This technical note advances the understanding of the key parameters controlling unconfined compressive strength (qu) of artificially cemented silty/clayey soils by considering distinct moisture contents, distinct specimen porosities (η), different Portland cement contents and any curing time periods. The qu values of the specimens moulded for each curing period were normalized (i.e. divided) by the qu attained by a specimen with a specific porosity/cement ratio. A unique relationship was found, establishing the relationship between strength for artificially cemented silty/clayey soils considering all porosities, Portland cement amounts, moisture contents and curing periods studied. From a practical viewpoint, this means that, at limit, carrying out only one unconfined compression test with a silty/clayey soil specimen, moulded with a specific Portland cement amount, a specific porosity and moisture content and cured for a given time period, allows the determination of a general relationship equation that controls the strength for an entire range of porosities and cement contents, reducing considerably the amount of moulded specimens and reducing projects development cost and time. controlling unconfined compressive strength (q u ) of artificially cemented silty/clayey soils by 10 considering distinct moisture contents, distinct specimen porosities (), different Portland 11 cement contents and any curing time periods. The q u values of the specimens moulded for 12 each curing period were normalized (i.e. divided) by the q u attained by a specimen with a 13 specific porosity/cement ratio. A unique relationship was found, establishing the relationship 14 between strength for artificially cemented silty/clayey soils considering all porosities, Portland 15 cement amounts, moisture contents and curing periods studied. From a practical viewpoint, 16 this means that, at limit, carrying out only one unconfined compression test with a silty/clayey 17 soil specimen, moulded with a specific Portland cement amount, a specific porosity and 18 moisture content and cured for a given time period, allows the determination of a general 19 relationship equation that controls the strength for an entire range of porosities and cement 20 contents, reducing considerably the amount of moulded specimens and reducing projects 21
The enhancement of local soils with fibres and cementitious materials for the construction of stabilised pavement bases, canal lining and support layer for shallow foundations shows great economic and environmental advantages, avoiding the use of borrow materials from elsewhere, as well as the need for a spoil area. A dosage methodology for fibre-reinforced, Portland cement treated soils has been previously established, based on rational criteria where the porosity/cement ratio plays a fundamental role in the assessment of the target unconfined compressive strength (qu). The present research has extended such work by quantifying the influence of the amount of lime, the porosity and the porosity/lime ratio in assessing the tensile (qt) and compressive (qu) strength of polypropylene-fibre-reinforced silt–lime mixtures, as well as in the evaluation of the qt/qu relationship. A programme of splitting tensile and unconfined compression tests was carried out in the present study, considering three distinct dry densities and four lime contents, varying from 3% to 9%. The results show that a linear function fits the qt and qu values well with increasing lime content, and a power function fits them well with reducing porosity of the compacted mixture. The porosity/lime ratio is shown to be an appropriate parameter to assess both qt and qu of the fibre-reinforced silt–lime mixtures studied. Finally, the qt/qu relationship is unique for the fibre-reinforced silt–lime mixtures studied, being independent of the porosity/lime ratio.
A dosage methodology for lime-treated soils has previously been established based on rational criteria where the porosity/lime ratio plays a fundamental role in the assessment of the target unconfined compressive strength (qu). The present research extends this previous work by quantifying the influence of the amount of lime, the porosity and the porosity/lime ratio in the assessment on tensile strength (qt) of soil–lime mixtures, as well as in the evaluation of the qt/qu relationship. A programme of splitting tensile tests and unconfined compression tests considering three distinct dry unit weights and four lime contents, varying from 3 to 9%, was carried out in the present study. The results show that a power function fits qt and qu values well with increasing volumetric lime content and a power function fits qt and qu values well with reducing porosity of the compacted mixture. The porosity/lime ratio is demonstrated to be an appropriate parameter to assess both qt and qu of the silt–lime mixture studied. Finally, the qt/qu relationship is unique for the silt–lime studied, being independent of the porosity/lime ratio.
This paper presents experimental triaxial tests conducted on two lightly cemented sand samples on the set-up conditions of a Hollow Cylinder Torsional Apparatus (HCTA). The laboratory study has been carried out on an angular to sub-angular silica sand reinforced with Portland cement of high early strength. The samples have identical porosity/volumetric cement content ratio, η/Civ, values. The Young's modulus and shear modulus were measured by the application of a series of small unload-reload cycles at different investigation points along the triaxial stress path up to about 50% of the maximum deviatoric stress. At these investigation points, additional series of unload-reload cycles of higher amplitudes were also applied and the stiffness moduli assessed using local instrumentation. While the peak strength seems to be controlled by the density of the sand matrix, as extensive bond cementation damages occur at peak and pre-peak stages, the Young's modulus and shear modulus normalised by the void ratio function show the effect of the cementation ratio with higher values for the sample with higher cementation ratio.
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