PDF Tepfers R. 2008. “Investigation of different types of

on-site wastewater treatment â€“ polonite and other filter

The use of calcium-based stabilizers such as calcium oxide (lime) in sulfate-bearing clay soils has historically led to distress due to the formation of an expansive mineral called ettringite and possibly another such mineral, thaumasite. Predicting the precipitation of these minerals is a KEYWORDS: Swelling, ettringite, gypsum, sulphate attack, embankments 1 INTRODUCTION Sulphate attack in cement and lime treated soils has been often reported in stabilised road bases and subbases when the soil has some proportion of gypsum, or the treated soil is exposed to sulphated waters. Sulphate attack results in loss of strength and Pretreatment of the artificial lime-treated soil mixes with barium compounds was effective in eliminating ettringite formation. Further research is needed to assess the effectiveness and the required levels of barium pretreatment in field applications. However, heaving was observed when ettringite was formed inside the lime-treated soil specimen by including ionic reactions.

Ettringite formation in lime treated soils

BRE found this reaction product (Figure 2) on the intended site of a retail store where Lower Lias Clay was lime/cement stabilised in May and in excess of 100mm of ground heave had occurred by September [1]. When expansive soils containing sulfates are treated with calcium based stabilizers, calcium from stabilizer reacts with soil sulfate and clay alumina to form expansive mineral Ettringite. Formation and growth of the mineral Ettringite was reported as the cause of severe heaving in several pavement failures. The swelling distress observed in stabilized soils is found to be due to one or a combination of three separate mechanisms: (1) volumetric expansion during ettringite formation, (2) water movement triggered by a high osmotic suction caused by sulfate salts, and (3) the ability of the ettringite mineral to absorb water and contribute to the swelling process.

av M Baeckstroem · 2009 — on the limestone by Fe- and Al-compounds is avoided by oxygen elimination. materials is the mineral ettringite, formed from the reaction of calcium aluminate treated with ash have a significantly higher pH compared to the samples treated the oxygen diffusion coefficient in unsaturated media, with applications to soil.

on-site wastewater treatment â€“ polonite and other filter

Predicting the precipitation of these minerals is a KEYWORDS: Swelling, ettringite, gypsum, sulphate attack, embankments 1 INTRODUCTION Sulphate attack in cement and lime treated soils has been often reported in stabilised road bases and subbases when the soil has some proportion of gypsum, or the treated soil is exposed to sulphated waters. Sulphate attack results in loss of strength and Pretreatment of the artificial lime-treated soil mixes with barium compounds was effective in eliminating ettringite formation. Further research is needed to assess the effectiveness and the required levels of barium pretreatment in field applications. However, heaving was observed when ettringite was formed inside the lime-treated soil specimen by including ionic reactions.

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Feldspars, oxyhydroxides, and amorphous forms of alumina are some of the additional sources for alumina in soils that can undergo congruent or incongruent dissolution, releasing aluminum into solution. The treated soils may be in-place (subgrade) or borrow materials. Subgrade stabilization usually involves in-place “road mixing,” and generally requires adding 3 to 6 percent lime by weight of the dry soil.2 Bases: Lime can permanently stabilize submarginal base materials (such as clay-gravel, “dirty” Ettringite Formation in Lime-treated Soils - Free download as PDF File (.pdf) or read online for free.

The formation of ettringite and thaumasite in the lime treated soil and, thereby resulting damage is also termed as ''Sulphate Induced Heave'', ''Sulphate Attack'' or, ''Manmade Expansive Soil Ettringite Formation in Lime-Treated Soils: Establishing Thermodynamic Foundations for Engineering Practice DALLAS N. LITTLE (Corresponding Author) Professor, Department of Civil Engineering, 603E CE/TTI Building, Texas A&M University, College Station, Texas 77843-3135 Phone: (979) 845-9963, Fax: (979) 845-0278, E-mail: d-little@tamu.edu Ettringite formation was evidenced in all lime-treated samples, whenever sulfates were present. A non-expansive monosulfate calcium-aluminum-hydrate forms first in the high alumina content lime Ettringite Formation in Lime-Treated Soils: Establishing Thermodynamic Foundations for Engineering Practice. The use of calcium-based stabilizers such as calcium oxide (lime) in sulfate-bearing clay soils has historically led to structural distress because of the formation of a mineral called ettringite and possibly thaumasite. Ettringite is a complex mineral that can be seen in cement and lime treated soils due to the reaction between solid material containing calcium, aluminium and iron, especially in the presence of sulphate enriched environment.
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17 Aug 2015 Transcript of Ettringite Formation in Lime-treated Soils. Invalid document format. Top related. 301 DIVISION 300 BASES AND GRANULAR Lime treatment of subgrade soils is intended to expedite construction, and no with the calcium from the lime or the alumina from the clay minerals to form ettringite, the formation of tufa (calcium deposits) clogging drains and fi 10 Aug 2006 A pilot-scale treatment study was implemented at a deposition site of chromite solution to delayed ettringite formation, which would hamper site redevelopment. Addressing Sulfate-Induced Heave in Lime Treated Soils References.

bränd kalk med hög kalciumhalt constantly being asked:How may I determine whether my soil is acid and in need of lime? powder prepared from quicklime : -in case of the alcohol-water successive treatment-However, the formation mechanism of surface area in the calcium hydroxide There were no measurable advantages on biomass growth or soil The mechanisms of such a fine structure formation were shown to manifest different Additionally, the efficiency of a pre-treated hydrated lime with larger specific surface and pore It is thus likely that ettringite governs antimony leachability at alkaline pH. It might also be structures in contact with saline soil or saline water. Delayed ettringite formation appears when the concrete has been cured at Thaumasite formation might occur when the concrete contains limestone aggregate or contains cement with limestone In section 8.2 frost attack in presence of salt is treated.
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The researchers tested the hypothesis that ettringite crystal growth could be inhibited by adding a specific chemical that would prevent nucleation of ettringite crystallites, much like The treated soils may be in-place (subgrade) or borrow materials.

clayey soil named Eagle Ford predominant in Texas, United States. Hydrated high-calcium lime with 94% of Ca(OH)2, henceforward called “hydrated lime” was used in this study contains. Lime-soil mixtures were prepared with dosage rates based on the dry weight of soil to be treated. The centrifuge test for evaluating swelling behavior of into question if the soil being treated contains sulfate. Indeed, the application of lime in this situation can lead to ettringite formation causing heave and sulfate-bearing soils.