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Cited by 41Geotechnical Engineering and Soil StabilizationGeotechnical and construction materials studiesConcrete and Cement Materials Research

Expansive Soil Stabilization Using Alkali-Activated Fly Ash

Open access
Wang, Huan, Liu, Tengjiao, Yan, Chao, Wang, Jianqi·2023·Processes
DOI 10.3390/pr11051550
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Abstract

Expansive soil swells with water and shrinks with water loss, causing serious safety problems for construction projects. This study emphasizes alkali-activated binder (NaOH excited fly ash) stabilized expansive soil. We found that swelling decreased with an increase in the amount of NaOH in alkali-activated binder. It was found that the alkali-activated binder stabilized expansive soils (AABS) had higher shear strength than untreated expansive soils (US), manifested by increased cohesion and friction angle. In AABS, the highest cohesion and the highest shear strength were found when the NaOH mass was 6% of the fly ash mass. The strength of AABS was similar to that of US without curing. AABS had higher strength than US after 7 and 14 days of curing. The unconfined compressive strength increased with extension of curing time. Combined with XRD and SEM analysis, it was shown that the mechanism of AABS was the formation of C–S–H and (C,N)–A–S–H and the change in the internal structure of expansive soil. This investigation can solve both the expansive soil problem and provide new concepts for green development.

AI snapshot

Written from the paper’s full text.

TL;DR

Alkali-activated fly ash (NaOH-excited low-calcium fly ash) reduced swelling and increased shear and unconfined compressive strength of expansive soil, with 6% NaOH by fly ash mass (AABS2) giving the best overall performance. Microstructural analysis attributed the improvement to C-S-H and (C,N)-A-S-H formation and pore filling.

Key findings

  • Unloaded swelling rates were 9.1% for untreated soil (US), 7.3% for fly-ash-only soil (FS), and 5.97%, 5.23%, 4.75%, and 4.51% for AABS1–AABS4 as NaOH increased. Under 25 kPa load, AABS1–AABS4 swelling rates were 1.12%, 0.56%, 0.36%, and 0.18%; under 50 kPa, AABS2 and AABS3 were almost 0 and AABS4 was −0.07%.
  • Direct shear showed AABS1 had the maximum internal friction angle (34.58°), while AABS2 had the maximum cohesion (109.09 kPa); AABS2 had the highest shear strength overall, and AABS strengths exceeded FS and US.
  • Unconfined compressive strength increased with curing time. FS was 213.6 kPa uncured and 290.7 kPa after 14 days, an increase of 77.1 kPa or 36%; AABS strength was similar to US without curing but higher after 7 and 14 days.
  • XRD, SEM, and EDS indicated reaction products including C-S-H and (C,N)-A-S-H, with tobermorite and beidellite observed; gels filled pores and cemented particles, while excess NaOH caused brittleness and strength loss.

Methods

  • Expansive soil from northern Xinxiang City, Henan Province, excavated at 1.5–2 m depth, was dried, ground, and sieved to <2 mm. Low-calcium fly ash was Grade 1 with 2.4% loss on ignition and 89% strength activity index; NaOH was added in solid form at 4%, 6%, 8%, and 10% of fly ash mass.
  • Groups were untreated expansive soil (US), fly-ash-only stabilized soil (FS, 9% fly ash), and alkali-activated binder stabilized soils AABS1–AABS4. Samples were prepared at W/s = 0.2 and cured at 20 ± 2 °C and >95% humidity.
  • Tests included unloaded and loaded swelling tests (25 kPa and 50 kPa), direct shear after 7 days curing, unconfined compressive strength at 0, 7, and 14 days, plus XRD and SEM/EDS microstructural analysis.

Limitations

  • The paper does not state a limitations section.
  • Evident from the text: curing was limited to 14 days, the study used a single expansive soil source, and NaOH content was tested only at 4–10% of fly ash mass; no durability or wet–dry cycling tests were performed despite such tests being mentioned in the literature review.
  • Evident from the text: loaded swelling results are reported with mixed units (kPa and %), and several sections and paragraphs are duplicated, which complicates interpretation.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.3390/pr11051550

Cites

33 of 34 references verified0 citation errors · 1 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

13 of 42 cited sources checked · 2 supported · 0 flagged · accuracy not yet measured

  • Interpretationcitation

    Beidellite is formed by the presence of Ca2+ and Na+ cations in the reaction during alkali activation.

    “Beidellite ((Na, Ca)Al2Si4O10(OH)2) is formed by the presence of Ca 2+ and Na + cations in the reaction during alkali activation [39].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [39] Kar, 2014, Characterizations and quantitative estimation of alkali-activated binder paste from microstructures, Int. J. Concr. Struct. Mater. source

      The Summary and Conclusions (section 5; page unavailable) identify sodium aluminosilicate gel, calcium silicate hydrate, and several crystalline phases, but do not mention beidellite. Searches for “beidellite” and its stated formula found no passage linking its formation to Ca²⁺ and Na⁺ during alkali activation. (LLM, conf=0.75)

      Experimental — accuracy not yet measured
  • Interpretationcitation

    The presence of tobermorite reveals the formation of reaction products, since the low crystalline C-S-H resembles the structure of this mineral.

    “The presence of tobermorite [Ca5Si6O16(OH)2·4H2O] reveals the formation of reaction products, since the low crystalline C-S-H resembles the structure of this mineral [38].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [38] Zailani, W.W.A., Bouaissi, A., and Fansuri, H. (2020). Bonding Strength characteristics of FA-based geopolymer paste as a repair material when applied on OPC substrate. Appl. Sci., 10. source

      The Phase Analysis section identifies beidellite and fayalite as newly formed phases, while section 3.5 discusses formation of C-A-S-H gel at the interface. Searches for tobermorite and low-crystallinity C-S-H found no passage stating that tobermorite was present or that C-S-H resembles its structure. The copy therefore does not address the claim’s specific point. (LLM, conf=0.75)

      Experimental — accuracy not yet measured
  • Interpretationcitation

    The heterodyne peaks between diffraction angles 20°-30° (2θ) are attributed to disordered structures and highly amorphous contents such as the reaction products C-S-H and (C,N)-A-S-H.

