Properties of fly ash geopolymer with calcium aluminate cement as an additive
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摘要: 为探讨铝酸盐水泥对粉煤灰基地聚合物性能的影响规律,用掺量分别为0、2%、4%、8%和12%铝酸盐水泥代替粉煤灰,运用SEM、XRD、FTIR与TG等测试方法,对复掺铝酸盐水泥的地聚合物进行微观机理探究;开展流动度试验、凝结时间与抗压强度试验,对复掺铝酸盐水泥的地聚合物进行宏观性能分析。结果表明,当铝酸盐水泥掺量从0增长到12%的过程中,C-S-H凝胶含量从2.16%增长到8.10%,富铝凝胶含量从55.22%增长到74.60%,增大铝酸盐水泥掺量,流动度从22.4 cm降低到21.5 cm,初凝时间从622 min减小到106 min,终凝时间从740 min减小到125 min,抗压强度从27.7 MPa增长到70.78 MPa。因此,复掺铝酸盐水泥有利于生成更多的C-S-H凝胶和富铝凝胶,C-S-H凝胶具有更大的生成速率,降低了地聚合物工作性能,增大了地聚合物抗压强度,丰富了地聚合物性能的提高方法。Abstract: In this study, the influence of calcium aluminate cement on the properties of fly ash based geopolymer was analysed. Calcium aluminate cement was used to replace fly ash, and the content was 0%, 2%, 4%, 8% and 12%, respectively. SEM, XRD, FTIR and TG were used to explore the micro-mechanism of geopolymer with calcium aluminate cement; fluidity test, setting time and compressive strength test were carried out to analyze the macro-performance of geopolymer with calcium aluminate cement. The results show that when the content of calcium aluminate cement increases from 0% to 12%, the content of C-S-H gel increases from 2.16% to 8.1%, and the content of aluminium-rich gel grows from 55.22% to 74.6%. Increasing the content of calcium aluminate cement, the fluidity decreases from 22.4 cm to 21.5 cm, initial setting time decreases from 622 min to 106 min, final setting time drops from 740 min to 125 min, and the compressive strength increases from 27.7 MPa to 70.78 MPa. Therefore, adding calcium aluminate cement is beneficial to the formation of more C-S-H gel and aluminum rich gel, and C-S-H gel has a greater generation rate, which reduces the working performance and improves the compressive strength of geopolymer, which enriches the method to improve the properties of geopolymer.
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Key words:
- fly ash geopolymer /
- calcium aluminate cement /
- micro-mechanism /
- compressive strength
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表 1 粉煤灰与CAC的主要化学组分
Table 1. Main chemical compositions of fly ash and CAC
单位:% 样品 SiO2 Al2O3 Fe2O3 CaO MgO K2O Na2O SO3 粉煤灰 48.73 33.41 5.19 4.81 1.79 1.61 1.29 1.04 CAC 7.21 48.89 2.01 35.56 0.41 0.61 0.13 0.71 表 2 粉煤灰的物理性能
Table 2. Physical properties of fly ash
样品 密度/(kg·m−3) 细度/% 活性指数/% 需水量比/% 烧失量/% 粉煤灰 2 284.6 8.6 90.2 87.2 1.8 表 3 CAC的物理与力学性能
Table 3. Physical and mechanical properties of CAC
样品 密度/
(kg·m−3)细度/
(m2·kg−1)凝结时间/
min抗压强度/
MPa抗折强度/
MPa初凝 终凝 7 d 28 d 7 d 28 d CAC 3 168 360 108 276 48.1 61.5 6.3 8.8 表 4 地聚合物组分
Table 4. Mix proportions of FAG
单位:kg/m3 Mix CAC/% 粉煤灰 Na2SiO3 NaOH H2O CAC M-0 0 1 134.4 323.0 74.1 235.1 0 M-1 2 1 111.7 323.0 74.1 235.1 22.7 M-2 4 1 089.1 323.0 74.1 235.1 45.4 M-3 8 1 043.7 323.0 74.1 235.1 90.8 M-4 12 998.3 323.0 74.1 235.1 136.1 表 5 不同CAC掺量的FAG质量损失
Table 5. Weight loss of FAG with different CAC contents
单位:% 掺量 总失重 自由水蒸发 C-S-H/Si-OH分解 CaCO3分解 0 10.98 3.31 2.55 1.81 2 11.80 3.69 3.03 0.76 4 11.44 3.19 3.36 0.77 8 11.60 3.24 3.20 0.73 12 11.73 3.20 3.31 0.74 -
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