Properties of an asphalt binder modified with calcium carbonate micro- and nanoparticles and a reactive elastomeric terpolymer

Abstract

This study evaluated calcium carbonate (CaCO 3 ) micro- and nanoparticles as modifiers of a penetration-grade asphalt binder (CAP 50/70), alone and combined with 1.8% of a reactive elastomeric terpolymer (RET). Three contents (3%, 7%, and 10%) were compared with the neat binder and a commercial polymer-modified binder (AMP 60/85-E). The fourteen binders were characterised by Fourier transform infrared spectroscopy (FTIR), by empirical tests before and after short-term ageing, and by performance grade, multiple stress creep and recovery, and linear amplitude sweep (LAS). The particles alone produced no qualitative chemical change, whereas combining them with the terpolymer altered FTIR bands and lowered the oxidation indices. Non-recoverable creep compliance at 3.2 kPa fell from 4.4 1/kPa for CAP 50/70 to 0.9 1/kPa with 10% particles and RET, reaching the V traffic designation; within the terpolymer systems, the particles accounted for 0.04 1/kPa per 1% of content. The LAS fatigue ranking changed with the failure criterion: at 1.25% strain, 3% nano-CaCO 3 with RET reached 4.5 times the fatigue life of CAP 50/70 under the stored pseudo-strain energy criterion, whereas the 7% system led under the crack-growth criterion. Master curves of the 7% nano- and micro-CaCO 3 binders nearly coincided, so the loss of fatigue efficiency at high nanoparticle contents arises in the damage regime, not from a stiffening particle network. Weighting rutting, fatigue, and short-term ageing equally, 7% nano-CaCO 3 with RET ranked first, ahead of AMP 60/85-E; the ordering of the binder groups held under ten alternative scoring schemes, whereas the leading position did not.

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