Field Performance of Emerging Concrete Technologies: CNT-Based Cementitious Strain Sensors and PCM Covers for Reducing Early-Age Cracking Potential

초록

This study presents the field performance of two emerging novel concrete technologies: (1) carbon nanotube (CNT)-based cementitious strain sensors for in situ sensing and monitoring, and (2) a bio-based phase change material (PCM) cover designed to reduce early-age temperature gradients and strain amplitudes associated with cracking potential in concrete pavements. Both technologies were implemented simultaneously in a newly constructed concrete slab section at the Kyle Fire Station in Kyle, Texas. The CNT-based cementitious strain sensors demonstrated reliable performance, with resistance measurements strongly correlating with temperature and strain (R2 > 0.8), confirming their applicability under field conditions. The PCM study examined the potential of a novel PCM cover method to reduce early-age thermal cracking potential. Although winter ambient temperatures did not reach the 29 °C melting point required for full phase change activation of PCM, the external cover still reduced surface heat gain, absorbing solar radiation and lowering peak temperatures by approximately 1.5 °C during the covered period. Correspondingly, the PCM section experienced a maximum 30% less peak thermal strain in one cycle and reduced moisture-induced expansion compared to the control section during the PCM-covered period. The reduced temperature gradients and strain amplitudes suggest that the PCM cover system may reduce early-age cracking potential. Because the PCM was applied externally and not incorporated into the concrete mixture, it is not expected to directly affect mixture-level mechanical properties. Overall, the results provide a comprehensive assessment of CNT-based strain sensors and PCM covers under field conditions, highlighting their potential for practical implementation in future pavement construction projects. © The Author(s) 2026.

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