The shrinkage and durability of concrete prepared with waste rock manufactured sand

Manufactured sand derived from solid wastes has not yet been widely adopted in engineering applications such as railway construction. This study systematically investigated concretes of two strength grades prepared with manufactured sands from tunnel-excavated tuff muck and granite cutting waste. Workability, mechanical strength, shrinkage, and various durability properties were evaluated and compared with river sand concretes of identical mix proportions. Mercury intrusion porosimetry, thermogravimetric analysis, and scanning electron microscopy were employed to investigate pore structure, hydration, and the interfacial transition zone. The results show that manufactured sand concretes met workability requirements and achieved higher mechanical strength. The 7-day compressive strength increased by 2.3–21.7 % and tensile strength by 2.5–11.1 %, while the ultimate tensile strain remained nearly unchanged. They also exhibited improved resistance to freeze–thaw cycles, water penetration, carbonation, and chloride ingress compared with river sand concrete, as a result of refined pore structures, higher hydration degrees, and a denser interfacial transition zone. However, early-age shrinkage measured from the initial setting was 8.5–32.4 % higher than that of river sand concrete at 3 days, but after three days of adequate curing, long-term shrinkage decreased by 4.3–13.9 %, highlighting the importance of proper early curing to prevent shrinkage-induced cracking and maintain the benefits of enhanced strength and durability.