    “The presence of heterodyne peaks between diffraction angles 20°-30° (2θ) is attributed to disordered structures and highly amorphous contents (i.e., reaction products such as C-S-H and (C,N)-A-S-H [24,39].”
    Quote in the paperNot a substantial claim1 of 2 sources checked
    • cites [24] Kar, 2013, Nondestructive characterizations of alkali activated fly ash and/orslag concrete, Eur. Sci. J. ESJ
    • cites [39] Kar, 2014, Characterizations and quantitative estimation of alkali-activated binder paste from microstructures, Int. J. Concr. Struct. Mater. source

      Section 3 (page unavailable) says an XRD hump or shoulder indicates amorphous phases and that small peaks in slag-containing samples indicate amorphous C-S-H. The copy does not place those features at 20°–30° (2θ) or identify a (C,N)-A-S-H product. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • Findingnone given

    The strength of AABS was similar to that of US without curing.

    “The strength of AABS was similar to that of US without curing.”
    Quote in the paperNot a substantial claim
  • Findingown data

    AABS had higher shear strength than untreated expansive soils (US), manifested by increased cohesion and friction angle.

    “It was found that the alkali-activated binder stabilized expansive soils (AABS) had higher shear strength than untreated expansive soils (US), manifested by increased cohesion and friction angle.”
    Quote in the paperSubstantial claim
  • May combine two claims. 86
  • The quote only partly states this claim. 4
  • Classified as probably not a substantial claim. 8

  • May combine two claims. The quote only partly states this claim.

    Interpretationcitation

    In AABS, NaOH provides a strong alkaline environment, inducing chemical reaction of amorphous silica and alumina in fly ash to generate N-A-S-H and C-S-H, which enhance connection between soil interiors and between soil and fly ash; these hydration products solidify and harden, fill soil interiors, and inhibit water-induced swelling.

    “The analysis concluded that in AABS, NaOH can provide a strong alkaline environment, which induces the chemical reaction of amorphous silica and alumina in fly ash to generate substances such as N-A-S-H, C-S-H, which enhance the connection between soil interiors and between soil and fly ash”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [33] Darius, Z., Danute, V., Stelmokaitis, G., and Viktoras, D. (2020). Clayey Soil Strength Improvement by Using Alkali Activated Slag Reinforcing. Minerals, 10. source

      Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured

  • May combine two claims.

    Premisecitation

    The alkali excitation process places material containing amorphous silica and alumina in an alkaline environment, and in a high-calcium system the C-A-S-H generated is similar to the C-S-H generated by Portland cement hydration.

    “The alkali excitation process means that the material containing amorphous silica (SiO 2 ) and alumina (Al 2 O 3 ) is placed in an alkaline environment, and in a system with high calcium (i.e., more calcium ions are present in the material), the C-A-S-H generated is similar to the C-S-H generated by the hydration of Portland cement [12,14].”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [12] Krivenko, 2017, Why alkaline activation—60 years of the theory and practice of alkali-activated materials, J. Ceram. Sci. Technol.

      Not checked in the free run.

    • cites [14] Palomo, 2014, A review on alkaline activation: New analytical perspectives, Mater. Construcc. source

      The available passages from the paper are reference entries, not its discussion of the reaction. Searches for alkaline activation of amorphous silica and alumina and for a comparison between high-calcium C-A-S-H and Portland-cement C-S-H found no passage in our copy that states the claim. (LLM, conf=0.73)

      Experimental — accuracy not yet measured

  • May combine two claims.

    Interpretationcitation

    Generated gel can promote connection between soil and soil, and soil and fly ash; fly ash appears as microbeads, and its outer layer is destroyed in alkaline environment, increasing contact with soil, thus increasing internal friction angle.

    “However, the generated gel can also promote the connection between soil and soil, and soil and fly ash [33], and the fly ash appears as microbeads, and the outer layer is destroyed in the alkaline environment, increasing the contact with the soil, thus increasing the internal friction angle.”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [33] Darius, Z., Danute, V., Stelmokaitis, G., and Viktoras, D. (2020). Clayey Soil Strength Improvement by Using Alkali Activated Slag Reinforcing. Minerals, 10. source

      Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Lime and cement treatment can effectively inhibit the expansion of expansive soil and provide significant strength increases.

    “A common treatment method in construction is to handle expansive soils with lime and cement, which can effectively inhibit the expansion of the soil and provide significant strength increases [5,8].”
    Quote in the paperSubstantial claim1 of 2 sources checked
    • cites [5] Woldesenbet, 2022, Experimental Study on Stabilized Expansive Soil by Blending Parts of the Soil Kilned and Powdered Glass Wastes, Adv. Civ. Eng. source
    • cites [8] Kamei, 2013, Durability of soft clay soil stabilized with recycled Bassanite and furnace cement mixtures, Soils Found. source

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The microstructure changes of AABS2 are similar to those reported in prior work.

    “The microstructure changes are similar to [37].”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites [37] Alemshet, 2023, Amelioration Effect of Fly Ash and Powdered Ground Steel Slag for Improving Expansive Subgrade Soil, Oxid. Med. Cell. Longev. source

  • May combine two claims.

    Premisecitation

    Use of lime and cement produces carbon dioxide, sulfur dioxide and other dust that affects air quality and has a deleterious environmental impact; carbon dioxide accounts for 8-10% of global emissions.

    “The use of lime and cement produces carbon dioxide, sulfur dioxide and other dust that affects air quality and that have a deleterious impact on the environment.Of these emissions, carbon dioxide accounts for 8-10% of global emissions [10][11][12].”
    Quote in the paperSubstantial claim2 of 3 sources checked
    • cites [10] Shihab, 2018, Effects of temperature in different initial duration time for soft clay stabilized by fly ash based geopolymer, Civ. Eng. J. source

      The Introduction says Portland cement production causes greenhouse-gas emissions and that controlling them is important. It does not say that lime production emits these pollutants, identify sulfur dioxide or dust as emissions affecting air quality, or give the claimed 8–10% share of global emissions. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites [11] Suhendro, 2014, Toward green concrete for better sustainable environment, Procedia Eng. source

      Section 1.1 and the Conclusions state that cement manufacturing accounts for 8–10% of worldwide CO₂ emissions and describe its environmental impact. The barriers-to-green-concrete table mentions SO₂, but the passages do not say that using lime and cement produces SO₂ or dust that affects air quality. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
    • cites [12] Krivenko, 2017, Why alkaline activation—60 years of the theory and practice of alkali-activated materials, J. Ceram. Sci. Technol.

