Bitumen Extraction Test: A laboratory method to determine exact bitumen (binder) content in asphalt mixes using solvent extraction (centrifuge / reflux). Also used to recover aggregates for gradation. Parameter Details Standard IS 13826 / ASTM D2172 Purpose Determine bitumen content & recover aggregates for gradation Sample ~1000 g typical On this page: Objective Apparatus Procedure Calculation & Example MoRTH Limits Notes & Safety Downloads FAQ 1. OBJECTIVE To determine percentage of binder (bitumen) in a bituminous mix by cold solvent extraction using a centrifugal extractor (ASTM D2172 / IS 13826). 2. APPARATUS Centrifugal extraction machine Analytical balance (0.1 g) Cold solvent (benzene / petrol / trichloroethylene) Filter paper (Watt 60) Oven, beakers, spatula, glass plate PPE: gloves, goggles, extractor ventilation 3. PROCEDURE Weigh a representative sample (W1 ≈ 1000 g) and place into the extractor bowl. Add sufficient commercial benzene (or specified solvent) to cover the sample and allow to stand up to 1 hour to soften the bitumen. Line the bowl with pre-weighed filter paper and assemble the bowl with the paper in place. Place a beaker to collect the solvent/bitumen extract. Start the extractor slowly and increase speed gradually up to 3600 rpm. Maintain until solvent flow reduces significantly. Stop the machine and add about 200 ml fresh solvent. Repeat extraction cycles at least 3 times or until the extract becomes light straw in colour. Remove filter paper with retained fines; dry in air then oven at 115°C to constant weight (record Wf). Recover fines in solvent by centrifuging the extract; dry and weigh recovered fines (W3). Dry remaining aggregate in oven to constant weight and record as W2. Record all weights and proceed to calculation. 4. CALCULATION & EXAMPLE % Binder Content = [(W1 − (W2 + W3)) / W1] × 100 Where: W1 = Original weight of sample (g) W2 = Weight of aggregate after extraction (g) W3 = Weight of fines recovered from extract (g) Parameter Value (g) W1 (sample) 1000.0 W2 (after extraction) 955.2 W3 (fines) 6.8 Binder % 3.80% W1 (g) W2 (g) W3 (g) Calculate 5. MoRTH Binder Content Requirements (Typical) Layer Typical Binder % DBM (Grade-I) 3.5 – 4.5% DBM (Grade-II) 4.0 – 4.5% BC (Grade-I) 5.0 – 5.4% BC (Grade-II) 5.2 – 5.6% 6. NOTES & SAFETY Handle solvents in a ventilated area and use PPE. Ensure extractor lid seals to avoid solvent loss. Dispose used solvent as hazardous waste per local rules. Repeat extraction until extract clears; incomplete extraction underestimates binder %. 7. DOWNLOADS & TEMPLATES Download Extraction Test Register (Excel) Quick Cheatsheet (PDF) 8. FAQ Q: Which solvent is used? A: Commercial benzene, trichloroethylene, or petrol—choose as per lab regulations and safety. Q: How many cycles are needed? A: Typically 3 cycles or until extract becomes light straw in colour. Q: How to calculate binder %? A: % Binder = [(W1 − (W2 + W3)) / W1] × 100 Related Tests Ductility Test Softening Point Penetration Test