PWM5-3 PWM5-4
50 50 50
30 25 20
20 25
PWM5-5 30 Legend: AE—Alkali equivalent; Ms—Silicate modulus; W/B—Water-binder ratio; wt.%—weight percentage.
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Figure 6. The compressive strength of PWM substitution proportion. Figure6. The compressive strength of PWM substitution proportion.
In Figure 7, the stress-time curves did not drop abruptly at the peak in the substitu- tion of BFS with mixed wastes. When the proportion of the lime mud in waste mixtures exceeded 10% of the total weight, curve optimization was performed. As the proportion of paper sludge in waste mixtures increased, the slope of the curve flattened out at the yield stress, suggesting that the flexibility of samples was optimized with the increase of paper sludge. When the proportion of paper sludge increased to 1% of the total weight, the slope of the curve over the yield point changed from − 2.5 to − 1, indicating a prominent enhancement of flexibility. Therefore, the stress-time curve was optimized when the paper sludge accounted for 20% of the total mixture weight. In Figure 7, the stress-time curves did not drop abruptly at the peak in the substitution of BFS with mixed wastes. When the proportion of the lime mud in waste mixtures exceeded 10% of the total weight, curve optimization was performed. As the proportion of paper sludge in waste mixtures increased, the slope of the curve flattened out at the yield stress, suggesting that the flexibility of samples was optimized with the increase of paper sludge. When the proportion of paper sludge increased to 1% of the total weight, the slope of the curve over the yield point changed from − 2.5 to − 1, indicating a prominent enhancement of flexibility. Therefore, the stress-time curve was optimized when the paper sludge accounted for 20% of the total mixture weight. 8 of 12
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Figure 7. The stress curve of the slurry with the 50% proportion of PWM substituted for BFS. Figure7. The stress curve of the slurry with the 50% proportion of PWM substituted for BFS.
3.3. Texture Change of PWM Slurry Considering the optimization of slurry texture and compressive strength, the wood chips were added to the slurry as seen in Table 4. Both wood chips and paper sludge improved the property of the stress-time curve. In addition, 5% of wood chips were used to gradually replace the paper sludge in the mixing proportion of up to 20% of the total weight. It can be seen from Figure 8 that when wood chips were added from 10% (PWM3-
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