Shielding Properties of Cement Composites Filled with Commercial Biochar

Abstract

The partial substitution of non-renewable materials in cementitious composites with eco-friendly materials is promising not only in terms of cost reduction, but also in improving the composites’ shielding properties. The water and carbon content of a commercial lignin-based biochar is analyzed with thermal gravimetric analysis. Cementitious composite samples of lignin-based biochar with 14 wt.% and 18 wt.% are realized. Good dispersion of the filler in the composites is observed by SEM analysis. The samples are fabricated in order to fit in a rectangular waveguide for measurements of the shielding effectiveness in the X-band. A shielding effectiveness of 15 dB was obtained at a frequency of 10 GHz in the case of composites with 18 wt.% biochar. Full-wave simulations are performed by fitting the measured shielding effectiveness to the simulated shielding effectiveness by varying material properties in the simulator. Analysis of the dimensional tolerances and thickness of the samples is performed with the help of full/wave simulations. Lignin-based biochar is a good candidate for partial substitution of cement in cementitious composites, as the shielding effectiveness of the composites increases substantially.

Shielding Effectiveness Measurements of Drywall Panel Coated with Biochar Layers

“…Biochar has been used for various applications, such as the removal of pollutants from water [16] or as filler in composites, improving their mechanical and electrical properties [17]. Biochar has recently been gaining attention as a natural electromagnetic shielding product [18], which can be a promising resource that can be used on a building envelope [19][20][21][22][23].…”

High Frequency Electromagnetic Shielding by Biochar-Based Composites

“…In this cases, usually, shielding materials are applied as a coating on wall surfaces. However, the use of shielding elements directly mixed with currently used building materials has been considered only recently, and could represent a sustainable route, especially if the additional materials are eco-friendly and cost-effective [ 1 , 2 ].…”

Iron Oxide Fe3O4 Nanoparticles for Electromagnetic Shielding

“…Singhal mentions the works by Yasir et al, 2020, who studied shielding properties of cement composites with commercial biochar. At 10 GHz, SE of plain cement was almost 5 dB; for samples with 14 wt.% biochar, SE was of 11 dB, and of 15 dB with 18 wt.% (4-mm-thick samples) (Yasir et al, 2020) For what is regarding the use of biochar in different matrices (included concrete) for EMI-SE evaluation, see please Torsello et al, 2021. Torsello and coworkers reported microwave shielding efficiency in the frequency range 100 MHz-8 GHz.…”