DENSITY AND VOIDS ANALYSIS OF BITUMINOUS MIX SPECIMEN

Soon after the compacted bituminous mix specimens have cooled to room temperature, and then the weight, average thickness and diameter of the specimen are noted. The specimens are also weighed in air and then in water. The bulk density value G_b of the specimen is calculated from the weight and volume. The voids analyses are made as given below:

 

Where,

            V_v = air voids in the mix, %

                        V_b = volume of bitumen

                        VMA = voids in mineral aggregates, %

                        VFB = voids filled with bitumen %

SPECIFIC GRAVITY OF COMPACTED SPECIMEN OF BITUMINOUS MIX

The specific gravity values of the different aggregates, filler and bitumen used are determined first. The theoretical specific gravity G_t of the mix is given by-

 Where,

W₁ = percent by weight of coarse aggregate

                        W₂ = percent by weight of fine aggregate

                        W₃ = percent by weight of mineral filler

                        W₄ = percent by weight of bitumen

                        G₁ = apparent specific gravity of coarse aggregate

                        G₂ = apparent specific gravity of fine aggregate

                        G₃ = apparent specific gravity of mineral filler

            G₄ = apparent specific gravity of bitumen

CHARACTER OF MATERIALS ARE USED IN MODIFIED BITUMINOUS MIXES

Characteristics of Materials used in modified bitumen:

i)          Bitumen

ii)         Polyethylene

i)                    Kerosene

ii)                   Ice

iii)                 Greece

iv)                 Stone aggregate

v)                  Fine aggregate

vi)        Filler materials.

 

Pure Bitumen

i)        Penetration grade: 80/100

ii)       Specific gravity: 1.02

iii)     Ductility value: 100⁺

iv)     Flash point: 290 ⁰C

v)      Fire point: 300 ⁰C

vi)     Softening point: 43 ⁰C

vii)  Solubility: 95.7%

 

Polyethylene

A particular type of polythene bags, transparent in color, mostly representing the low-density polyethylene purchased from the local market is used. Specific gravity of this specimen varies from 0.95 to 0.93.
 

Coarse Aggregate

It was collected from the hump beside Strength of Materials Lab, Transportation Lab, and from site of under construction Computer Science and Engineering building. The white stone aggregate was used with rather mix of black stone. The aggregate was to pass through 20 mm sieve. Other sieves where retained aggregates were collected are   12.5mm, 9.5mm, 4.75mm and 2.36mm.

Fine Aggregate

Fine aggregate of grade 2.36mm passing and retained at 600mm, 300mm, 150mm, and 75 mm. It was collected from the construction site of new student hostel.

Mineral Filler

It was the residuals received after sieving the fine aggregate in the soil lab by mechanical shaker. It was passed through 75mm sieve.