Improvement Interfacial Transition Zone of Green Concrete by utilization of nano-SiO2 particles

چکیده مقاله

Concretes made by the recycled aggregates are one of the green concrete subgroups. Reuse of construction demolitions in order to produce construction materials has become one of the most important parameters in the development of green concrete industry, regarding to solving the environmental complexities and ecological problems. Besides, developing this new industry, because of the results it surely has, can form one of the strong factors along with the move toward sustainable development. Hence, the development of green concrete industry and specifically concretes made by the recycled aggregates can play a significant role in moving toward the sustainable development of concrete industry. However the too slow and unsecure development of recycled aggregate concrete is a considerable point, since in the first step, constructing a high quality concrete is the target and in the next step, producing a green concrete is our priority. Therefore, production of high quality green concrete has become the main aim of concrete investigators. Alongside, by the aid of different pozolans and specific mix procedures, the quality of recycled concretes has remarkably been enhanced. In this study, according to appearance of the nano-technology resulted the presence of nano-materials and also appropriate application of nano-particles in the structure of cement based materials, the chosen target is enhancement of recycled concrete with the help of nano-SiO2 particles. Because the enhancement of concrete quality is a result of enhancement in the quality of interfacial transition zone (ITZ) between paste and aggregates, the micro-performance in this zone and also macro-performance effect on the mechanical properties of concretes made by the recycled aggregates are investigated. Consequently, mixtures with constant W/B ratio of 0.4 and cement amount of 400 kg/m3 were constructed. In addition, regarding to examining the ITZ and mechanical properties of recycled concrete, Scanning Electron Microscopy (SEM) test and compressive strength have been applied respectively. The results show notable development in the ITZ properties and compressive strength of recycled concretes.