Chapter 9Chapter 9

High temperature stabilityLow temperature crack resistanceDurabilitySkid resistanceConstruction workability

Chapter 9Chapter 9

§9.3 Technical Property of §9.3 Technical Property of Bituminous MixtureBituminous Mixture

Definition ： High temperature stability refers that

bituminous mixture can not form much plastic deformation under repeated loads at high temperature. Influencing factors ：

Bituminous cohesion, the mutual influence between bituminous and stone, the property of

the stone.

High Temperature StabilityHigh Temperature Stability

Test Test MethodMethod

Wheel rut testWheel rut test

Triaxial Triaxial Shear testShear test

VB stability VB stability testtest

Marshall Marshall testtest

High Temperature StabilityHigh Temperature Stability

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Low Temperature Crack ResistanceLow Temperature Crack Resistance Low Temperature Crack ResistanceLow Temperature Crack Resistance

Definition ： Low temperature crack resistance refers that bituminous admixture material resists shrinkage deformation without cracks Reasons of bituminous pavement cracks

① Repeated load → fatigue cracking

② Embrittlement at low temperature → low ability to deform → cracking

③ Shrinkage at low temperature

④ ①+②

Influencing factorsInfluencing factors includes: quality and includes: quality and quantity of bitumen and mineral material quantity of bitumen and mineral material gradationgradation

TestTest ：： Pure draw test: → to test the stress, strain, tensile strength and

limiting deformation of the cylinder specimen → to make out the stiffness modulus and the

index of temperature shrinkage → to evaluate the breakage temperature of

bituminous mixture.

Low Temperature Crack ResistanceLow Temperature Crack Resistance Low Temperature Crack ResistanceLow Temperature Crack Resistance

DurabilityDurability

Definition: Durability refers that bituminous mixture

obtains the abilities to endure the influence of atmosphere for a long time with traveling load.

Influencing factors : chemical properties of bituminous the component of mineral material the composite structure of bituminous

mixture the quantity of bitumen

For example:

With reduction of 0.5% of bitumen, Vv will increase and bituminous mixture’s life will shorten one year.

DurabilityDurabilityInfluencing factors

Measures of Improving Durability:Employing hard mineral material;Improving the density of bituminous mixture;Selecting bituminous mixture with fine particles and dense gradation; Increasing the quantity of bitumen

Test ： Accelerated weathering test Marshall test

Index

Durability can be evaluated by the index available porositysaturation degree bituminous interstitial rateresidual stability

DurabilityDurability

Skid ResistanceSkid Resistance Influencing Factors ： Mineral material surface structure,

gradation, composites of mixture and quantity of bitumen.

Improvement measures ： ① Selecting anti-friction stone with required

rate of wearing and impact value. Notice: It is necessary to add some

antistripping agent because the hard stone often belongs to the acid stone.

② Controlling the quantity of bitumen: the quantity of bitumen ↑→smoothness of the surface ↑→anti-slide ↓

Construction Workability Construction Workability

Construction Feasibility Construction Feasibility is determined by: Mineral material’s gradation: It is not easy to occur isolation with

appropriate gradation Cohesion and quantity of bitumen Temperature and construction

condition