Non-destructive monitoring of curing kinetics and internal curing effects in biochar-incorporated cement mortar via Time Domain Reflectometry (TDR)

초록

The integration of biochar as a carbon-sequestering supplementary cementitious material (SCM) presents a sustainable pathway for the construction industry, yet its complex influence on early-age hydration kinetics remains a challenge for real-time assessment. This study employs Time Domain Reflectometry (TDR) as a robust non-destructive technique to evaluate the curing process and microstructural evolution of wood-based biocharincorporated mortar. Mortar specimens with 0%, 3%, and 5% biochar replacement by weight were analyzed. The experimental results revealed that while biochar slightly reduced workability, it significantly enhanced the 28day compressive strength at a 3% replacement ratio, attributed to the "internal curing" mechanism facilitated by its porous structure. TDR measurements identified a distinct dielectric signature; biochar-containing specimens exhibited higher initial relative permittivity due to the water-filled macropores, followed by a steeper decline compared to the control group as hydration progressed. This dielectric behavior was further validated through Mercury Intrusion Porosimetry (MIP) and Thermogravimetric Analysis (TGA), which confirmed a denser pore structure and a higher degree of hydration in biochar-modified matrices. This research demonstrates that TDR is not only a viable tool for monitoring moisture dynamics but also provides quantitative insights into the hydration-driven structural transformation of sustainable cementitious systems.

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