      Not checked in the free run.

  • May combine two claims.

    Premisecitation

    In case of high water content, expansive soil expands and bulges, making the superstructure rise; when water content is small, it rapidly depresses causing the building to settle, often leading to disasters threatening people and property.

    “In the case of a high water content, the soil expands and bulges, making the superstructure rise; when the water content is small, the expansive soil will rapidly depress causing the building to settle, often leading to disasters that cause a serious threat to people and property [5][6][7].”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [5] Woldesenbet, 2022, Experimental Study on Stabilized Expansive Soil by Blending Parts of the Soil Kilned and Powdered Glass Wastes, Adv. Civ. Eng. source

      The Introduction (page unavailable) says expansive soil swells when wet and loses volume when dry; it also links swell–shrink behavior and settling to structural damage. It does not specifically say that swelling raises the superstructure, that drying causes rapid depression, or that this sequence often threatens people and property. (LLM, conf=0.85)

      Experimental — accuracy not yet measured
    • cites [6] Zha, 2008, Behavior of expansive soils stabilized with fly ash, Nat. Hazards source
    • cites [7] Jones, L.D., and Jefferson, J. (2012). ICE Manual of Geotechnical Engineering Volume 1: Geotechnical Engineering Principles, Problematic Soils and Site Investigation, The National Academies of Sciences, Engineering, and Medicine.

      Not checked in the free run.

  • May combine two claims.

    Findingcitation

    EDS analysis shows Si, Al, Na and Ca distributed in the mixtures, indicating the coexistence of C-S-H and (C,N)-A-S-H, the latter incorporating sodium cations from the activator.

    “These elements are distributed in the mixtures and indicate the coexistence of C-S-H and (C,N)-A-S-H, the latter incorporating sodium cations from the activator [33].”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites [33] Darius, Z., Danute, V., Stelmokaitis, G., and Viktoras, D. (2020). Clayey Soil Strength Improvement by Using Alkali Activated Slag Reinforcing. Minerals, 10. source

      Section 3.3 reports C-S-H and C-A-S-H phases in the alkali-activated slag–clay contact zone. It does not report EDS evidence that Si, Al, Na and Ca are distributed through the mixtures, or identify sodium incorporation in a (C,N)-A-S-H phase. The reported phase is C-A-S-H, not specifically (C,N)-A-S-H. (LLM, conf=0.85)

      Experimental — accuracy not yet measured

  • May combine two claims. The quote only partly states this claim.

    Interpretationown data

    The alkali excitation reaction explains the formation of the precipitates: dissolution of SiO2 and Al2O3 in fly ash in a strong alkali environment; CaO reacting with silicate and aluminate monomers to form reaction products and C-A-S-H and C-S-H; Na+ balancing charge and being absorbed by the silica-alumina phase to form N-A-S-H; and some Ca2+ displacing Na+ to form C-A-S-H.

    “The alkali excitation reaction can explain the formation of the above precipitates: (i) The dissolution of SiO 2 and Al 2 O 3 in fly ash in a strong alkali environment; (ii) A small amount of CaO in fly ash reacts with silicate and aluminate monomers to form reaction products; (iii) Some CaO reacts with silicate and aluminate monomers to form C-A-S-H, and some CaO reacts with silicate monomers to”
    Quote in the paperSubstantial claim1 of 3 sources checked
    • cites [19] Syed, 2020, Stabilization of expansive clayey soil with alkali activated binders, Geotech. Geol. Eng. source
    • cites [40] Palomo, 2013, Hydration kinetics in hybrid binders: Early reaction stages, Cem. Concr. Compos. source
    • cites [41] Ma, H., Zhu, H., Yi, C., Fan, J., Chen, H., Xu, X., and Wang, T. (2019). Preparation and reaction mechanism characterization of alkali-activated coal gangue-slag materials. Materials, 12. source

      Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

      Experimental — accuracy not yet measured

  • May combine two claims.

    Findingown data

    Compared to FS, the unloaded swelling rate decreased by 3.13%, 3.87%, 4.35% and 4.59% for AABS1, AABS2, AABS3, and AABS4, respectively.

    “Compared to FS, the unloaded swelling rate decreased by 3.13%, 3.87%, 4.35% and 4.59%.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    When the overlying load is 25 kPa, the swelling rate is 2.63 kPa for untreated expansive soil (US) and 1.82 kPa for FS, a decrease of 0.81 kPa without alkali excitation.

    “The swelling rate was 2.63 kPa for US and 1.82 kPa for FS when the overlying load was 25 kPa, and the swelling rate decreased by 0.81 kPa when there was no alkali excitation.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Alkali excitation causes the unloaded swelling rate to decrease, but the rate of decrease slows down as the NaOH content increases.

    “It was found that alkali excitation could cause the unloaded swelling rate to decrease, but the rate of decrease appeared to slow down as the NaOH content increased.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In AABS, internal friction angle and cohesion are further enhanced; AABS1 reaches a maximum internal friction angle of 34.58°, followed by a decrease in internal friction angle with increasing NaOH.

    “The internal friction angle and cohesion were further enhanced in AABS, with AABS1 reaching a maximum internal friction angle of 34.58°, followed by a decrease in internal friction angle with the increase in NaOH.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The difference in unloaded swelling rate between FS and AABS1 is 1.33%, while the difference between AABS3 and AABS4 is only 0.24%.

    “The difference in the unloaded swelling rate between FS and AABS1 is 1.33%, while the difference in the unloaded swelling rate between AABS3 and AABS4 is only 0.24%.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In AABS, the highest cohesion and the highest shear strength were found when the NaOH mass was 6% of the fly ash mass.

    “In AABS, the highest cohesion and the highest shear strength were found when the NaOH mass was 6% of the fly ash mass.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The expansibility of AABS2 and AABS3 is almost 0 under a 50 kPa overburden load, indicating no expansibility and expansion force consistent with the upper pressure.

    “The expansibility of AABS2 and AABS3 is almost 0, indicating that there is no expansibility at this point, and the expansion force is consistent with the upper pressure.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The unloaded swelling rates of AABS1, AABS2, AABS3, and AABS4 are 5.97%, 5.23%, 4.75%, and 4.51%, respectively.

