Sustainable development has been growing concern worldwide, with special emphasis to its effects on climate change. An important action to reduce the environmental damage is the decrease of cement use. In this study the pozzolanicity of Sugarcane Straw Ashes (SCSA), thermal treated, at different curing times was investigated. Synchrotron X-ray Powder Diffraction measurements allowed the quantification of several phases of the cement pasts through Rietveld analysis. The properties of cement paste are directly related to the concentrations of Alite, Belite, Portlandite, Brownmilite and amorphous phases. Tomography technique was also used to study the differences amongst the pore structures according to type of ash used. The SCSA substitution of 20% (weight) in Ordinary Portland Cement (OPC) shows to be a good option to recover the agroindustrial wastes. (C) 2017 Elsevier Ltd. All rights reserved.141343352