A Multifunctional Cementitious Composite for Pavement Subgrade.

Area of Science:

• Materials Science
• Civil Engineering
• Smart Structures

Background:

• Premature failure and degradation of transportation infrastructure layers pose significant challenges.
• Structural Health Monitoring (SHM) is crucial for pavement construction layers to address these issues.

Purpose of the Study:

• To investigate the stress/strain sensing and damage detection capabilities of a novel self-sensing cementitious composite.
• To evaluate the composite's potential for use in intelligent subgrade layers.

Main Methods:

• Fabrication of a self-sensing cementitious composite using cement, multiwalled carbon nanotubes (MWCNTs), and graphene nanoplatelets (GNPs).
• Piezoresistive analysis to assess stress/strain-sensing performance.
• Electrochemical Impedance Spectroscopy (EIS) for damage detection.
• Scanning Electron Microscopy (SEM) for microstructural analysis.

Main Results:

• Electrical resistivity is sensitive to MWCNT/GNP concentration, with >0.5% required for responsiveness.
• Increased MWCNT/GNP concentration and stress levels enhance stress/strain-sensing performance.
• Fractional Changes in Resistivity (FCR) correlate with resilient modulus, indicating stiffness changes.
• EIS analysis shows distinct changes in Nyquist plots before and after material failure.
• SEM images reveal MWCNT bridging and GNP filling effects within the composite.

Conclusions:

• The developed self-sensing cementitious composite demonstrates promising capabilities for SHM in pavement construction.
• The composite's piezoresistive and electrochemical properties can effectively monitor structural integrity and damage.
• This intelligent subgrade material offers a pathway to improved durability and reduced maintenance costs for transportation infrastructure.