（宁夏大学 土木与水利工程学院，宁夏 银川 750021）
郝伟伟，张树祥，买英东，等. 超吸水聚合物对碱激发泡沫混凝土性能的影响［J］. 中国粉体技术，2024，30（5）：70-80.
HAO Weiwei， ZHANG Shuxiang， MAI Yingdong， et al. Influence of super-absorbent polymer on properties of alkali-activated foamed concrete［J］. China Powder Science and Technology，2024，30（5）：70−80.
DOI：10.13732/j.issn.1008-5548.2024.05.007
收稿日期：2024-04-16，修回日期：2024-05-20，上线日期：2024-08-28。
基金项目：国家自然科学基金项目，编号：52368044；宁夏回族自治区重点研发项目，编号：2021BEG02014。
第一作者简介：郝伟伟（1999—），男，硕士生，研究方向为新型建筑材料。E-mail：chenwu234@foxmail. com。
通信作者简介：毛明杰（1972—），男，教授，博士，宁夏回族自治区“百人计划”首批入选者，博士生导师，研究方向为土木工程结构、新型建筑材料研究。E-mail：maomj@nxu. edu. cn。
摘要：【目的】 研究超吸水聚合物（super‐absorbent polymer，SAP）对提升以矿渣和再生微粉为主要材料的碱激发泡沫混凝土性能的影响。【方法】 调节SAP预吸NaOH溶液的质量分数和SAP掺量（质量分数，下同），考察其对碱激发泡沫混凝土的流动性、吸水率、凝结时间、导热系数、孔隙结构及强度的影响；借助扫描电子显微镜和傅里叶红外光谱分析，从微观角度揭示SAP对泡沫混凝土性能影响机制。【结果】 随着SAP掺量的增加，碱激发泡沫混凝土的流动度、凝结时间和导热系数呈下降趋势，但吸水率增大。SAP的掺入会导致碱激发泡沫混凝土孔隙率增大和孔隙分布的改变，掺入预吸水和预吸质量分数为0. 4%的NaOH溶液的SAP后，增大了碱激发泡沫混凝土中孔隙直径大于550 μm的孔隙比例；掺入预吸质量分数为 0. 9% 的 NaOH 溶液的 SAP后，则增大了碱激发泡沫混凝土中孔隙直径小于 250 μm的孔隙比例。适量的掺入SAP可以显著改善碱激发泡沫混凝土的抗压、抗折强度，当SAP预吸质量分数为0. 4%的NaOH溶液且掺量为0. 10%时，碱激发泡沫混凝土的抗压、抗折强度最高。【结论】 SAP预吸NaOH溶液处理后，可以明显改善碱激发泡沫混凝土的工作性能、孔隙结构和力学性能。
关键词：泡沫混凝土；超吸水聚合物；再生微粉；碱激发；孔隙结构
Objective Using recycled concrete powder as an auxiliary cementing material to partially replace slag in the preparation of alkali-activated foamed concrete helps reduce costs and address the problem of air pollution caused by construction waste crushing dust. However， a higher amount of recycled fine powder usually reduces the performance of concrete. To improve the properties of alkali-activated foamed concrete with recycled micropowder and slag as the main raw materials， internal curing method was considered. The influence of superabsorbent polymer （SAP） on the properties of alkali-activated foamed concrete was studied in the paper.
Methods The experiment evaluated the influence of SAP on the fluidity， water absorption rate， setting time， thermal conductivity， pore structure， and strength of alkali-activated foamed concrete by adjusting the mass concentration and dosage of SAP pre-absorbed with NaOH solution. Using alkali-activated foamed concrete without SAP as the control group， the study explored the influence of different SAP dosages （0. 05%，0. 10%，0. 15%，0. 2%） on the performance of alkali-activated foamed concrete with recycled micropowder and slag as the main raw materials， when SAP was pre-absorbed with 0%，0. 4%， and 0. 9% NaOH solution. The mechanism by which SAP affects the performance of alkali-activated foamed concrete was investigated by electron microscopy and infrared spectroscopy analysis.
Results and Discussion The study on the viability of alkali-activated foamed concrete showed that SAP significantly affected the fluidity of the concrete. With the increase of SAP content， its fluidity showed a general trend of decreasing. The influence of SAP-Water on fluidity was the largest. The water absorption rate of alkali-activated foamed concrete increased gradually with the increase in SAP content. When the content of SAP-Water increased from 0. 05% to 0. 2%， the water absorption rate increased from 46. 7% to 53. 5%. Regardless of the mass concentration of NaOH solution added to SAP beforehand， the setting time of alkali-activated foamed concrete was shorter that of the control group. It initially decreased and then increased with the increase in SAP-Water content， but gradually decreased with the increase in SAP-0. 4% NaOH or SAP-0. 9% NaOH content. In addition， SAP significantly influenced the thermal conductivity of alkali-activated foamed concrete. With the increase in SAP-Water and SAP-0. 4% NaOH content and the decrease of the mass concentration of NaOH solution pre-absorbed by SAP， the thermal conductivity of alkali-activated foamed concrete decreased， which was related to the changes in pore structure. Pore structure analysis showed that SAP not only increased the porosity of the concrete， but also changed its porosity distribution. Among them， SAP-Water increased the porosity of the concrete most significantly. When the content of SAP-Water increased from 0% to 0. 2%， the porosity of the specimen increased from 64. 8% to 67. 9%， an increase of 4. 8%. SAP-Water and SAP-0. 4% NaOH increased the proportion of pores larger than 550μm in alkali-activated foamed concrete， while SAP-0. 9% NaOH increased the proportion of pores smaller than 250μm. Microscopic analysis of the pore structure showed that pre-absorbed SAP-0. 4% NaOH improved the pore wall products， reduced internal defects， and improved the material's pore structure. Mechanical property test showed that adding an appropriate amount of SAP significantly improved the compressive and flexural strength of alkali-activated foamed concrete. With the increase in SAP-Water and SAP-0. 4% NaOH dosage， the compressive strength of the concrete initially increased and then decreased. Microscopic analysis showed that SAP did not produce new hydration products but changed its hydration degree and microstructure. SAP promoted the formation of C-A-S-H gel， improving material compactness. SAP pre-absorbed with 0. 4% NaOH solution not only improved the pore structure of the specimen， but also deepened the hydration degree of the matrix， enhancing the mechanical properties of the specimen. When the dosage was 0. 1%， the 28-day compressive strength of the specimen reached 4. 94 MPa， and the flexural strength was 17. 5% higher than the control group. When the dosage of SAP exceeded the optimal value， excess SAP introduced additional pores in the matrix of alkali-activated foamed concrete， thereby reducing material compactness and consequently its strength.
Conclusion Pre-absorbed SAP with NaOH solution， serving as an internal curing agent， significantly enhances the hydration degree and pore structure of alkali-activated foamed concrete that incorporates recycled concrete powder. This improvement in microstructure contributes to better viability and increases the strength of the concrete. The proposed method provides a new approach to improving the properties of alkali-activated foamed concrete materials mixed with recycled micropowder.
Keywords： foamed concrete； super-absorbent polymer；recycled concrete powder； alkali activation； pore structure
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