Abstract
AbstractThis paper shows that besides the particle size reduction, prolonged high-energy ball milling of portland cement leads to mechanically induced phase transformation from the crystalline to the amorphous state. This research has also investigated the improvement of the mechanical and microstructural properties of cement pastes incorporating mechanically activated cement milled for various durations as partial replacement of the unprocessed cement. Results have shown that compressive strength increases with prolonging mill duration as well as the amorphization degree of the processed cement. The setting times and porosity are significantly reduced, and the degree of hydration is improved by increasing the mill duration and the amorphization degree of the modified cement. The most significant results were observed when 10% by weight of amorphous cement was added to the unprocessed cement. In this experimental condition, the compressive strength was increased by 107% (at 28 curing days), the initial and final setting times were reduced approximately threefold, the porosity was reduced by 52%, and the early degree of hydration was improved by 162%.