🧪 Specific Gravity & Water Absorption Test of Aggregates – Complete Practical Guide for Site Engineers

Introduction

Specific Gravity & Water Absorption Test aggregates की density और porosity (voids) determine करने के लिए किया जाता है। यह test road construction (GSB, WMM, concrete, bituminous work) में बहुत important है।

👉 “Aggregate कितना strong और durable है – यह इस test से पता चलता है”

What is Specific Gravity?

Specific Gravity का मतलब है:
👉 Aggregate का weight compared to equal volume of water

What is Water Absorption?

Water Absorption बताता है:
👉 Aggregate कितना पानी absorb करता है

क्यों जरूरी है यह test?

• Aggregate quality check करने के लिए

• Mix design accuracy के लिए

• Durability ensure करने के लिए

Required Equipment

Coarse Aggregate:

• Wire Basket

• Water Tank

• Weighing Balance

Fine Aggregate:

• Pycnometer

• Oven

• Balance

Test for Coarse Aggregate (Step-by-Step)

1. Dry Weight

• Oven dry sample लें

• Weight note करें (W1)

2. Water Immersion

• Sample को water में immerse करें

• 24 घंटे soak करें

3. Surface Dry Weight

• Sample निकालकर surface dry करें

• Weight note करें (W2)

4. Weight in Water

• Water में weight लें (W3)

Calculation

Specific Gravity:

= W1 / (W2 – W3)

Water Absorption (%):

= ((W2 – W1) / W1) × 100

Standard Values

Interpretation

• High SG → Strong aggregate

• High absorption → Weak aggregate

Importance in Road Construction

• Mix design accuracy

• Strength & durability

• Moisture correction

Common Mistakes

❌ Surface drying सही नहीं करना
❌ गलत weighing
❌ Sample contamination

Site Engineer Responsibilities

• Material approval

• Lab test verification

• Mix adjustment

Practical Tips

✔ Accurate weighing करें
✔ Proper drying करें
✔ Clean water use करें

Conclusion

Specific Gravity & Water Absorption Test aggregates की quality determine करने के लिए essential है। यह ensure करता है कि material durable और strong है।

Final Words

👉 “Good Aggregate Quality = Strong & Durable Road” 🪨🚧