The Effects of Classifying CRM Sources on the Asphalt Cement Modification for Paving Roads

Abstract

The improvement of Basrah asphalt cement that used in hot mix pavement can be achieved by using four influencing variables, which are the value of temperature needed for mixing, time of mixing, the amount of wasted car tire rubber (WCR) and the amount of wasted truck tire rubber (WTR). The main virtue of this study is to know the affecting of classifying the CRM sources, and how that will enhance the properties of tire rubber modified asphalt binder. The improvement is estimated through using the ranges (150-180 oC) of temperature, (20-60) minute of mixing time, (10-20) gm of WCR and (0-4) gm of WTR.
The using of two different types of waste tires had shown clearly the affecting on the results of responses studied. The effect of independent variables was studied by using Box-Wilson technique of experimental design. Moreover, the regression coefficients for responses models equation and the optimum conditions were estimated by using STATISTICA software.
The results had shown that the optimum values of the independent variables to submit the best responses of penetration test and softening point test was at temperature (180oC), mixing time (60 minute), WCR (20 gm), and WTR (4gm) and then found new mathematical models to estimate these responses at any values of independent variables. The Marshall stability result of the modified asphalt mixes was higher than of the unmodified asphalt mixes.