    “The unloaded swelling rates of AABS1, AABS2, AABS3, and AABS4 were 5.97%, 5.23%, 4.75%, and 4.51%.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    From cohesion and internal friction angle, expansive soil values are the smallest, and FS shows a small increase in cohesion and internal friction angle.

    “From the perspective of cohesion and internal friction angle, the values of expansive soil are the smallest, and there is a small increase in cohesion and the internal friction angle of FS.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    When the overlying load is 50 kPa, the swelling rate is 1.46 kPa for US and 1.06 kPa for FS, a decrease of 0.4 kPa.

    “The swelling rate is 1.46 kPa for US and 1.06 kPa for FS when the overlying load is 50 kPa, and the swelling rate decreases by 0.4 kPa.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The cohesion of AABS2 is 109.09 kPa, the maximum among all groups, after which cohesion decreases with increasing NaOH.

    “The cohesion of AABS2 was 109.09kPa, which was the maximum among all groups, after which the cohesion also appeared to decrease with increasing NaOH.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Figure 6a shows more pores and cracks on the surface of the expansive soil, very poor internal denseness, and irregularly arranged pores that can easily become a water passage to make the soil swell.

    “Figure 6a shows that there are more pores and cracks on the surface of the expansive soil, and the internal denseness of the soil is very poor, and the pores are obviously irregularly arranged, and can easily become a water passage to make the soil swell.”
    Quote in the paperNot a substantial claim
    • The authors state this as an assumption: US, FS, and AABS2 are representative of their respective groups for SEM microstructural analysis.

  • May combine two claims.

    Findingown data

    When the overlying load is 25 kPa, the swelling rates of AABS1, AABS2, AABS3, and AABS4 are 1.12%, 0.56%, 0.36%, and 0.18%, respectively, which are 0.7%, 1.26%, 1.46%, and 1.64% lower than that of FS.

    “When the overlying load of all samples was 25 kPa, the swelling rates of AABS1, AABS2, AABS3, and AABS4 were 1.12%, 0.56%, 0.36%, and 0.18%, respectively, which were 0.7%, 1.26%, 1.46%, and 1.64% lower compared to the swelling rate of FS.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In AABS2 at 2000× magnification, a large fracture and many fine pores are observed; the newly generated objects such as calcium carbonate adsorbed by the gel fill the small pores, but the effect on the large fractures is not obvious.

    “Figure 8c shows the image magnified 2000 times, and a large fracture and many fine pores can be observed.It is thought that the newly generated objects such as calcium carbonate adsorbed by the gel have a filling effect on the small pores, and the effect on the large fractures is not obvious.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The pores of the expansive soil appear multi-layered, with layers superimposed by face-to-face contact, an overall wave pattern constituting a turbulent structure, locally oriented and irregularly arranged as a whole.

    “The pores appear multi-layered on the surface of soil samples, and the soil samples of different layers are superimposed by face-to-face contact, and the overall view shows a wave pattern, which constitutes a turbulent structure, and is locally oriented and irregularly arranged as a whole.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    AABS2 becomes more irregular, disorganized and finely fragmented internally in contrast to US; the stack and fish scale formed by sheet folding decreases and the block formed by gel and clay-like agglomerate accumulation increases.

    “AABS2 becomes more irregular, disorganized and finely fragmented internally in contrast to US.The stack and fish scale formed by sheet folding decreases, and the block formed by gel and clay-like agglomerate accumulation increases.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Too little NaOH is not significant for strength enhancement, and too much alkalinity decreases the strength and the destruction results in brittleness.

    “Too little NaOH is not significant for strength enhancement, too much alkalinity also decreases the strength and the destruction results in brittleness.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The shear strength of AABS2 was the highest, and the shear strength of AABS was greater than that of FS.

    “The shear strength of AABS2 was the highest, and the shear strength of AABS was greater than that of FS.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Under the cementation of colloid, fly ash is embedded and fixed in the soil sample, and the flake and flocculent structures of the soil sample bond into a smooth-massive structure.

    “Under the cementation of colloid, fly ash is embedded and fixed in the soil sample, and the flake structure and flocculent structure of the soil sample bond into a smooth and a smooth-massive structure.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    At 2000× magnification, the expansive soil sample mostly exists in flakes with a curved shape and an overall thick structure, with flocculating materials centered on montmorillonite in the pores and a small amount of montmorillonite distributed on the flakes.

    “The image in Figure 6c shows the surface of the soil sample at 2000 times magnification and the soil sample mostly exists in flakes with a curved shape, and an overall thick structure.Flocculating materials (centered on montmorillonite) can be found in the pores, and a small amount of montmorillonite is distributed on the flakes.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    AAB can improve the mechanical strength of soil, AABS2 can reach the maximum strength, and more NaOH makes the soil sample brittle and causes strength to decline.

    “According to the straight shear test and unconfined compressive strength test, AAB can improve the mechanical strength of soil, AABS2 can reach the maximum strength, and more NaOH will make the soil sample brittle and cause strength to decline.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Microscopic tests demonstrated that the reactions in AAB produced C-S-H and (C,N)-A-S-H, and that the new substances changed the internal structural arrangement of the soil, filled the pores and created adhesion with the clay.

    “Microscopic tests demonstrated that the reactions in AAB produced C-S-H and (C,N)-A-S-H, and that the new substances generated changed the internal structural arrangement of the soil, filled the pores and created adhesion with the clay.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    At 3000× magnification, the expansive soil lamellae are stacked and scaled, the surface aggregates into large particles, and the lamellae between particles show face-to-face, edge-to-edge, edge-to-surface and point-to-point contacts.

    “In Figure 6d, the accumulation of lamellae on the surface of the soil sample can be observed at 3000× as stacked and scaled.The surface of the soil sample becomes aggregated into large particles, and the lamellae between the particles are stacked in face-to-face contact and the surface overlaps into edge-to-edge contact and edge-to-surface contact, and point-to-point contact mainly exists near the”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingreasoning

    The strength of AABS still grows but slows down after 14 days of curing, and the strength of AABS is still higher than that of fly ash amended soil.

    “The strength of AABS still grows, but slows down after 14 days of curing, and the strength of AABS is still higher than that of fly ash amended soil”
    Quote in the paperSubstantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data

    At 2000× magnification, the fibrous gel overlaps and forms a bridge between the fly ash and soil particles, and the generated gel makes the spherical fly ash stack on top of each other and become a whole.

