Cementitious Composites that Shield Electromagnetic Interference

Stacey Louie^*
*Correspondence: Stacey Louie, Department Structural Engineering, University of New Haven, Texas, USA, Email:

Introduction

With the progress of modern technology, the number of electronic gadgets has expanded dramatically, and with this growth has come growing concern about the Electromagnetic (EM) radiation released by these devices. Since it was discovered that the EM radiation generated intentionally by a nuclear bomb is strong enough to kill most current electronic devices, research into Electromagnetic Interference (EMI) shielding materials has exploded. Metals have long been thought to be the best shielding material because of their high Shielding Efficiency (SE), which is a result of their great electrical conductivity [1].

However, due to certain of these metallic materials' unfavourable qualities, such as corrosion, fresh research into the development of other materials that can be employed as an efficient EMI shield have been conducted. While some of the research focuses on the development of cementitious composites, others are concerned with the development of lightweight polymer-based shielding materials. The innovative cementitious composite materials created to guard against EMI are discussed in this research. The review focuses on the types of additives utilised in composite manufacturing that result in adequate SE as defined by industry requirements.

Description

Partially substituting eco-friendly elements for non-renewable components in cementitious composites is promising not just in terms of cost savings, but also in terms of strengthening the composites' shielding qualities. Thermal gravimetric analysis is used to determine the water and carbon content of a commercial lignin-based biochar. It is possible to make cementitious composite samples of lignin-based biochar with 14 and 18 percent lignin. SEM analysis shows that the filler in the composites is well dispersed. The samples are built to fit inside a rectangular waveguide for X-band shielding effectiveness tests. At a frequency of 10 GHz, composites containing 18 wt. percent biochar had a shielding efficiency of 15 dB. Full-wave simulations are accomplished by altering material parameters in the simulator to adapt the measured shielding effectiveness to the simulated shielding effectiveness. Full/wave simulations are used to analyse the dimensional tolerances and thickness of the samples. Because the shielding efficiency of cementitious composites increases significantly when lignin-based biochar is used as a partial replacement for cement, it is a viable option for partial substitution of cement in cementitious composites [2,3].

In the last few decades, the human population has exploded. The building sector has seen a significant increase in demand as the world's population has grown. As a result, cement production's greenhouse gas emissions have increased. In terms of cost and environmental preservation, replacing nonrenewable raw materials used in the building sector with eco-friendly materials obtained from trash is promising. To save money on disposal, agriculture and forestry waste is generally burned on the field. When turned into biochar, this waste can be used as a partial replacement for cement, lowering greenhouse gas emissions while also enhancing the mechanical characteristics of concrete. A rise in electromagnetic radiation was caused by an increase in the number of devices operating at microwave and millimeter-wave frequencies. To protect sensitive devices from electromagnetic interference, electromagnetic shields are used. Shielding materials can be put as a coating on wall surfaces in regions where electromagnetic interference is a problem. In the medical field, a variety of microwave and millimeter-wave devices are utilised for imaging, tomography, and other purposes. Radar communications, such as air traffic control, weather monitoring, maritime vessel traffic management, defence tracking, and vehicle speed detection, all benefit from the X-band [4].

Shielding materials in buildings can aid in the isolation of equipment that is susceptible to electromagnetic interference. For determining the shielding efficacy of materials, a variety of measurement techniques can be used. The reverberation chamber, free-space measurements in an anechoic chamber, and coaxial and waveguide approaches are the most frequent measuring techniques. Each measurement approach necessitates a different sample size and frequency band. The X-band is critical for satellite communications and radar applications. The utilisation of carbon-based materials in epoxy composites, as well as the analysis of their morphological and electrical properties, has received a great deal of attention. Traditional carbon-based compounds, such as graphene and carbon nanotubes, are costly and difficult to make. The usage of biochar-substituted carbon nanotubes and graphene as fillers in composites has been studied in recent years. When compared to other carbon-based products, biochar is more cost-effective. Biochar is a porous carbonaceous material made from biomass that has been thermally treated in the absence of oxygen. It can be created from a variety of waste materials, including agricultural waste, food waste, and sewage sludge. Biochar was previously utilised as a soil amendment in agriculture and for landfilling. Biochar's usage in alternative applications is being researched on a large scale, with a focus on carbon sequestration, energy storage, and construction and building [5].

Conclusion

Commercial lignin-based biochar was employed as a partial replacement for cement in composites. The water, carbon, and other biochar leftovers were investigated using Thermo Gravimetric Analysis (TGA). For evaluations of the shielding efficiency inside a waveguide functioning in the X-band microwave frequency, composites of 4 mm thickness with plain cement, 14 wt. percent biochar, and 18 wt. percent biochar were manufactured with precise dimensions. The samples containing 18 wt.% biochar were cured in water for seven or 28 days. SEM was used to examine the microstructural characteristics of the composites as well as the filler distribution in the composite matrix. Shielding efficacy measurements were compared to simulated results produced with a full-wave simulator.

References

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