DESIGN PROCEDURE OF BITUMINOUS MIXES

In the design procedure of a bituminous mix, following steps are involved.

i) Selection of aggregate to be employed in the mix.

ii) Selection of aggregate grading.

iii) Determination of the proportion of each aggregate required to develop the design grading.

iv) Determination of the specific-gravity of the aggregate blend.

v) Determination S.G. of the bitumen.

vi) Make up trial specimens with varying bitumen contents.

vii) Determination of the specific-gravity (S.G) of each compacted specimen.

viii) Make stability test on the specimen.

ix) Determine the percentage of voids in each paving specimen and if the design method in use requires it, calculate the VMA and percent voids filled with bitumen.

x) Selection of the optimum bitumen content from the obtained data.

EFFECTS OF POLYETHYLENE AND KEROSENE ON THE PROPERTIES OF BITUMEN

TEST PROCEDURE & GRAPHICAL PRESENTATION

Specific Gravity Test

           (a)        Wt. of bottle at clean and dry condition = A gm

           (b)        Wt. of (bottle+ water full) at 25⁰ C after 30 min = B gm

           (c)        Wt. of (bottle+ bitumen) at 25⁰ C after 60 min = C gm

           (d)        Wt. of (bottle+ bitumen +water full) at 25⁰ C after 30 min = D gm

                                                    Sp. Gr. = (C-A) / ((B-A)-(D-C))

Penetration Test

(a) Bitumen at 100-1100 C was poured into the container and then cooled to room temperature for one hour.
(b) Container with bitumen was submersed in water at 250 C for one hour.

(c) At constant temp. of 250C, the sample was placed in penetrometer and then readings were recorded for a period of 5 seconds.

Ductility Test

(a) Bitumen was strained through 0.6 mm sieves and then poured into the briquette and was cooled to room temperature for 30 min.
(b) Then sample was placed in water at 25 0C for 30 min.
(c) Excess bitumen was cut off and the briquette was placed in water at 250 C for 1.5 hour. 

(d) Briquette was placed in ductility machine and recorded the reading in cm at which the bitumen threads were broken.

Result of Specific gravity, Penetration and Ductility Test.
(Modified Bitumen Sample made with mixing of Pure Bitumen,
Polyethylene and Kerosene)

Type of Sample	% of Polyethylene content	% of Kerosene content	Specific Gravity	Penetration value	Ductility value
Pure bitumen	0	0	1.020	85	100+
Sample-1	1	1	1.016	41	74
Sample-2	2	2	1.013	53	60
Sample-3	3	3	1.009	50	44
Sample-4	4	4	1.006	41	26
Sample-5	5	5	1.003	38	18

 

Result of Penetration Test (only for % of kerosene content)

Type of Sample	% of Kerosene content	Penetration value
Pure bitumen	0	85
Sample-1	1	80
Sample-2	2	60
Sample-3	3	55
Sample-4	4	54
Sample-5	5	82

 

Solubility Test

(a) 0.50 gm asbestos fiber was thoroughly shaked in 150 cc water.

(b) The crucible was filled with some of the suspension of asbestos in water and applied a light suction to draw off the water, leaving a firm mat of asbestos in the crucible.

(c) The crucible was heated for 10 to 15 min. for the constant weight of A.
(d) 2 gm bitumen was stirred in 100 cc CS2 until all lumps were disappeared and no undissolved sample was adhered to the container. (e) The prepared weighed Gooch crucible was placed in the filter flask. Decanted the solution through the asbestos mat of the crucible with light suction. Removing the crucible from the flask and then heating for 10 to 15 min. for constant weight of B gm.

 

Softening Point Test

(a) Completely fluid bitumen was poured in heated rings placed on metal plate.
(b) After cooling the rings in air for 30 min. the excess bitumen was trimmed.
(c) At this time the temperature of water was kept at 50C for 15 min. and then the balls were placed in position. 

(d) The temperature of water was raised at uniform rate of 50C/min. until the bitumen was softened and touched the bottom plate by sinking of balls.

  

Flash and Fire Point Test

(a) Bitumen was poured into the clean and dried cup up to a filling mark.
(b) Sample was then heated at the rate of 5 to 60C/ min.

(c) Test flame was applied at intervals depending upon the expected flash and fire points.

Result of Solubility, Softening, Flash and Fire Point Test.
(Modified Bitumen Sample made with mixing of Pure Bitumen,
Polyethylene and Kerosene)

Type Of Sample	% of Polyethylene content	% of Kerosene content	Solubility (%)	Softening Point (0C)	Flash Point (0C)	Fire Point (0C)
Pure bitumen	0	0	95.70	43	290	300
Sample-1	1	1	90.05	55	280	295
Sample-2	2	2	85.70	56	270	285
Sample-3	3	3	82.13	57	260	275
Sample-4	4	4	84.30	58	255	270
Sample-5	5	5	87.50	59	250	265

PREPARATION OF SAMPLE FOR MODIFIED BITUMINOUS MIXES

The samples are prepared by adding polyethylene and kerosene with pure bitumen. The amounts of polyethylene and kerosene are added by weight of percentage of pure bitumen separately.

First of all fresh bitumen, without debris and adulterants was collected. The properties of the bitumen were justified. Five bowls for preparing samples was weighed. Hot bitumen was poured in those bowls. The weight of the bitumen was taken. Then polyethylene was weighed with respect to 1%, 2%, 3%, 4%, and 5% weight of the bitumen. The kerosene was also weighed with respect to 1%, 2%, 3%, 4%, and 5% weight of the bitumen. The samples were prepared one after another. At first the bitumen for 1% polyethylene and 1% kerosene content was heated till it fully liquefied and was in a state to dissolve polyethylene and kerosene. The polyethylene bags were gradually left in the bitumen. The softened form of the polyethylene bags was floating on the hot bitumen. But after continuous stirring by steel spoon it was thoroughly mixed with the bitumen. Though the final mixing temperature was not observed but it is assumed that it was near the flash point of the bitumen. There was a little change in the color. This mother sample is kept for further experiments. Thus five samples were prepared with variable polyethylene and kerosene contents. When a test was to be performed the sample was thoroughly heated so that a homogeneous liquid state could be gained and neither precipitation nor floatation nor suspension was observed.

Sample-1. Weight of pure bitumen + 1% polyethylene of pure bitumen + 1% kerosene of pure bitumen (by weight)

Sample-2. Weight of pure bitumen + 2% polyethylene of pure bitumen + 2% kerosene of pure bitumen (by weight)

Sample-3. Weight of pure bitumen + 3% polyethylene of pure bitumen + 3% kerosene of pure bitumen (by weight)

Sample-4. Weight of pure bitumen + 4% polyethylene of pure bitumen + 4% kerosene of pure bitumen (by weight)

Sample-5. Weight of pure bitumen + 5% polyethylene of pure bitumen + 5% kerosene of pure bitumen (by weight).