Chapter 9

 Technical Requirement Technical Requirement  Technical Index Technical Index Chapter Technical Standard of Bituminous Mixture §9.5 Technical Standard of Bituminous Mixture

According to the regulations of GB and GBJ94-86, the standard should be based on Marshall stability test and conformed with the requirements listed in Tab Tab Fig.9.5.1Marshall test machine Technical Requirement

Tab Technical Standard of Bituminous Concrete Admixture Material Traffic property>5000 /day Kinds of bituminous concrete Coarse graded Medium graded Fine graded Technical property Stability S m （ N ） Flow value （ 1/100cm ） 20~40 Voidage V v （ % ） Ⅰ 3~6 Ⅱ 6~10 Residual stability S m （ O ） ，（ % ） Ⅰ＞ 75 Ⅱ＞ 70

Tab Technical Standard of Bituminous Concrete Admixture Material Traffic Property<5000 /day Kinds of bituminous concrete Coarse graded Medium graded Fine graded Technical property Stability S m （ N ） Flow Value （ 1/100cm ） 20~45 Voidage V v （ % ） Ⅰ 3～63～6 Ⅱ 6 ～ 10 Residual Stability S m （ O ） ，（ % ） Ⅰ ＞ 75 Ⅱ ＞ 70

Tab Technical Standard of Bituminous Concrete Admixture Material Traffic propertyPavement, Bike lane, Pavement square Kinds of bituminous concrete Technical property Stability S m （ N ） 3000 Flow value （ 1/100cm ） 20 ~50 Voidage V v （ % ） type Ⅰ 2~5 type Ⅱ - Residual stability S m （ O ），（ % ） type Ⅰ＞ 75 type Ⅱ -

Marshall stability test Instrument: Marshall test machine Methods: First weighing some mineral material and bitumen, then heating and mixing them as required, molding them into the shape of D=101.6mm ， h=63.5mm cylinder, finally testing stability and flow value on Marshall test machines.

 Stability (S m ) ： Stability is the index of evaluating the high temperature stability. Definition: The maximum load of the specimen bearing loads at 50±5mm/min speed at 60 ℃ for more than 30min is the stability. Technical Index

 Flow value (f m )  It shows the ability to resist plastic deformation.  It means the instant condense deformation value by the maximum load. It can be tested when testing S m.  Voidage (V v ) ：  It means the index of bituminous mixture density.  V v ↑→ heat stability and skid resistance, durability Technical Index

Actual density of bituminous mixture specimen can be tested by using hydrostatic balance and calculated by the following formula. Small space specimen Big space specimen Actual Density of Bituminous Mixture Specimen Technical Index

ρ 0 、 ρ w － Actual density of specimen and density of water at normal atmosphere temperature( g ／ cm 3 ） m 0 － Weight of specimen in the air （ g ） m 1 － Weight of specimen in the water （ g ） m 2 － Quantity of specimen in the air after wax-sealing （ g ） m 3 － Quantity of specimen in the water after wax- sealing （ g ） γ p － Relative density of the wax ρ w － Density of water in normal atmosphere temperature g/cm 3 Actual Density of Bituminous Mixture Specimen

The theoretical density of the specimen can be calculated on the supposition that bituminous mixture is condensed ultimately excluding the internal space. Technical Index Theoretical Density of Specimen

q 1 q 2 ……q n － Quantity of all kinds of composite mineral materials (%) γ 1 γ 2 …… γ n － Relative density of all kinds of composite mineral materials q a － Quantity of bituminous (%) γ a － Relative density of bituminous ρ w － Water density at normal atmosphere temperature( g/cm 3 )

ρ 0 -Practical dense of specimen (g ／ cm 3 ) ρ t -Theoretical dense of specimen (g ／ cm 3 ) Voidage of Specimen Technical Index Bituminous Mixture Fig Sketch map of Bituminous Mixture

Technical Index  Definition: Bituminous saturation of specimen is the percentage of bituminous volume to mineral void volume  Formula Bituminous Saturation of Specimen (VFA)

Meaning:  Meaning: too low VFA→ mineral material cannot be wrapped by bitumen→ durability↓ too high VFA → small space → low heat stability Bituminous Saturation of Specimen (VFA)

 Definition : Residual stability is the Marshall stability ratio of the two specimens in water after 48h and that in normal station  Formula S m(0) － Residual Stability S m(w) ， S m － Stability of the specimen in water after 48h and that out of water  Meaning:  Meaning: Evaluating water resistance, reflecting durability to some extent Residual Stability S(0) Residual Stability S m (0) Technical Index