Wave absorption and mechanical properties of fiber-modified electromagnetic wave absorbing aggregate concrete
Aiming at the problems such as weak electromagnetic protection ability of ordinary concrete,insufficient mechanical properties and poor durability of traditional cement-based wave absorbing materials,a new concrete design method was proposed by combining electromagnetic wave absorbing ceramsite and functional fiber components.Carbon fiber(CF),basalt fiber(BF)and polypropylene fiber(PF)were used to toughen and optimize the electromagnetic parameters of the concrete.The electromagnetic wave absorption and the mechanical properties such as compressive strength,splitting tensile strength,flexural strength and frost resistance of electromagnetic wave absorbing aggregate concrete under different fiber types and volume contents were studied through experiments.Experimental results showed that the wave absorption of electromagnetic wave absorbing aggregate concrete was improved by adding these three fibers,especially in the higher frequency Ku band(12-18 GHz),where the bandwidth broadened greatly when the reflectivity is less than-7 dB,and the peak reflectivity decreased significantly.The compressive and splitting tensile strength of the electromagnetic wave absorbing aggregate concrete was increased distinctly by BF and PF,BF improved the early mechanical strength greatly,and PF optimized the mechanical strength at every age.All three fibers increased the flexural strength of electromagnetic wave absorbing aggregate concrete by more than 50%with the base group,and the frost resistance of the concrete was optimized by the fibers also.After 150 freeze-thaw cycles,the specimens were reduced by more than 50%compared with the base group,and the relative dynamic elastic moduli were increased by 8%-24%.
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