Recycling hazardous zinc industry waste (commonly known as Jarosite) in concrete mixtures has gained importance in recent years in lieu of the stringent environmental protection measures enforced worldwide to combat the waste disposal issue. The present study investigated the potential of utilising Jarosite as a partial substitute for Portland cement in two separate series of concrete mixtures to be used for preparing concrete blocks and conventional concrete pavements. Processed (finely powdered) Jarosite waste was substituted for Portland cement up to 25% at certain proportions of 0%, 5%, 10%, 15%, 20%, and 25% in concrete mixtures and tested for fresh, mechanical, durability, and microstructure properties. Based on laboratory test results and analyses, the increase in proportion of Jarosite up to 15% improved the mechanical properties of concrete mixtures, thereafter decreasing to some extent. Meanwhile, the durability characteristics of concrete mixtures demonstrated continuous improvement with an increase in Jarosite proportion up to 25%. Microstructural investigation revealed denser pore structure and improved transition zone characteristics for Jarosite concrete, which may have resulted from the filler effect and pozzolanic activity of finely powdered Jarosite waste, thereby contributing to its better performance compared to the control concrete mixture. It was also observed that Jarosite-added concrete becomes more vulnerable to acid attack at higher Jarosite substitution levels due to delayed ettringite formation. Furthermore, the heavy metal leachability of Jarosite concrete mixtures predicted from leaching test data for similar classes of concrete confirmed their environmental suitability. Therefore, an optimum Jarosite incorporation level of 15% may be conservatively recommended for concrete blocks (medium-traffic application) and conventional concrete pavements based on the criterion of strength enhancement or concreting application in an aggressive environment while using Jarosite as Portland cement substitute. Otherwise, higher substitution levels of Jarosite up to 25% may be used without compromising the desired engineering properties for pavement applications in the road sector.
