Experimental study on engineering characteristics of foamed lightweight soil based on saline soil
LU Zheng1，2，ZHANG Rong1，3，ZHAO Yang1，QIN Lang4，LIU Jie5，YAN Tingzhou6，LI Jian6，LI Bingwei7，ZHANG Jing8
(1. State Key Laboratory of Geomechanics and Geotechnical Engineering Safety，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. Hubei Key Laboratory of Geo-Environmental Engineering，Wuhan，Hubei 430071，China；3. University of Chinese Academy of Sciences，Beijing 100049，China；4. Sichuan Chengnan Expressway
Co.，Ltd.，Chengdu，Sichuan 610051，China；5. Xinjiang Transport Planning Survey and Design Institute Co.，Ltd.，
Urumqi，Xinjiang 830006，China；6. Hubei Communications Planning and Design Institute Co.，Ltd.，Wuhan，
Hubei 430051，China；7. Urumqi Transportation Infrastructure Construction Management Center，
Urumqi，Xinjiang 830063，China；8. Xizang Railway Construction Co.，Ltd.，Lhasa，
Xizang 850000，China)
Abstract：Saline soil is widely distributed in Xinjiang area，where using saline soil as foamed lightweight soil in subgrade backfill can effectively utilize excavated waste soil，and improve the durability of subgrade in Xinjiang cold and dry area due to the good thermal insulation performance. From this perspective，the influence of density，soil content and water to dry-material ratio on engineering characteristics of saline soil-based foam lightweight soil was studied in this paper. Firstly，a series of tests were conducted to compare the thermal conductivity，fluidity，water absorption and stability of different ratios. Secondly，the unconfined compressive strength of samples under various conditions(e.g.，freeze-thaw cycle and dry-wet cycle) was obtained，in which the mechanical properties index and energy absorption rate were also studied. Finally，the pore microstructure of foamed lightweight soil was deeply analyzed by SEM and image processing software. The experimental results show that moisture and foam content greatly affect the fluidity of foamed lightweight soil. The water absorption decreases gradually with the increase in density. The foamed lightweight soil presents good thermal insulation performance. In detail，the thermal conductivity is about 1/6‐1/10 of the ordinary compacted soil. Also，there is a well-linear relationship between the density and the thermal conductivity. Under the freeze-thaw cycles，dry-wet cycles and immersed water conditions，the unconfined compressive strength of the samples decreases by 40%‐50%. Regarding microstructure characteristics，the number and roundness of pores increased with the increase in density. The structure of pores can serve as a“bridge”to establish a connection between its microstructure and macroscopic mechanical properties. In the study，it is recommended that the density of 800‐1 200 kg/m3，the salt soil content is not more than 40%，and the water-material ratio is 0.45‐0.55 can be regarded as the optimum ratio. The unconfined compressive strength of the described above ratio is about 0.6‐1.0 MPa，meeting the requirement of subgrade strength，thermal insulation，and durability.
[1] 陈正汉，郭 楠. 非饱和土与特殊土力学及工程应用研究的新进展[J]. 岩土力学，2019，40(1)：51–54.(CHEN Zhenghan，GUO Nan. New developments of mechanics and application for unsaturated soils and special soils[J]. Rock and Soil Mechanics，2019，40(1)：51–54.(in Chinese))
[2] AMRAN Y H M，FARZADNIA N，ALI A A A. Properties and applications of foamed concrete；a review[J]. Construction and Building Materials，2015，101：990–1005.
[3] YE Y Q，HAN J，LIU H，et al. Pullout resistance of geogrid and steel reinforcement embedded in lightweight cellular concrete backfill[J]. Geotextiles and Geomembranes，2022，50(3)：432–443.
[4] MAGNUSSON S，LUNDBERG K，SVEDBERG B，et al. Sustainable management of excavated soil and rock in urban areas-a literature review[J]. Journal of Cleaner Production，2015，93：18–25.
[5] HUANG T，KOU S C，LIU D Y，et al. Evaluation of the techno-economic feasibility for excavated soil recycling in Shenzhen，China[J]. Sustainability，2022，14(5)：3 028.
[6] KIM Y T，KIM H J，LEE G H. Mechanical behavior of lightweight soil reinforced with waste fishing net[J]. Geotextiles and Geomembranes，2008，26(6)：512–518.
[7] ERAS J J C，GUTIÉRREZ A S，CAPOTE D H，et al. Improving the environmental performance of an earthwork project using cleaner production strategies[J]. Journal of Cleaner Production，2013，47：368–376.
