张彩利^1，2，王 犇³，于焱龙¹，张崇僖¹，孟庆营⁴，龚芳媛^1，2

（1. 河北工业大学 土木与交通学院，天津 300401；2. 天津市交通工程绿色材料技术工程中心，天津 300401；3. 黑龙江龙高公路养护工程有限公司，黑龙江 哈尔滨150000；4. 天津市凯曼德工程技术有限公司，天津 300450）

引用格式：

DOI：10.13732/j.issn.1008-5548.2024.03.005

第一作者简介：张彩利（1978—），女，副教授，博士，硕士生导师，研究方向为固废资源化利用。E-mail：zhangcailimeng@163. com。

摘要：【目的】 提高钢渣利用率，实现部分钢渣替代水泥制备钢渣微粉-水泥泡沫轻质土，制备更加经济型的高性能泡沫轻质土。【方法】 采用抗压强度、抗硫酸盐腐蚀等试验研究不同钢渣微粉掺量（质量比，下同）、水灰比（质量比，下同）、湿密度等泡沫轻质土物理力学特性及耐久性。【结果】 随着钢渣微粉掺量的增加，泡沫轻质土抗压强度降低，吸水率增大，沉陷距减小；随着水灰比增大，泡沫轻质土吸水率、流值、沉陷距增大，抗压强度呈现先增后减的趋势，水灰比为0. 7时，龄期为 7、28、60 d的抗压强度达到最高，分别为 0. 68、0. 90、1. 28 MPa；随着湿密度的增大，抗压强度和流值增大，吸水率减小，沉陷距增大；施工湿密度为 600 kg/m3、水灰比为 0. 70、钢渣微粉掺量为 50%时，泡沫轻质土水稳定系数为0. 852，冻融稳定系数为0. 752，28 d抗压强度可以达到0. 90 MPa。【结论】 钢渣微粉和碱性激发剂的掺入，能够有效提高钢渣利用率，同时减少水泥使用量；掺量为50%的钢渣微粉-水泥泡沫轻质土的力学性能得到保障。

关键词：泡沫轻质土；钢渣微粉；物理特性；力学性能；耐久性

Abstract

Objective To enhance the utilization efficiency of steel slag solid waste， a method is devised to prepare steel slag powder-cement foam lightweight soil by substituting a portion of cement with steel slag. The road performance of foamed lightweight soil is then analyzed upon the incorporation of steel slag powder to develop economically viable， high-performance foamed lightweight soil.

Methods The PO42. 5 ordinary Portland cement and steel slag micro-powder were used as the main materials， complemented by sodium carbonate and triethanolamine agents， along with a composite foaming agent for preparation. During the experimental process， materials were weighed using an electronic balance and then mixed in a blender according to the designed proportions. Subsequently， diluted foaming agent was added to water to generate fine and dense foam. The foam was thoroughly mixed with the steel slag micro-powder-cement slurry and poured into cubic molds， followed by surface leveling. Regarding performance testing， standards were referenced for determining flowability， water absorption rate， water stability， and freeze-thaw stability. Additionally， settlement distance and compressive strength tests were conducted to measure the settlement and compressive strength of specimens at different ages. Furthermore， an anti-sulfate corrosion test was performed by immersing specimens in solutions of varying sulfate concentrations to assess changes in compressive strength over time. This work investigated the impact of varying steel slag powder content （40% to 70%）， water-cement ratio （0. 60 to 0. 75）， wet density grade （600 kg/m³ to 900 kg/m³）， and curing time on the flow value， water absorption， settlement distance， compressive strength， water stability，freeze-thaw stability， and sulfate corrosion resistance of foamed lightweight soil.

Results and Discussion As the steel slag powder content increases， the water absorption rate and flow value of steel slag powder-cement foam lightweight soil gradually increase. Simultaneously， the subsidence distance increases with the rise in water-cement ratio. The compressive strength initially increases and then decreases with the elevation of the water-cement ratio. This behavior is attributed to water's pivotal role as a raw material in facilitating the hydration reaction between steel slag powder and cement. Insufficient water content at low water-cement ratios impedes full hydration of the slurry material， causing agglomeration of steel slag powder and cement particles. Consequently， the generated hydration products inadequately fill the pores or adhere to the pore wall， resulting in reduced compressive strength of the specimen. At a water-cement ratio of 0. 7， the compressive strength at 28 days reaches its peak value of 0. 9 MPa， satisfying the specification requirements.

  At the same age， an increase in steel slag powder content leads to a significant decrease in the compressive strength of the specimens. This decline occurs because the gradual replacement of cement by steel slag powder results in a reduction of material actively participating in the overall reaction， leading to decreased hydration product formation and a looser structure.

