With the exponential growth in the electronic industry, more and more portable devices have entered the consumer market. Each of these devices emits electromagnetic radiation that could be responsible for the malfunction of other devices. Hence, it is crucial to have shielding materials to prevent the transmission of radiation. Recent research has shown that porous composites can have a high level of shielding owing to radiation having higher interaction within the porous structure. However, it is also crucial to have accurate measurement techniques to assess the performance of these materials. This chapter discusses the most commonly used radiation shielding measurement techniques that are used in wide commercial as well as in military applications. Such different methods are employed for shielding measurements due to the broad frequency range and different shielding requirements. Some of these methods have been developed to well-established standards, some are being used for specific laboratory-scale measurements.

To impart electromagnetic interference (EMI) shielding in cementitious composites, electrically conductive and electromagnetic absorbing additives are generally used. This research examined the effect of adding electric arc furnace slag (EAFS) or heavyweight aggregates (HWA), alone and in combination with carbon fibre (CF), on the EMI shielding properties of cementitious composites. Different percentages of both additives were added to a control mix to study the effect on mechanical properties, electrical conductivity and EMI shielding. Optimal shielding was produced for aggregate contents of 1.5 wt%, with values of 5.18 dB for the EAFS mixes and 3.25 dB for the HWA mixes, within the frequency range 30 MHz to 1.5 GHz. Hybrid mixes were fabricated using 0.7 wt% of 12 mm long CF and three different percentages of each aggregate. In combination with the CF, the optimal level of shielding was produced with EAFS and HWA contents of 1 wt%. These optimal shielding levels were 34.21 dB and 36.78 dB, respectively, within the 30 MHz to 1.5 GHz frequency range. A further increase in either type of aggregate produced a gradual reduction in EMI shielding effectiveness.

Generation of waste has been a significant problem in recent decades in many engineering fields. Self‐compacting rubberized concrete (SCRC) is a new type of SCC, which replaces part of natural aggregates by rubber aggregates in SCC to increase the application range of waste tyre rubber. This study investigates the effect of age and crumb rubber aggregate ratio on fresh and mechanical performance. Eight different SCRC mixtures using 2–5 mm rubber aggregates to replace 10%, 20%, 30%, and 40% natural aggregates by volume respectively, and 5–10 mm rubber aggregates to replace 10%, 20%, 30%, and 40% natural aggregates by volume respectively, are tested after 7, 28, 56, and 91 days for their mechanical properties. Results show that both the compressive and the tensile strength increase with the aging time, both of these properties drop with the amount and size of the crumb rubber content. Similar to compressive and tensile properties, flexural toughness and the modulus of rupture showed increased with the aging time. Small addition of crumb rubber has shown improvements in both rupture and fracture toughness properties, which diminishes when the crumb rubber content becomes significantly large.

Interference caused by electromagnetic radiation is a common reason for the malfunction of many sensitive electronic devices, which has a significant impact in areas such as defence and medical instrumentation. This research aims to fabricate a cementitious mix that could be used to prevent electromagnetic interference (EMI) and also be 3D printed so that required structures could be fabricated in a short amount of time. Additives with high electrical conductivity were mixed in different percentages to an established control mix to impart EMI shielding properties. To observe the effect of 3D printing, cast specimens with the same mix design were fabricated and tested after 28 days in conditions identical to the 3D printed specimens. EMI shielding properties were measured in accordance with ASTM D4935 - 18 standard to ensure results from this research can be compared with similar research that utilised the same standard. Results revealed that 3D printed specimens had better mechanical properties than cast specimens. EMI shielding properties of 3D printed specimens with 3 mm carbon fibres had better overall shielding properties than the cast specimens. In specimens with 12 mm carbon fibre, cast specimens showed better properties when the fibre content was low but the properties were similar to those of the printed ones when the fibre content was increased. 3D printed specimens with 0.7 % of 12 mm carbon fibre showed an average EMI shielding effectiveness (SE) of 43.61 dB within the 30 MHz to 1.5 GHz frequency range. Activated carbon powder was used in conjunction with carbon fibre to improve the EMI shielding properties. However, activated carbon powder failed to yield expected results and produced specimens with lower SE. Scanning electron microscope images revealed that carbon fibres are oriented in the direction of printing in 3D printed specimens and they have a lower amount of porosity compared to cast specimens.

