Avaliação da atividade pozolânica das cinzas do capim elefante por análise termogravimétrica e ensaio de variação de condutividade elétrica em solução de hidróxido de cálcio

Abstract

The aim of this work was determining the pozzolanic activity of elephant grass Cameroon ash by thermal analysis. With thermogravimetric results, the appropriate calcining temperature was 600°C. The ashes were milled and homogenized using a ball mill. The characterization was determined by x ray fluorescence, and x ray diffraction analysis. The diffractograms of ash indicated the presence of Silvita, Magnesite and Arcanite peaks.Moreover, the chemical composition of ash is composed by mainly by silica and presents high amount of potassium and phosphorus. The pozzolanic activity was determined by electricalconductivity and by TGA and DTA. By the electrical conductivity the ashes were not classified as pozzolanic material. Furthermore, the increase of electrical conductivity happened due to potassium/phosphor ions. Portland cement pastes with water/binder ratio of 0.50 and 20% of ash as partial replacement of Portland cement were prepared for the thermogravimetric analysis. The results showed the hydration of Portland cement pastes with 7, 28 and 90 days due to formation of CS-H. Furthermore, the amount of calcium hydroxide decrease when elephantgrass ash was used. Concluding, the elephant grass Cameroon ash presents potential to be uses as pozzolanic material.