Research Advisor

Dr. J Murali Krishnan
BSB 233, Dept. of Civil Engineering
Indian Institute of Technology, Madras
Chennai - TN 600036, India
Email ID: jmk@iitm.ac.in

About Research

Investigations on the Inhomogeneity and Anisotropy of Bituminous Mixtures

A biaxial testing scheme in indirect tensile mode can aid in capturing the response of the material in the principal direction. The choice of gauge length depends on the aggregate size distribution, the magnitude of load applied, temperature, and the sensitivity of the measurement device used for capturing the deformation. Rigorous experimental investigations are required to select the suitable gauge length for a particular mix type. As of now, not much clarity exists on the delineation of linear/non-linear limits of the response of the material for the biaxial experimental data. Once the challenges related to the above are addressed, appropriate linear/non- linear viscoelastic models are required to be identified to explain the response of the material.

Outcomes

• Modulus of the material using biaxial testing
• Time-temperature dependent viscoelastic Poisson’s ratio
• Distress prediction – Rutting and fatigue damage

Challenges

• Mode of testing
• Choice of appropriate gauge length
• Delineation of the linear/non-linear limits for bituminous mixtures

Objectives and Deliverables

• Objectives and Deliverables
• To investigate the extent of inhomogeneity and anisotropy of bituminous mixtures and establish the linear viscoelastic limits for the biaxial experimental data
• To characterize the response of bituminous mixtures from the biaxial experimental data using a linear viscoelastic model
• To investigate the fatigue response of bituminous mixtures using indirect tensile fatigue test

Biaxial Testing - Check for steady state and Linearity

• Steady state: Steady strain or steady strain rate ?
• Linearity: Using scaling and superposition principle
• Estimation of material modulus and Poisson’s ratio

Test Parameters

Frequency	10, 5 and 1 Hz
Guage Length	Half & Quarter
Test Temperature	20 degree celcius
Load Levels	5, 7.5, and 10%

Data Analysis

• Estimation of steady state

• Conference Administration

• Workshop held

• Lab Activities