A process for preparation of a polymer modified bitumen emulsion, the process consisting the steps of: (a) heating a softer grade bitumen to a temperature ranging between 150-200°C; (b) adding styrene-butadiene-styrene linear co-polymer in a period of 10-20 minutes to the softer grade bitumen to obtain a mixture, wherein the styrene-butadiene-styrene linear co-polymer is added in an amount ranging from 15-20% by weight of the softer grade bitumen; (c) dispersing the mixture obtained in step (b) at a temperature ranging from 150-200°C for 2 hours, followed by milling for 20-30 minutes to obtain a homogenous matrix; (d) adding a harder grade bitumen to the homogenous matrix obtained in step (c) to obtain a mixture, wherein the mixture comprises styrene-butadiene-styrene linear co-polymer in an amount ranging between 3-5% by weight of the mixture; (e) stirring the mixture obtained in step (d) at a temperature ranging from 150-200°C followed by milling to obtain a polymer modified bitumen; (f) mixing the polymer modified bitumen obtained in step (e) with an organic solvent to obtain an organic phase, wherein the organic solvent is selected from Straight run Kerosene Oil or Mineral Turpentine Oil; (g) mixing water, an acid, calcium chloride salt solution and an emulsifier to obtain an aqueous phase, wherein the aqueous phase comprises: 30-35 wt% water, 1-2 wt% of mineral acid, 0.15-0.5 wt % of calcium chloride salt solution and 0.25-1.5 wt% of emulsifier; wherein the wt% of each of the components is calculated based on the total weight of the polymer modified bitumen emulsion, wherein the emulsifier in the aqueous phase is an amine selected from the group consisting of secondary, tertiary amine, and long chain fatty amines; and (h) mixing the organic phase obtained in step (f) with the aqueous phase obtained in step (g) by milling to obtain the polymer modified bitumen emulsion; wherein the polymer modified bitumen emulsion comprises styrene-butadiene-styrene linear co-polymer in an amount ranging between 3-5% by weight of the polymer modified bitumen; wherein the softer grade bitumen has an absolute viscosity ranging from 800-1200 poise at a temperature of 60°C and the harder grade bitumen has an absolute viscosity ranging from 2400-3600poise at a temperature of 60°C. (a) heating a softer grade bitumen to a temperature ranging between 150-200°C; (b) adding styrene-butadiene-styrene linear co-polymer in a period of 10-20 minutes to the softer grade bitumen to obtain a mixture, wherein the styrene-butadiene-styrene linear co-polymer is added in an amount ranging from 15-20% by weight of the softer grade bitumen; (c) dispersing the mixture obtained in step (b) at a temperature ranging from 150-200°C for 2 hours, followed by milling for 20-30 minutes to obtain a homogenous matrix; (d) adding a harder grade bitumen to the homogenous matrix obtained in step (c) to obtain a mixture, wherein the mixture comprises styrene-butadiene-styrene linear co-polymer in an amount ranging between 3-5% by weight of the mixture; (e) stirring the mixture obtained in step (d) at a temperature ranging from 150-200°C followed by milling to obtain a polymer modified bitumen; (f) mixing the polymer modified bitumen obtained in step (e) with an organic solvent to obtain an organic phase, wherein the organic solvent is selected from Straight run Kerosene Oil or Mineral Turpentine Oil; (g) mixing water, an acid, calcium chloride salt solution and an emulsifier to obtain an aqueous phase, wherein the aqueous phase comprises: 30-35 wt% water, 1-2 wt% of mineral acid, 0.15-0.5 wt % of calcium chloride salt solution and 0.25-1.5 wt% of emulsifier; wherein the wt% of each of the components is calculated based on the total weight of the polymer modified bitumen emulsion, wherein the emulsifier in the aqueous phase is an amine selected from the group consisting of secondary, tertiary amine, and long chain fatty amines; and (h) mixing the organic phase obtained in step (f) with the aqueous phase obtained in step (g) by milling to obtain the polymer modified bitumen emulsion; wherein the polymer modified bitumen emulsion comprises styrene-butadiene-styrene linear co-polymer in an amount ranging between 3-5% by weight of the polymer modified bitumen; wherein the softer grade bitumen has an absolute viscosity ranging from 800-1200 poise at a temperature of 60°C and the harder grade bitumen has an absolute viscosity ranging from 2400-3600poise at a temperature of 60°C. wherein the aqueous phase comprises: 30-35 wt% water, 1-2 wt% of mineral acid, 0.15-0.5 wt % of calcium chloride salt solution and 0.25-1.5 wt% of emulsifier; wherein the wt% of each of the components is calculated based on the total weight of the polymer modified bitumen emulsion, wherein the emulsifier in the aqueous phase is an amine selected from the group consisting of secondary, tertiary amine, and long chain fatty amines; and (h) mixing the organic phase obtained in step (f) with the aqueous phase obtained in step (g) by milling to obtain the polymer modified bitumen emulsion;