The strength and longevity of pavements can be enhanced by the addition of various materials for example polymer modifiers. Desirable properties of the pavements, such as having elasticity and having increased viscosity, can work to increase the lifetimes and load resistance of the roadway. Polymer additives increase the cost of the pavement so that modeling in collaboration with laboratory studies are both necessary to show the benefits of adding the polymers, and of which and how much polymer must be added. The polymer asphalt mixture must be compatible with engineering requirements over a large range of temperatures (that is phase separation should be prevented in the pouring and in the cooling/solidification process, shear thinning at moderate temperatures aids in the pouring/spreading process) to prevent poor and uneven physical properties. The goal is that the polymer/bitumen mixture forms a continuous network binding the asphalt inclusions. A number of experiments have been carried out in the laboratory on bituminous and on modified asphalt binders.