Mechanical Characteristics Of Cold Asphalt Mixes Containing (RAP) With Bitumen Emulsion And/Without Cement

Abstract

The concept of deep cold in-place recycling (CIR) of asphalt pavement with bitumen emulsion is based on milling the upper damaged bituminous layers with a part of the   granular base course, and then re-mix them with binder materials to form a cold treated base course. In this research the Reclaimed Asphalt Pavement (RAP) were brought from Khirbet Ghazalah - Ataman road in Daraa city, where The grains of aggregates more than 19mm are rejected, and new aggregates were also brought from one of quarries in the same area, locally available bitumen emulsion and portland cement of the class CEM II/A-P were used. Three Cold Asphalt  Mixes were studied, the first one used as reference mix which consists of 100%NA (New Aggregates) with bitumen emulsion/ without cement, and the other two mixes containing aggregates (RAP)(80%RAP-20%NA) with bitumen emulsion and/without cement, respectively. The aim of this study is to find the effect of using (RAP) aggregates on the  optimum content of bitumen emulsion, and to study the mechanical characteristics of the mixes like:   (Indirect Tensile Strength (ITS) and Indirect Tensile Ratio (TSR) to measure the  mixture's sensitivity to moisture), also to study the effect of adding cement.  It had been found that the optimum content of bitumen emulsion was reduced up to 2.9% with mixes containing recycled aggregates (RAP), comparing with the reference mix100%NA, Also it has been found that using cement with percentage 3% by aggregates weight, with the optimum content of bitumen emulsion (5.6%) has achieved the required technical requirements and specifications for cold treatment of the base course according to the 2014 American standard specifications, in terms of  Indirect Tensile Strength (ITS) and Indirect Tensile Ratio (TSR).  The results also showed that the mix containing 100%NA have higher value of (ITS), but it required a higher percentage of bitumen emulsion. Therefore the process of Deep Cold pavement Recycling with bitumen emulsion and cement, can be used for cold treatment of base course layer, with saving both of new aggregates, and bitumen emulsion.