Characteristic influence of carbon fibers on fresh state, mechanical properties and microstructure of carbon fiber based self compacting concrete
Iftekar Gull, Manzoor Tantray
Abstract
The development of Self Compacting Concrete is an innovative landmark in the history of infrastrucrutural industry resulting in principal usage of SCC worldwide nowadays. The integration of fibers further influences its properties specially related to the filling and passing abilities in the fresh state properties. This paper presents the characterisitic influence of carbon fibers (CFs) on the fresh state (filling ability, passing ability and resistance to segregation) and hardened state (compressive and tensile strength) properties of carbon fiber based self compacting concrete (CFBSCC). Three different water to cement ratios of 0.38%, 0.40% and 0.42% were used in producing 15 different CFBSCC mixes incorporating 0–2% CFs. The micro structure of the CFBSCC post failure and the failure modes of carbon fibers in the hardened CFBSCC was also studied using scanning electron microscope and is presented in this study. The observations made in this study reveal that the incorporation of carbon fibers influence the properties of the SCC both in fresh and hardened state, however the lower percentages of CFs yield positive impact on the strength properties. The compressive strength was increased to a maximum of 24.5% with the inclusion of 1%CF to 1.5%CF. The variations in the splitting tensile strength varied from a maximum increase of 7.78% at 1%CF to a maximum decrease of 8.67% at 2%CF. It was observed that the maximum threshold of the carbon fibers in SCC should be restricted to 1.5% for the improvement of the fresh state properties and hardened state properties. The micro structural study confirmed the mechanism of crack bridging by the micro threads of carbon filaments.