Effect of carbon fibers on the vibration-reduction ability of cement

The addition of short carbon fibers (0.5% by weight of cement) to cement pa ste containing silica fume (15% by weight of cement) and methylcellulose (0 .4% by weight of cement) causes the loss tangent under flexure at a loading frequency of less than or equal to 1 Hz to decrease by up to 25% and the s torage modulus (less than or equal to 2 Hz) to increase by up to 67%, such that both effects increase in the order: as-received fibers, ozone-treated fibers, dichromate-treated fibers, and silane-treated fibers. The addition of methylcellulose to cement paste containing silica fume causes the loss t angent to increase by up to 50% and the storage modulus to decrease by up t o 14%. Silane treatment of silica fume has little effect on the loss tangen t, but increases the storage modulus by up to 38%. (C) 1999 Elsevier Scienc e Ltd. All rights reserved.