    “In Figure 7c, the fibrous gel image is magnified 2000 times, and it can be observed that the fibrous gel can overlap with each other and form a”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    After 7 days of curing, the shear strength of US was the lowest, the shear strength of FS increased but was limited, and the shear strength of AABS showed a substantial increase.

    “The shear strength of US was the lowest, the shear strength of FS increased but was limited, and the shear strength of AABS showed a substantial increase.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In AABS2 at 500× magnification, the spherical fly ash microbeads are significantly reduced and the gel increases; penetrating fractures are reduced but new tiny pores are created in the gel adhesion.

    “In Figure 8a, the fly ash in the form of spherical microbeads is significantly reduced and the gel increases.The penetrating fractures are reduced, but new tiny pores are created in the gel adhesion.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    The surface layer of the AABS2 soil sample is blocky as a whole, smooth in the area with few relevant reactions, and disordered and irregular in the area with concentrated reactions.

    “It can also be seen that the surface layer of the soil sample is blocky as a whole, but the surface still shows smoothness in the area with few relevant reactions, and in the area with concentrated reactions, the surface is disordered and irregular.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    At 1000× magnification, the surface of the expansive soil sample is curved, wrinkled and flattened, mostly curved and wrinkled, and the interior is mostly blocky with smooth edges.

    “The image in Figure 6b is magnified 1000 times, and shows that the surface of the soil sample is curved, wrinkled and flattened, flattened less, mostly curved and wrinkled, and the interior of the soil is mostly blocky with smooth edges.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The compressive strength of FS was 213.6 kPa when not cured and 290.7 kPa after 14 days of curing, an increase of 77.1 kPa or 36%.

    “The compressive strength of FS was 213.6 kPa when not cured, and 290.7 kPa after 14 days of curing, which increased the strength by a total of 77.1 kpa or 36%.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In all SEM images, the soil is embedded in a cementitious matrix composed of reaction products, and these products present great compositional heterogeneity and an amorphous structure.

    “In all SEM images, the soil is embedded in a cementitious matrix composed of reaction products.These products present a great compositional heterogeneity and amorphous structure, as seen in the XRD analysis.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    AAB can further reduce the swelling property of the soil, but the swelling property does not change significantly when the NaOH content is greater than 8%.

    “According to the unloaded swelling test and the loaded swelling test, it was found that AAB can further reduce the swelling property of the soil, but the swelling property does not change significantly when the NaOH content is greater than 8%.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In AABS2 at 1000× magnification, the fly ash is overall round but its surface changes from smooth to rough, NaOH erodes the surface and accelerates the release of activity, and gels and newly generated substances are attached to the surface.

    “At this time, the fly ash has an overall round shape, but the surface changes from smooth to rough, the NaOH erodes the surface and accelerates the release of activity, and there are gels and newly generated substances attached to the surface.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The expansive soil (US) has more pores and cracks on its surface, very poor internal denseness, and obviously irregularly arranged pores that can easily become a water passage to make the soil swell.

    “Figure 6a shows that there are more pores and cracks on the surface of the expansive soil, and the internal denseness of the soil is very poor, and the pores are obviously irregularly arranged, and can easily become a water passage to make the soil swell.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    At 1000× magnification, under the adhesive effect of the gel, fly ash and soil aggregate with each other into larger aggregates, and the large pores are filled, promoting the compactness of the soil sample.

    “Figure 7b shows the image with 1000× magnification, and it can be seen that under the adhesive effect of the gel, the fly ash and soil aggregate with each other and become larger aggregates.The large pores in the soil sample are filled and this promotes the compactness of the soil sample.”
    Quote in the paperSubstantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data

    At 3000× magnification, part of the gel clings to the fly ash and becomes its surface, increasing the viscosity and giving higher adhesion to the soil particles.

    “In Figure 7d, it can be observed that part of the gel clings to the fly ash and becomes the surface of the fly ash, thus increasing the viscosity and a higher adhesion to the soil particles.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    XRD shows the presence of quartzite, calcite, montmorillonite, illite, tobermorite and beidellite in the soil.

    “The presence of quartzite, calcite, montmorillonite and illite, tobermorite and beidillite can be observed in the soil.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingnone given

    Long pores are reduced and more tiny pores and cracks are created in the agglomerate.

    “Long pores are reduced and more tiny pores and cracks are created in the agglomerate.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The main components of fly ash are SiO2 and Al2O3, with amorphous and crystalline minerals co-existing in fly ash.

    “The main components of fly ash are SiO 2 and Al 2 O 3 , with amorphous and crystalline minerals co-existing in fly ash [23].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [23] Pannirselvam, 2018, Pulse Velocity Test on BananaFibre Concrete with Nano Silica, Int. J. Civ. Eng. Technol.

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    In AABS, NaOH reacts with silica and alumina to generate C-S-H and N-A-S-H gels, but the products are not generated immediately and need to react slowly over time.

    “In AABS, NaOH reacts with silica and alumina, respectively, and can generate C-S-H gels and N-A-S-H gels, but the products are not generated immediately, and need to react slowly over a period of time.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

    Interpretationown data

    This investigation can solve both the expansive soil problem and provide new concepts for green development.

    “This investigation can solve both the expansive soil problem and provide new concepts for green development.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    AABS1 has a high friction angle but low cohesion, so its overall shear strength is not the highest.

    “AABS1 has a high friction angle but low cohesion, so the overall shear strength is not the highest.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    NaOH corrodes clay particles and dissolves cementing material, causing the internal structure of the soil to loosen and become brittle, resulting in loss of strength.

    “The NaOH will corrode the clay particles and dissolve the cementing material in them, causing the internal structure of the soil to loosen and become brittle as a whole, resulting in a loss of strength [27,34].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [27] Gupta, 2018, Performance of alkali-activated binder-treated jute geotextile as reinforcement for subgrade stabilization, Int. J. Geotech. Eng. source
    • cites [34] Yu, 2015, Experimental study on the deformation characteristics and microstructure of clay polluted by alkaline solution, China Sci. Pap.

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Excessive NaOH in AABS4 destroys the surface layer of fly ash; fly ash shows mutual fusion and gels small particles into large agglomerates, so friction angle decreases.

