🏗️ Concrete Slump Cone Test – Easy to Understand Technical Guide

🔹 What is Slump Cone Test?

Slump Cone Test is a simple field test used to measure the workability and consistency of fresh concrete. Workability means how easily concrete can be mixed, placed, compacted, and finished without segregation or bleeding.

 

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🔹 Apparatus Required

• Slump Cone → Height 300 mm, Top dia 100 mm, Bottom dia 200 mm
• Tamping Rod → 16 mm dia, 600 mm long, rounded ends
• Steel Base Plate (non-absorbent)
• Measuring Scale
• Fresh Concrete Sample

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🔹 Test Procedure (Step by Step)

1. Place the slump cone on a clean, level steel plate.
2. Fill the cone with fresh concrete in 3 equal layers.
3. Compact each layer with 25 strokes of tamping rod.
4. Strike off extra concrete from the top surface.
5. Carefully lift the cone vertically in 5–10 seconds without disturbing concrete.
6. Measure the slump → Difference between cone height and highest point of subsided concrete.

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🔹 Types of Slump

• True Slump → Concrete subsides evenly (ideal result).
• Shear Slump → Concrete shears off; indicates low cohesion.
• Collapse Slump → Concrete collapses completely; very high workability.
• Zero Slump → No subsidence; stiff concrete (road pavements).

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🔹 Acceptable Slump Values (as per IS 456:2000)

• Mass Concrete → 25–75 mm
• RCC Beams & Slabs → 50–100 mm
• RCC Columns → 75–150 mm
• Pumped Concrete → 100–150 mm

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🔹 Importance of Slump Cone Test

✔ Quick check for workability of fresh concrete
✔ Ensures uniformity in different batches of concrete
✔ Helps in adjusting water–cement ratio on site
✔ Detects problems like segregation or excess water
✔ Useful in quality control at construction sites