Unprecedented vibration damping with high values of loss modulus and loss tangent, exhibited by cement-matrix graphite network composite

This paper reports a material with unprecedented vibration damping ability, as shown by high values of both the loss tangent (vibration amplitude decay rate) and the loss modulus (energy dissipation ability, equal to the product of the storage modulus and the loss tangent) under flexure at 0 2 Hz at room temperature The loss modulus (7 5 GPa) exceeds that of any previously reported material, including the best metal-based material, which suffers from a low loss tangent The loss tangent (0 81) is comparable to or exceeds that of any previously reported material, including rubber, which suffers from a low loss modulus This material is a cement-matrix graphite network composite containing 8 vol % graphite and made by compressing a mixture of cement particles and exfoliated graphite, which binds by mechanical interlocking, followed by curing in water The graphite network structure is supported by microscopy and the low electrical resistivity of the composite (0 04 0 cm perpendicular to the compression direction and 0 5 Q cm in the compression direction) The composite is much more conductive than the most conductive cement-matrix composite containing a conductive admixture The high loss tangent is attributed to the graphite network, while the high storage modulus is attributed to the cement matrix (C) 2009 Elsevier Ltd All rights reserved