Slump Cone Test – Workability Test of Concrete (IS 1199:1959)
What is the Slump Cone Test?
The Slump Cone Test is a simple and widely used field and laboratory test to determine the workability or consistency of freshly mixed concrete. It indicates how easily concrete can be mixed, placed, compacted, and finished.
The slump value obtained reflects the moisture condition and uniformity of concrete, serving as a quality control parameter in both site and lab work.
Reference Standards for Slump Cone Test
- IS 1199:1959 – Methods of Sampling and Analysis of Concrete
- IS 456:2000 – Plain and Reinforced Concrete – Code of Practice
- IS 10262:2019 – Concrete Mix Proportioning – Guidelines for workability
Purpose of the Test
The main objective of the Slump Test is to determine the ease of placement and compactability of concrete. The test ensures that the concrete mix has sufficient workability for the intended type of construction.
Apparatus Required for Slump Cone Test
| S. No | Apparatus | Specification |
|---|---|---|
| 1 | Slump cone (Abrams cone) | Top dia = 100 mm, Bottom dia = 200 mm, Height = 300 mm |
| 2 | Tamping rod | 16 mm diameter, 600 mm long, rounded ends |
| 3 | Base plate | Flat, rigid, non-absorbent surface (steel or glass plate) |
| 4 | Trowel & scoop | For filling concrete |
| 5 | Scale / ruler | For measuring slump (nearest 5 mm) |
Step-by-Step Procedure of Slump Cone Test
1. Preparation of Equipment
- Clean the slump cone and base plate.
- Moisten both with a damp cloth.
- Place the cone vertically on the base plate and hold it firmly by footrests or handles.
2. Filling the Cone
Fill the cone in four equal layers by volume. Compact each layer with 25 strokes of the tamping rod. Ensure strokes penetrate the layer below.
| Layer | Filling Height | Compaction |
|---|---|---|
| 1st | ¼ height | 25 strokes |
| 2nd | ½ height | 25 strokes |
| 3rd | ¾ height | 25 strokes |
| 4th | Full height | 25 strokes |
3. Levelling the Top Surface
- Strike off the concrete flush with the top using a trowel.
- Clean the outside surface before lifting.
4. Lifting the Cone
- Lift the cone vertically upward, slowly and steadily, within 5–10 seconds.
- Do not twist or jerk the cone while lifting.
5. Measurement of Slump
After removing the cone, the concrete will slump. Measure the vertical difference between the cone’s height and the highest point of the slumped concrete.
Slump Value (mm) = H₁ − H₂
Where H₁ = 300 mm (height of cone) and H₂ = height of slumped concrete.
Types of Slump Observed in Concrete
| Type | Description | Indication |
|---|---|---|
| True slump | Concrete subsides uniformly | Good workability |
| Shear slump | Concrete slips on one side | Indicates lack of cohesion |
| Collapse slump | Concrete collapses completely | Very high workability / too wet mix |
Note: Shear or collapse slump results are invalid; repeat test with a drier mix.
Standard Slump Values for Different Types of Concrete Works
| Type of Concrete Work | Recommended Slump (mm) |
|---|---|
| Mass concrete (RCC footing) | 25 – 50 |
| Reinforced beams and slabs | 50 – 100 |
| Pumped concrete or thin sections | 100 – 150 |
| Self-compacting concrete | >180 (Use Slump Flow Test) |
Interpretation of Slump Test Results
- Low slump → Stiff mix, difficult to compact.
- High slump → Fluid mix, easy to place but may segregate.
- Consistency of slump values ensures uniform workability between batches.
Reporting of Results
- Identification of concrete mix (e.g., M25)
- Date and time of test
- Slump value (in mm)
- Type of slump (true, shear, or collapse)
- Temperature and weather conditions
Precautions While Performing Slump Cone Test
- Do not vibrate or jar the cone during filling.
- Perform the test immediately after mixing.
- Use a level, non-absorbent surface.
- Clean cone after each test.
- Same operator should perform all tests for consistency.
Key Takeaways
- Slump Cone Test provides a quick indication of workability.
- It does not directly measure concrete strength.
- Always compare with design workability in IS 10262.
Top 10 FAQs on Slump Cone Test
- 1. What is the purpose of the Slump Cone Test?
- To measure the workability and consistency of freshly mixed concrete for ease of placement and compaction.
- 2. Which IS code covers the Slump Test procedure?
- IS 1199:1959 – Methods of Sampling and Analysis of Concrete.
- 3. What are the standard dimensions of the slump cone?
- Top dia = 100 mm; Bottom dia = 200 mm; Height = 300 mm.
- 4. How many layers and tamping strokes are used?
- Four layers, 25 strokes per layer using a 16 mm diameter, 600 mm long tamping rod.
- 5. What does slump value represent?
- It represents the vertical subsidence of concrete; higher slump means more fluid concrete.
- 6. What are the types of slump?
- True slump, Shear slump, and Collapse slump.
- 7. What are typical slump ranges for concrete works?
- 25–150 mm depending on application; SCC uses the Slump Flow Test instead.
- 8. Why do slump values vary?
- Due to changes in water content, mixing time, temperature, and aggregate properties.
- 9. What are the limitations of Slump Test?
- Not suitable for very dry or very wet mixes and cannot detect segregation accurately.
- 10. How is slump test used in mix design?
- It verifies field workability against mix design targets per IS 10262:2019.
Bonus Tip: Always perform the test immediately after mixing on a clean, level surface for reliable results.
