Effect of aggregate type on moisture susceptibility of modified cold recycled mix asphalt: evaluation by mechanical tests and Surface Free Energy method

Hassan Latifi Hassan Latifi,Nahid Amini Nahid Amini

doi:10.3221/igf-esis.52.17

Hassan Latifi Hassan Latifi, Nahid Amini Nahid Amini

Open Access

https://doi.org/10.3221/igf-esis.52.17

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Abstract

There are deficiencies associated with cold mix asphalts, specifically, cold recycled mix asphalts in comparison with hot mix asphalt or hot recycled mix asphalt such as higher moisture susceptibility. Moisture damage of asphalt mixtures is inversely related to the bond quality between aggregates and binder. In this study, Portland cement (PC) and acryl polymer (AP) additives were employed to improve this bond. The effectiveness of used additives in improving the moisture susceptibility of cold recycled mix asphalt was examined using Surface Free Energy (SFE) method. Indirect Tensile Strength test and Dynamic Modulus test were performed to validate SFE method results. Moreover, scanning electron microscope (SEM) images were obtained for better understanding of mixture's microstructure. Also, effect of using granite, limestone and recycled asphalt pavement (RAP) aggregates was evaluated. The findings showed that cement and acryl polymer additives improved resistance of different studied mixtures, specifically, cold recycled mix asphalt against moisture damage by improving the adhesion between aggregate and asphalt. Considering effect of aggregates on moisture susceptibility, limestone-mixtures had the highest resistance while the RAP-mixtures performed the worst among the three. Finally, it was shown that results of SFE method were compatible with the mechanical tests in predicting moisture damage.

Highlights

I n many cases, one of the best alternatives to hot mix asphalts (HMAs) are the cold mix asphalts which have comparatively lower costs and are more environmentally-friendly due to their reduced hydrocarbon emissions, energy consumption, and toxic fumes as well as the ease of paving and repairing at rural roads far from a hot mix plant [1].Generally, cold mix asphalt is liquefied with emulsified asphalt besides heat
A considerable point about the surface free energy (SFE) of binders is that the factors which are related to the polarity are so affective in creating a binder more prepared to form a bond with aggregates [26]
In addition to cold recycled mix asphalts (CRMA), scanning electron microscope (SEM) photos were taken from raw asphalt and Portland cement to help having a better understanding about the shape of those materials in micro scale

Summary

Introduction

I n many cases, one of the best alternatives to hot mix asphalts (HMAs) are the cold mix asphalts which have comparatively lower costs and are more environmentally-friendly due to their reduced hydrocarbon emissions, energy consumption, and toxic fumes as well as the ease of paving and repairing at rural roads far from a hot mix plant [1].Generally, cold mix asphalt is liquefied with emulsified asphalt besides heat.

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