Carbonation and Chloride Resistance Characteristics of Self-Developed Limestone Calcined Clay Cement (LC3) Derived from Excavated Spoil

To validate the long-term performance of self-developed limestone calcined clay cement (LC3), this study evaluated the durability performance of LC3 produced using calcined excavated spoil. Results showed that LC3 exhibited a faster chloride adsorption rate than OPC, achieving peak binding capacity within 14 days, although its total chloride-binding capacity was slightly lower. The chloride diffusion coefficient of LC3 was approximately one order of magnitude lower than that of OPC, enhancing chloride resistance. However, LC3 demonstrated weaker carbonation resistance due to complete decomposition of portlandite (Ca(OH)₂) and ettringite (AFt), alongside partial degradation of calcium silicate hydrate (C-S-H) gels, resulting in pore structure coarsening. Compared to LC3 made with commercial metakaolin (K0), the self-developed LC3 using K1 and K2 clays from excavated spoil showed comparable chloride-binding capacity but slightly weaker chloride penetration resistance. Its carbonation resistance surpassed K0-based LC3. Overall, the self-developed LC3 matched commercial metakaolin-based LC3 in durability, validating the use of locally sourced clays. Producing LC3 from calcined excavated spoil addresses environmental challenges associated with spoil disposal while delivering satisfactory durability.