scholarly journals The Equilibrium Time and Salt Expansion Characteristic of Sulfate Saline Soil upon Cooling

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Yanjie Ji ◽  
Xu Li ◽  
Wei Wang ◽  
Li Liu
Keyword(s):  
Sodium Sulfate ◽  
Saline Soil ◽  
Standard Procedure ◽  
Sulfate Solution ◽  
Soil Consolidation ◽  
Stabilization Time ◽  
Equilibrium Time ◽  
One Dimensional ◽  
Expansion Test ◽  
Stability Time

The salt expansion disease is severe for the soil containing sodium sulfate in cold regions. This paper carried out one-dimensional salt expansion tests of saline soil, the crystallization test of saturated sodium sulfate solution, and the numerical cooling tests to explore the stability time of the salt expansion test and determine the standard procedure of salt expansion tests. The test results demonstrate that (i) the temperature equilibrium and the crystallization process are almost simultaneously completed in both sulfate saline soil and sulfate solution upon cooling; (ii) referring to the deformation equilibrium standard used in soil consolidation test, an expansion rate of less than 0.02 mm/h is suggested in the saline expansion test; and (iii) the equilibrium time is found to have a quadratic polynomial relationship to sample size and is much shorter under liquid bath conditions than under gas bath conditions. Based on these findings, a standard procedure of the one-dimensional salt expansion test is proposed, in which the test equipment, the test process, the deformation stabilization time of salt expansion, and the data processing method are provided. As the deformation and the temperature are synchronized, the deformation stabilization time of samples with different sizes in different cooling media is recommended.

scholarly journals The equilibrium time and deformation characteristic of sulfate saline soil in 1D saline expansion test

2021 ◽  
Vol 135 (2) ◽  
pp. 58-63
Author(s):  
Y.J. Ji ◽  
◽  
X. Li ◽  
Keyword(s):  
Saline Soil ◽  
Standard Procedure ◽  
Deformation Characteristic ◽  
Test Method ◽  
Equilibrium Time ◽  
One Dimensional ◽  
Expansion Test ◽  
Temperature Equilibrium ◽  
Cooling Media ◽  
Stability Time

The salt expansion disease is serious for the soil containing sodium sulfate in cold regions. This paper carried out one-dimensional swelling tests of saline soil, and numerical cooling tests of soil to explore the stability time of salt swelling deformation and determine the standard procedure of the salt swelling test method. The test results demonstrate that: (A) the temperature equilibrium and crystallization process are almost completed simultaneously in the one-dimensional (1D) salt expansion test; (B) Referring to the standard of consolidation test, a standard that the expansion rate is less than 0.02mm/h can be used in the salt expansion test; (C) The required time for temperature equilibrium of soil is quadratic to sample size and is much faster with liquid bath condition comparing to gas bath condition. Because the deformation and temperature are synchronized, the deformation stabilization time of different size samples in different cooling media is recommended.This can provide a reference for the deformation equilibrium time of the salt swelling test.

scholarly journals Experimental Study on Influence of Vaporous Water on Salt Expansion of Sulfate Saline Soil

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Shuquan Peng ◽  
Fan Wang ◽  
Ling Fan
Keyword(s):  
Relative Humidity ◽  
Liquid Water ◽  
Sodium Sulfate ◽  
Saline Soil ◽  
Sulfate Solution ◽  
Experimental Results ◽  
X Ray Diffraction ◽  
Expansion Test ◽  
Expansion Mechanism ◽  
New Treatment

The harm of salt expansion of saline soil in arid areas has always been a major problem to be solved urgently. According to the conversion rule between sodium sulfate and sodium sulfate decahydrate, sodium sulfate decahydrate crystals can be precipitated from sodium sulfate solution by cooling. Besides, when the relative humidity (RH) exceeds the critical relative humidity (CRH), sodium sulfate decahydrate can be formed by the combination of sodium sulfate and vaporous water, resulting in the salt volume expansion. However, at present, in the salt expansion mechanism of sulfate saline soil, only the influence of liquid water is considered while vaporous water is not involved. To study the effects of temperature, salinity, and ARH on salt expansion, the salt expansion test of dry sulfate saline soil under the action of vaporous water was conducted, and its composition was analyzed by X-ray diffraction (XRD) technology. Experimental results showed that sodium sulfate decahydrate crystals were produced in the sulfate saline soil if the relative humidity (RH) of pore gas exceeded the critical one so that salt expansion occurred. Salt expansion and salt expansion rate of sulfate saline soil increased with the increase of RH and salinity but decreased with the increase of temperature. Therefore, the new salt expansion mechanism of sulfate saline soil under vaporous water is verified. The experimental results further perfected the original salt expansion mechanism of sulfate saline soil under the action of liquid water and guided the study of new treatment methods of sulfate saline soil.

scholarly journals A Novel Approach to the Analysis of the Soil Consolidation Problem by Using Non-Classical Rheological Schemes

2021 ◽  
Vol 11 (5) ◽  
pp. 1980
Author(s):  
Kazimierz Józefiak ◽  
Artur Zbiciak ◽  
Karol Brzeziński ◽  
Maciej Maślakowski
Keyword(s):  
Constitutive Models ◽  
Organic Soil ◽  
Organic Soils ◽  
Soil Consolidation ◽  
Flexible Tool ◽  
One Dimensional ◽  
Novel Approach ◽  
Soil Skeleton ◽  
The One ◽  
The Relationship

The paper presents classical and non-classical rheological schemes used to formulate constitutive models of the one-dimensional consolidation problem. The authors paid special attention to the secondary consolidation effects in organic soils as well as the soil over-consolidation phenomenon. The systems of partial differential equations were formulated for every model and solved numerically to obtain settlement curves. Selected numerical results were compared with standard oedometer laboratory test data carried out by the authors on organic soil samples. Additionally, plasticity phenomenon and non-classical rheological elements were included in order to take into account soil over-consolidation behaviour in the one-dimensional settlement model. A new way of formulating constitutive equations for the soil skeleton and predicting the relationship between the effective stress and strain or void ratio was presented. Rheological structures provide a flexible tool for creating complex constitutive relationships of soil.

