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Porcino D.,University of Calabria | Ghionna V.N.,Studio Geotecnco Italiano | Granata R.,The Trevi Group | Marciano V.,University of Calabria
Geomechanics and Geoengineering | Year: 2016

The purpose of this paper is to investigate mechanical and hydraulic properties of sands treated with mineral-based grouts through the results of a laboratory test programme consisting of unconfined compression tests (UCS), triaxial bender element tests (BeT) and constant flow permeability tests in triaxial apparatus. An improved apparatus was set up for obtaining high quality, multiple grouted specimens from a single column. Two selected natural sands having different grain sizes were grouted with two mineral-based silica grouts, resulting in different levels of improvement. The behaviour of the sands treated by mineral grouts, in terms of strength, initial stiffness and permeability, was compared with that exhibited by more traditional silicate grouts. The results of this study indicate that sands treated with mineral grouts result in higher strengths, higher initial shear modulus and lower permeability values than the sands treated with the silicate solution. The effect of grout type, effective confining pressure, and sand particle-size on small-strain shear modulus of grouted sand specimens was evaluated. Based on test results, the small strain shear modulus increment from treated to untreated specimens has been correlated with the unconfined compressive strength, obtaining a unique relationship regardless of grout type and grain-size of tested sands. © 2015 Taylor & Francis.


Porcino D.,University of Reggio Calabria | Marciano V.,University of Reggio Calabria | Granata R.,The Trevi Group
Soil Dynamics and Earthquake Engineering | Year: 2015

The aim of this paper is to provide an insight into the effects of a previous cyclic history "triggering" full liquefaction on the subsequent undrained cyclic behaviour of a moderately cemented grouted sand in terms of strength, deformability and pore pressure response. The research was conducted on sand specimens stabilized by a commercial mineral based chemical grout ("Silacsol"), capable of imparting unconfined compression strength (UCS) values ranging between 500kPa and 700kPa. Monotonic shear strength parameters of treated specimens were preliminary assessed through a series of isotropically consolidated drained triaxial tests (TX-CID). Afterwards, stress-controlled undrained cyclic simple shear (SS) tests were conducted on both treated and untreated sand specimens in order to evaluate the improvement provided by the grout on the liquefaction resistance of the sand. A significant beneficial effect of the grout was observed, regardless of the initial density of the pure sand. Finally the influence of a cyclic large preshearing on the undrained cyclic behaviour of the grouted sand was investigated by subjecting the specimens to a sequence of two cyclic loadings with the same stress ratio (CSR). After the first loading in which specimens were brought to full liquefaction, they were allowed to reconsolidate in approximately K0 conditions and then subjected to the second loading. An increase in liquefaction resistance induced by cyclic history was clearly apparent on treated specimens. Excess pore pressures build-up during the first cyclic loading on treated specimens followed a different trend compared to that observed on untreated ones. A significant difference was also observed on the excess pore pressure trends developed in the second loading compared to that developed in the primary loading. A simple model for the prediction of pore water pressure build-up of grouted sands during cyclic loading is proposed. © 2015 Elsevier Ltd.


Porcino D.,University of Reggio Calabria | Marciano V.,University of Reggio Calabria | Granata R.,The Trevi Group
Canadian Geotechnical Journal | Year: 2012

This paper describes the results of an experimental investigation on the behaviour of a lightly grouted loose medium sand under both monotonic and cyclic loading. The experimental programme in the present study was carried out on both untreated and treated sand specimens stabilized with a silica-based grout, and comprises isotropic triaxial compression tests equipped with bender elements, drained triaxial monotonic shearing tests, and undrained cyclic tests in a simple shear (SS) apparatus. The results highlight that the weak cementation level induced by chemical treatment was sufficient to moderately increase small-strain stiffness and stress-dilatancy of the grouted sand during drained monotonic shear. A small cohesion intercept was observed in the analyzed failure envelope, while cyclic liquefaction resistance exhibited a much more significant increase, with a different pattern of behaviour between low and high stress levels. Finally, undrained cyclic SS test results evidenced that silicate grout employed in this research improves undrained cyclic shear strength in a manner similar to densification of the same material up to a density index of approximately 75%.


Porcino D.,University of Reggio Calabria | Ghionna V.N.,Studio Geotecnco Italiano | Granata R.,The Trevi Group | Marciano V.,University of Reggio Calabria
Geomechanics and Geoengineering | Year: 2015

The purpose of this paper is to investigate mechanical and hydraulic properties of sands treated with mineral-based grouts through the results of a laboratory test programme consisting of unconfined compression tests (UCS), triaxial bender element tests (BeT) and constant flow permeability tests in triaxial apparatus. An improved apparatus was set up for obtaining high quality, multiple grouted specimens from a single column. Two selected natural sands having different grain sizes were grouted with two mineral-based silica grouts, resulting in different levels of improvement. The behaviour of the sands treated by mineral grouts, in terms of strength, initial stiffness and permeability, was compared with that exhibited by more traditional silicate grouts. The results of this study indicate that sands treated with mineral grouts result in higher strengths, higher initial shear modulus and lower permeability values than the sands treated with the silicate solution. The effect of grout type, effective confining pressure, and sand particle-size on small-strain shear modulus of grouted sand specimens was evaluated. Based on test results, the small strain shear modulus increment from treated to untreated specimens has been correlated with the unconfined compressive strength, obtaining a unique relationship regardless of grout type and grain-size of tested sands. © 2015 Taylor & Francis


Porcino D.,University of Reggio Calabria | Marciano V.,University of Reggio Calabria | Granata R.,The Trevi Group
Geomechanics and Geoengineering | Year: 2011

An experimental comparative study of a silicate-grouted sand is presented. The experimental procedure adopted for preparing high-quality treated samples is accurately described together with test procedures. The overall experimental investigation comprises unconfined compressive strength (UCS) tests, undrained monotonic simple shear (SS) tests, undrained cyclic simple shear and triaxial (TX) tests. A gain in strength due to the sodium-silicate grout is apparent from both undrained monotonic and cyclic test results. The influence of loading mode on undrained cyclic stress- strain-strength behaviour of treated sand samples is explored based on a comparison between simple shear and conventional triaxial stress conditions. The simple shear device is properly adopted to allow a reliable assessment of liquefaction resistance improvement in untreated sand samples. The paper highlights that, regardless of test conditions, similarities exist between the behaviour of loose-treated samples and that of dense- untreated samples, in terms of undrained cyclic shear strength. Time effects are also explored taking into account the variation of curing time and loading frequency. © 2011 Taylor & Francis.


About THE TREVI GROUP:Since 2008, we've been helping companies hire engineers, architects, and management in the IT industry. Our specialties include Data Center Infrastructure, Storage, Virtualization, Networking, Unified Communications, Cloud technologies, and Corporate IT ...


The Trevi Group | Entity website

About THE TREVI GROUP:Since 2008, we've been helping companies hire engineers, architects, and management in the IT industry. Our specialties include Data Center Infrastructure, Storage, Virtualization, Networking, Unified Communications, Cloud technologies, and Corporate IT ...


The Trevi Group | Entity website

About THE TREVI GROUP:Since 2008, we've been helping companies hire engineers, architects, and management in the IT industry. Our specialties include Data Center Infrastructure, Storage, Virtualization, Networking, Unified Communications, Cloud technologies, and Corporate IT ...


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The Trevi Group | Date: 2010-12-14

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