Comparison of Polyphosphoric Acid-Modified Asphalt Binders with Straight and Polymer-Modified Materials

Abstract

This paper discusses the effects of polyphosphoric acid (PPA) modification on asphalt binders. Findings are compared with those for straight and polymer-modified materials of similar grades. The effect of PPA modification was investigated by means of conventional protocols as well as three new binder tests developed in Ontario, Canada. The compact tension test and the extended bending beam rheometer protocol were used to investigate low-temperature performance properties. The double edge-notched tension test was used to study the resistance to ductile failure. The brittle state fracture properties and the reversible aging processes were largely unaffected by PPA modification. However, changes in the low-temperature grade were considerable in some instances. While the essential work of fracture increases with the addition of PPA, the yield stress increases more rapidly in most binders and thus results in an overall drop in strain tolerance in the ductile state. Recent field experience in Ontario suggests that the use of PPA may either prevent or contribute to wheelpath cracking, depending on the formulation and concurrent use of polymer.

Adhesion Promoters in Bituminous Road Materials: A Review

“…Bagampadde et al [42] showed that Styrene Butadiene Styrene (SBS) copolymer significantly enhanced moisture resistance of slag aggregates in harsh desert environments. Moreover, bitumen modified with SBS in conjunction with polyphosphoric acid (PPA) positively affected wettability performance and increased binder stability during long-time storage at elevated temperatures [43][44][45][46]. For example, PPA added to bitumen in a few wt.…”

Modification of thermal and rheological behavior of asphalt binder by the addition of an ethylene-methyl acrylate-glycidyl methacrylate terpolymer and polyphosphoric acid

“…The addition of PPA in modified asphalts can also decrease the amount of polymer, reducing costs [8,9] . Related to the rheological properties, a system of PAC + EBGMA + PPA showed a very high deformation recovery and a very low non-recoverable compliance (J nr ) values, as well presented more resistance when subjected to a sudden increase in stress level [5] .…”

Dynamical characteristics of asphalt binder containing Polyphosphoric acid modifiers

“…Concerns have been raised by some researchers about the actual performance characteristics of the last polymer, PPA. These concerns include reversibility of the stiffening effect of PPA on asphalt binders and interactions with other additives in the mixtures such as hydrated lime [1]. Several grades of phosphoric acid containing different amounts of orthophosphoric acid are commercially available.…”