Calculation and Analysis on the Soft Soil Foundation Settlement with Elastic-Visco-Plasticity (EVP) Model

2018 ◽  
Vol 1145 ◽  
pp. 8-16 ◽  
Author(s):  
Jing Rui Guo ◽  
Xian Chang Zheng ◽  
Ji Qing Zhang ◽  
Zhi Meng Zhao
Keyword(s):  
Soft Soil ◽  
Soil Consolidation ◽  
One Dimensional ◽  
Model Study ◽  
Long Time ◽  
Soft Soil Area ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Soil Area ◽  
Engineering Monitoring

The EVP model is an available method to apply to the vertical settlement of soft soil consolidation calculation and analysis. Compared with Visco-Plasticity model, it shows more consistent with the actual stress conditions of the soil. In this paper, We have extracted soil samples in BinHai garden for assay. Then through the comparison with calculating results and a long-time engineering monitoring in BinHai garden soft soil area, a feasibility EVP model study on the vertical settlement in soft soil area is peoposed. Further a consequent sedimentation forecast was made according with the EVP model calculation. In the end, the settlement influence from creep was analyzed through one-dimensional consolidation theory.

X-Ray Microtomography of an Astm C109 Mortar Exposed to Sulfate Attack

1994 ◽  
Vol 370 ◽  
Author(s):  
D.P. Bentz ◽  
Nicos. S. Martys ◽  
P. Stutzman ◽  
M. S. Levenson ◽  
E.J. Garboczi ◽  
...  
Keyword(s):  
Cement Paste ◽  
Sodium Sulfate ◽  
Three Dimensional ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Mortar Sample ◽  
Air Voids ◽  
X Ray ◽  
Dimensional Image

AbstractX-ray microtomography can be used to generate three-dimensional 5123 images of random materials at a resolution of a few micrometers per voxel. This technique has been used to obtain an image of an ASTM C109 mortar sample that had been exposed to a sodium sulfate solution. The three-dimensional image clearly shows sand grains, cement paste, air voids, cracks, and needle-like crystals growing in the air voids. Volume fractions of sand and cement paste determined from the image agree well with the known quantities. Implications for the study of microstructure and proposed uses of X-ray microtomography on cement-based composites are discussed.

Impact of the Kinetics of Salt Crystallization on Stone Damage During Rewetting/Drying and Humidity Cycling

2013 ◽  
Vol 80 (2) ◽  
Author(s):  
Julie Desarnaud ◽  
François Bertrand ◽  
Noushine Shahidzadeh-Bonn
Keyword(s):  
Sodium Sulfate ◽  
Phase Contrast ◽  
Sulfate Solution ◽  
Salt Crystallization ◽  
Severe Damage ◽  
Contrast Microscopy ◽  
Salt Crystals ◽  
High Concentrations ◽  
The Impact ◽  
Kinetics Of

In this study, we show that the key to understand why the same salt can cause damage in some conditions and not in others is the kinetics of crystallization. We present experiments assessing the impact of the recrystallization dynamics of sodium sulfate on damage observed in sandstone after repeated cycles of rewetting/drying and humidification/drying. Macroscopic and microscopic scale experiments using magnetic resonance imaging and phase contrast microscopy demonstrate that sodium sulfate that has both hydrated and anhydrous phases can lead to severe damage in sandstone during rewetting/drying cycles, but not during humidity cycling. During rewetting (a rapid process) in regions (pores) that are highly concentrated in salt, anhydrous microcrystals dissolve only partially, giving rise to a heterogeneous salt solution that is supersaturated with respect to the hydrated phase. The remaining anhydrous crystals then act as seeds for the formation of large amounts of hydrated crystals, creating grape-like structures that expand rapidly. These clusters can generate stresses larger than the tensile strength of the stone, leading to damage. On the other hand, with humidification (a slow process) and after complete deliquescence of salt crystals, the homogeneous sodium sulfate solution can reach high concentrations during evaporation without any nucleation, favoring the formation of isolated anhydrous crystals (thenardite). The crystallization of the anhydrous salt generates only very small stresses compared to the hydrated clusters and therefore causes hardly any damage to the stone.

Durability of cement mortars incorporating limestone filler exposed to sodium sulfate solution

2014 ◽  
Vol 19 (5) ◽  
pp. 1347-1358 ◽  
Author(s):  
Jaesuk Ryou ◽  
Seungtae Lee ◽  
Daewook Park ◽  
Seongsoo Kim ◽  
Hoseop Jung
Keyword(s):  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Sodium Sulfate Solution ◽  
Limestone Filler ◽  
Cement Mortars
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