scholarly journals Effects of pyrolysis temperature, feedstock type and compaction on water retention of biochar amended soil

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
He Huang ◽  
Narala Gangadhara Reddy ◽  
Xilong Huang ◽  
Peinan Chen ◽  
Peiying Wang ◽  
...  
Keyword(s):  
Water Retention ◽  
Pyrolysis Temperature ◽  
Chemical Properties ◽  
Bare Soil ◽  
Chicken Manure ◽  
Soil Water Retention ◽  
Amended Soils ◽  
Retention Behaviour ◽  
Water Retention Behaviour ◽  
Amended Soil

AbstractRecent studies on water retention behaviour of biochar amended soil rarely considers the effect of pyrolysis temperature and also feedstock type into account. It is well known that pyrolysis temperature and feedstock type influences the physical and chemical properties of biochar due to stagewise decomposition of structure and chemical bonds. Further, soil density, which is in a loose state (in agricultural applications) and dense (in geo-environmental engineering applications) can also influence water retention behaviour of biochar amended soils. The major objective of this study is to investigate the water retention properties of soil amended with three different biochars in both loose and dense state. The biochars, i.e. water hyacinth biochar (WHB), chicken manure biochar (CMB) and wood biochar (WB) were produced in-house at different pyrolysis temperature. After then, biochars at 5% and 10% (w/w%) were amended to the soil. Water retention behaviour (soil suction and gravimetric water content) was studied under drying and wetting cycle simulated by varying relative humidity (RH, 50–90%). Results show that 10% WHB produced at 300 °C were found to possess highest water retention. CMB is found to possess higher water retention than WB for 10% amendment ratio. In general, the addition of three biochars (at both 300 °C and 600 °C) at 10% (w/w) significantly improved the water retention at all suction ranges in both loose and dense compaction state as compared to that of the bare soil. The adsorption (wetting) and desorption (drying) capacity of biochar amended soils is constant at corresponding RH.

scholarly journals Investigation into water retention behaviour of deformable soils

2013 ◽  
Vol 50 (2) ◽  
pp. 200-208 ◽  
Author(s):  
Simon Salager ◽  
Mathieu Nuth ◽  
Alessio Ferrari ◽  
Lyesse Laloui
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Water Retention ◽  
Void Ratio ◽  
Degree Of Saturation ◽  
Retention Data ◽  
Soil Water Retention ◽  
Retention Behaviour ◽  
Wide Range ◽  
Water Retention Behaviour

The paper presents an experimental and modelling approach for the soil-water retention behaviour of two deformable soils. The objective is to investigate the physical mechanisms that govern the soil-water retention properties and to propose a constitutive framework for the soil-water retention curve accounting for the initial state of compaction and deformability of soils. A granular soil and a clayey soil were subjected to drying over a wide range of suctions so that the residual state of saturation could be attained. Different initial densities were tested for each material. The soil-water retention curves (SWRCs) obtained are synthesized and compared in terms of water content, void ratio, and degree of saturation, and are expressed as a function of the total suction. The studies enable assessment of the effect of the past and present soil deformation on the shape of the curves. The void ratio exerts a clear influence on the air-entry value, revealing that the breakthrough of air into the pores of the soil is more arduous in denser states. In the plane of water content versus suction, the experimental results highlight the fact that from a certain value of suction, the retention curves corresponding to different densities of the same soil are convergent. The observed features of behaviour are conceptualized into a modelling framework expressing the evolution of the degree of saturation as a function of suction. The proposed retention model makes use of the theory of elastoplasticity and can thus be generalized into a hysteretic model applicable to drying–wetting cycles. The calibration of the model requires the experimental retention data for two initial void ratios. The prediction of tests for further ranges of void ratios proves to be accurate, which supports the adequacy of formulated concepts.

scholarly journals Soil Water Retention Behaviour of a Sandy Clay Fill Material

2016 ◽  
Vol 143 ◽  
pp. 308-314
Author(s):  
D.G. Toll ◽  
J.D. Asquith ◽  
P.N. Hughes ◽  
P. Osinski
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
Soil Water Retention ◽  
Retention Behaviour ◽  
Fill Material ◽  
Sandy Clay ◽  
Water Retention Behaviour

scholarly journals A new technique for deep in situ measurements of soil water retention behaviour

2018 ◽  
Vol 5 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Irene Rocchi ◽  
Carmine Gerardo Gragnano ◽  
Laura Govoni ◽  
Alessio Mentani ◽  
Marco Bittelli ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Retention ◽  
In Situ Measurements ◽  
New Technique ◽  
Soil Water Retention ◽  
Retention Behaviour ◽  
A New Technique ◽  
Water Retention Behaviour

scholarly journals An experimental investigation on the water retention behaviour of a silty soil for the computation of the lateral earth thrust on a retaining wall

2019 ◽  
Vol 92 ◽  
pp. 07011 ◽  
Author(s):  
Gianluca Speranza ◽  
Alessio Ferrari ◽  
Maxime Pousse ◽  
Lyesse Laloui
Keyword(s):  
Water Retention ◽  
Retaining Wall ◽  
Dew Point ◽  
Soil Water Retention ◽  
Retaining Structures ◽  
Analysis And Design ◽  
Silty Soil ◽  
Retention Behaviour ◽  
Environmental Actions ◽  
Water Retention Behaviour

Retaining structures often interact with soils in unsaturated conditions and their performance is influenced by environmental actions. Currently, geotechnical analysis and design approaches mainly consider the soils either totally dry or totally saturated. Environmental actions, like infiltration due to rainfall, can significantly affect the lateral earth pressure of soils, influencing the performance of both temporary or permanent retaining structures. This paper deals with the investigation of the water retention behaviour of a silty soil for the computation of the soil thrust on a retaining wall during rainfall events. In this regard, the retention property of the involved geomaterial is investigated in laboratory through the combined use of high capacity tensiometers (HCT) and a dew-point hygrometer (WP4C). Considering drying and wetting paths, the experimental results are employed to calibrate the water retention behaviour for the computation of the failure shear strength of the geomaterial. The importance to monitor volume change during the characterization of the water retention behaviour of fine soils is highlighted. A series of analytical uncoupled hydro-mechanical analyses is performed to estimate the changing in the thrust of an unsaturated soil on a retaining wall under several infiltration rates. An appropriate modelling of the soil water retention behaviour is resulted to be crucial for the computation of lateral earth thrust.

scholarly journals A general mathematical framework for modelling soil-water retention behaviour

2021 ◽  
Vol 337 ◽  
pp. 02006
Author(s):  
Carlos Pereira ◽  
João Ribas Maranha ◽  
Rafaela Cardoso
Keyword(s):  
Soil Water ◽  
Specific Volume ◽  
Unsaturated Soils ◽  
Water Retention ◽  
Degree Of Saturation ◽  
Mathematical Framework ◽  
Soil Water Retention ◽  
Retention Behaviour ◽  
Entrapped Air ◽  
Water Retention Behaviour

A new constitutive model for the soil-water retention behaviour of unsaturated soils is proposed, able to reproduce the main drying and wetting paths, the cyclic retention behaviour and its dependence on the specific volume. The most significant aspect is the inclusion of the evolution, with the specific volume, of the degree of saturation when suction tends to zero in wetting paths considering the presence of entrapped air bubbles. The model is used to reproduce with success the drying/wetting cycles of two Pearl clay samples.

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