Multi-walled carbon nanotube reinforced mortar-aggregate interfacial properties

This paper presents the test results of the mortar-aggregate interfacial strength properties considering six dosages of industrial grade pre-dispersed multi-walled carbon nanotube paste. Mechanical and ultrasonication dispersion were carried out and scanning electron microscope was taken for dispersion inspection. The test results indicated a stable yet negative effect of carbon nanotube paste on the mortar compression strength; while a widely scattered (coefficient of variation up to 23.6%) positive effect on the interfacial tensile strength (maximum 8.4% increase at 0.2 wt% carbon nanotube) was observed. It was also found that the increase of the interfacial shear strength was much more significant (maximum 51.5% at 0.05 wt% carbon nanotube) with a medium variation. Analysis of the mortar strength, interfacial tensile strength and shear strength showed no solid correlation amongst the three strength properties, which implies that the reinforcing mechanism of the carbon nanotube to the mortar-aggregate interface along various directions can be substantially different. The generated knowledge will be incorporated in a meso-scale analysis of carbon nanotube reinforced concrete, in which the aggregate, mortar and interface will be considered separately.