  Furthermore， with an increase in steel slag powder content， steel slag powder-cement foam lightweight soil exhibits an upward trend， accompanied by a decrease in settlement distance. This phenomenon arises from the addition of an activator to enhance the activity of steel slag，promoting synergistic reactions with cement that rapidly elevate the early strength of steel slag powder-cement foam lightweight soil. This acceleration of the hydration reaction rate consequently reduces the settlement distance. Notably， the content of steel slag powder has minimal impact on the fluidity of steel slag powder-cement foam lightweight soil.

  The wet density grade exerts a significant influence on the compressive strength and flow value of steel slag powder-cement foam lightweight soil. With an increase in wet density grade， there is a notable improvement in compressive strength and flow value， accompanied by a reduction in water absorption rate. This enhancement is attributed to the increased proportion of cement and steel slag powder， resulting in reduced foam content and fewer pores. Concurrently， the subsidence distance exhibits an increasing trend with the rise in wet density grade due to decreased foam content， leading to slurry thinning and increased setting time.

  Steel slag powder-cement foam lightweight soil demonstrates favorable water stability and freeze-thaw stability. Although the dry-wet cycle diminishes the compressive strength of steel slag powder-cement foam lightweight soil， the strength loss is minimal. Similarly， the compressive strength of the specimen decreases under the influence of freeze-thaw cycles， with insignificant strength loss.

  For specimens with a steel slag powder content of 50%， water-cement ratio of 0. 70， and wet density grade of 600 kg/m³，the compressive strength in 5%，10%， and 15% sodium sulfate solutions is measured at 0. 76 MPa，0. 79 MPa， and 0. 83 MPa，respectively. Compared to the 7-day compressive strength of the G2 test group， these values represent an increase of 11. 76%，16. 18%， and 22. 05%， respectively. However， at the age of 28 days， the compressive strength remains unchanged when the concentration of sodium sulfate solution is 15%. Beyond 60 days， a significant decrease in compressive strength occurs，indicating excessive generation of ettringite crystals filling the pores and causing internal stress-induced cracking. When the stress surpasses the ultimate tensile stress of cement-steel slag powder foamed lightweight soil， plastic deformation occurs， leading to surface peeling.

Conclusion The incorporation of steel slag powder and alkaline activator proves to be an effective strategy in enhancing the utilization efficiency of steel slag. The mechanical properties of 50% high volume steel slag powder-cement foam lightweight soil are guaranteed.

Keywords：foam lightweight soil； steel slag powder； physical property； mechanical property； durability

参考文献（References）

［1］段德峰，刘润喜，王晓川，等. 钢渣在道路工程中的应用研究进展［J］. 河南科技，2021，40（23）：129-132.DUAN D F， LIU R X， WANG X C，et al. Research progress on the application of steel slag in road engineering［J］. Henan Science and Technology，2021，40（23）：129-132.

［2］GUO J， BAO Y， WANG M. Steel slag in China： treatment， recycling， and management［J］. Waste Management，2018，78：318-330.

［3］吴跃东，彭犇，吴龙，等. 国内外钢渣处理与资源化利用技术发展现状综述［J］. 环境工程，2021，39（1）：161-165.WU Y D， PENG B， WU L， et al. Development status overview of steel slag treatment and resource utilization technologies at home and abroad［J］. Environmental Engineering，2021，39（1）：161-165.

［4］KRISHNA A S， SIEMPU R， KUMAR G S. Study on the fresh and hardened properties of foam concrete incorporating fly ash［J］. Materials Today： Proceedings，2021，46：8639-8644.

［5］CHEN Y G， GUAN L L， ZHU S Y， et al. Foamed concrete containing fly ash： properties and application to backfilling［J］.Construction and Building Materials，2020，273（2）：121685.

［6］HE D L， LIAO H Q， GUO Z C， et al. Influence of steel slag powder with different specific surface area on the properties of foam concrete［C］//Advanced Materials Research. Zurich： Trans Tech Publications Ltd，2012，575：95-99.

［7］WANG Q， YAN P Y， HAN S. The influence of steel slag on the hydration of cement during the hydration process of complex binder ［J］. Science China Technological Sciences，2011，54（2）：388-394.

［8］赵正峰，王笑风，王国栋，等. 工业废渣复合胶凝材料泡沫轻质土制备及性能［J］. 硅酸盐通报，2022，41（6）：2108-2116. ZHAO Z F， WANG X F， WANG G D， et al. Preparation and properties of industrial waste composite cementitious foam lightweight soil［J］. Bulletin of the Chinese Ceramic Society，2022，41（6）：2108-2116.

［9］谢洪阳，戴宜文，任宇航，等. 多因素及干湿循环对泡沫混凝土性能的影响［J］. 中国粉体技术，2023，29（5）：125-134.XIE H Y， DAI Y W， REN Y H， et al. Influence of multiple factors and dry-wet cycles on the properties of foam concrete［J］. China Powder Science and Technology，2023，29（5）：125-134.