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.
Highlights
The human population saw rapid growth in the past few decades
The substitution of non-renewable raw materials used in the construction industry with eco-friendly materials derived from waste is promising in terms of cost and environmental protection [3]
The composite samples produced were with 14 wt.% and 18 wt.% biochar in Portland cement (PC)
Summary
The demand for the construction industry increased manifold [1] This resulted in increasing greenhouse gas emissions from cement production [2]. Different measurement techniques can be deployed for the determination of the shielding effectiveness of materials. Biochar is cost-effective as compared to other carbon-based materials. Biochar is a porous carbonaceous material produced by thermal treatment of biomass in the absence of oxygen [26] It can be made from a number of different waste products such as agricultural waste, food waste, or sewage sludge [27]. Biochar were fabricated with specific dimensions for measurements of the shielding effectiveness inside a waveguide working in the X-band microwave frequency. The shielding effectiveness increased by approximately 5 dB in the whole frequency range for the sample cured in water for 28 days with respect to the sample cured in water for seven days
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