    “The excessive amount of NaOH in AABS4, means the surface layer of fly ash is destroyed, and the fly ash shows mutual fusion and gels small particles into large agglomerates, so the friction angle decreases.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Low NaOH content makes the environment alkaline but cannot fully stimulate low calcium fly ash to produce silicate gel, so cohesion is not high enough.

    “The analysis shows that the low content of NaOH makes the environment alkaline which cannot fully stimulate the low calcium fly ash to produce silicate gel, so the cohesion is not high enough.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationcitation

    Low calcium fly ash has less calcium oxide content and poor early activity, cannot react with silica and alumina in the soil interior, so fly ash mainly relies on pore filling and ion exchange to reduce swelling.

    “Because low calcium fly ash has less calcium oxide content and poor early activity, it cannot react with silica and alumina in the soil interior, so fly ash mainly relies on pore filling and ion exchange to reduce swelling [19,32].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [19] Syed, 2020, Stabilization of expansive clayey soil with alkali activated binders, Geotech. Geol. Eng. source
    • cites [32] Alsafi, 2017, Collapsibility potential of gypseous soil stabilized with fly ash geopolymer; characterization and assessment, Constr. Build. Mater. source

  • May combine two claims.

    Premisecitation

    Production of lime and cement consumes large amounts of limestone, electricity and heat, with 7500 J/ton of electricity consumed to make cement.

    “Unfortunately, these two materials consume large amounts of limestone, electricity and heat in their production, with 7500 J/ton of electricity consumed to make cement [9].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [9] Higgins, 2007, Briefing: GGBS and sustainability, Const. Mater. source

  • May combine two claims.

    Interpretationown data

    Both FS and AABS can reduce the swelling of expansive soils, and AAB has a better effect.

    “Comprehensive analysis of the two swelling tests shows that both FS and AABS can reduce the swelling of expansive soils, and AAB has a better effect.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Fine particle size of fly ash fills the middle of clay particles, improves overall compactness, and makes compressive strength increase, but the increase is limited.

    “The fine particle size of fly ash fills in the middle of the clay particles, improves the overall compactness of the soil sample and makes the compressive strength increase, but the increase is limited.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    The new material generated from activation of fly ash by NaOH is similar to, but not identical to, the product of cement setting and hardening, so it is believed that the improvement of expansive soil also has the same effect.

    “The new material generated from the activation of fly ash by NaOH is similar to, but not identical to, the product of cement setting and hardening [24,25], so it is believed that the improvement of expansive soil also has the same effect.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [24] Kar, 2013, Nondestructive characterizations of alkali activated fly ash and/orslag concrete, Eur. Sci. J. ESJ
    • cites [25] Horpibulsuk, 2012, Soil stabilization by calcium carbide residue and fly ash, J. Mater. Civ. Eng. source

  • May combine two claims.

    Interpretationreasoning

    When there is no curing, the FS strength increase is small and mainly comes from the fill of fly ash.

    “When there is no curing, the FS strength increase is small and the increase is mainly from the fill of fly ash.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Fly ash contains high valence ions; Ca2+ and Mg2+ replace Na+ and K+ inside expansive soil, making the double electron layer thinner and reducing swelling stress.

    “On the other hand, fly ash contains more high valence ions, Ca 2+ and Mg 2+ replace Na + and K + inside the expansive soil, which makes the double electron layer thinner, thus reducing the generation of swelling stress.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    FS reduces expansibility because fly ash does not have expansibility itself, but replaces part of the expansive material and covers clay with a large specific surface area, preventing water from entering the soil interior and restraining expansion.

    “The analysis shows that on the one hand, FS reduces the expansibility because fly ash does not have the expansibility itself, but replaces part of the expansive material and covers the clay with a large specific surface area, which prevents part of the water from entering the soil interior and thus restrains the expansion of the soil sample.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    The mechanism of AABS is the formation of C-S-H and (C,N)-A-S-H and the change in the internal structure of expansive soil.

    “Combined with XRD and SEM analysis, it was shown that the mechanism of AABS was the formation of C-S-H and (C,N)-A-S-H and the change in the internal structure of expansive soil.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: US, FS, and AABS2 are representative of their respective groups for SEM microstructural analysis.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductreasoning

    The swelling tests were taken for each group of three specimens in parallel, and the average value was taken as the final result to reduce test error.

    “In order to reduce the test error, the swelling tests were taken for each group of three specimens in parallel, and the average value was taken as the final result.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationown data

    Excessive NaOH destroys adhesion between clay particles, so overall cohesion of AABS decreases.

    “The excessive amount of NaOH destroys the adhesion between clay particles, so that the overall cohesion of AABS appears to decrease.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Alkali-activated binders have a similar effect to cement but are less expensive to produce and more eco-friendly.

    “Alkali-activated binders have a similar effect to cement but are less expensive to produce and more eco-friendly [26,27].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [26] Miao, 2018, Mineral abundances quantification to reveal the swelling property of the black cotton soil in Kenya, Appl. Clay Sci. source
    • cites [27] Gupta, 2018, Performance of alkali-activated binder-treated jute geotextile as reinforcement for subgrade stabilization, Int. J. Geotech. Eng. source

  • May combine two claims.

    Interpretationown data

    Over all expansive soil pores there are irregular structures and soil sample particles with large specific surface areas that easily combine with water, resulting in swellability.

    “Over all the expansive soil pores there are irregular structures and soil sample particles with large specific surface areas that easily combine with water, resulting in swellability.”
    Quote in the paperSubstantial claim
    • The authors state this as an assumption: US, FS, and AABS2 are representative of their respective groups for SEM microstructural analysis.

  • May combine two claims.

    Premisecitation

    Alkali-activated binders can effectively replace cement and lime to stabilize soils, reducing greenhouse gas emissions by up to 80% compared to Portland cement applications.

    “Alkaliactivated binders, also known as alkaline cements, can effectively replace cement and lime to stabilize soils, reducing greenhouse gas emissions by up to 80% compared to Portland cement applications [13].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [13] Davidovits, 2015, False values on CO2 emission for geopolymer cement/concrete published in Scientific Papers, Geopolym. Inst. Libr. Tech. Pap.

      Not checked in the free run.

  • May combine two claims.

