The manufacture of Ordinary Portland cement (OPC) generates about 8% of all anthropogenic CO2 emissions; therefore, carbon dioxide footprint reduction represents the main challenge for the cement industry. The development of environmentally friendly binders, as alternative to OPC, absolutely represents an efficient way to cut carbon emissions. In this regard, during the last twenty years particular attention has been paid to calcium sulfoaluminate (CSA) cements thanks to their valuable technical properties as well as the environmentally friendly features mainly related to their manufacturing process. In addition, a further reduction in carbon dioxide emissions can be achieved diluting CSA cements with supplementary cementitious materials (SCMs) such as industrial wastes. In this title, biomass fly ashes (BFAs) were used as SCMs in CSA-blended cements; BFAs were preliminarily washed (W_BFAs) in order to lower their content in alkali. The influence of the ashes on both hydration properties and technical behaviour of two CSA blended cements, respectively containing 10% and 20% by mass of W_BFAs, was investigated by means of mechanical compressive strength and dimensional stability measurements associated with X-ray diffraction, differential thermal-thermogravimetric and mercury intrusion porosimetric analyses.