Segregation-Resistant Carbon Microfibre Reinforced Self-Consolidating Concrete

This paper presents the segregation resistance and flowability of self-consolidating concrete (SCC) including carbon microfibres. Initially, six SCCs were produced incorporating 0–0.50 vol.% of carbon microfibres at the two water-to-binder (W/B) ratios of 0.40 and 0.50. Later, two more SCCs were prepared using viscosity-modifying admixture (VMA) with 0% and 0.25% carbon microfibres at the W/B ratio of 0.40 for further improvement of segregation resistance. All SCCs were tested for slump flow and T50 flow time to determine flowability. The segregation resistance of SCCs was measured with respect to sieve segregation index (SSI). In addition, the appearance of SCCs was checked after the slump flow test to obtain visual stability index (VSI). The distribution of coarse aggregate particles in the two split halves of Ø100 mm x 200 mm cylinders was also examined as another indicator of the segregation resistance of SCC. Test results revealed that the SCCs made with the W/B ratio of 0.40 had excellent segregation resistance and good flowability. Carbon microfibres significantly decreased the flowability of SCC but increased its segregation resistance. Therefore, slump flow and SSI were lower whereas T50 flow time was higher for the SCCs with carbon microfibres. Moreover, the VSI of SCC became better with the inclusion of carbon microfibres. VMA further improved the SSI and VSI of SCC through enhanced viscosity. The distribution of coarse aggregate particles was also more uniform in the SCCs including carbon microfibres with or without VMA. Overall, the best performance of SCC with respect to both segregation resistance and flowability was observed for 0.25% carbon microfibres. Keywords: carbon microfibres, flowability, segregation resistance, self-consolidating concrete, viscosity-modifying admixture.