Hardened Properties of Eco-Friendly Concrete Using Crushed Waste Shells as All Fine Aggregates

Considering the environmental problems arising from random disposal of waste shells and the overexploitation of river sand, crushed waste shells (CWS) can be recycled and used as fine aggregates in eco-friendly concrete production. Nevertheless, existing studies on CWS concrete still present notable limitations, including a low optimal replacement level and poor workability caused by the high water absorption of CWS. This study primarily explored the feasibility of 100% CWS replacement of fine aggregates for producing eco-friendly concrete with different strength grades and satisfactory workability. With pre-absorption treatment applied to CWS aggregates, three groups of eco-friendly CWS concrete (C30, C40 and C50) were made instead of direct sand replacement based on ordinary river sand concrete. The hardened properties of CWS concrete, including mechanical strength, durability-related transport characteristics, pore structure, mineral composition and microstructure, were systematically investigated and compared with those of ordinary river sand concrete. This study provides a technical basis for the efficient recycling of waste shell resources and the practical engineering application of eco-friendly CWS concrete.