Sludge solidification based on carbon dioxide foam cement slurry
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摘要: 河湖疏浚会产生大量疏浚淤泥，其含水率、压缩性均较高。采用二氧化碳作为泡沫气体源制备二氧化碳泡沫水泥浆材料并以此作为固化材料开展淤泥改良，对疏浚淤泥的资源再利用及对实现碳中和目标具有重要的意义。基于传统空气泡沫水泥浆制备技术与普通水泥基固碳机理，采用二氧化碳替代空气制备二氧化碳泡沫水泥浆并以此进行淤泥固化，对泡沫浆液养护后形成结石体试块的力学性能以及疏浚淤泥固化后形成填料的力学性能和微观结构进行了试验研究。研究结果表明：发泡剂A2和稳泡剂C1的最佳组合为4，5 g/L；水泥水化水解产物中Ca(OH)2与CO2生成CaCO3的转化率约增加26.1；水泥浆中粉煤灰的最佳掺量为30%；固化后形成的固化料的无侧限抗压强度、内摩擦角及黏聚力与泡沫浆液的掺量呈近似线性递增关系，而渗透系数与泡沫浆液的掺量呈近似线性递减关系。研究成果为淤泥固化的工程应用和二氧化碳“变废为宝”的途径提供重要指导。Abstract: River and lake dredging will produce a large amount of dredged sludge with high water content and compressibility. Using the carbon dioxide as the foam gas source to prepare carbon dioxide foam cement slurry and use it as the solidification material to carry out sludge improvement is of great significance to the reuse of dredged sludge resources and to achieve the goal of carbon neutrality. Based on the traditional air foam cement slurry preparation technology and ordinary cement-based carbon fixation mechanism, the carbon dioxide foam cement slurry is prepared with carbon dioxide instead of air, which is used to solidify the sludge. The mechanical properties of stone test blocks formed after the curing of foam slurry and the mechanical properties and microstructure of filler formed after the solidification of dredged sludge are studied experimentally. The results show that the best combination of foaming agent and foam stabilizer is A2 4g/L, C1 5g/L. The conversion rate of Ca (OH)2 and CO2 to CaCO3 in the cement hydration hydrolysis product increases by about 26.1%. The optimal content of fly ash in cement slurry is 30%. The unconfined compressive strength, internal friction angle and cohesion of the solidified materials formed after curing approximately linearly increase with the content of foam slurry, while the permeability coefficient approximately linearly decreases with the content of foam slurry. The research results provide important guidance for the engineering application of sludge solidification and the way to "turn waste into treasure" of carbon dioxide.
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Keywords:
- dredged silt /
- carbon dioxide /
- foam cement slurry /
- sludge solidification /
- mechanical property
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图 4 水灰比与密度、抗压强度变化百分比的关系
Figure 4. Relationship between water-cement ratio and change percentages of density and compressive strength
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图 5 浆泡比与密度、抗压强度变化百分比的关系
Figure 5. Relationship between slurry-bubble ratio and change percentage of, density and compressive strength
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图 6 泡沫浆液密度与粉煤灰掺量的关系
Figure 6. Variation of density of foam slurry with content of fly ash
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图 7 泡沫浆液抗压强度与粉煤灰掺量的关系
Figure 7. Variation of compressive strength of foam slurry with content of fly ash
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图 8 固化料无侧限抗压强度与浆液掺量的关系
Figure 8. Curves of unconfined compressive strength and slurry content of solidified materials
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图 9 泡沫水泥浆液掺量与内摩擦角曲线
Figure 9. Curves of foam cement slurry dosage and internal friction angle
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图 12 对比试验无侧限抗压强度分析
Figure 12. Analysis of unconfined compressive strength in comparative tests
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图 14 水泥基泡沫浆液固化淤泥微观结构光学成像图
Figure 14. Optical image of microstructure of cement-based foam slurry-solidified sludge
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图 15 水泥基泡沫浆液固化淤泥X射线衍射图谱
