Optimising the effect of natural filler on asphalt-aggregate interfaces based on surface free energy measurements

Abstract

Current hot-mix asphalt (HMA) mixture design includes general criteria to define the amount and type of natural filler (or filler) leading to proper mixture performance and response. In this context, this research evaluated the feasibility of optimising the effect of natural fillers on the response of asphalt-aggregate interfaces of HMA mixtures by improving the selection of both the type and amount of filler to be used. The assessment, based on energy parameters derived from surface free energy measurements of the constituent materials, included evaluation of materials combinations from seven natural fillers, three asphalts, and six aggregates. Results suggest that optimisation of both the amount and type of filler is possible based on the energy parameters assessed. Namely, the material combinations analysed led to recommend an optimum range of filler volumetric concentrations between 0.13 and 0.24 to simultaneously optimise all the energy parameters for resistance to fracture and moisture damage, as well as the mastic wettability over aggregate. Additional research is suggested to relate the responses reported here and HMA mixture-performance and -response as well as to analyse the effect of asphalt aging on both the energy parameters quantified and recommended optimum range of filler volumetric concentration.

Keywords:

• filler
• asphalt mastic
• surface free energy
• volumetric concentration (VC)
• mastic-aggregate interfaces
• pavements

Acknowledgements

The authors express special thanks to the Universidad del Magdalena, for providing funding through FONCIENCIAS, and to the Universidad Militar Nueva Granada, for providing additional funding through the High Impact Project IMP-ING-2132, to complete this study. The authors also acknowledge the support provided by the students of Civil Engineering at the Universidad del Magdalena, Mary M. Caballero, Mayra Cardenas, Eduardo Ospino, Asmiriam M. Perea, Ricardo A. Mejia, Hector Perdomo, Mayra Bolivar, and Jessica Jacome to perform some laboratory testing. In addition, thanks are due to the construction companies Pavimentos Universal, INTERCAL, CONCRESCOL, GAYCO, and INCOASFALTOS for facilitating some of the material samples. This paper does not constitute a standard, specification, nor is it intended for design, construction, bidding, contracting, or permit purposes. Trade names were used solely for information and not for product endorsement.

Additional information

Funding

This work was supported by Fonciencias-Universidad del Magdalena [grant number FONCIENCIAS V-020-2016]; Universidad Militar Nueva Granada [grant number High Impact Project IMP-ING-2132].