Optimizing the pore structure and permeability of calcined clay limestone cement through shell powder

Abstract

Limestone calcined clay cement (LC3) as a novel low-carbon cement shows potential as an OPC replacement due to its lower clinker content and excellent performance. Nevertheless, Low degree of hydration in early age resulted in high porosity impacting properties. In this study, shell powder was employed as a carbonate filler to optimize the pore structure of LC3. The results indicated that adding shell powder improved pore structure, consequently enhancing compressive strength from 35.8MPa to 40.5 MPa at 28 day. The collaboration of shell powder with limestone led to the highest compressive strength 41.2 MPa and lowest porosity 18.4% at 28 days. The matrix had good compatibility when limestone and shell powder are combined for LC3. With the increased content of shell powder, the volume fraction of gel pores gradually increased, and the harmful pores decreased, which promoted the transformation of pores into gel pores. Pore connectivity was reduced, resulting in a denser LC3 matrix. Therefore, shell powder was a material that can effectively improve the mechanical properties and pore structure of LC3.