lant. Similarly the bitumen is to be heated up to a maximum of 160°c.
The 8% of waste plastic to the weight of bitumen are added in the conveyor belt or special mechanical device is developed which will spray the plastics inside the chamber to coat the plastics effectively.
Central mixing plant helps to have better control of temperature and better mixing of this material thus helping to have a uniform coating and heated bitumen is also sprayed.
Fig. central mixing plant d. LAYING OF BITUMENOUS MIX:-
The plastics waste coated aggregate is mixed with hot bitumen and the resulted mix is used for road construction. The road laying temperature is between 1100c to 1200c. The roller used is 8-ton capacity.
I. MIX DESIGN BY MARSHALL METHOD
a) Optimum Waste Plastic Content
b) Comparison of Two Mixes
c) Volumetric properties of BC Mixes
II. PERFORMANCE STUDIES OF WASTE PLASTIC
i. Indirect Tensile Strength
ii. Rutting Test
I. MIX DESIGN BY MARSHALL METHOD:-MARSHALL TEST:-
Laboratory studies were carried out at the Centre for Transportation Engineering of Bangalore University on the possible use of the processed plastic bags as an additive in bituminous concrete mixes. The material used in this study was supplied by M/s KK Poly Flex (P) Ltd., Bangalore. The processed plastic was used as an additive with heated bitumen in different proportions (ranging from zero to 12 % by weight of bitumen) and mixed well by hand, to obtain the modified bitumen.
Auto Marshall Compactor Auto
The properties of the modified bitumen were compared with ordinary bitumen. It was observed that the penetration and ductility values of the modified bitumen decreased with the increase in proportion of the plastic additive, up to 12 % by weight. The softening point of the modified bitumen increased with the addition of plastic additive, up to 8.0 % by weight.
OPTIMUM WASTE PLASTIC CONTENT:
> Varying percentages of waste plastic by weight of bitumen was added into the heated aggregates
> Marshall specimen with varying waste plastic content was tested for bulk density and stability
> Maximum value of stability was considered as criteria for optimum waste plastic content
Studies were carried out on Bituminous mixes using 60/70 grade bitumen having average Marshall Stability Value (MSV) of 1300 kg at optimum bitumen content of 5.0 % by weight of the mix. Further studies on mixes were carried out using the modified binder obtained by the addition of varying proportions of processed plastic bags (percentage by weight of bitumen) with the conventional 80 /100 grade bitumen. The optimum modified binder content fulfilling the Marshall Mix design criteria was found to be 5.0 % by weight of the mix, consisting of 8.0 % by weight of processed plastic added to the bitumen. The average MSV of the mix using the modified binder was found to be as high as 1750 kg at this optimum binder content, resulting in about three fold increase in stability of the BC mix, which contains 4.6 % bitumen plus 8 % processed plastic by weight of bitumen, i.e., 0.4 % processed plastic by weight of the mix.
In order to evaluate the ability of the mix prepared with the above-modified bitumen to withstand adverse soaking condition under water, Marshall Stability tests were conducted after soaking in water at 60 Co for 24 hours. The average MSV of the BC mix with modified binder (using 8 % processed plastic by weight of bitumen, as above) was found to increase by about 2.6 times of the mix with ordinary bitumen. Further laboratory studies carried out on the BC mixes using this modified binder also indicated note worthy increase in fatigue life under repeated application of loads.
COMPARISON OF TWO MIXES:
VOLUMETRIC PROPERTIES OF MIXES:-
Volumetric properties of Mixes
Properties Modified Mix (Waste plastic) 8 % by wt of bitumen Conventional Mix
Marshall Stability (kg) 1700 1350
Bulk Density(gm/cc) 2.374 2.350
Air Voids (%) 4.4 3.5
VFB (%) 73 76
Flow (mm) 4 4
VMA (%) 16.5 15.6
Retained Stability (%) 98 88
II. POST TESTING OF WASTE PLASTIC BITUMINOUS MIXES:-
A) PERFORMANCE STUDIES OF THE MIXES
i. Indire