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Lime Stabilization. Lime : Definitions – Properties – Applications Treatment Techniques in Europe Tremti 2005 : Introduction Tremti 2005 : Lime Treatment Feed Back. Daniel Puiatti March 2O th , 2006. Lime Definitions - Properties - Applications. Daniel Puiatti March 21 st , 2006.
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LimeStabilization • Lime : Definitions – Properties – Applications • Treatment Techniques in Europe • Tremti 2005 : Introduction • Tremti 2005 : Lime Treatment Feed Back Daniel Puiatti March 2Oth, 2006 daniel.puiatti@lhoist.com
LimeDefinitions -Properties - Applications Daniel Puiatti March 21st, 2006 daniel.puiatti@lhoist.com
Synopsis • Part I: Definitions • Part II:Lime Properties • Part III:Lime Applications daniel.puiatti@lhoist.com
Definitions (1) Calcium Air lime • Produced by calcination of limestone (T > 900°C) • Slowly hardens in the air by combination with CO2 Hydraulic lime • Produced by calcination of clayey or siliceous limestone(T > 1000°C) • Hardens with water daniel.puiatti@lhoist.com
CaO Calcium oxide Quicklime T > 900°C + Water CaCO3 Calcium carbonate Limestone + CO2 Ca(OH)2 Calcium hydroxide Hydrated Lime Definitions (2) : Calcium air lime cycle daniel.puiatti@lhoist.com
Synopsis • Part I: Definitions • Part II:Lime Properties • Part III:Lime Applications daniel.puiatti@lhoist.com
Lime Properties (1) • Hydrate : Chemical BaseCa++ + 2OH- • Ca++ • pH • Quicklime hydrationCaO + H2O => Ca(OH)2 + heat daniel.puiatti@lhoist.com
Lime Properties (2) • Hydrate : Chemical Base • Multi-Functional Modifying Agent • Clayey materials • Aggregates • Bitumen • Chemical reagent for « cementitious » reaction • Clay • Fly Ash • Limestone • Blast Furnace Slag • Quicklime hydration • Moisture reduction of wet soils or materials daniel.puiatti@lhoist.com
(1% CaO may reduce water content by 1 to 5% by mass of wet soils depending on weather and mixing conditions) Wn PI • Immediate reduction of the clay activity due to the flocculation CBR Example : Lime action on wet clayey soilsShort term (1) • Immediate reduction of the water content • Improvement of the bearing capacity. Immediate Improvement of the Workability daniel.puiatti@lhoist.com
Before Lime Treatment After Lime Treatment Example : Lime action on wet clayey soilsShort term (2) Immediate Improvement of the Workability ! daniel.puiatti@lhoist.com
Gradual hardening of the mixture thanks to bonds formed during the pozzolanic reaction between clay & lime Without lime With lime Example : Lime action on wet clayey soilsMiddle to long term (1) Better Resistance to Traffic, Water, Frost daniel.puiatti@lhoist.com
Water + high pH Ca++ Clay (SiO2 + Al2O3) Ca++ CSH CAH = + Ca++ Ca++ Example : Lime action on wet clayey soilsMiddle to long term (2) Pozzolanic reactions with clayey soils Ca++ + SiO2 + H2O = Hydrated Calcium Silicate (CSH) Ca++ + Al2O3 + H2O= Hydrated Calcium Aluminate (CAH) daniel.puiatti@lhoist.com
Benefit of Lime action on wet clayey soils (1) • Reduction of the swelling potential of the clay • Reduction of the risk of settlements • Increase of the cohesion • Resistance to water and frost • Increase of the mechanical performance(Rc, Rt, E) = f(type of soil, temperature, time) daniel.puiatti@lhoist.com
Evolution of shear strength(Lime treated silt : PI = 14 ; CaO = 2%) Benefit of Lime action on wet clayey soils (2) daniel.puiatti@lhoist.com
Synopsis • Part I: Definitions • Part II:Lime Properties • Part III:Lime Applications daniel.puiatti@lhoist.com
Roman Roads(3rd Cent. BC to 4th Cent.) Lime in structures is a long story ! daniel.puiatti@lhoist.com
Lime Applications • Soil Treatment • Soil improvement (embankment) : milled quicklime • Soil stabilization (capping layer, platform) : milled quicklime and slurry • Hot Mix Asphalt (HMA) – Cold Mix Asphalt (CMA) • Adhesion improvement between acidic aggregates & bitumen • Bitumen stiffening and age hardening reduction • Reagent mixed with industrial by-productsfor the production of hydraulic binders • Fly ash • Blast furnace slag • Component of specific mortars • Tunnels • Soil injections daniel.puiatti@lhoist.com
Soil Treatment Stabilization (Platforms) Improvement (Earthworks) before lime after lime Roadworks Pavement Capping layer Earthworks Embankment Lime Applications : Soil Treatment daniel.puiatti@lhoist.com