WARM ASPHALT MIXTURES Necessity for a thermal approach The case of LEA Y.Martineau USIRF LEA-CO 31th MAY 2007

Change in coating practice Warm Mix Warm or Half-Warm Mixtures ? Warm or Half-Warm Mixtures ? Warm above 100°C Half-Warm under 100°C What is the right choice ? What is the right choice ?

Energy conditions the characterisrics and performances of asphalt mixtures An happy influence on environment  The reduction of heating energy produce the same level of reduction on Green House Gas emission Influence of a full or partial, water elimination A possible non happy influence on the mixture characteristics  Properties for production and placing mixtures  Mechanical performances

Warm mixtures : a global approach including, thermal, mechanical and chemical concepts. Use the different physical state of asphalt binder. Chemical additives to minimize the influence of water During mixing, inter-action between physical characteristic, temperature, existing water and mechanical effect Analysis of thermal content and thermal transfer between components.

The basis: Understand thermal ways for heating and drying components Influence of mineral skeleton temperature on heating energy consumption Mineral skeleton temperature Energy

Thermal properties of mixture constituents Cp of aggregate = kj/kg/°C Cp of aggregate = kj/kg/°C Cp of asphalt binder = kj/kg/°C Cp of asphalt binder = kj/kg/°C Cp of water = kj/kg/°C Cp of water = kj/kg/°C L v Latent heat of water vaporisation = 2,256 kj/kg L v Latent heat of water vaporisation = 2,256 kj/kg C vap Sensible heat of water vapor = kj/kg C vap Sensible heat of water vapor = kj/kg

Thermal properties of mixture constituents Energy content in one ton of each component, at 100°C, from 0°C Thermal properties of mixture constituents Energy content in one ton of each component, at 100°C, from 0°C Yves LE GOFF

Functionality of components Element Usage function Manufacturing function Coarse aggregate Bearing structure « Specific heat » reservoir Fine aggregate Filling of voids in bearing structure Transport of water capture of heat bitumen Warm, it has the capacity to coat the coarse aggregate Heat bridge between coarse aggregate and fine aggregate Water Emulsion and foam support Foaming and lubricating agent, heat bridge and temperature limiter Foam bitumen Binder coating the fine elements preferentially Heat insulator and “latent heat” reservoir

HOT COATING COARSE AGGREGATE EXPANDED COATING FINE AGGREGATE WORKABILITY WATER/BITUMEN IMMEDIATE STABILITY 130°C 90°- 130°C 60°- 90°C 100°C LEA ® a dynamic process < 50°C

Heat transfer thermograms during the mixing Core coarse aggr Surface coarse agg Bitumen Water Fine aggregate Temperature in °C Time in secondes

Comparison of heating energy require to produce the same formula of mixture, HMA or HW CS Comparison of heating energy require to produce the same formula of mixture, HMA or HW CS Data % in mixes Mass in kg Heating energy to produce a hot mix ashalt Initial water content of fine aggregate (sand) in % 3.0 Water content of coarse aggregate in % 1.0 Initial temperature of aggregate in °C15.0 Initial temperature of asphalt binder in °C160.0 Input of dry and hot aggregate (coarse aggregate, part of fine aggregate, sand and filler ) in % Input of wet aggregate in dry weight (fine aggregate, sand) in % Asphalt binder in pph Water remaining in hot mix in % Eliminated coarse aggregate and sand water in kg/t Totals Final temperature of mix in °C Heating energy in KJ 176, Heavy fuel oil consumption not including losses in kg/t 4.36 LEA-CO 2007

Heating energy to produce half-warm mix CS Initial water content of fine aggregate (sand) in % 3.0 Water content of coarse aggregate in % 1.0 Initial temperature of wet fine aggregate (sand) in °C 15.0 Input temperature of coarse aggregate in °C Initial temperature of asphalt binder in °C Dry coarse aggregate in % Fine aggregate in dry weight in % Asphalt binder in pph Water remaining in half warm mix in % Eliminated coarse aggregate water 6.21 Initial water transformed into vapor in % Totals 1000,00 Final temperature of mix in °C 95.0 Heating energy in KJ 91, Heavy fuel oil consumption not including losses in kg/t 2.26 Comparison of heating energy require to produce the same formula of mixture, HMA and HW CS Comparison of heating energy require to produce the same formula of mixture, HMA and HW CS Data % in mixes Mass in kg LEA-CO 2007

The model can be applied to: Laboratory mix design, Industrial production, Industrial quality control, for any type of warm or half-warm mix and hot mix

Influence of type of fuel on consumed energy and GGEs NHVMJ/kg Mass of CO2 emission /mass of fuel Fuel oil natural gas

The quantity of dust, through the dry filter is reduced of more than 85% The dry filter can be downsized Dry Mat. (kg) FinesDust %(kg)HMALEA Coarse aggregate 618,316,180,19 Fine aggregate322,91445,201,360 TOTAL94151,381,540,19

LEA ® Performances Aspect and characteristics of HMA, but… at 80°C The same HMA formulas (mineral skeleton and binder content). Any limitation of binder content. Definitive mechanical performances, as soon as cooling is achieved. Mechanical performances of HMA

LEA ® is a friendly environmental-product – –Heating energy savings more than 50% – –Reduction of Greenhouse emission, VOC et NOx more than 50% – –Improvement of safety and comfort of labours, laying temperature < 90°C – –LEA can include recycling – –Improvement of safety traffic during works

Half-Warm Mix in industrial practices Half-Warm Mix in industrial practices Use existing Hot Mix Asphalt plants, with complementary equipment Use existing Hot Mix Asphalt plants, with complementary equipment Apply existing standards from Hot Mix Asphalt specs Apply existing standards from Hot Mix Asphalt specs WMA Quality = HMA Quality WMA Quality = HMA Quality Quantity of energy Mix temperature Water content of the mix

Right behaviour under trafic

Cortland, DOT NY STATE,09/09/2006

Cortland,DOT NY State, 09/09/2006

Cortland, DOT NY, 09/09/2006

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