Cone
Carefully lift the cone vertically upwards, without jerking or twisting, within 5–10 seconds. Do not disturb the concrete mass while lifting.
Step 6 – Allowing the Concrete to Settle
Let the concrete subside (slump) naturally. The concrete will either remain more or less in a cone shape, shear to one side, or collapse.
Step 7 – Measuring the Slump
Place a scale or ruler vertically beside the concrete and measure the difference between:
• The original height of the cone (300 mm), and
• The highest point of the slumped concrete
This difference is the slump value, expressed in millimetres.
Slump Test Formula
The basic slump test formula is:
Slump Value (mm) = Height of Cone − Height of Slumped Concrete
Example Calculation
• Height of cone = 300 mm
• Measured height of concrete after slump = 225 mm
Then:
• Slump = 300 − 225 = 75 mm
So, the slump value is 75 mm, which generally indicates medium workability concrete suitable for many types of RCC work.
Use our Slump Cone Test Calculator to find the Slump value
Page Contents
Calculation for Slump Value
Inputs
• Cone height (mm)
• Height of concrete after removing the mould (mm)
Formula
Slump (mm) = Cone height − Final concrete height
Based on the computed slump value, workability can be classified approximately as:
• 0–25 mm → Very low workability
• 26–50 mm → Low workability
• 51–100 mm → Medium workability
• 101–150 mm → High workability
• 150 mm → Very high workability
Types of Slump in Concrete
When the cone is removed, the shape of the concrete indicates not only the workability but also the cohesion and stability of the mix. The three commonly observed types of slump are:
1. True Slump
In a true slump, the concrete settles uniformly and retains a more or less conical shape, only slightly reduced in height.
Characteristics:
• Indicates good cohesion and stability
• Typically represents a well‑proportioned mix
• Generally considered a desired slump pattern for normal workable concrete
2. Shear Slump
In a shear slump, part of the concrete mass shears off and slips sideways, giving an uneven profile.
Characteristics:
• Suggests poor cohesion or possible lack of stability
• Indicates that the concrete mix may be harsh or unworkable
• The test is usually repeated, and the mix should be reviewed
3. Collapse Slump
A collapse slump occurs when the concrete totally collapses or flattens upon removal of the cone.
Characteristics:
• Sign of excess water content or an overly wet mix
• High potential for segregation and bleeding
• Often unsuitable for normal RCC work unless a high‑slump or flowable concrete is specifically required
These visual patterns are very useful for quick field assessment of concrete behaviour.
Recommended Slump Values for Different Types of Work
Typical recommended slump ranges (in mm) for various concrete applications are:
• Road and pavement concrete: 25–50 mm
• Mass concrete (e.g., dams, large foundations): 25–50 mm
• Footings: 50–75 mm
• Slabs: 50–100 mm
• Beams: 75–100 mm
• Columns: 75–100 mm
• Pumped concrete: 100–150 mm
These ranges may be adjusted based on placement conditions, the degree of reinforcement congestion, formwork type, and project specifications.
Advantages of the Slump Test
The slump cone test of concrete is popular because it offers several practical benefits:
• Very quick and simple to perform
• Low cost and requires minimal equipment
• Ideal for field testing and site quality control
• Provides immediate results for decision‑making
• Helps monitor workability from batch to batch during concreting operations
Limitations of the Slump Test
Despite its usefulness, the slump test has some limitations:
• It does not measure compressive strength directly
• Less suitable for very dry, harsh, or zero‑slump mixes
• Not accurate for self‑compacting or very high‑flow concretes
• Correct procedure and interpretation depend on the operator’s skill
• Cannot fully predict long‑term performance or durability of concrete by itself
For critical projects, the slump test must be supplemented by other tests (e.g., compaction factor, V‑be test, flow test, and standard strength tests).
Slump Test vs Compaction Factor Test
Both the slump test and compaction factor test are used to assess concrete workability, but they differ in precision and application.
1. Purpose
• Slump test: Quick check of workability and consistency
• Compaction factor test: More precise measurement of workability, especially for low‑workability mixes
2. Accuracy
• Slump test: Moderate accuracy, mainly comparative
• Compaction factor test: Higher accuracy and better suited for research or laboratory work
3. Time Required
• Slump test: Very fast and convenient on-site
• Compaction factor test: Takes more time and effort
4. Equipment
• Slump test: Simple cone, base plate, and tamping rod
• Compaction factor test: More complex apparatus with hoppers and a cylinder
5. Field Use
• Slump test: Excellent for routine field quality control
• Compaction factor test: Limited field use; mainly in laboratories or in detailed investigations
Practical Applications of the Slump Cone Test
The slump cone test of concrete is commonly used for checking the workability of concrete for the following:
• Residential buildings and small commercial projects
• RCC framed structures – beams, columns, slabs and footings
• Bridges and flyovers
• Culverts and retaining structures
• High‑rise buildings and towers
• Overhead and underground water tanks
• Roads, pavements and industrial floors
• Industrial structures and heavy foundations
On most construction sites, every transit mixer or concrete batch is checked by a slump test before acceptance.
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Frequently Asked Questions (FAQs)
Q1. What is the slump cone test of concrete?
Answer: The slump cone test is a field test used to determine the workability and consistency of fresh concrete. Concrete is placed in a standard slump cone, compacted, and the cone is lifted to measure how much the concrete slumps (settles).
Q2. What are the standard dimensions of a slump cone?
Answer: As per IS 1199 (Part 2): 2018, the standard slump cone has:
• Height: 300 mm
• Top diameter: 100 mm
• Bottom diameter: 200 mm
Q3. Why is the slump test carried out on site?
Answer: The slump test is conducted to check whether the fresh concrete mix has sufficient workability for proper placing, compaction and finishing. It also helps maintain batch‑to‑batch uniformity.
Q4. What are the main types of slump observed?
Answer: The three common types of slump are:
• True slump – uniform settlement, indicates a cohesive and stable mix
• Shear slump – part of the concrete shears off to one side, suggesting poor cohesion
• Collapse slump – concrete collapses completely, usually due to high water content
Q5. What is a suitable slump value for RCC works?
Answer: For typical RCC beams and columns, a slump range of about 75–100 mm is often used. For slabs, the slump is usually in the range of 50–100 mm, depending on reinforcement congestion and placement method. Practically, as we are using a concrete pump for the construction works, generally the slump value 100 to 150mm is being used.
Q6. Does slump value represent the compressive strength of concrete?
Answer: No. Slump only indicates workability and consistency of fresh concrete. Compressive strength must be determined by standard cube or cylinder tests as per IS 516 or relevant codes.
Q7. What are the consequences of a very high slump?
Answer: A very high slump often means excessive water in the mix, leading to:
• Segregation and bleeding
• Increased shrinkage and cracking
• Reduction in compressive strength and durability
Q8. What happens if the slump is too low?
Answer: A very low slump indicates stiff concrete, which is difficult to place, spread and compact. This can result in honeycombing, poor surface finish and inadequate compaction, especially in heavily reinforced sections.
Conclusion
The slump cone test is one of the most important and practical quality-control tests for fresh concrete on construction sites. It provides a quick indication of workability, helping engineers and contractors ensure that concrete can be placed and compacted properly without compromising strength, durability and performance.
By following IS 1199 (Part 2): 2018 and maintaining proper slump control, site engineers can achieve better uniformity between batches, reduce defects such as honeycombing and segregation, and significantly improve the overall quality of concrete construction.
