To Investigate the Mechanical Properties of Cement Mortar Incorporated with Graphite Nano-Platelets

Abstract

Concrete has been used as a construction material since 700 BC. It offers high compressive strength but is weak in tensile strength. These investigations mainly focus on feasibility of graphite nano materials in improving mechanical properties of cementitious composites. A lot of work had been done on this by using nano materials as fiber reinforcement. But all nano reinforcement and micro scale fibers had some sort of flaws either in term of strength improvement, in terms of dispersion or in cost. This study used GNP as a replacement of all other nano materials because of its unique Geometry (high aspect ratio and large surface area), cost effectiveness and great mechanical strength as compared to carbon black, carbon Nano tubes (both single and multiwall) and other micro scale fibers. There are dispersion problems with graphite nano-platelets, so success of the study lies in thorough dispersion of GNPs in cement composite. For the aforementioned problem three methods are used on the basis of literature review, first and simple is by using super plasticizer or dispersant which automatically disperse the GNPs by allocating same charge on each particle, second is by mechanical means in which ultrasonic waves are showered on GNPs to break weak van der Waal forces which make this material hydrophobic, and third method is by using Surfactant which is a surface modification technique, in which surfactant molecules are attached on defect sites of GNPs by simple chemical process . As GNPs are an inert material, it does not react with cement paste as silica fume does. To improve the efficiency of that material, functionalization technique is used in this research. In Functionalizing technique, carboxylic group is attached on GNPs which, then, reacts with hydroxide ion and makes bond with cement. The results and investigations showed that the proportion in which GNPs increased the flexure and compressive strength was less. Even achieving this little increase in strength properties was difficult and cumbersome as it involved a lot of techniques to improve dispersion and surface properties of GNP. Increase in strength properties were meager as compared to the efforts involved in achieving them.