Engineering Characteristics and Microscopic Mechanism of Expansive Soil Improved by Carbide Slag

doi:10.16552/j.cnki.issn1001-1625.2025.0923

Abstract

Abstract:

Addressing the engineering geological disasters caused by the swelling-shrinking deformation and deteriorating mechanical properties of expansive soil in Yanbian area， Jilin Province， the improvement of expansive soil using carbide slag as a solidification material was studied in this paper. The expansion characteristics of carbide slag-improved expansive soil were explored through tests on free expansion rate， unloaded expansion rate， and expansion force. The strength and water stability characteristics of carbide slag-improved expansive soil were studied through unconfined compressive strength， direct shear， and water stability tests. The mechanism of carbide slag-improved expansive soil was investigated through tests on limit moisture content， conductivity， pH value， particle size distribution， X-ray diffraction， and scanning electron microscopy. The results indicate that the incorporation of carbide slag can inhibit the expansion characteristics of expansive soil and enhance the strength and water stability of the soil. The improvement effect is optimal when using 8% （mass fraction） carbide slag. The ion exchange reaction between carbide slag and expansive soil leads to flocculation and agglomeration of particles， resulting in a decrease in the clay particle content and an increase in the sand particle content of the improved expansive soil， as well as a reduction in the plasticity index. The high pH value of carbide slag provides a favorable alkaline environment for the pozzolanic reaction， and the hydrated calcium silicate and calcium silicoaluminate formed by hydration， along with calcium carbonate formed by carbonation， jointly bond and harden the soil particles to form a dense overall structure， thereby enhancing the strength of the improved expansive soil.

Key words: carbide slag, expansive soil, expansion characteristic, strength characteristic, water stability, microscopic mechanism

CLC Number:

TU443

YUAN Xiaoqing, ZHAO Xiangming, NIU Cencen, LIU Tiantian, GOU Yilin. Engineering Characteristics and Microscopic Mechanism of Expansive Soil Improved by Carbide Slag[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(4): 1445-1458.

Figures/Tables 21

Table 1 Basic physical and chemical indicators of expansive soil

Natural water content/%	Liquidlimit/%	Plasticlimit/%	Plasticityindex/%	Maximum dry density/（g·cm^-3）	Optimalmoisturecontent/%	Naturaldensity/（g·cm^-3）	Freeexpansion rate/%	pH value
20.61	50.29	25.07	25.22	1.675	19.513	2.02	71	7.3

Fig.1 Particle size distribution curves of expansive soil and carbide slag

Table 2 Mineral composition of expansive soil

Composition	Illite-smectite mixed layer	Illite	Kaolinite	Quartz	K-feldspar	Plagioclase	Hematite
Mass fraction/%	29.1	8.5	1.2	38.1	9.5	13.0	0.6

Table 3 Expansive potential classification of expansive soil

Degree of expansion	Free expansion rate/%	Montmorillonite content/%	Cation exchange capacity/（mmol·kg^-1）
Strong	≥90	≥27	≥360
Moderate	60~90	17~27	260~360
Weak	40~60	7~17	170~260

Table 4 Main chemical composition of carbide slag

Composition	SiO₂	Fe₂O₃	Al₂O₃	CaO	MgO	SO₃	Loss on ignition	Moisture	Other
Mass fraction/%	1.53	0.45	1.93	67.95	0	0.31	25.75	0.50	1.58

Fig.2 Preparation of specimens and test methods

Fig.3 Relationship between free expansion rate and carbide slag content

Fig.4 Relationship between unloaded expansion rate and carbide slag content

Fig.5 Relationship between expansive force and carbide slag content

Fig.6 Relationship between unconfined compressive strength and carbide slag content

Fig.7 Effect of carbide slag content on cohesion and internal friction angle

Fig.8 Morphology of soil after water immersion

Table 5 Water stability test results

CS content/%	Strength of specimen after28 d of curing/kPa	Strength after immersion for 1 d/kPa	Water stabilitycoefficient/%
2	389	124	31.9
4	749	458	61.1
6	1 187	847	71.4
8	1 342	1 039	77.4