    Interpretationreasoning

    Cohesion and internal friction angle of expansive soils are relatively minimal, so their shear strength is the lowest.

    “The cohesion and internal friction angle of expansive soils are relatively minimal, so their shear strength is the lowest.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Premisecitation

    C-A-S-H has adhesive properties, which can fill the internal pores of soil and improve the overall strength and durability of soil samples.

    “C-A-S-H has adhesive properties, which can fill the internal pores of soil and improve the overall strength and durability of soil samples [15].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [15] Jia, 2018, Hydration products, internal relative humidity and drying shrinkage of alkali activated slag mortar with expansion agents, Constr. Build. Mater. source

  • May combine two claims.

    Interpretationreasoning

    High valence ions Ca2+, Mg2+, and Fe3+ in fly ash exchange with low valence ions Na+ and K+ in the soil, reducing the thickness of the double electric layer around soil particles, thus improving flocculation around clay particles.

    “The high valence ions Ca 2+ , Mg 2+ and Fe 3+ in fly ash exchange with the low valence ions Na + and K + in the soil, reducing the thickness of the double electric layer around the soil particles, thus improving the flocculation around the clay particles”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Poor early activity of FS leads to a slow reaction of volcanic ash, and strength increase comes from filling with fly ash on one hand and ion exchange on the other.

    “Poor early activity of FS leads to a slow reaction of volcanic ash, and strength increase comes from filling with fly ash on the one hand, and ion exchange on the other.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    The expansive soil particles have large specific surface areas that easily combine with water, resulting in swellability.

    “Over all the expansive soil pores there are irregular structures and soil sample particles with large specific surface areas that easily combine with water, resulting in swellability.”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    The conclusion that AABS2 has the best comprehensive effect is similar to the findings of prior studies.

    “This conclusion is similar to the findings in [27,35,36].”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [27] Gupta, 2018, Performance of alkali-activated binder-treated jute geotextile as reinforcement for subgrade stabilization, Int. J. Geotech. Eng. source
    • cites [35] Parhi, P.S., Garanayak, L., and Mahamaya, M. (2018). Sustainable Civil Infrastructures, Springer.

      Not checked in the free run.

    • cites [36] Santhikala, 2022, Stabilization of expansive soil using fly ash based geopolymer, Mater. Proc. source

  • May combine two claims.

    Interpretationown data

    Quartz comes from expanded clay and fly ash, and calcite comes from the reaction of calcium oxide in fly ash.

    “Quartz is chemically composed of silica, which comes from expanded clay and fly ash, and calcite is mainly composed of calcium carbonate, which comes from the reaction of calcium oxide in fly ash to produce an expansive clay.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    Elements in the lattice of illite and montmorillonite are replaced during chemical reactions, and Al3+ and Si4+ in the Al-OH octahedra and Si-O tetrahedra of montmorillonite are easily replaced by low-valent ions such as Na+ and Ca2+ in fly ash.

    “It is thought that there are elements in the lattice of illite and montmorillonite that are replaced during chemical reactions, and Al 3+ and Si 4+ in Al-OH octahedra and Si-O tetrahedra in montmorillonite are easily replaced by low-valent ions such as Na + and Ca 2+ in fly ash.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The presence of montmorillonite and illite is the reason for the swelling of expansive soils, and these minerals have become undetectable in FS and AABS.

    “The presence of montmorillonite and illite is the reason for the swelling of expansive soils, which has been undetectable in FS and ABBS.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The strength increase of fly ash improved soil is because fly ash activity is slowly excited in the soil with curing time, the alkali excitation reaction intensifies, and the generated silica-alumina gel fills the soil interior.

    “This is because it takes some time to harden via its own solidification, and with the increase in curing time, the activity of fly ash is slowly excited in the soil, the alkali excitation reaction is intensified, and the generated silica-alumina gel fills the soil interior.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The excessive addition of NaOH causes the soil to show overall brittleness and strength loss.

    “Considering that too many tiny cracks and pores make the soil sample brittle, the excessive addition of NaOH causes the soil to show overall brittleness and strength loss.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    In AABS, NaOH reacts with silica and alumina in fly ash to produce sodium silicate and sodium meta-aluminate, which mix to produce N-A-S-H gel.

    “The alkaline excitation of fly ash in AABS accelerates the alkali excitation reaction, and NaOH reacts with silica and alumina in fly ash to produce sodium silicate and sodium meta-aluminate, respectively, which are mixed to produce N-A-S-H gel.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    Fewer gels correspond to a more limited strength increase, consistent with the mechanical test conclusion.

    “However, fewer gels correspond to more limited strength increase.This is the same as result as the mechanical test conclusion.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The generation of new substances such as N-A-S-H gel enhances the internal association of the soil and forms agglomerates, causing the compressive capacity to increase significantly.

    “The generation of new substances such as N-A-S-H gel can enhance the internal association of the soil and form agglomerates, which causes the compressive capacity to increase significantly.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    The addition of fly ash reduces the proportion of cohesive particles, destroying the original structure of the expansive soil, while the gel fills the pores and improves overall compactness, so that strength is further improved and swelling is better resisted.

    “The addition of fly ash on the one hand reduces the proportion of cohesive particles, which destroys the original structure of the expansive soil and makes the internal structural arrangement change.On the other hand, gel is located inside the soil to fill the pores and improve the overall compactness, so that the strength can be further improved, and the swelling can be better resisted.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Uneven distribution of water in expansive soil leads to a great difference in expansion and contraction rate, leading to irregular distribution of cracks and instability after repeated water losses.

    “The uneven distribution of water in expansive soil leads to a great difference in the expansion and contraction rate of expansive soil, which leads to an irregular distribution of cracks and the instability of the soil after repeated water losses [4].”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [4] Puppala, 2017, Innovative ground improvement techniques for expansive soils, Innov. Infrastruct. Solut. source

  • May combine two claims.

    Interpretationreasoning

    At the end of the reaction, the hydrolysis products solidify and harden, interlocking the soil's internal mosaic of compact structure and increasing the later strength.

    “At the end of the reaction, the hydrolysis products begin to solidify and harden, interlocking the soil's internal mosaic of compact structure, thus increasing the later strength.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Overconsolidation causes expansive soil to have greater strength and stress.

    “Overconsolidation causes expansive soil to have greater strength and stress [1].”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [1] Chen, F.H. (1975). Foundations on Expansive Soils, Elsevier.