Many of the construction materials available are known to cause a drastic level of damage to the environment during their manufacturing stages. Hence, many researchers have attempted to formulate construction materials that are more environmentally friendly. Additionally, the rise in wireless communications in recent decades has seen a rapid increase in electromagnetic pollution and interference, which affects the functionality of sensitive electronic devices. This research is focused on fabricating a more sustainable construction material that could prevent electromagnetic interference for electronic devices housed inside. Carbon fibres of three different lengths were added in four variations to a geopolymer control mix to study their effect on electromagnetic interference shielding. The results showed that the amount of shielding produced by these composites increases with carbon fibre length and quantity. Morphological analyses showed that the interconnectivity of the fibres plays a crucial role in having a high level of shielding. While the flexural strength showed an improvement with the addition of carbon fibre, the compressive strength showed a slight reduction with the increase in carbon fibre length. The optimal level of shielding was produced by the specimen containing 0.7% of 12 mm carbon fibre, which was the maximum amount of fibre of any length used in this study; the optimal level of shielding generated was 43.43 dB within the frequency range of 30 MHz to 1.5 GHz.

Research into electromagnetic interference (EMI) shielding has been growing over the last couple of decades due to shortcomings of existing methods and increased demand. Therefore, the construction industry has also been interested in fabricating a cement-based composite that could be used for EMI shielding without the use of additional cladding material. This research is focused on fabricating a cement-based composite that could be used for EMI shielding with the addition of carbonyl iron powder, heavyweight aggregate powder, and carbon fibres. Several mix designs were carried out by varying the additives used to find the content that would produce optimal properties. All the mixes were tested for their mechanical, electrical conductivity, and EMI shielding properties. EMI shielding tests were carried out per ASTM D4935 - 18 standard within 30 MHz to 1.5 GHz frequency range. The mix consisting of 20% carbonyl iron powder in combination with 0.7% of 12 mm CF produced an EMI shielding of 51.30 dB, which was the best result obtained for any mix in this research. An additional simulation was carried out using CST Studio software to see the theoretical level of shielding produced by these mixes. The simulation results showed near identical results to that of the experimental with smaller variation at specific frequencies.

Exposure to electromagnetic radiation is known to cause many adverse effects such as malfunction of electronic devices and health problems in humans. Since currently used metallic shields suffer from various drawbacks, using construction materials that would provide the same amount of shielding has become a novel research area in the construction industry. Set of experiments were carried out to find the effect of carbon nanofibers, zinc oxide, and activated carbon powder on electromagnetic interference shielding in cementitious composites. Additionally, the impact of these additives on mechanical and electrical conductivity was measured. For these experiments, four different types of carbon nanofibers were used to establish the best type of carbon nanofibers. Different contents of each additive were mixed into the cementitious composite to find the optimal content of each additive. These three different types of additives were then combined with 12 mm unsized carbon fibre within the cementitious matrix. Effects of the hybrid composites were measured similar to previous tests to find out the best combination of additives that would provide the optimum amount of electromagnetic shielding. Electromagnetic shielding tests were carried out within the frequency range of 30 MHz to 1.5 GHz according to ASTM D4935 - 18 standard method. Results showed that the inclusion of individual additives did not have a significant impact on the electromagnetic shielding properties. The best shielding properties were obtained when 0.5% of activated carbon powder was combined with the carbon fibre, which was 42.5-60.0 dB. (C) 2021 Elsevier Ltd. All rights reserved.

Polymer matrix composites have generated a great deal of attention in recent decades in various fields due to numerous advantages polymer offer. The advancement of technology has led to stringent requirements in shielding materials as more and more electronic devices are known to cause electromagnetic interference (EMI) in other devices. The drive to fabricate alternative materials is generated by the shortcomings of the existing metallic panels. While polymers are more economical, easy to fabricate, and corrosion resistant, they are known to be inherent electrical insulators. Since high electrical conductivity is a sought after property of EMI shielding materials, polymers with fillers to increase their electrical conductivity are commonly investigated for EMI shielding. Recently, composites with nanofillers also have attracted attention due to the superior properties they provide compared to their micro counterparts. In this review polymer composites with various types of fillers have been analysed to assess the EMI shielding properties generated by each. Apart from the properties, the manufacturing processes and morphological properties of composites have been analysed in this review to find the best polymer matrix composites for EMI shielding.

The need for construction materials with high electromagnetic (EM) shielding properties is growing globally due to the rapid development of electronic devices. This study has aimed at fabricating a cement-based composite that could be developed for electromagnetic shielding applications within the industry. To impart EM shielding properties, unsized carbon fibres with lengths of 3 mm, 6 mm, and 12 mm and desized carbon fibres with lengths of 6 mm and 12 mm were mixed to a control mix. Different weight fractions of 0.1%, 0.3%, 0.5%, and 0.7% of carbon fibres of each type were used in the fabrication of specimens. Each mix was subjected to mechanical, electrical conductivity, electromagnetic interference shielding, and scanning electron microscope analyses for characterisation. Results show that the addition of carbon fibres has a significant improvement in flexural, electrical conductivity, and electromagnetic interference shielding properties. The mix with the highest electrical conductivity was the one with unsized 12 mm carbon fibres with a weight fraction of 0.7%. The same mix showed the best electromagnetic interference shielding properties, which was about 40-60 dB within 300 MHz to 1.5 GHz frequency range. Comparison of obtained results with mixes reported in the literature containing carbon within a cement matrix showed that electromagnetic interference shielding performance of the best mix in this study exceeded performance reported in the literature for the same frequency range. (C) 2020 Elsevier Ltd. All rights reserved.

