🧪 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
| Property | Value |
|---|---|
| Specific Gravity | 2.5 – 3.0 |
| Water Absorption | < 2% |
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” 🪨🚧