Computational Nanomechanics Modeling of Asphalt-Aggregate Interface

From macro to nano, a cross-scale image characterization of asphalt-aggregate interfaces

The development of high resolution transmission electron microscopy (TEM) techniques and investigations into the microstructural evolution resulting from thermal processing and aging damage in a variety of systems. The second topic is to investigate two topics: one using in-situ straining experiments to study deformation mechanisms in metals, and another using a new in-situ TEM gas cell stage to study environmental degradation mechanisms in asphalt interfacial layer around aggregate.

Asphalt surface shrinkage crack - characterized by TEM technology

sample 2 micro cracks 2Kx w-meas_003

sample 2 micro cracks 100x

Asphalt concrete intersurface microstructure - characterized by TEM technology

High resolution image characterization of the interface cut by FIB

ESEM chemistry map

This in-depth research has unraveled the structure of asphalt-mineral aggregate interface with almost atom-by-atom precision, after many years of analysis by some of the world’s most powerful computers and comparison with laboratory experiments to confirm the computed results.

Atomistic modeling of asphalt-aggregate interface: the yellow, red spheres are Silicon and Oxygen atoms; the grey, white and bright yellow spheres are carbon, hydrogen and sulphur atoms.

Yang Lu, Linbing Wang, Nano-Mechanics Modeling of Deformation and Failure Behaviors at Asphalt-Aggregate Interfaces, International Journal of Pavement Engineering, Vol. 12, No. 4, 311-323, August 2011

Yang Lu, Linbing Wang, Nanoscale Modeling of Mechanical Properties of Bitumen-Rock Interface under Tensile Loading, International Journal of Pavement Engineering, Vol. 11, No. 5, 393-401, October 2010

Yang Lu, Linbing Wang, Atomistic Modeling into the Interfacial Friction Behaviors of Bitumen-Mineral Interfaces, (under review)

Fundamental analysis of asphalt concrete moisture damage using atomistic simulations

Asphalt moisture damage is a widespread problem with distress mechanisms stemming from multiple sources including materials selected (both asphalt and aggregates), stockpile moisture content, plant production, and construction. In this research, nano-mechanics method is employed to model the interfacial adhesion properties with moisture existence.

For the future research, I plan to improve the resistance of hot-mix asphalt to moisture damage. We aim to establish a comprehensive plan to alleviate moisture damage effects from a fundamental level, e.g. (1) nano-sensor system to detect internal cracking and the initial path of moisture infill; (2) polymer additives and coatings, as well as nano-additives to improve the moisture resistance of HMA pavement; (3) optimizing the nano-structure of pavement surface materials to obtain a proper structural-property relation from nanoscale. In addition, a dynamic internal curing system made by thermal-sensitive nano-additives will be built in asphalt pavement. When it is heated by external control, the internal defects, e.g. microcracks, debonding, decohesion, and pores inside the asphalt concrete pavement will be cured automatically.

Interfacial moisture adhesion models

Hydrated Asphalt-Quartz Interfaces

Hydrated Aspahlt-Calcite Interfaces

Yang Lu, Linbing Wang, Nano-Mechanics Modeling of Bitumen Cohension & Adhension properties with the presence of Water, ASCE Journal of Nanomechanics and Micromechanics, (accepted)