Laboratory investigation of the strength development of alkali-activated slag-stabilized chloride saline soil

Yin, Chao; Yu, Hao; Zhu, Bo; Wei, Daoxin

doi:10.1631/jzus.a1500185

Cited by 16 publications

(4 citation statements)

References 15 publications

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“…Rajasekaran [3] investigated the treatment method of calcareous aluminite lime to treat clays and suggested that stabilization techniques should be used with caution in sulfate-rich clays. Cheng et al [4] explored the solidification of chlorine saline soil of slag and found that sodium chloride was the main cause affecting the strength of slag solidified chlorine saline soil. The relationship between strength increase and chlorine content was also identified.…”

Section: Introductionmentioning

confidence: 99%

Experiment and Improvement Mechanism Analysis on the Mechanical Properties of Improved Chlorine Saline Soil

Maimaitiyusupu,

Zhao,

Tao

2023

Advances in Civil Engineering

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Chlorine saline soil has adverse engineering geology such as dissolution, collapse, and pulping, the recycling of saline soil in subgrade treatment is of great research significance. First, the unconfined compressive strength (UCS) test was conducted using an orthogonal test design, and the optimal ratios of salt content, cement content, lime content, fiber content, and fiber length were determined. Second, the cyclic loading (CL) test was conducted using an orthogonal test design, and the influence of five factors, including freeze–thaw (FT) times, CL times, stress level (SL), amplitude, and frequency, on peak intensity, peak strain, and cumulative strain under FT cycles and natural air-drying (A-D) conditions were determined. Finally, the improvement mechanism of the above inorganic materials was microscopically analyzed by scanning electron microscope-energy dispersive spectrometer and X-ray diffraction tests. The UCS test results show that the improving effect of the optimal ratio for chlorine saline soil was best when the optimal ratio values were 3% (salt content), 8% (cement content), 12% (lime content), 0.2% (fiber content), and 18 mm (fiber length). CL test results show that with the increase in natural A-D time, it was found that the FT number and SL have significant effects on the strength, the number of FT times and cycle times have significant effects on the deformation, and the frequency and cycle times have significant effects on the cumulative deformation. From the microstructure analysis, the improvement mechanism is mainly the filling of pores and linking particles by water-hard gels and gas rigid gels to make the microstructure dense, effectively reduce pores, and effectively improve the engineering characteristics of chlorine saline soil. The results of this study provide a scientific basis for the engineering design of subgrade in arid areas and the in situ recycling of saline soil.

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Section: Introductionmentioning

confidence: 99%

Experiment and Improvement Mechanism Analysis on the Mechanical Properties of Improved Chlorine Saline Soil

Maimaitiyusupu,

Zhao,

Tao

2023

Advances in Civil Engineering

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“…Cheng et al [24] found that the addition of NaCl at a dosage between 0% and 5% resulted in a greater improvement in the strength of slag-based geopolymers. However, when the NaCl content exceeded 5%, the strength increase in slag-based geopolymers becomes lower.…”

Section: Introductionmentioning

confidence: 99%

Associated Effects of Sodium Chloride and Dihydrate Gypsum on the Mechanical Performance and Hydration Properties of Slag-Based Geopolymer

Shen

et al. 2023

Buildings

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The associated effect of sodium chloride and dihydrate gypsum on the mechanical performance of a slag-based geopolymer activated by quicklime was investigated by compressive strength, shrinkage, and square circle anti-cracking tests of mortar with a 0.5 water–binder ratio and a 1:3 binder–sand ratio, as well as paste soundness, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and mercury intrusion porosimetry (MIP) of the paste. The results indicate that (1) when dihydrate gypsum is used alone, it combines with calcium aluminate hydrate (C-A-H) to form calcium sulfoaluminate hydrate (AFt), which encourages the hydration process of slag. A 7.5% addition can result in an increase of 97.33% and 36.92% in 3-day and 28-day compressive strengths, respectively. When NaCl is used by itself, it facilitates the condensation of the aluminum silicate tetrahedron unit and generates zeolite. A 2% dosage can lead to a 66.67% increase in the 3-day compressive strength, while causing a 15.89% reduction in the 28-day compressive strength. (2) The combined effect of 2% NaCl and 7.5% gypsum results in the formation of needle-like and rod-shaped AFt, Friedel’s salt, and plate-like Kuzel’s salt in the geopolymer. This leads to an increase in 3-day and 28-day compressive strengths by 148% and 37.85%, respectively. Furthermore, it reduces the porosity by 18.7%. (3) Both NaCl and gypsum enhance the paste soundness of the slag-based geopolymer, and they do no harm to the crack resistance of the geopolymer. The drying shrinkage of the geopolymer at 28 days is just 0.48 × 10−3, which is only 66.7% of OPC. This slag-based geopolymer has a simple preparation process, good volume stability, low raw material cost, low energy consumption, and low carbon emissions. It can be used instead of 32.5 slag Portland cement in plain concrete applications, and has high engineering, economic, and environmental values.

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“…Qingfeng et al [9] used a nuclear magnetic resonance (NMR) technique to test the microstructural characteristics of the saline soil solidified with different proportions of water glass, lime and fly ash, lime, fly ash, and water glass, respectively, and analysed the solidifying effect of the saline soil. Research showed that saline soil stabilised by solidifying materials exhibited a higher strength [10][11][12]; however, solidifying materials also suffer certain disadvantages. For example, saline soil solidified by utilising lime has poor water stability; the strength of saline soil solidified with fly ash is low; saline soils solidified by using cement and high-performance cementitious composite materials are expensive.…”

Section: Introductionmentioning

confidence: 99%

Application Research of New Cementitious Composite Materials in Saline Soil Subgrade Aseismic Strengthening

Huang

Lyu

Peng

2020

Advances in Civil Engineering

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Saline soil affected by earthquakes and groundwater can lead to subgrade subsidence and collapse in highway construction. Consequently, considering the potential activity of the waste slag and magnesia, new cementitious composite materials used in solid saline soil were developed in our study. The unconfined compressive strengths of the saline soil solidified by the new cementitious composite materials with a combination of magnesium oxide, calcium oxide, gypsum, and mineral powder and cement were investigated, and the optimum dosage proportion of the new cementitious composite material for solidifying saline soil was determined; then the SEM, EDS, and XRD of the saline soil solidified by the new cementitious composite materials and cement were analysed. The research result showed that the saline soil solidified by our newly developed cementitious composite material showed compact internal structure and uniformly distributed soil particles; moreover, the new cementitious composite material exhibited a favourable solidifying effect on harmful ions in saline soil, and the Cl− trapping capacity of the new cementitious composite materials was stronger than that of cement. Finally, our developed cementitious composite material was applied to saline soil subgrade strengthening, and the displacement, acceleration, excess pore water pressure, and damage degree of the subgrade strengthening by our newly developed cementitious composite materials decreased remarkably; therefore, our newly developed cementitious composite material can improve the seismic behaviour of the saline soil subgrade and show potential future engineering application value.

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Laboratory investigation of the strength development of alkali-activated slag-stabilized chloride saline soil

Cited by 16 publications

References 15 publications

Experiment and Improvement Mechanism Analysis on the Mechanical Properties of Improved Chlorine Saline Soil

Experiment and Improvement Mechanism Analysis on the Mechanical Properties of Improved Chlorine Saline Soil

Associated Effects of Sodium Chloride and Dihydrate Gypsum on the Mechanical Performance and Hydration Properties of Slag-Based Geopolymer

Application Research of New Cementitious Composite Materials in Saline Soil Subgrade Aseismic Strengthening

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