Recycling of hazardous medical waste ash toward cleaner utilization in concrete mixtures

Medical Waste Bottom Ash (MWBA) is considered a toxic material with a high potential to cause serious health damage to the atmosphere and humans. It has relatively low pozzolanic reactivity that limits its utilization in construction materials. The following study provides an experimental investigation of the recycling MWBA to enhance the reactivity of the ash toward cleaner use in concrete mixtures. Four activation methods were investigated in this work: (i) dry ball milling, (ii) calcination, (iii) wet milling, and (iv) wet milling followed by calcination. Mortar specimens were prepared with 40% replacement of the untreated MWBA, and the treated ones were to be tested for compressive strength after 7, 28, 56, and 90 d. The results indicated that ball milling (wet or dry) of MWBA increased the ash reactivity and the mortar compressive strength by 20%. Calcination has also enhanced compressive strength by more than 35%. A combination of wet milling followed by calcination of the ash was found to significantly enhance the compressive strength of mortar by more than 70%. The inclusion of 40% of calcined MWBA provided concrete specimens with 47% enhanced acid resistance compared to con-crete with untreated MWBA. The leaching test results for the heavy metals Cd, Cr, Cu, and Zn revealed that activation of the ash dramatically reduced the leachability.

Automated summary

Medical Waste Bottom Ash (MWBA) is a toxic material that poses serious health risks to the atmosphere and humans. This study investigates methods to enhance the reactivity of MWBA for its use in concrete mixtures. Results show that ball milling (wet or dry) and calcination increase the ash reactivity and compressive strength of mortar, while a combination of wet milling followed by calcination significantly enhances compressive strength. The inclusion of 40% calcined MWBA improves acid resistance in concrete.