Properties of high yield synthesised carbon nano fibres/Portland cement composite

The compressive strength and electrical resistivity of hardened pastes produced either from nanomodified Portland sulfate-resistant cement (CHH) or a mixture of nanomodified and pristine sulfate-resistant cements were determined. The nanomodification included grow carbon nanotubes (CNTs) and carbon nanofibres (CNFs) on the cement particles. Pastes having a water-to-binder ratio of 0·5 were produced. The test results revealed that partial replacement of sulfate-resistant cement by CHH cement decreased the electrical resistivity of the 28 day old specimens but worsened the mechanical properties. The lower compressive strength was attributed to a lower degree of hydration of the CHH cement. The addition of a mixture of surfactants enabled the production of specimens consisting entirely of CHH cement. The hardened material obtained was characterised by a nearly doubled compressive strength in comparison with the reference specimens made from pristine sulfate-resistant cement. This was attributed to a high degree of hydration as well as reinforcing action of the CNTs and CNFs. The electrical resistivity was lowered by one order of magnitude classifying this material as a semiconductor.