Ultra-high strength carbonated slab prepared with steel slag powders via accelerated carbonation for CO2 sequestration

In this paper, an ultra-high strength carbonated slab was prepared with steel slag powders via accelerated carbonation at normal pressure and temperature. The carbonation process of steel slag powders had been explored through carbonation heat, change of pH values and CO2 uptake over time. The synergistic effect of accelerated carbonation process, water -solid ratio (w/s), porosity of compact (Pc), voids in compact (Vc) and content of activator on the compressive strength and CO2 uptake of carbonated slab were investigated. The results show that when the Pc is larger than about 5%, more water is beneficial for the CO2 uptake of carbonated slab and the lower the Vc results in higher compressive strength of carbonated slab. The compressive strength of carbonated slab maximizes 232 MPa at op-timum condition (w/s of 0.08, Vc of 24%, 1.6% Na2CO3 and 0.1 MPa CO2 for 8 h), and its physical and mechanical properties are close to that of natural limestone slab. An addi-tional advantage is that the carbonated slab sequesters about 120 g CO2/kg carbonated slab. This provides a new idea for artificial materials to replace natural stone.& COPY; 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).