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    The study proposed an eco-friendly sustainable binder that can be used to improve the performance of expansive soil.

    “This study proposed an eco-friendly sustainable binder, which can be used to improve the performance of expansive soil.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationreasoning

    After the gel was hydrated and hardened, the high strength of the soil was ensured and the newly generated gel wraps around the clay particles, suppressing the swelling properties.

    “After the gel was hydrated and hardened, the high strength of the soil was ensured and the newly generated gel wraps around the clay particles, thus suppressing the swelling properties.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Premisecitation

    Expansive soils have hydrophilic minerals such as montmorillonite and illite, especially montmorillonite, which exhibits greater expansion potential at higher water content and higher sensitivity to water.

    “Expansive soils have hydrophilic minerals such as montmorillonite and illite, especially montmorillonite, which exhibits a greater potential for expansion at higher water content and has a higher sensitivity to water [2,3].”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [2] Mazhar, 2021, Strength characterisation of fiber reinforced expansive subgrade soil stabilized with alkali activated binder, Road Mater. Pavement.

      Not checked in the free run.

    • cites [3] Yi, 2015, Microstructural and mechanical properties of marine soft clay stabilized by lime-activated ground granulated blast furnace slag, Appl. Clay Sci. source
89 of 89

  • The paper relies on this without support.

    In China, the utilization rate of low-calcium fly ash is lower due to its own low calcium oxide content.

    “In China, the utilization rate of low-calcium fly ash is lower due to its own low calcium oxide content.”

  • The paper relies on this without support.

    The current production of fly ash in China greatly exceeds its consumption.

    “The current production of fly ash in China greatly exceeds its consumption.”

  • The authors state this as an assumption.

    US, FS, and AABS2 are representative of their respective groups for SEM microstructural analysis.

    “US, FS and AABS2 were selected as representative soil samples for microscopic qualitative analysis by SEM.”

  • The authors state this as an assumption.

    The rapid increase in strength of the fly ash improved soil occurs after 7 days of curing.

    “it can be assumed that the rapid increase in strength of fly ash improved soil is after 7 days”

  • The paper relies on this without support.

    The tested expansive soil and low-calcium fly ash are representative of expansive soils and low-calcium fly ash generally, so the findings generalize beyond the specific materials tested.

    “This study proposed an eco-friendly sustainable binder, which can be used to improve the performance of expansive soil.”
5 of 5

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • AABS3 swelling reduction uses the wrong baseline

    Minor

    The reduction from FS (7.3%) to AABS3 (4.75%) is 2.55 percentage points, not the reported 4.35. The reported value instead uses untreated soil as the baseline.

    Reported 4.35 · recomputed 2.55

  • AABS2 swelling reduction uses the wrong baseline

    Minor

    The reduction from FS (7.3%) to AABS2 (5.23%) is 2.07 percentage points, not the reported 3.87. The reported value instead uses untreated soil as the baseline.

    Reported 3.87 · recomputed 2.07

  • AABS1 swelling reduction uses the wrong baseline

    Minor

    The reported 3.13-percentage-point reduction is relative to untreated soil (9.1%), not FS (7.3%). Relative to FS, the reduction is 1.33 percentage points.

    Reported 3.13 · recomputed 1.33

  • AABS4 swelling reduction uses the wrong baseline

    Minor

    The reduction from FS (7.3%) to AABS4 (4.51%) is 2.79 percentage points, not the reported 4.59. The reported value instead uses untreated soil as the baseline.

    Reported 4.59 · recomputed 2.79

  • Loaded swelling rates are given in conflicting units

    Minor

    For the same 25 kPa overlying-load test, the US and FS swelling rates are stated in kPa, while the AABS swelling rates and their differences from FS are stated in percent.

5 of 5

Cites

Flagged first, then by citations

Research works printed but not linked: 7

  1. Chen, F.H. (1975). Foundations on Expansive Soils, Elsevier.
  2. Davidovits, 2015, False values on CO2 emission for geopolymer cement/concrete published in Scientific Papers, Geopolym. Inst. Libr. Tech. Pap., 24, 1
  3. Pannirselvam, 2018, Pulse Velocity Test on BananaFibre Concrete with Nano Silica, Int. J. Civ. Eng. Technol., 9, 2853
  4. Das, 2014, Current applications of x-ray powder diffraction—A review, Rev. Adv. Mater. Sci., 38, 95
  5. Mohammed, A., and Abdullah, A. (2018, January 7–9). Scanning Electron Microscopy (SEM): A Review. Proceedings of the 2018 International Conference on Hydraulics and Pneumatics, Băile Govora, Romania.
  6. Yu, 2015, Experimental study on the deformation characteristics and microstructure of clay polluted by alkaline solution, China Sci. Pap., 10, 1578
  7. Parhi, P.S., Garanayak, L., and Mahamaya, M. (2018). Sustainable Civil Infrastructures, Springer.

Cited by

Sorted by citations

Related

Authors
Wang, H., Liu, T., Yan, C., & Wang, J.
Affiliations
  • Henan University (CN)
  • Xinpu Construction Group Co., Ltd., Zhengzhou 450046, China
Corresponding author
Wang, Huan
ORCID
Venue
Processes
Publisher
MDPI AG
Published
2023-05-18
Volume
11
Issue
5
Pages
1550
ISSN
2227-9717 (ISSN-L)
DOI
10.3390/pr11051550
OpenAlex
W4377020448
Cited by
41
References
34
Citations by year
2026: 14 · 2025: 18 · 2024: 9
FWCI
4.80
Type
journal article
Language
en
Open access
Licence
Locations
Processes (publishedVersion, cc-by)
Topics
  • Physical Sciences › Engineering › Civil and Structural Engineering › Geotechnical Engineering and Soil Stabilization
  • Physical Sciences › Engineering › Civil and Structural Engineering › Geotechnical and construction materials studies
  • Physical Sciences › Engineering › Civil and Structural Engineering › Concrete and Cement Materials Research
Keywords
expansive soil, alkali-activated fly ash, soil stabilization, sodium hydroxide, swelling behavior, shear strength, cohesion and friction angle, unconfined compressive strength, curing, calcium silicate hydrate, sustainable construction materials

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-31.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-31.

Cited sources are checked by gpt-6-sol.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

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