Fig.9 Relationship between limit moisture content and carbide slag content

Fig.10 Conductivity of improved expansive soil at different curing ages

Fig.11 pH value of improved expensive soil at different curing ages

Fig.12 Particle size distribution of plain soil and improved expansive soil

Fig.13 XRD patterns of plain soil and improved expansive soil

Fig.14 SEM images of plain soil and improved expansive soil

Fig.15 EDS analysis results of hydration products

Fig.16 Schematic diagram of microscopic reaction mechanism

References 27

[1]	刘祖强，罗红明，郑敏，等. 南水北调渠坡膨胀土胀缩特性及变形模型研究［J］. 岩土力学， 2019， 40（增刊1）： 409-414.
	LIU Z Q， LUO H M， ZHENG M， et al. Study on swelling and shrinkage characteristics and deformation model of expansive soil on canal slope of South-to-North Water Transfer Project［J］. Rock and Soil Mechanics， 2019， 40（supplement 1）： 409-414 （in Chinese）.
[2]	曾浩，唐朝生，刘昌黎，等. 膨胀土干燥过程中收缩应力的测试与分析［J］. 岩土工程学报， 2019， 41（4）： 717-725.
	ZENG H， TANG C S， LIU C L， et al. Measurement and analysis of shrinkage stress of expansive soils during drying process［J］. Chinese Journal of Geotechnical Engineering， 2019， 41（4）： 717-725 （in Chinese）.
[3]	李治嘉，张登飞，李世雄，等. 干湿-冻融循环下膨胀土裂隙发育和强度劣化研究［J/OL］. 工程地质学报， 2024： 1-13 （2024-09-24）［2025-04-02］. https：//kns.cnki.net/kcms/detail/11.3249.P.20240924.1151.002.html.
	LI Z J， ZHANG D F， LI S X， et al. Study on crack development and strength deterioration of expansive soil under dry-wet-freeze-thaw cycle［J/OL］. Journal of Engineering Geology， 2024： 1-13 （2024-09-24）［2025-04-02］. https：//kns.cnki.net/kcms/detail/11.3249.P.20240924.1151.002.html （in Chinese）.
[4]	孙逊. 冻融循环作用下绥化地区膨胀土强度效应研究［D］. 长春：吉林大学， 2024： 1-3.
	SUN X. Study on strength effect of expansive soil in Suihua area under freeze-thaw cycle［D］. Changchun： Jilin University， 2024： 1-3 （in Chinese）.
[5]	许鹏. 汪延公路膨胀性软岩滑坡抗滑桩桩土效应研究［D］. 长春：吉林大学， 2013： 1-3.
	XU P. Study on pile-soil effect of anti-slide pile in expansive soft rock landslide of Wangyan Highway［D］. Changchun： Jilin University， 2013： 1-3 （in Chinese）.
[6]	胡其志，李俊杰，陶高梁，等. 高炉矿渣-电石渣复合改良膨胀土工程特性与机理研究［J］. 硅酸盐通报， 2025， 44（2）： 602-612.
	HU Q Z， LI J J， TAO G L， et al. Engineering property and mechanism of ground granulated blast slag-carbide slag composite improved expansive soil［J］. Bulletin of the Chinese Ceramic Society， 2025， 44（2）： 602-612 （in Chinese）.
[7]	ZHU J F， WANG Z Q， TAO Y L， et al. Macro-micro investigation on stabilization sludge as subgrade filler by the ternary blending of steel slag and fly ash and calcium carbide residue［J］. Journal of Cleaner Production， 2024， 447： 141496.
[8]	LIU Y W， WANG Q， LIU S W， et al. Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling［J］. Cold Regions Science and Technology， 2019， 161： 32-42.
[9]	SOUNDARA B， SENTHIL KUMAR K P. Industrial wastes as additive for stabilization of expansive soils： a review［J］. Discovery， 2015， 41（186）： 8-14.
[10]	ZHAO G W， YAN D Y， REN G Z， et al. Influence of ground granulated blast furnace slag on the dispersivity and mechanical property of dispersive soil［J］. Construction and Building Materials， 2023， 409： 134036.
[11]	孙树林，郑青海，唐俊，等. 碱渣改良膨胀土室内试验研究［J］. 岩土力学， 2012， 33（6）： 1608-1612.
	SUN S L， ZHENG Q H， TANG J， et al. Experimental research on expansive soil improved by soda residue［J］. Rock and Soil Mechanics， 2012， 33（6）： 1608-1612 （in Chinese）.
[12]	张玉国，赵春豪，张兆彬，等. 石灰-沸石粉改良膨胀土强度特性及微观机理研究［J］. 硅酸盐通报， 2024， 43（11）： 4167-4176.
	ZHANG Y G， ZHAO C H， ZHANG Z B， et al. Strength characteristics and microscopic mechanism of expansive soil improved by lime-zeolite powder［J］. Bulletin of the Chinese Ceramic Society， 2024， 43（11）： 4167-4176 （in Chinese）.
