The sequel of modified fly ashes using high energy ball milling on mechanical performance of substituted past cement. (15th January 2016) - Hamzaoui, Rabah
ABSTRACT: The consideration of planetary ball mill processing is attempted to obtain modified fly ashes powders that are used as substitutes in a cement paste. Ball milling conditions are related to structural modifications of processed powders. These modifications are retrieved from X-ray diffraction, infrared spectroscopy, powder granulometry, and scanning electron microscopy. As an industrial application, the milled fly ashes are substituted to two different cements to show possible effect on compressive strength of cement pastes. Structural analysis of milled fly ashes show loss of crystallinity of the magnetite phase, nanosizing trend of quartz and mullite phases with some straining that takes place after only 1 h of milling. The drop of particle size of the milled fly ashes is also evidenced but with tendency to agglomeration and particle shape modification from spherical to irregular forms. Mechanical performance results related to modified cement pastes indicate successful substitution of cements by milled fly ashes up to 50%. Substitution results in levels of compressive strength as large as 70 MPa for particular combination of milling time, fly ash content and curing time. Graphical Abstract: Highlights: Major structural changes achieved for fly ashes processed using ball milling Fracturing is responsible for nanocrystalline quartz and mullite formation. Size reduction and agglomerations opposed in short time powder milling For milled fly ash, the higher milling time, the higher cement paste consistency Milled fly ashes substitution generates large mechanical strength of modified cement.