[8] 欧孝夺，彭远胜，莫 鹏，等. 掺铝土尾矿泡沫轻质土的物理力学及水力特性研究[J]. 材料导报，2020，34(增1)：241–245.(OU Xiaoduo，PENG Yuansheng，MO Peng，et al. Study on the physical mechanical and hydraulic properties of foamed mixture lightweight soil mixed with bauxite tailings[J]. Materials Reports，2020，34(Supp.1)：241–245.(in Chinese))
[9] 胡新萍，李翔宇，韩保清，等. 泡沫混凝土的导热系数和强度研究[J]. 硅酸盐通报，2014，33(11)：2 940–2 945.(HU Xinping，LI Xiangyu，HAN Baoqing，et al. Study on thermal conductivity and mechanical strength of foamed concrete[J]. Bulletin of the Chinese Ceramic Society，2014，33(11)：2 940–2 945.(in Chinese))
[10] 彭远胜，欧孝夺，姬凤玲. 铝土尾矿泡沫轻质土的物理力学性能及细观特征[J]. 材料导报，2022，36(17)：128–133.(PENG Yuansheng，OU Xiaoduo，JI Fengling. Physical and mechanical properties and meso-characteristics of foamed mixture lightweight soil with bauxite tailings[J]. Materials Reports，2022，36(17)：128–133.(in Chinese))
[11] 石锦炎，韩 丹，刘嫄春，等. 不同温度下泡沫混凝土热物理性能的研究[J]. 工程热物理学报，2020，41(7)：1 719–1 727.(SHI Jinyan，HAN Dan，LIU Yuanchun，et al. Investigation on thermophysical properties of foamed concrete at different temperatures[J]. Journal of Engineering Thermophysics，2020，41(7)：1 719–1 727.(in Chinese))
[12] 刘晓贺，岳祖润，胡田飞. 新型寒区高速铁路路基保温强化层的抑制冻胀效果研究[J]. 铁道学报，2022，44(2)：108–116.(LIU Xiaohe，YUE Zurun，HU Tianfei. Study on effect of frost heaving suppression of new type of thermal insulation strengthening layer for high-speed railway subgrade in cold region[J].Journal of the China Railway Society，2022，44(2)：108–116.(in Chinese))
[13] 陈成华，黄志超，黄俊杰，等. 纤维丝和网加筋泡沫轻质土力学特性和抗冻性[J]. 西南交通大学学报，2023，58(2)：462–469.(CHEN Chenghua，HUANG Zhichao，HUANG Junjie，et al. Mechanical property and frost resistance analysis of foamed lightweight soil with fiber filament and mesh reinforcement[J]. Journal of Southwest Jiaotong University，2023，58(2)：462–469.(in Chinese))
[14] 赵武胜，陈卫忠，谭贤君，等. 高性能泡沫混凝土隧道隔震材料研究[J]. 岩土工程学报，2013，35(8)：1 544–1 552.(ZHAO Wusheng，CHEN Weizhong，TAN Xianjun，et al. High-performance foam concrete for seismic-isolation materials of tunnels[J]. Chinese Journal of Geotechnical Engineering，2013，35(8)：1 544–1 552.(in Chinese))
[15] 袁志颖，陈 波，陈家林，等. 泡沫混凝土孔结构表征及其对力学性能的影响[J]. 复合材料学报，2023，40(7)：4 117–4 127.(YUAN Zhiying，CHEN Bo，CHEN Jialin，et al. Characterization of pore structure of foamed concrete and its influence on performance[J]. Acta Materiae Compositae Sinica，2023，40(7)：4 117–4 127.(in Chinese))
[16] 徐 方，顾功辉，黄晓明，等. 地质聚合物泡沫混凝土气孔结构形成机理研究[J]. 建筑材料学报，2020，23(5)：1 024–1 029.(XU Fang，GU Gonghui，HUANG Xiaoming，et al. Investigation on formation mechanism of pore structure in geopolymer foam concrete[J]. Journal of Building Materials，2020，23(5)：1 024–1 029.(in Chinese))
[17] 刘奎周，张建仁，田 湘，等. 利用H2O2发泡和碳化养护改善RMFC的固碳、力学和保温隔热性能[J]. 材料导报，2023，37(23)：11–15.(LIU Kuizhou，ZHANG Jianren，TIAN Xiang，et al. Improving carbon sequestration，mechanical properties and thermal insulation of RMFC by foaming with H2O2 and carbonization curing[J]. Materials Reports，2023，37(23)：11–15.(in Chinese))
[18] 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，2021，273：121685.
[19] 王小娟，刘 路，贾昆程，等. 陶粒泡沫混凝土的力学性能及吸能特性[J]. 建筑材料学报，2021，24(1)：207–215.(WANG Xiaojuan，LIU Lu，JIA Kuncheng，et al. Mechanical properties and energy absorption characteristics of ceramsite foam concrete[J]. Journal of Building Materials，2021，24(1)：207–215.(in Chinese))
[20] WASANTHA P L P，RANJITH P G，ZHAO J，et al. Strain rate effect on the mechanical behaviour of sandstones with different grain sizes[J]. Rock Mechanics and Rock Engineering，2015，48(5)：1 883–1 895.
[21] GHADAKPOUR M，CHOOBBASTI A J，KUTANAEI S S. Investigation of the deformability properties of fiber reinforced cemented sand[J]. Journal of Adhesion Science and Technology，2019，33(17)：1 913–1 938.
[22] RIO E，DRENCKHAN W，SALONEN A，et al. Unusually stable liquid foams[J]. Advances in Colloid and Interface Science，2014，205：74–86.
2025, Vol. 44 
