Papers by Author: Dong Ming Yan

Abstract: Advancement in the study of carbon nanotube has enabled its application in civil engineering as constitutive materials or additives. In this study, the availability of applying multi-walled carbon nanotube to improve the characteristics of cement composites was investigated with experiments on more than 30 specimens. The multi-walled carbon nanotubes (MWCNTs) were effectively dispersed in the water with surfactant, which can keep stable for over 3 months. Specimens with MWCNTs of 0.025%, 0.05% and 0.1% of cement (by weight) were tested with a loading machine and then analyzed with a SEM. It was found that the compressive strength of the samples increased with the increasing MWCNTs, it can improve the 7-day compressive strength by 22% . Microscopic analysis (SEM) revealed that carbon nanotubes were surrounded with hydration products. The bridging and debonding of carbon nanotubes in cement pastes was observed as well.

Abstract: In this study, the effect of loading rate on the bonding strength between rebar and concrete substrate is investigated through pull-out test on 24 concrete cylinders. The load capacity, shear deformation and fracture characteristics of the interface are examined carefully. It is found that with the increase of loading rate, the load capacity increases correspondingly and their relationship can be characterized with a semi-logarithm equation. The load-deflection curves expand with the increase of loading rate, which is an indication of a gradually increasing energy absorption capacity with the increase of loading rate. Generally, with higher loading rate, more energy is dissipated.