Swell–shrink–consolidation behavior of compacted expansive clays

Azam, Shahid; Chowdhury, Rashedul H.

doi:10.1179/1939787913y.0000000005

Cited by 21 publications

(15 citation statements)

References 15 publications

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“…Marinho and Oliveira [13] reported that for cohesive soils the optimum water content is within ±5% of the plastic limit. These data are similar to those reported by Azam and Chowdhury [14] for the same material. The corresponding values of dry density and optimum water content were 1.60 g/cm 3 at 22% for CS-I and 1.65 g/cm 3 at 20% for CS-II.…”

Section: Resultssupporting

confidence: 92%

Compressive Strength of Compacted Clay-Sand Mixes

Khan

Azam

Raghunandan

et al. 2014

Advances in Materials Science and Engineering

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The use of sand to improve the strength of natural clays provides a viable alternative for civil infrastructure construction involving earthwork. The main objective of this note was to investigate the compressive strength of compacted clay-sand mixes. A natural clay of high plasticity was mixed with 20% and 40% sand (SP) and their compaction and strength properties were determined. Results indicated that the investigated materials exhibited a brittle behaviour on the dry side of optimum and a ductile behaviour on the wet side of optimum. For each material, the compressive strength increased with an increase in density following a power law function. Conversely, the compressive strength increased with decreasing water content of the material following a similar function. Finally, the compressive strength decreased with an increase in sand content because of increased material heterogeneity and loss of sand grains from the sides during shearing.

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Section: Resultssupporting

confidence: 92%

Compressive Strength of Compacted Clay-Sand Mixes

Khan

Azam

Raghunandan

et al. 2014

Advances in Materials Science and Engineering

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“…The kaolinite 100K showed a maximum dry density of 1.7 g/ cm 3 at an optimum water content wSPO equal to 17.2%, which is close to PL = 20%. These data are similar to those reported by Khan et al [16], Azam and Chowdhury [35] and Marinho and Oliveira [36]. Marinho and Oliveira [36] reported that for cohesive soils, the optimum water content is within ±5% of the PL.…”

Section: Materials Characterisationsupporting

confidence: 91%

Effect of suction on the mechanical behaviour of unsaturated compacted clay–sand mixtures

Bouchemella

Taïbi

2022

Studia Geotechnica Et Mechanica

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In this work, a series of unconfined compression tests at different water contents were performed to investigate the mechanical behaviour of clay–sand mixtures compacted in standard Proctor conditions. For studying the effect of water content and suction on unconfined compressive strength (UCS) and on strain secant modulus (E50 modulus) of these mixtures, drying–wetting paths were defined by measuring the soil–water characteristic curves (SWCCs) using osmotic and salt solution techniques and filter paper method. The results highlighted that an increase in sand content of the mixture leads to an increase in the maximum dry densities and a decrease in the optimum water content of the materials. However, at the given state, when clay is mixed with 25% of sand, the UCS and E50 modulus increase to 37% and 70%, respectively, compared to those of clayey samples. But when clay is mixed with 50% of sand, the UCS and E50 modulus decrease to 38% and 46%, respectively, compared to those of clayey samples. The results also indicate that the UCS and E50 increase with a decrease in the water content and an increase in suction, irrespective of the sand content.

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“…The various types of WRC have their respective utilities: w-based is most accurate because it is directly measured, θ-based is useful for the determination of water storage capacity, and S-based is the most clear in depicting soil behavior. However, none of these curves can capture volumetric changes due to capillary water through soil pores and adsorbed water on clay particles within lumps [73]. The data indicate that about 90% of volume change in the soil occurred in the plastic zone (from liquid limit of 29% to shrinkage limit of 12%) with a change in S from 100% to 60% and negligible thereafter, albeit a change in S from 60% to 0.…”

Section: Volumetric Changesmentioning

confidence: 91%

Section: Water Retentionmentioning

confidence: 99%

Effect of Composition on Engineering Behavior of Clay Tills

Paranthaman

Azam

2021

Geosciences

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Glacial geology, marine environment, and arid climate govern the composition of clay tills. The main purpose of this work is to develop a clear understanding of the engineering behavior of compacted clay till under soil suction and applied stress. The results indicate moderate water adsorption due to the presence of clay minerals (26% corrensite, 10% illite, and 8% kaolinite) with Ca2+ as the dominant cation and a flocculated fabric in a slightly basic (pH = 7.5) pore water. The water retention curve comprised four transition points that are associated with capillary water drainage from large pores (air entry value of 2 kPa and residual suction value of 20 kPa) and small pores (air entry value of 700 kPa and residual suction value of 5 × 104 kPa). Beyond the last value, vapor flow is dominant and removes the adsorbed water by evaporation. The ratio of soil volume change to water volume change best described the s-shaped shrinkage path that also comprised four stages, namely: from most large pores with low volume change; from remaining large and most small pores along with almost equal volume change; from some small pores with low volume change; and from the rest of the small pores with no volume change. Likewise, the s-shaped swelling potential curve comprised three stages and correlated well with bimodal hydraulic conductivity curve, that is, slow initial swelling (unsaturated hydraulic conductivity around 10−14 m/s) due to expansion of peripheral clay in lumps; high primary swelling (unsaturated hydraulic conductivity of up to 10−11 m/s) due to thickened double layer of most colloids; and slow secondary swelling (albeit unsaturated hydraulic conductivity around 10−10 m/s) due to expansion of remaining particles. Soil compression (compression index of 0.164) was due to a gradual reduction in number of large pores, whereas rebound (swelling index of 0.047) was due to water adsorption on clay with part of the deformations recovered. Finally, the consolidation rate was related to saturated hydraulic conductivity, which varied by three orders of magnitude.

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Swell–shrink–consolidation behavior of compacted expansive clays

Cited by 21 publications

References 15 publications

Compressive Strength of Compacted Clay-Sand Mixes

Compressive Strength of Compacted Clay-Sand Mixes

Effect of suction on the mechanical behaviour of unsaturated compacted clay–sand mixtures

Effect of Composition on Engineering Behavior of Clay Tills

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