Estimating unconfined compressive behavior of HMA using soft computing
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TECHNICAL PAPER
Estimating unconfined compressive behavior of HMA using soft computing Lee P. Leon1 · Indrajit Ray1 Received: 22 June 2020 / Accepted: 29 September 2020 © Springer Nature Switzerland AG 2020
Abstract The mechanical properties of materials such as elastic tangential modulus (Et) and unconfined compressive strength (UCS) can be used to predict their performance during service life. This paper utilizes gene expression programming (GEP) as an alternative method to estimate the unconfined uniaxial compression properties of hot mix asphalt. Short-term static compression was used to evaluate modes of failure and stress–strain relationship of cylindrical and prismatic asphalt concrete specimens due to mixture types, specimen shape, height, temperature, binder type and testing orientation. The results show that cubic specimens tested parallel to the direction of compaction achieved higher compressive strength and peak strains than specimens tested to the perpendicular direction. Cylindrical specimens had greater elastic stiffness than prismatic specimens with similar aspect ratios. The GEP and multiple linear regression approaches for the assessment of UCS and Et concluded satisfactory outcomes. The coefficient of determination (R2) for USC-GEP was 0.887 and 0.908 and similarly Et-GEP of 0.785 and 0.648 was more significant than regression models. The models developed provide a cheap, simple and quick methodology of estimating the stress–strain properties of dense-graded asphalt concrete by eliminating the need for the compression test. Keywords Asphalt concrete · Compressive strength · Elastic modulus · HMA · Soft computing
Introduction Uniaxial‑compressive behavior of asphalt concrete Flexible pavement and materials stress–strain analysis is an ideal methodology for diagnostic demonstration of pavement behavior and thus, institutes a fundamental part in the design and performance evaluation of pavement. It is the fundamental origin of mechanistic design theory. The stress–strain analysis of a material is utilized to decide factors such as the yield point, compressive strength, ultimate tensile and fracture strength. These material attributes are used in the selection of the material for various applications and structural design. This concept is adopted in the procedures of * Lee P. Leon [email protected] Indrajit Ray [email protected] 1
Department of Civil and Environmental Engineering, University of the West Indies (UWI), Saint Augustine, Trinidad and Tobago
pavement structural design and analysis. Although asphalt concrete is extensively used as a pavement material over the world, the literature on its stress–strain behavior is limited compared to other commonly used materials, such as cement concrete and steel alloys. Accurate numerical modeling of the behavior of road pavement layers is an important requirement for the design and evaluation of road pavements [1]. Asphalt concrete (AC) is a composite material made up of different grades of aggregates bound together with bitumen (bi
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