This presentation will provide an overview of the research activities within the Department of Civil Engineering at Monash University (Australia) on nano reinforced infrastructural materials. Since 2009, Dr Duan’s group has investigated the effect of emerging nano particles extensively, including carbon nanotubes (CNTs) and graphene oxide (GO) sheets on enhancing the mechanical properties of cement/polymer-based materials. Analytical, molecular dynamics simualtions, and experimentation have been adopted in the research. In particluar, a theoretical framework with supporting experiments will be disucssed to address the effect of ultrasonication energy for carbon nanotube (CNT) reinforced OPC pastes.  The distribution of CNT lengths and the concentration of dispersed CNTs are characterized using scanning electron microscopy images and UV-vis spectra. After ultrasonication, the length of CNT is found to follow log-normal distributions which show a shortening effect. The concentration of dispersed CNT increases with ultrasonication energy but reaches a plateau after about 250 J/ml. The distribution of CNT lengths and the concentration of dispersed CNTs are incorporated into a micromechanics-based model to simulate the crack bridging behavior of CNTs. Results show that the distribution of CNT lengths leads to better estimation of reinforcing effect than does the average length. Furthermore, for unit volume of dispersed CNTs, the reinforcing efficiency decreases monotonically with increased ultrasonication. Based on the proposed model, the predicted optimal ultrasonication energy (89 J/ml) for reinforcing is found before the dispersion plateau is reached. In addition, the preliminary results on graphene oxide (GO) reinforced OPC pastes will be presented as well with the comments on the advantages/disadvantages of GO for reinforcing purpose.

This presentation will provide an overview of the research activities within the Department of Civil Engineering at Monash University (Australia) on nano reinforced infrastructural materials. Since 2009, Dr Duan’s group has investigated the effect of emerging nano particles extensively, including carbon nanotubes (CNTs) and graphene oxide (GO) sheets on enhancing the mechanical properties of cement/polymer-based materials. Analytical, molecular dynamics simualtions, and experimentation have been adopted in the research. In particluar, a theoretical framework with supporting experiments will be disucssed to address the effect of ultrasonication energy for carbon nanotube (CNT) reinforced OPC pastes.  The distribution of CNT lengths and the concentration of dispersed CNTs are characterized using scanning electron microscopy images and UV-vis spectra. After ultrasonication, the length of CNT is found to follow log-normal distributions which show a shortening effect. The concentration of dispersed CNT increases with ultrasonication energy but reaches a plateau after about 250 J/ml. The distribution of CNT lengths and the concentration of dispersed CNTs are incorporated into a micromechanics-based model to simulate the crack bridging behavior of CNTs. Results show that the distribution of CNT lengths leads to better estimation of reinforcing effect than does the average length. Furthermore, for unit volume of dispersed CNTs, the reinforcing efficiency decreases monotonically with increased ultrasonication. Based on the proposed model, the predicted optimal ultrasonication energy (89 J/ml) for reinforcing is found before the dispersion plateau is reached. In addition, the preliminary results on graphene oxide (GO) reinforced OPC pastes will be presented as well with the comments on the advantages/disadvantages of GO for reinforcing purpose.