Electromagnetic (EM) shielding has become an important aspect in the modern world as the increased usage of electronic devices has a profound effect on the risk of EM pollution within the atmosphere and the harmful effects of EM on humans. In the recent decade, there has been an increased number of research focusing on using cementitious materials to be used as EM shielding materials. Many of these researches have focused on the addition of various additives into the cementitious mix to increase the EM shielding properties. This work investigates the effect of water to cement (W/C) ratio and primary additives such as fly ash (FA) and ground-granulated blast-furnace slag (GGBFS) on the EM shielding. Wide range of properties including mechanical, electrical conductivity, EM shielding, and microstructural properties were analysed to identify the ideal W/C ratio, FA, and GGBFS content that would result in higher shielding with adequate mechanical properties. Electromagnetic shielding tests were carried out in accordance with ASTM D4935 - 18 standards within 30 MHz to 1.5 GHz frequency range. Test results show that the ideal W/C ratio in cementitious composites for an optimal EM shielding amount of 1.89 dB, should be 0.3. For the mixes with additives, maximum EM shielding amounts of 3.38 dB and 5.06 dB were obtained at a frequency of 1.5 GHz, when the FA content was 1.8 with a W/C ratio of 0.4 and GGBFS content of 1.2 with a W/C ratio of 0.4, respectively. (C) 2020 Elsevier Ltd. All rights reserved.

The demand for new materials in the field of electromagnetic interference shielding has increased dramatically in the last few decades due to the advancements in the electronics industry. To meet these growing demands, many new materials are being investigated to replace traditionally used metal sheets. Some of the promising materials being researched are polymer-based composites due to their low specific weight, ease of fabrication, and low cost. Some researchers have also looked into the modification and synthetization of new metal-based shielding materials. One of the significant disadvantages of modifying metallic materials is the reduction of their electrical conductivity that adversely affects the shielding effectiveness. Hence, the modifications carried out should be able to maintain the shielding effectiveness at high values while eliminating the shortcomings of metal sheets. In this review article, novel metal-based materials are analyzed for their shielding effectiveness. While some of the materials reviewed in this paper are merely metal-based composites, others consist of more complex additives including metal oxides and carbides. Apart from the shielding effectiveness, this article analyses the variation of other important properties such as electrical conductivity and mechanical properties for a few of these materials.

With the advancement of modern technology, there has been a rapid rise in the electronic devices, and along with this growth, there has been an increased concern over the electromagnetic (EM) radiation emitted by these devices. Research into electromagnetic interference (EMI) shielding materials has been on the rise since it is known that the EM radiation generated artificially by a nuclear detonation is strong enough to destroy most modern electronic devices. Traditionally, metals have been used as the ideal shielding material simply due to their high shielding effectiveness (SE) that arises as a result of their high electrical conductivity. However, due to a few undesirable characteristics of these metallic materials such as the corrosion, there have been novel experiments into the development of other materials that can be used as an effective EMI shield. While some of these research work focuses on developing cementitious composites, others have focused on creating lightweight polymer-based shielding materials. This paper reviews such novel cementitious composite materials which have been developed to shield against EMI. The review emphasises the type of additives used in the fabrication of the composite giving rise to adequate SE as described in industrial standards.

Clay has been a predominant industrial raw material from ancient periods in Sri Lanka. Abundant availability and quality of available clay has been few of the many reasons why clay products have been very popular in the country. Not much has been changed in the technology used in the fabrication of clay products mined from various sources, since ancient time. But with the development of the technology more research has been focused on using the existing minerals of the country for advanced applications. In many recent developments in polymer-clay nano composites, it has been discovered that usage of Montmorillonite clay in a polymer composite can greatly enhance many of its properties. Hence more focus has been given on the isolating of Montmorillonite nano particles which are suited for these composites applications. This research has been focused on extracting Montmorillonite nano particles from already existing clay deposits of the country, which in turn can be used in the synthetization of polymer-clay nano composite. Preliminary analyses were conducted on selected clay deposits to confirm the presence of Montmorillonite and then they were subjected to various processed to increase the clay constituents while removing the impurity contents. Afterward selected specimens were subjected to the Montmorillonite extraction which involved mainly the isolation of this clay mineral from other types. Resultants were then analyzed by using various techniques to confirm the presence of required properties.