CIVE 320 Chapter 5.1, Spring 2016

CIVE 320 Construction Materials & Technology Dr. Ghassan Chehab Slides Set: 5-a Asphalt Binder: An Introduction Asphalt Types Bitumen Asphalt Tar Asphalt Cement Emulsifiers AC + petroleum solvent: Slow, Med., & Rapid Curing AC + Water + Agent: Anionic or Cationic Different Grades Petroleum-Based Natural Deposits Cutbacks Petroleum-Based Asphalts Asphalt is waste product from refinery processing of crude oil: Sometimes called the “bottom of the barrel” 0.05$/Gal Properties depend on: Refinery operations Crude source Gasoline Kerosene Lt. Gas Oil Diesel Motor Oils Asphalt Barrel of Crude Oil Refinery Operation FIELD STORAGE PUMPING STATION LIGHT DISTILLATE HEAVY DISTILLATE PROCESS UNIT ASPHALT CEMENTS FOR PROCESSING INTO EMULSIFIED AND CUTBACK ASPHALTS STILL AIR AIR BLOWN ASPHALT STORAGE TOWER DISTILLATION REFINERY RESIDUUM OR GAS PETROLEUM SAND AND WATER CONDENSERS AND COOLERS TUBE HEATER MEDIUM DISTILLATE Fractional Distillation Fawley Refinery, UK Largest in Europe Refineries and Oil Rigs in Rita’s Path Molecular Structure Asphaltenes discrete phase  high MW (C/H >0.8)  aromatics w/few side chains Resins compatibilize asphaltenes  intermediate MW, C/H >0.6  more side chains Oils continuous phase  lightest MW, C/H <0.6  primarily aliphatics Resin-covered asphaltenes floating in an oil base Molecular Structure Asphaltines C C C C C H H H H H H H H H H H C H C C C C C H H H H H H H H H H H C H C H C C C C C H H H H H C H C C C C C H H H H H H H H H H H H H H H H H H H C C C C C C H H H H H H H H H H H H H H C C C C C C Resins Oils Cutbacks Rapid cure (RC) (Naphtha or Gasoline) High volatility of solvent Tack coats, surface treatments Medium cure (MC) (Kerosene) Moderate volatility Stockpile patching mix Slow cure (SC) (Low viscosity oil) Low volatility Prime coat, dust control 30% solvent 10% solvent GRADE NAPTHA FOR RC KEROSENE FOR MC LIGHT OIL FOR SC SOLVENT ASPHALT CEMENT APPRX. FUROL VIS., 140°F, SEC. APPROX. KINEMATIC VIS. 140°F, CS 30 70 250 800 3000 15-30 35-70 125-250 400-800 1500-3000 30-60 70-140 250-500 800-1600 3000-6000 Cutback Types & Composition Emulsions Emulsifier gives surface charge to asphalt droplets suspended in water medium Anionic Negative charge Alkaline Good with limestone (positive charge) Cationic Positive charge Acid Good with silica gravels (negative charge) HOT ASPHALT TANK WATER EMULSIFIER STORAGE STORAGE STORAGE PUMP PUMP COLLOID MILL STATOR ROTOR Clearance 0.005 - 0.030” Manufacture of Asphalt Emulsions Emulsions: Chemical Activity ASPHALT + WATER + EMULSIFIER ANIONIC (-) ALKALINE CATIONIC (+) ACID LIMESTONE SILICA (Sil. Gravel) Emulsions RAPID SETTING (RS) Tack Coat Surface Treatment (spray applications) MEDIUM SETTING (MS) Road Mix (open-graded) SLOW SETTING (SS) Road Mix (dense) Slurry Seals Tack Coat Fog Seal weaker surface charge more emulsifying agent Emulsion Types & Applications Emulsions in Surface Treatments Emulsion Breaking Fiber-Reinforced Surface Treatments Demo at PTI Test-track Aging Hardening  Long-Term  Changes in properties (chemical and physical) over time  MW & quantity of solvents decreases  Irreversible Volatilization  Short term  Volatile components (lighter petroleum products) evaporate  During mixing and construction  Irreversible Aging, cont’d Oxidation  Long-term  Organic molecules react with oxygen  Occurs faster in warmer climates  Irreversible Molecular Structuring  Reversible - overcome by heating Simulating Aging Thin-Film Oven Test (TFO) 5 hours, 163C Rolling Thin-Film Oven Test (RTFO) 85 min, 163C Simulates short-term aging Pressure Aging Vessel (PAV) 300psi, 90-110C, 20 hours Simulates long-term aging Purpose  To subject asphalt to hardening conditions approximating those that occur in normal HMA batch plant operations. Test (ASTM D1754)  Forced draft oven (325°F)  Rotating shelf (5-6 RPM)  1/8” film of Asphalt heated in pans  Time: 5 hours  Weight loss determined (%)  Viscosity or penetration of TFOT residue measured Thin Film Oven Test Purpose  To subject asphalt to hardening conditions approximating those that occur in normal HMA batch plant operations. Test (ASTM D2872)  Forced draft oven (325°F)  Moving thin film in glass bottle  Rack rotates at a prescribed rate  Air jet (air flow 4000 ml/min)  Time: 75 minutes  Weight loss measured  Viscosity of RTFOT residue measured Rolling Thin Film Oven Test (RTFOT) Rolling Thin Film Oven (RTFO) Inside of RTFO Fan Air Line Rotating Bottle Carriage Opening in Bottle After Before Pressure Aging Vessel (PAV) (Long Term Aging) Simulates aging of an asphalt binder for 7 to 10 years 50 gram sample is aged for 20 hours Pressure of 2,070 kPa (300 psi) At 90, 100 or 110 C Bottom of pressure aging vessel Rack of individual pans (50g of asphalt / pan) Vessel Lid Components Oven