USE OF BITUMEN EMULSION IN WMM LAYER OF FLEXIBLE PAVEMENT

Abstract

In developing countries such as India , there are many limitations that do not satisfy the high volume of loads anymore (e.g., limited time schedule , lack of quantity of good quality material, budget and over loading passing trucks), the conventional methods are costly and time taking.Thus, new methods must be adopted for new roads to increase the bearing capacity of the pavements. Bitumen in its emulsified form has got wide range of applications.The concept of basestabilization with emulsion and cement can be one answer to this problem. The prime objective of this research is to assess the suitability of bitumen emulsions in the WMM layer of the pavement. For attaining the desired objectives, cement and emulsion were used in different proportions i.e. cement(1-3%) and bitumen emulsion(2-4%). Various tests such as Modified Proctor Density test, CBR test(soaked) , UCS test(soaked) and Constant Head Permeability test were carried out on the WMM mixes. The tests were carried out on two different aggregates type that are the virgin aggregates and rap aggregates(with 60% repalcement). Wherein Proctor Density tests tell about the properties of the WMM mix, the CBR test and UCS test determine its strength. The Permeability test displays the drainage characteristics of the mix It was inferred from the results that the WMM mix with emulsion showed a decrease in its MDD both with rap and virgin aggregates. The CBR and UCS values increased both with rap and virgin aggregates as compared to the non cement emulsion mix but still were less than the mix with only cement as modifier. The Permeability values for the mix increased with the incorporation of emulsion in the WMM mix. So,it is clear from the results that although the stiffness and cohesion increases by incorporation of emulsion, yet it is less than only cement values. On the other hand, emulsion seems to improve the drainage properties. This result justifies the use usage of emulsion modified bases in high rainfall areas. Emulsion can also be used for WMM layer in heavy traffic areas and rural areas along with incorporation of rap to cut down the cost to a significant extent.