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This article presents a discussion of the Arabian Journal of Geosciences, 394, Vol. 13, No. 11, which (among other things) proposed a new empirical correlation for the prediction of the plasticity index magnitude (and hence by association the plastic limit value) of fine-grained soils sampled from different depths in the Bakırköy District of Istanbul City. As inputs, the proposed correlation employs the activity index, along with defining parameters of the semi-logarithmic flow curve obtained from the Casagrande (percussion-cup) liquid limit test. This article presents the following: (i) a discussion of the relevant literature that was not covered in the original paper; (ii) clarifications on, and observations regarding, the general approach adopted in the original investigation; (iii) concerns over whether the proposed new empirical correlation can be meaningfully recalibrated for particular clay soil types specific to other regions around the world; and (iv) suggestions for improvement of the new empirical correlation by adopting a different set of input parameters. [ABSTRACT FROM AUTHOR]

Background: Geologic and geotechnical conditions of soils where Nanka and Ajali Formations outcropped in Anambra Basin, Southeastern Nigeria were investigated and accessed. This was done using detailed mapping and mechanical soil laboratory tests to unravel the genesis and continued expansion of gully erosion in the study areas. Results: Field study revealed that gully erosions are more pronounced in the study area with poor vegetation cover and a high degree of slope steepness. Grain size analysis revealed that the soils of the Nanka Formation have an average sand content value of 90.90% (sandy) and silt content value of 3.0% (low fine portions). The plasticity index of the fine portions indicates that the soils are weak plastic, with a mean value of 5.29%. The soils have an average cohesion value of 0.30 kg/cm2 indicating a very weak cohesion. The soils are highly permeable; with an average value of 2.67 × 10–3 cm/s. The compaction test further revealed that the soils are loosely compacted. The soils for the Ajali Formation have an average sand content value of 95.10% (sandy) and silt content value of 1.43% (low fine portions). The plasticity index of the fine portions indicates that the soils are weak plastic, with a mean value of 2.70%. The soils have an average cohesion value of 0.30 kg/cm2 indicating a very weak cohesion. The soils are highly permeable; with an average value of 2.70 × 10–3 cm/s. The compaction test revealed that the soils are loosely compacted. Conclusion: After field surveys and laboratory analyses, it was found that the gully erosions have been developing respectively on steep slopes and non-vegetated areas, and their genesis facilitated by the cohesionless and very permeable nature of the sandy formations. Following those key findings, it was proposed many practices (agronomic and engineering mainly) that can help mitigate the formations as well as the expansion of this very damaging hazard type. The potential implications of these gully erosion include damaging of buildings, residential houses, bridges, and roads, loss of farmland and vegetation, isolation of villages and towns, increased migration of inhabitants as well as degradation of agricultural fertile land. [ABSTRACT FROM AUTHOR]

Unbound aggregate base and subbase layers distribute traffic induced wheel loads in a pavement and protect the weak subgrade. In this study, effects of plasticity index (PI), fines content (FC) (per cent passing No. 200 sieve size) and dust ratio (DR) (ratio of per cent passing No. 200 sieve to per cent passing No. 40 sieve) of unbound aggregates on the base/subbase layer modulus and deformation characteristics are investigated. Repeated load triaxial tests were conducted on crushed gravel and limestone specimens prepared at optimum moisture contents for two Illinois dense-graded gradations, i.e. CA 6 and CA 2, to determine the resilient modulus and deformational behaviour. Samples with 9% PI showed lower resilient moduli and greater deformations than samples with 5% PI. The effects of FC on the modulus and deformation behaviour depend on the DR. Increasing DR from 0.4 to 0.6 and eventually to 1.0 increased deformations and decreased resilient moduli at the FC of 5%. An opposite trend was observed when the DR increased from 0.4 to 0.6 and eventually to 1.0 at 12% FC. The test results were used to develop improved resilient modulus and deformation prediction models, which capture important effects of aggregate FC, PI and DR. [ABSTRACT FROM AUTHOR]

Some species intrinsically have a high invasiveness capacity, shown by high phenotypic plasticity and rapid growth, enabling a wide distribution across their native habitats and successful invasion in the introduced range. For such species, information from native habitats is critically important. An example is Glechoma hederacea, native to Eurasia but introduced and widespread in the USA. Our main objective was to investigate variation in traits of native G. hederacea populations across contrasting habitats: open, forest edge and understory. Vegetation was sampled and the ecophysiological and morphological traits were measured with accompanying environmental parameters. Results showed that in native habitats environmental conditions cover wide gradients of light and soil moisture. Plants had the highest cover in nutrient-rich, shaded habitats, representing the optimal habitat, indicating shade tolerance of G. hederacea. Plants from forest understory exhibited strong similarities in investigated traits to plants from the forest edge, even though this was a drier, sunnier habitat. Plants from open, sunny habitats experienced stress as indicated by the quantum efficiency of PSII and significantly higher sexual reproduction. Results show that G. hederacea is moderately tolerant simultaneously to shade and drought, a characteristic that has been reported for numerous invasive species, while at the same time it shares some characteristics with weedy plants. [ABSTRACT FROM AUTHOR]

