A STUDY ON MECHANICAL, DURABILITY AND MICROSTRUCTURAL PROPERTIES OF GRAPHENE OXIDE REINFORCED CONCRETE COMPOSITE

Abstract

Concrete is widely used construction material in all over the world. Advancements in nanotechnology have now paved the way for novel strategies for improving the performance of cement composites. Several investigations have been carried out in recent years to produce cement composites using identified nanomaterials, such as nano titanium oxide, nano-iron, nano-alumina, nano-silica, carbon nanotubes, and recently graphene oxide (GO) was also widely employed. These nanomaterials as reinforcements in the cement matrix are much more beneficial than conventional reinforcements such as steel rebars and different types of fibres, because these nano reinforcement materials arrest the cracks at nanoscale in cement composite prior to their propagation. The aim of the present study is to develop the GO reinforced concrete composite, with the aim to investigate the influence of GO on the static and dynamic mechanical characteristics, durability properties of concrete, the mechanism of development of crystals and to find the hydration crystals that are beneficial for the formation of distinct microstructures in the concrete composites related to the performance. The present study also focussed on the sustainable development of concrete by introducing GO and fly ash, and to investigate the combined effect of nanomaterial and supplementary cementitious materials on the performance and microstructural characterization. To achieve the aim of the present study, the experimental investigation is planned and carried out in three different phases. In the first phase of experimental program, the static mechanical, dynamic mechanical, durability properties and microstructural characteristics of GO reinforced cement concrete were evaluated. Two different grades of concrete mixes such as standard concrete (SC) and high strength concrete (HSC). In this study, GO content varied from 0% to 0.2% with an increment of 0.05% by weight of cement was considered. This phase is divided into two main parts. The first part focused on the evaluation of static vi mechanical and dynamic mechanical properties. The microstructural characterization was carried out using SEM, EDX, XRD, FTIR and TGDTA. The second part consists of assessment of durability performance of GO reinforced cement concrete. From the experimental results the mechanical and durability properties of cement concrete is significantly improved with the addition of the GO compared to the control concrete. The optimum influence of the GO addition was identified at a dosage of 0.15%. The detailed mechanism for the related improvements was developed with the results of microstructural characterisation. Second phase of experimental program, the combined effect of GO and fly ash on the static mechanical, dynamic mechanical, durability properties and microstructural characteristics concrete was investigated. In this phase, the optimum dosage of GO attained from Phase-I experimental results and further replacement of cement with fly ash at 10%, 20%, and 30% by weight of cement was considered. This phase is also carried out in two different parts. The first part focused on the evaluation of static mechanical, dynamic mechanical and microstructural characteristics. The second part consists of evaluation of durability performance. The performance of GO reinforced fly ash concrete is compared with control concrete. From the experimental results the mechanical and durability properties of concrete is significantly improved with the addition of the GO and replacement of cement with fly ash compared to the control concrete. The detailed mechanism was identified for the improved performance with the results of microstructural characterisation. Third phase of the investigation consists the validation of experimental findings with results obtained through finite element modelling (FEM). Commercially available finite element software was used to model 100x200mm cylinders in order to obtain the stress strain curves analytically. Thereafter, a flexure specimen of 500x100x100mm was modelled and analysed using inputs from the 100x200mm cylindrical model. Experimental results of GO-cement concrete and GO-fly ash concrete are in good agreement with the values obtained by the finite element modelling of cylinders and prismatic beams. The percentage variation observed between experimental and analytical results is less than 15%.