Abstract Details
296 / 2023-02-17 15:59:03
Carbonation characteristics of BOFS aggregate and properties analysis of carbonated pure BOFS blocks
BOFS aggregate; Carbonation; Block; CO2 absorption; ITZ
Abstract Accepted
To increase the use of basic oxygen furnace slag (BOFS), this study aims to prepare pure BOFS blocks using BOFS powder (<75 μm) and aggregate (<5 mm) as raw materials. BOFS aggregates were first subjected to carbonation through two distinct methods (dry carbonation and slurry carbonation). Then, three types of BOFS aggregates (two carbonated aggregates and fresh aggregates) mixed with BOFS powders were pressed into blocks and have a dry carbonation. (Fig.1).
Characterization of the carbonated aggregate revealed that the dry carbonated aggregates contained less CaCO3 than the slurry carbonated specimens, but had more Mg(OH)2 and residual Ca(OH)2 (Fig.2). This was caused by the difference in solubility of Ca and Mg under different moisture contents.
Subsequently, the properties of pure BOFS blocks prepared with different BOFS aggregates were investigated. Compared with blocks prepared from fresh BOFS aggregate (SAB), blocks prepared with two types of carbonated BOFS aggregates exhibited higher CO2 absorption and displayed continued strength growth during the subsequent standard curing process (Fig.3). This was because the CaCO3 produced from BOFS powder carbonation in SAB obstructed the contact between the aggregates and the diffused CO2, and a denser microstructure also reduced the residual CO32-/HCO3- in the pore solution. Despite a lower level of carbonate formation, the SAB still exhibited the highest compressive strength (Fig.4). This was attributed to the co-carbonation of the powder and aggregate, which effectively reinforced the ITZ. The bonding between the carbonated aggregate and the paste was hindered by the carbonate layer formed on the surface of the aggregate, resulting in a porous structure (Fig.5). Conversely, the presence of larger pores was conducive to CO2 absorption and thereby increase the potential of subsequent improvements in mechanical properties. Findings from this study have the potential to facilitate the utilization of BOFS as an eco-friendly material in the field of construction, paving the way for its wider adoption and integration into the construction industry.
Keywords: BOFS aggregate; Carbonation; Block; CO2 absorption; ITZ
Characterization of the carbonated aggregate revealed that the dry carbonated aggregates contained less CaCO3 than the slurry carbonated specimens, but had more Mg(OH)2 and residual Ca(OH)2 (Fig.2). This was caused by the difference in solubility of Ca and Mg under different moisture contents.
Subsequently, the properties of pure BOFS blocks prepared with different BOFS aggregates were investigated. Compared with blocks prepared from fresh BOFS aggregate (SAB), blocks prepared with two types of carbonated BOFS aggregates exhibited higher CO2 absorption and displayed continued strength growth during the subsequent standard curing process (Fig.3). This was because the CaCO3 produced from BOFS powder carbonation in SAB obstructed the contact between the aggregates and the diffused CO2, and a denser microstructure also reduced the residual CO32-/HCO3- in the pore solution. Despite a lower level of carbonate formation, the SAB still exhibited the highest compressive strength (Fig.4). This was attributed to the co-carbonation of the powder and aggregate, which effectively reinforced the ITZ. The bonding between the carbonated aggregate and the paste was hindered by the carbonate layer formed on the surface of the aggregate, resulting in a porous structure (Fig.5). Conversely, the presence of larger pores was conducive to CO2 absorption and thereby increase the potential of subsequent improvements in mechanical properties. Findings from this study have the potential to facilitate the utilization of BOFS as an eco-friendly material in the field of construction, paving the way for its wider adoption and integration into the construction industry.
Keywords: BOFS aggregate; Carbonation; Block; CO2 absorption; ITZ
Important Date
Sponsored By
Shenzhen University
The Hong Kong Polytechnic University Contact Information
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