Ultra-high-performance concrete properties containing rice straw ash and nano eggshell powder

Egypt produces more rice straw than any other nation, and this residue is currently discarded in untreated landfills and open fields, causing environmental damage in the country. Furthermore, eggshells, a waste product used in bakeries, restaurants, and poultry farms, were typically disposed of in landfills, posing health hazards. So, grinding eggshells into nanoparticles, known as nano eggshell powder (NEP), increases its activity. In addition, to its high calcium content, NEP may be used with pozzolanic substances like rice straw ash (RSA), which have a lower calcium concentration. This study examined the characteristics of ultra-high-performance concrete (UHPC) produced using RSA and NEP eco-friendly components within partial cement substitution. The ratios of RSA to cement were 0%, 10%, 20%, and 30%, while the NEP quantities were 2, 4, and 6% of the total binder. The results indicate that combining NEP and RSA as pozzolanic materials can improve concrete characteristics while decreasing cement content and reducing environmental contamination. Using RSA and NEP as substitutes for cement has also improved the material's mechanical characteristics, durability, and dry shrinkage.