Figures (12)  Tables (4)

    • Figure 1. 

      The morphology of biochar at different magnifications.

    • Figure 2. 

      Experimental preparation process.

    • Figure 3. 

      Schematic diagram of the CO2 uptake evaluation apparatus.

    • Figure 4. 

      Compressive strength of biochar-modified NHL composites: (a) 3 d; (b)7 d; (c) 28 d.

    • Figure 5. 

      Effect of biochar dosage on the CO2 uptake performance of the specimens: (a) carbonation kinetics; (b) CO2 uptake.

    • Figure 6. 

      Effect of biochar particle size and dosage on the pH value of the specimens: (a) 100 mesh; (b) 200 mesh; (c) 325 mesh.

    • Figure 7. 

      Porosity of biochar-modified NHL composites: (a) effect of biochar particle size on porosity; (b) effect of biochar dosage on porosity.

    • Figure 8. 

      XRD patterns of biochar-modified NHL composites: (a) XRD patterns; (b) phase assemblage diagram.

    • Figure 9. 

      FTIR spectra of biochar-modified NHL composites.

    • Figure 10. 

      TG-DTG curves of biochar-modified NHL composites.

    • Figure 11. 

      SEM images of biochar-modified NHL composites: (a) P00 ×100; (b) P00 × 5,000; (c) P32 × 100; and (d) P32 × 5,000.

    • Figure 12. 

      Schematic diagram of the mechanism of biochar on the CO2 uptake behavior of NHL.

    • ID Mesh Biochar (g) NHL2 (g) W/B
      P00 − − 100 0.6
      P11 100 1 99 0.6
      P12 100 2 98 0.6
      P13 100 3 97 0.6
      P14 100 4 96 0.6
      P21 200 1 99 0.6
      P22 200 2 98 0.6
      P23 200 3 97 0.6
      P24 200 4 96 0.6
      P31 325 1 99 0.6
      P32 325 2 98 0.6
      P33 325 3 97 0.6
      P34 325 4 96 0.6
      P35 325 5 95 0.6

      Table 1. 

      Mix proportions of biochar-modified NHL paste mixtures

    • ID Mesh Biochar (g) NHL2 (g) Sand (g) W/B
      M00 − − 100 300 0.6
      M11 100 1 99 300 0.6
      M12 100 2 98 300 0.6
      M13 100 3 97 300 0.6
      M14 100 4 96 300 0.6
      M21 200 1 99 300 0.6
      M22 200 2 98 300 0.6
      M23 200 3 97 300 0.6
      M24 200 4 96 300 0.6
      M31 325 1 99 300 0.6
      M32 325 2 98 300 0.6
      M33 325 3 97 300 0.6
      M34 325 4 96 300 0.6

      Table 2. 

      Mix proportions of biochar-modified NHL mortar specimens

    • ID A B R2
      P00 0.115 2.584 0.988
      P31 0.191 2.278 0.983
      P32 0.142 2.667 0.994
      P33 0.121 3.226 0.991
      P34 0.146 3.344 0.975

      Table 3. 

      Fitted parameters of carbonation kinetics for the specimens

    • ID II mass
      loss (%)      		 Ca(OH)2
      content (%)      		 III mass
      loss (%)      		 CaCO3
      content (%)
      P00 1.2 4.9 29.9 67.8
      P32 1.5 6.1 30.2 68.7

      Table 4. 

      Mineral composition calculated from TG analysis (%)