Feasibility of Using Sugar Cane Bagasse Ash in Partial Replacement of Portland Cement Clinker

This work presents a technical and economic study using sugar cane bagasse ash (SCBA) to partially replace Portland cement clinker. To evaluate the technical viability, the replacement rates of 10, 20, and 30% of Portland cement were used in the experiments. The ashes used were in the following conditions: (i) as collected (AC), (ii) ground (G), and (iii) re-burnt and ground (RG). Three composition parameters were used in the mortar mix procedures: (i) mix with water factor/fixed binder in volume, (ii) mix with water factor/fixed binder in weight, and (iii) mix with the fixed flow. After the technical feasibility analysis, the benefit of the substitutions and an analysis of the relationship between cement consumption and the acquired compressive strength, correlating with possible economic costs, were discussed. SCBA AC was not suitable for the partial replacement of Portland cement clinker. SCBA G presented a satisfactory performance and SCBA RG was the ash that presented the best performance in the partial replacement of Portland cement clinker. For the same levels of compressive strength, the consumption of Portland cement per cubic meter of concrete reduced; from this, the cost of concrete and mortar could be reduced by 8%, with the ash having the same value as cement. Furthermore, the use of SCBA RG at 30% inhibited the alkali-silica reaction (ASR) in concretes with a reactive basalt and quartzite aggregate. SCBA G (20 and 30%) and SCBA RG (10 and 20%) inhibited the ASR in concretes with a reactive basalt aggregate and reduced the expandability in concretes with a reactive quartzite aggregate. Another point to highlight was the durability shown by the cements with SCBA, which, 900 days after the accelerated test of expansion by the alkali-aggregate reaction, maintained high levels of flexural strength when compared to the results obtained before the accelerated test of expansion. The present work concluded that using sugar cane bagasse ash to replace Portland cement is feasible from a technical, environmental, and economic perspective.