The green transition in construction requires, among other measures, reducing of the carbon footprint of concrete, which remains the most widely used construction material worldwide. In addition to the well-established use of secondary raw materials in cement production, increasing attention is being paid to the use of recycled aggregate as a partial or complete replacement for natural stone aggregate. Since recycled aggregate may originate from various industrial processes, it often contains impurities that affect the hydration processes of cement. This has been observed in recycled aggregate from the mining industry, where ore-bound heavy metals delay the cement matrix setting and slow down the strength development. In this study, recycled aggregate and its influence on the properties of cement composites were systematically characterized. We determined its mineralogical composition, monitored changes in ultrasonic pulse velocity and temperature during the setting and hardening of cement composites with different recycled aggregate contents, and measured the time-dependent development of compressive and flexural strength. Based on the analysis of the results, we identified the threshold concentration of recycled aggregate that is suitable for use in construction.
|
