Finite Element Modelling of Repeated Load Axial Test of Laboratory Cylindrical HMA Using Constitutive Creep Model

Estimation of the effects of aggregate angularity on permanent deformation of asphalt concrete is understudied, largely on account of its complexity. This paper presents a method for estimating the deformation behaviour of asphalt concrete mixes as relates to aggregate angularity. This is achieved through laboratory prepared cylindrical samples of 100 mm diameter, and 100 and 150 mm in height, where samples are prepared to represent a range of angularity from rounded (<2,000), sub-rounded, sub-angular to angular (>4,500); as per the coarse aggregate angularity index (CAI) scale. A finite element method (FEM) implementation using elastic and creep (plastic) constitutive material models, with capacity to represent viscoelastic and viscoplastic mechanisms, is used to quantify permanent deformations of hot mix asphalt (HMA) mixes. The FEM models facilitated the development of power law creep regression coefficients relating to mix aggregate angularity, temperature, load, and sample heights, where the results of the simulations showed good correlations between coarse angularity effects on the permanent deformation strains. The relationships developed can facilitate the design of asphalt concrete mixes (of variable angularity) and predict their likely mechanical deformation behaviour under repeated loading.