Deep soft soil improvement by alkaline activation

Cristelo, Nuno; Glendinning, S. G.; Pinto, Amândio Teixeira

doi:10.1680/grim.900032

Cited by 152 publications

(113 citation statements)

References 12 publications

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“…Basically, this is a consequence of the different nature of the soluble or glassy mass governing each material, in the sense that a calcium-based glass structure is more reactive with water than a siliceous-based glass structure (Diaz et al, 2010). The results presented show that the UCS of the low-Ca geopolymer almost doubled between the 28 and 90 days of curing, in agreement with previous research (Cristelo et al, 2011(Cristelo et al, , 2013. However, even if strength is continuously increasing, for tight construction projects it is not necessary to wait for such a long time, since considerable strength is obtained for smaller periods.…”

Section: Strength Analysissupporting

confidence: 90%

“…The use of local strain instrumentation by means of LDTs allowed a more accurate definition of the stress-strain curves, from which a representative example of each case is presented in Figure 6, clearly showing the significant effect of the alkaline binder on the strength increase. Such improvement has already been reported by Cristelo et al (2011Cristelo et al ( , 2012b, although using different activator compositions. The initial tangent stiffness obtained from the initial part of the stress-strain curves also showed a significant increase due to the alkaline binder, indicating that both strength and stiffness are affected by this stabilization.…”

Section: Strength Analysissupporting

confidence: 72%

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Structural Performance of Alkali-Activated Soil Ash versus Soil Cement

Rı́os

Cristelo

Fonseca

et al. 2016

J. Mater. Civ. Eng.

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115

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Alkaline activation of fly ash was used to improve the mechanical performance of a silty sand, considering this new material as a replacement of soil-cement applications namely bases and subbases for transportation infrastructures. For that purpose, specimens were molded from mixtures of soil, fly ash and an alkaline activator made from sodium hydroxide and sodium silicate. Uniaxial compression tests showed that strength is highly increased by the addition of this new binder. The results described a high stiffness material, with an initial volume reduction followed by significant dilation. All specimens have clearly reached the respective yield surface during shearing, and peak strength Mohr-Coulomb parameters were defined for each mixture. The evolution of the microstructure during curing, responsible for the mechanical behavior detected in the previous tests, was observed by scanning electron microscopy. These results were compared to soil-cement data obtained previously with the same soil at similar compaction conditions. The main difference between both binders was the curing rate, with alkali activated specimens showing a more progressive and long-lasting strength increase. This was analyzed taking into account the chemical process responsible for the behavior of the mixtures.

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Section: Strength Analysissupporting

confidence: 90%

Section: Strength Analysissupporting

confidence: 72%

Structural Performance of Alkali-Activated Soil Ash versus Soil Cement

Rı́os

Cristelo

Fonseca

et al. 2016

J. Mater. Civ. Eng.

Self Cite

115

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show abstract

“…These literatures are limited mainly to concrete, mortar and paste. Only recently, limited literatures for soil stabilization by alkali activated fly ash, metakaolin and slag have been reported (Verdolotti et al 2008;Cristelo et al 2011Cristelo et al , 2012Zhang et al 2013;Yaolin et al 2015;Du et al 2016). Among the works reported on alkali activation of slag (Yaolin et al 2015;Du et al 2016), study reported by Yaolin et al (2015) mainly emphasizes on effect of several alkali activator on the strength and microstructure properties of soft clay in grouting process.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, slag activated systems have very rapid setting time and low workability and can be improved by addition of fly ash to slag system (Nicholson and Fletcher 2005). Likewise, strength gain process is very slow for fly ash based system at ambient temperature and significant strength can only be achieved by elevated temperature curing (Verdolotti et al 2008;Cristelo et al 2011Cristelo et al , 2012. However, from practical consideration, curing at ambient temperature is much more convenient and realistic contrary to elevated temperature curing.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Behavior and Sulfate Resistance of Alkali Activated Stabilized Clayey Soil

2017

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Clayey subgrade soil requires treatment in order to make the subgrade stable for pavement structures. Treatment of clayey soil i.e. stabilization of clayey soil by cement, lime, and fly ash are established techniques used in geotechnical and highway engineering. Stabilization by alkali activation of fly ash is reported recently but literatures are limited. Present study investigates the stress strain behavior, peak stress and ultimate strain of clayey soil stabilized by slag and slag-fly ash blending by alkali activation. The peak stress as high as 25.0 N/mm 2 may be obtained at 50% slags content when 12 molar sodium hydroxide solutions were used. Peak stress, ultimate strain and slope of stress-strain curve of stabilized clay are controlled by Na/Al and Si/Al ratios. Stress-strain response and peak stress of slag and fly ash blended specimen are not governed by Na/Al and Si/Al ratios; rather the behavior is dependent predominantly on slag content.

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“…Cristelo et al (2011) [16] researched the optimum fly ash-based alkaline activated binder for the improvement of soil to be used in rammed earth construction through a parametric analysis using laboratory tests. Rios et al (2016) [17] compared the mechanical behaviour of samples of sand improved by alkali activated fly ash binder and by cement, highlighting the effective increase of shear strength soil properties induced by alkali activated binders.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Behaviour of Soil Improved by Alkali Activated Binders

et al. 2017

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Abstract:The use of alkali activated binders to improve engineering properties of clayey soils is a novel solution, and an alternative to the widely diffused improvement based on the use of traditional binders such as lime and cement. In the paper the alkaline activation of two fly ashes, by-products of coal combustion thermoelectric power plants, has been presented. These alkali activated binders have been mixed with a clayey soil for evaluating the improvement of its mechanical behaviour. One-dimensional compression tests on raw and treated samples have been performed with reference to the effects induced by type of binder, binder contents and curing time. The experimental evidences at volume scale of the treated samples have been directly linked to the chemo-physical evolution of the binders, investigated over curing time by means of X Ray Diffraction. Test results showed a high reactivity of the alkali activated binders promoting the formation of new mineralogical phases responsible for the mechanical improvement of treated soil. The efficiency of alkali activated binders soil treatment has been highlighted by comparison with mechanical performance induced by Portland cement.

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Deep soft soil improvement by alkaline activation

Cited by 152 publications

References 12 publications

Structural Performance of Alkali-Activated Soil Ash versus Soil Cement

Structural Performance of Alkali-Activated Soil Ash versus Soil Cement

Mechanical Behavior and Sulfate Resistance of Alkali Activated Stabilized Clayey Soil

Mechanical Behaviour of Soil Improved by Alkali Activated Binders

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