Effect of the chemical attack on the properties of cimentititous composites with partial substitution of ash from sugar cane bagasse in natura

Abstract

Seeking the reutilization of waste from agriculture and urban sources, studies have presented an option in the inclusion of such waste into new low-cost materials that are environmentally viable. One possibility is the reutilization of sugarcane bagasse ashes (SBA), the final waste in the productive process of the Brazilian alcohol sector. In addition to the behavior of materials with the use of SBA as additions in cement-based materials under normal environmental conditions, the study of the behavior of these materials when exposed to harsh environments is required. Thus, this project evaluated the properties, the compression strength and the bulk density of cement composites with partial replacement of cement by SBA without prior treatment. Also, it analyzed the weight loss and compressive strength of the composites subjected to environments with the presence of chloride ions. A factorial design was adopted to verify the influence of the addition of SBA (5wt%, 10wt% and 15wt%) and water/cement ratio (0.45 and 0.55) in the studied properties. The interaction between the factors was significant. The values obtained from the compressive strength of the manufactured composites showed that it is possible to replace up to 15wt% of cement for in natura SBA. After a chemical attack with an acid solution of HCl 30%, it could be observed that all materials had a lower compressive strength, which can be explained by the high weight loss suffered by all composites. Based on the results of compressive resistance, density and weight loss after the attack, it was observed that the mechanical behavior of the composites in relation to the referential conditions were similar. This study showed that it is feasible, in accordance to the studied properties, to use these composites in promoting the partial replacement of ce-ment by this type of waste and its reutilization.