Graphene Oxide Admixed Aerated Concrete Composite with Carbon Fibres

Abstract

Concrete is the widely used construction material and research focus is towards customizing the mixture proportion to suit the application for various construction facilities. Advancement in construction industry has resulted in fast track construction facilities with the use of precast structural elements. Lightweight concrete is gaining importance due to the popularity of prefabricated construction. This paper highlights the optimized mixture proportion of aerated concrete composite with certain chemical and mineral admixtures so that it can be suitably used for precast structural elements. Aluminium powder was used as the aerating agent. Lime powder of about 30% by weight of cement was used to facilitate the aeration process. Lime reacts with aluminium powder liberating hydrogen gas which is responsible for the air voids in concrete. Fly ash class F was used as replacement for sand by 20%. The sand used for this concrete was pulverized and the fraction passing 1.18 mm sieve was used for the concrete. Since the mixture proportion is a multivariable process, statistically designed experiments using central composite design of response surface methodology was used to design the trial mixes. The significance of the interacting factors and the validity of experimentation were analyzed using ANOVA analysis. The strength properties and durability tests were performed to access the characteristics of the material. The density of the concrete was 1285 kg/m3 .The compressive strength obtained was 27.5 MPa, the tensile strength was 2.89 MPa and flexural strength was 3.4 MPa. Chopped carbon fibres and graphene oxide were admixed to the concrete and it was observed that there was 13% increase in the compressive strength when 0.05% of graphene oxide was added. Also carbon fibres increased the flexural strength of the concrete bridging the cracks that were formed when load was applied. Response surface graphs were drawn for all the characteristics that were studied. The significant interaction effects were assessed for all the observed characteristics. There is a general view that aerated concrete being a porous material will not be durable in terms of performance. Hence durability tests like carbonation test, concrete impermeability test and rapid chloride penetration tests were performed to access the durability of the material. It was observed that there were isolated pores and hence the durability of the concrete was the same as conventional concrete. Hence optimized mixture ratio was obtained for low density, high strength and low water permeability. This material can be potentially used for the fabrication of precast structural components so that the process of handling these members will be easy due to the reduced weight of the concrete. Also it has been reported that aerated concrete has good acoustical and thermal insulation properties.