Field experiment of cement-modified loess

Article in Press
Pages: 
pp. 19-25
Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
Abstract: 

The construction of a compacted and stabilized layer with local soil from the excavation, mixed with Portland cement, is a soil improvement technique widely applied in foundation works in collapsible loess ground in Bulgaria. Commonly, the role of that cement-modified layer is to replace a part of the collapsible ground, to increase the bearing capacity of the soil base, and/or to be an engineering barrier against migration of harmful substances in the geoenvironment.
   A multi-barrier near-surface short-lived low- and intermediate-level radioactive waste repository is under construction in Bulgaria. A cement-modified soil layer beneath the disposal cells is going to be built by in-situ compacted mixture of local loess and Portland cement. The cement-modified layer (indicated as loess-cement
cushion) is not a continuation of the foundation, but it is a part of the soil base and performs two main functions: to be an engineering barrier against eventual migration of radionuclides in the geoenvironment and to increase the bearing capacity to restrict deferential settlement of the soil base.
The present paper describes a field experiment aiming to verify the strength and deformation characteristics of a selected optimum loess–cement mixture by implementation of in-situ cement-modified loess ground. After 28-day curing at in-situ conditions, the loess-cement did not exhibit any fissuring or other disturbances.
   The allowable bearing capacity qa of the cement-modified loess ground exceeded 900 kN/m2, and it possessed the following strength and deformation characteristics: deformation (plate) modulus EPLT = 500 MPa; coefficient of sub-grade reaction ks = 2158 МPa/m, and unconfined compressive strength qu = 2.00 MPa.

Keywords: 

soil stabilization, cement-modified loess, field experiment

DOI: 
10.52321/GeolBalc.51.2.19

VOLUME 51 (2)/August 2022

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria

Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Interoceanmetal Joint Organization, 9 Cyryla i Metodego Str., 71-541 Szczecin, Poland
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Geological Institute, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 24, 1113 Sofia, Bulgaria
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Faculty of Chemistry and Pharmacy, Sofia University “St Kliment Ohridski”, 1 James Bourchier Blvd, 1164 Sofia, Bulgaria
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Maritime University of Szczecin, 1/2 Wały Chrobrego, 70-500 Szczecin, Poland