Long-Term Compressive Behavior of Concretes with Sugarcane Bagasse Ash as a Supplementary Cementitious Material

This paper reports an investigation of a very-long-term compressive-behavior evaluation of concretes containing sugarcane bagasse ash (SCBA). Initially, two different SCBA samples collected in two sugarcane plants located 1,800 km apart and 8 years apart in sampling interval were compared. From these ashes, two series of conventional and high-strength concretes were mix-designed within the Compressible Packing Model aiming for 28-day compressive strengths of 25 and 60 MPa, respectively. In the first series, a SCBA (SCBA-1) was used as a cement replacement with 10 %, 15 %, and 20 % by mass content. The different concretes were evaluated by compressive strength at 7, 28, 90, 180 days, and 1 and 10 years, and by modulus of elasticity at 28 days and 10 years. The second series of concretes was examined with similar procedures performed on the first series and another SCBA (SCBA-2, 15 % cement replacement). Compressive strength in 7, 28, 90, and 180 days, and modulus of elasticity at 28 days were evaluated. The results showed that both SCBA-1 and SCBA-2 presented similar characteristics to be considered pozzolanic materials. The effect of these ashes on the compressive strength was positive considering the cement-replacement levels used, especially for later testing ages. The results also demonstrated that all first-series concretes presented gain in compressive strength and modulus of elasticity up to 10 years of hydration. At this age, no significant differences were found in compressive strength for conventional and high-strength mixes containing SCBA compared to their respective reference mixes.