| Abstract Scope |
For microwave reflection/absorption, concrete needs to be modified with functional admixtures. Electromagnetic interference (EMI) shielding is needed for transformer vaults and buildings housing sensitive electronics. The shielding of electromagnetic pulse (EMP) is needed for buildings during nuclear blasts. Microwave reflectivity can be exploited for lateral guidance in automatic highways. Microwave absorption is needed for Stealth buildings. The first report of the microwave behavior of cement-based materials was in 1989 in the context of EMI shielding and involves the use of short carbon fiber as the conductive admixture. More effective than carbon fiber is steel microfiber, which exhibits high conductivity and magnetic character, but is very expensive. Due to the skin effect, a small filler unit size is preferred. With the nanotechnology growth, research has been broadened to include conductive nanofibers/nanoparticles. However, the high cost of the nanofibers and the relative difficulty of their dispersion limit the practicality of their usage. |