[13]	NALBANTOĞLU Z. Effectiveness of Class C fly ash as an expansive soil stabilizer［J］. Construction and Building Materials， 2004， 18（6）： 377-381.
[14]	董永刚，曹建新，刘飞，等. 电石渣理化性质的分析与表征［J］. 环境科学与技术， 2008， 31（9）： 95-98.
	DONG Y G， CAO J X， LIU F， et al. Analysis and characterization of physiochemical property of carbide slag［J］. Environmental Science & Technology， 2008， 31（9）： 95-98 （in Chinese）.
[15]	戈铭. 电石渣稳定土路基的试验研究［J］. 现代交通技术， 2015， 12（6）： 8-10+31.
	GE M. Experimental research on carbide slag stabilized soil subgrade［J］. Modern Transportation Technology， 2015， 12（6）： 8-10+31 （in Chinese）.
[16]	杜延军，刘松玉，魏明俐，等. 电石渣改良路基过湿土的微观机制研究［J］. 岩石力学与工程学报， 2014， 33（6）： 1278-1285.
	DU Y J， LIU S Y， WEI M L， et al. Micromechanism of over-wet clayey soils stabilized by calcium carbide residues［J］. Chinese Journal of Rock Mechanics and Engineering， 2014， 33（6）： 1278-1285 （in Chinese）.
[17]	查甫生，郝爱玲，赵林，等. 电石渣改良膨胀土试验研究［J］. 工业建筑， 2014， 44（5）： 65-69+105.
	ZHA F S， HAO A L， ZHAO L， et al. Experimental study of expansive soil treated with carbide slag［J］. Industrial Construction， 2014， 44（5）： 65-69+105 （in Chinese）.
[18]	WANG H X， JIANG M Y， CAO B Y， et al. Stabilized/solidified chlorine saline soils with ground granulated blast furnace slag and calcium carbide residue［J］. Construction and Building Materials， 2024， 449： 138490.
[19]	黎宇，胡明鉴，郑思维，等. 电石渣-矿渣固化膨胀土强度及微观机制研究［J］. 岩土力学， 2024， 45（增刊1）： 461-470.
	LI Y， HU M J， ZHENG S W， et al. Study on the strength and microscopic mechanism of calcium carbide slag-slag cured expansive soil［J］. Rock and Soil Mechanics， 2024， 45（supplement 1）： 461-470 （in Chinese）.
[20]	LIU Y Y， CHANG C W， NAMDAR A， et al. Stabilization of expansive soil using cementing material from rice husk ash and calcium carbide residue［J］. Construction and Building Materials， 2019， 221： 1-11.
[21]	邱明明，杨萌，李晓敏，等. 水泥固化高填方黄土抗压强度特性及其影响因素［J］. 硅酸盐通报， 2025， 44（5）： 1927-1938.
	QIU M M， YANG M， LI X M， et al. Compressive strength characteristics and its influencing factors of high fill loess solidified by cement［J］. Bulletin of the Chinese Ceramic Society， 2025， 44（5）： 1927-1938 （in Chinese）.
[22]	HORPIBULSUK S， PHETCHUAY C， CHINKULKIJNIWAT A. Soil stabilization by calcium carbide residue and fly ash［J］. Journal of Materials in Civil Engineering， 2012， 24（2）： 184-193.
[23]	谭鹏，谢振文，邓奇春，等. 复合固化高液限土的力学及水稳性研究［J］. 铁道科学与工程学报， 2022， 19（5）： 1298-1308.
	TAN P， XIE Z W， DENG Q C， et al. Mechanics and water stability of composite solidified soil with high liquid limit［J］. Journal of Railway Science and Engineering， 2022， 19（5）： 1298-1308 （in Chinese）.
[24]	XU X， LEI H M， WANG Q， et al. Polyaluminum chloride （PAC） modification of dispersive soil： a comprehensive study on dispersivity， mechanical properties， and microscale mechanisms［J］. Construction and Building Materials， 2024， 425： 135890.
[25]	刘宇翼. 电石渣-稻壳灰基胶凝材料固化膨胀土机理及其物理力学特性研究［D］. 徐州：中国矿业大学， 2019： 75-90.
	LIU Y Y. Study on mechanism and physical-mechanical properties of stabilized expansive soil by cementitious material from calcium carbide residue and rice husk ash［D］. Xuzhou： China University of Mining and Technology， 2019： 75-90 （in Chinese）.
[26]	吴燕开，王浩，苗盛瑶，等. 钢渣粉水泥改良膨胀土干湿循环下力学性能及机理分析［J］. 山东科技大学学报（自然科学版）， 2021， 40（2）： 41-50.
	WU Y K， WANG H， MIAO S Y， et al. Mechanical properties and mechanism of expansive soil modified by steel slag powder cement under dry-wet cycles［J］. Journal of Shandong University of Science and Technology （Natural Science）， 2021， 40（2）： 41-50 （in Chinese）.
[27]	SHEN Q， WANG C H， YAN Y， et al. Study on mechanism of mechanical property enhancement of expansive soil by alkali-activated slag［J］. Materials， 2025， 18（4）： 800.