Dynamic Modulus and Flow Number Tests conducted with the Asphalt Mixer PerformanceTester

Instrument Detail

Make : IPC Global, Australia
Model : AASHTO:TP 79-2009

Working Principles, Specification and Applications

NCHRP Project 9-29 developed commercial equipment which recommended three simple performance tests:

Dynamic Modulus – Absolute value of Complex Modulus (dividing peak to peak stress by peak to peak strain subjected to sinusoidal loading)
Flow Number – Number of repeated load cycles (repeated compressive stress pulses) corresponding to the minimum accumulation rate of change of permanent axial strain
- Related to rutting resistance of HMA
- Flow number increases rutting resistance also increases
Flow Time – In this a constant rather than repeated load is applied to the sample and total deformation is observed, therefore, it is simply static creep test. It is the time corresponding to the minimum rate of change of permanent axial strain

Components of Equipment

It comprises a triaxial cell , Environmental chamber , Hydraulic actuator and pump, Refrigeration and heating unit with heat exchanger , Control and data acquisition system, Quiet built-in hydraulic pump provides pressure for the vertical loading system, Compressed air is used for confining pressure and to raise and lower the triaxial cell.

User Instructions

Prepare sample
Fix the LVDTs
Condition the chamber with respect to testing temperature
Operate the system

Contact Details

Director
CSIR-CENTRAL ROAD RESEARCH INSTITUTE
Delhi-Mathura Road
P.O: CRRI, New Delhi-110025
Tel.:+91-11-26848917, Fax:+91-11-26845943
Email Id: director [dot] crri [at] nic [dot] in