Effect of water content on the piezoresistivity of MWNT/cement composites

The piezoresistive behaviors of multi-walled carbon nanotube (MWNT)/cement composites with different water contents under uniaxial compression are investigated. Experimental results indicate that the piezoresistive sensitivities of MWNT/cement composites with 0.1, 1.3, 3.3, 5.7, 7.6, and 9.9% of water content are 0.60, 0.61, 0.73, 0.68, 0.34, and 0.06 k Omega/MPa, respectively. These findings indicate that piezoresistive sensitivities of MWNT/cement composites strongly depend on the water content in the composites. The mechanism behind the non-linear relationship between piezoresistivity and water content is also studied via the changes of contact resistance induced by field emission effect of MWNTs in the composites.