This paper reports new hierarchical cementitious composites developed using microcrystalline cellulose (MCC), sisal fibers and cetyltrimethylammonium bromide (CTAB) as the dispersing agent. MCC was dispersed in water without and with CTAB at different concentrations using ultrasonication and the optimum CTAB concentration for achieving homogeneous and stable MCC suspensions was found to be 40%. Hierarchical composites were fabricated using MCC (0.1–1.5 wt% of cement), sisal fibers (20 mm, 0.25% and 0.50 wt% of cement), 40% CTAB and tri-butyl phosphate as the defoaming agent. Mechanical strengths of composites improved significantly at 0.1 wt% MCC, which along with 0.5% sisal fibers improved compressive and flexural strengths by ~ 24% and ~ 18%, respectively. The hybrid reinforcement exhibited a synergistic effect on the fracture behavior of composites improving the fracture energy up to 40%. Hierarchical composites also showed improved fiber-matrix bonding, lower porosity and water absorption, superior hydration, carbonation resistance and durability up to 90 ageing cycles.

In this work, the axial compressive strength at 3, 7 and 28 days of age and the tensile strength at 28 days of age of specimens of two self-compacting concrete (SCC) compositions were evaluated. The difference between them was the presence of the sugarcane bagasse ash (SCBA) in the substitution rate of 10% of the sand mass in the second trace. The traces were developed based on the rheological parameters of the NBR 15823 Brazilian standard. The strengths at 28 days were evaluated by the confidence interval of the Student’s t-test with α of 5%. The results in the fresh state have proved that the rheological performances between the SCC’S are similar. Moreover, the SCC with SCBA obtained equivalent performances in the compressive and tensile strengths at all ages when compared to the SCC without SCBA, with an effective reduction of 87 Kg of sand per cubic meter of concrete.