Figure 15. X-ray diffraction patterns of cement-based foam slurry- solidified sludge
表 1 淤泥基本物理性质参数
Table 1 Basic physical property parameters of sludge
含水率/% 湿密度/
(g·cm-3)干密度/
(g·cm-3)相对质量密度 63.26 1.69 1.03 2.70 
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表 2 普通硅酸盐水泥性能测试结果
Table 2 Performance test results of ordinary portland cement
比表面积/
(m2·kg-1)初凝/ min 终凝/ min 抗折强度/MPa 抗压强度/MPa 3 d 28 d 3 d 28 d 357 203 250 5.9 7.7 27.4 45.0
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表 3 马鞍山海螺牌普通硅酸盐42.5水泥主要化学组分及含量
Table 3 Main chemical components and content of Ma'anshan Hailuo ordinary portland 42.5 cement
单位: % SiO2 Al2O3 Fe2O3 SO3 CaO MgO 22.55 5.91 2.63 2.01 63.22 2.68
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表 4 L9（34）水平及因素信息表
Table 4 Information of orthogonal tests
序号 发泡剂(A) 发浓度(B) 稳泡剂(C) 稳浓度(D) 1 A1 2 g/L(B1) C1 3 g/L(D1) 2 A2 4 g/L(B2) C2 5 g/L(D2) 3 A3 6 g/L(B3) C3 7 g/L(D3)
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表 5 L9（34）正交试验结果
Table 5 Results of orthogonal tests
组号 发泡剂种类 发泡剂浓度 稳泡剂种类 稳泡剂浓度 结石率/% 密度/(g·cm-3) 7 d抗压强度/MPa 稳泡时间/min ① 1(A1) 1(B1) 1(C1) 1(D1) 0.98 1.38 3.33 24.2 ② 1(A1) 2(B2) 2(C2) 2(D2) 0.97 1.41 4.50 52.4 ③ 1(A1) 3(B3) 3(C3) 3(D3) 0.99 1.44 4.62 33.8 ④ 2(A2) 1(B1) 2(C2) 3(D3) 0.96 1.31 5.62 41.1 ⑤ 2(A2) 2(B2) 3(C3) 1(D1) 0.96 1.52 4.28 55.6 ⑥ 2(A2) 3(B3) 1(C1) 2(D2) 0.93 1.41 4.51 37.2 ⑦ 3(A3) 1(B1) 3(C3) 2(D2) 0.96 1.49 4.69 38.4 ⑧ 3(A3) 2(B2) 1(C1) 3(D3) 0.99 1.54 4.42 42.9 ⑨ 3(A3) 3(B3) 2(C2) 1(D1) 0.99 1.32 4.46 29.6
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表 6 各水平数据平均值与极差
Table 6 Averages and ranges of data at all levels
平均水平与极差 7 d强度/
MPa密度/
(g·cm-3)结石率 稳泡时间/
minA $ \overline {{K_{\text{1}}}} $ 4.05 1.41 0.98 36.80 $ \overline {{K_2}} $ 4.97 1.41 0.96 41.30 $ \overline {{K_{\text{3}}}} $ 4.52 1.45 0.98 36.97 R 0.92 0.04 0.02 4.50 B $ \overline {{K_{\text{1}}}} $ 4.55 1.39 0.97 34.57 $ \overline {{K_2}} $ 4.40 1.49 0.97 50.30 $ \overline {{K_{\text{3}}}} $ 4.53 1.39 0.97 33.53 R 0.15 0.10 0 16.77 C $ \overline {{K_{\text{1}}}} $ 4.09 1.34 0.97 34.77 $ \overline {{K_2}} $ 4.86 1.35 0.98 41.03 $ \overline {{K_{\text{3}}}} $ 4.53 1.48 0.97 42.60 R 0.77 0.14 0.01 7.83 D $ \overline {{K_{\text{1}}}} $ 4.02 1.44 0.97 36.46 $ \overline {{K_2}} $ 4.57 1.44 0.95 42.67 $ \overline {{K_{\text{3}}}} $ 4.89 1.43 0.98 39.27 R 0.87 0.01 0.03 6.21
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表 7 泡浆比与水灰比全面试验组别示意图
Table 7 Schematic diagram of comprehensive test groups
泡浆比 水灰比 1︰2.2 1︰2.4 1︰2.6 1︰2.8 3︰1 1 4 7 10 5︰1 2 5 8 11 7︰1 3 6 9 12
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表 8 水泥基泡沫浆液固化淤泥试样中物相检索物质主要组成和百分含量
Table 8 Main compositions and percentage contents of phase retrieved substances in cement-based foam slurry cured silt sample
单位: % 组分 CaSiO3 CaCO3 CaAl2O4 Ca(OH)2 百分含量 32.65 30.27 13.07 10.04
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表 9 普通水泥浆固化淤泥试样中物相检索物质组成和百分含量
Table 9 Compositions and percentage content of phase retrievable substances in common cement slurry cured silt sample
单位：% 组分 CaSiO3 CaCO3 CaAl2O4 Ca(OH)2 百分含量 38.18 24.63 14.92 14.61
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表 10 泡沫水泥浆液淤泥固化料各组分掺量
Table 10 Dosages of each component of foam cement slurry sludge solidification materials
成分 用量/% 价格/(元·m-3) 茶皂素 0.73 441 SDBS 0.95 896 42.5水泥 23.52 720 粉煤灰 30.00 107 淤泥 35.00 110 水 9.80 0
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表 11 普通水泥浆液淤泥固化料各组分掺量
Table 11 Dosages of each component of cement slurry sludge solidification materials
成分 用量/% 价格/(元·m-3) 42.5水泥 48 720 淤泥 32 110 水 20 0
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