Reaction mechanisms in geopolymers produced from sugarcane bagasse ash

Abstract

The production of Portland cement exhibits significant importance for social and economic development of a country, however also generates environmental impacts from the extraction of raw materials to the production of clinker. Despite the impacts, the demand for Portland cement is still growing in developing countries such as India, China, and Brazil. Faced with this impasse, research for the development of alternative materials to Portland cement is growing around the world. Among these researches, those related to alkali-activated materials (AAMs) stand out. AAMs are considered more sustainable than Portland cement because emit less CO2 during their production process. In addition, the raw materials used in its development are generally wastes from other industrial processes. Sugarcane bagasse ash (SCBA) is an example of residue generated on a large scale in Brazil and with great potential for use in the production of AAMs. Therefore, the present work seeks to develop AAMs using SCBA as an exclusive precursor. For this, the material's viability was verified through physical, mechanical, morphological, and calorimetric tests. As a result, concluded that SCBA is a viable precursor for AAMs, promoting sustainability and innovation in the field of construction materials. In addition, the main mechanism of the reaction of SCBA pastes is the diffusion process, independent of paste formulation and the silicate is crucial for the degree of reaction at early age. At the same time, the compressive strength and microstructure are strongly dependent on alkalis and silicate content and SiO2/Na2O proportions around 1.0 are the optimum point for SCBA pastes.