The present paper presents different approaches which includes plasticity based criteria that helps in distinguish between liquefiable and non-liquefiable soils deposits having fine content. A brief review of the previous work has been mentioned to emphasise on the need of new parameters for liquefaction susceptibility of clayey soils. Clay content, liquid limit and water content are considered as key parameters that helps in liquefaction assessment. Several recommendations proposed by prominent researchers are described here to present wide range of plasticity index, liquid limit and other parameters that affects liquefaction behaviour of clayey soil significantly. But the differences in the range of plasticity index leads to confusion and misperception in determination of liquefaction susceptibility of fine grained soil. One of the high seismic zone site is analyzed using different approach which consider fine content of soil mass. It is found that for a better and proper segregation of the layers Bray and Sancio criteria may be adopted which uses plasticity as one of its input parameter and clearly differentiate site in between liquefiable, non-liquefiable and sites that may liquefy i.e. moderately liquefiable. This summarizes that plasticity is one of the significant criteria which draws a clear differentiating line between liquefiable and non-liquefiable soil deposits. [ABSTRACT FROM AUTHOR]

The dynamic behaviour of soils from Kutch (seismically active region of Gujarat, India) was explored under cyclic triaxial (CTX) and cyclic simple shear (CSS) testing conditions. Under both the CTX and CSS conditions, the soil specimens exhibited cyclic strength that decreased rapidly at lower plasticity index and lower fines content. The reduction in cyclic strength was evaluated to be higher and faster for the clayey-sand specimens as compared to clayey specimens. Specimens with low plasticity index and lower fines content showed higher pore pressure response in both CTX and CSS tests. Pore pressure ratio under CSS conditions was observed to be higher as compared to CTX conditions. Degradation in shear modulus was found to be higher and quicker for clayey-sand specimens as compared to clayey specimens. Degradation index increased with plasticity index and fines content at a given number of loading cycles under both CSS and CTX conditions. [ABSTRACT FROM AUTHOR]

Consistency limits are essential and simple design parameters that are utilized as standard entries of all kinds of soil investigation programs conducted for geotechnical projects which are constructed in/on fine grained soils. These limits also represent mineralogical and physical properties of clayey soils directly and used to estimate their strength and rigidity properties indirectly. However, the consistency tests are assumed as the simple and basic tests of geotechnical engineering investigations, but the effects of operator, calibration of the device and environmental aspects at the tests damage the reliability and correctness of results. In this paper, it is aimed to overcome these challenges by evaluating the consistency characteristics of clayey soils considering only the values of liquid limit of specific clays with the use of simple regression analysis. A database is prepared by using 500 soil investigation reports that are involving the site characterization information, laboratory and field tests of Istanbul Province European side clayey soils, including Avcılar, Esenyurt, Küçükçekmece, Büyükçekmece, Çatalca, Zeytinburnu, Bahçelievler, Bakırköy districts. 1523 liquid limit tests are obtained from the mentioned database for high and very high plastic clays. The regression analyses have been applied to query the parameter effect ratio on the consistent characteristics and relationships have been tried to be developed to evaluate the values of plastic limit and plasticity index directly from only liquid limit test applications. The effects of fine material content, depth and natural water content is also investigated. Verifications of the suggested equations have been done for different cases and comparisons are made with the well-known sources of literature. Consequently, strong equations are acquired to determine the plasticity index value in terms of liquid limit, liquid limit-depth, liquid limit-fine content, natural water content-fine content respectively based on the actual experimental tests conducted in Istanbul. [ABSTRACT FROM AUTHOR]

Samples of clay deposits in Obudu and its environs, southeastern Nigeria were evaluated to establish their potential for industrial use. Geochemical, mineralogical and geotechnical properties were employed in assessing the suitability of the clay deposits for potential industrial uses. Mineralogical analyses reveal kaolinite as the dominant clay mineral with quartz as the dominant non-clay mineral. The physical and geotechnical properties indicate that the hydrous and marginal expansive clays are fine-grained (75 μm > 2%), have low to medium plasticity (plasticity index 12.8–40.8%), low density (1.69 to 2.60 g/cm3) and low linear shrinkage (4–6%) on drying and firing. Geochemical analysis shows significant amounts (> 1.0 wt%) of SiO2, Al2O3, Fe2O3, MgO, CaO, and Na2O, and relatively low values (< 1.0 wt%) of K2O, FeO and TiO2. The clays meet the requirements for production of building bricks, roofing tiles, local pottery products and domestic ceramic wares other than ceramic white wares. However, these low grade clays will require a high degree of refining or beneficiation to remove the undesirable minerals to qualify for use in rubber, paper, paint and cosmetic industries. [ABSTRACT FROM AUTHOR]

The stability and strength of soil aggregates to external forces such as raindrop impact and tillage may be affected by biochar application. In line with this, a three-year field experiment was conducted to investigate the effect of rice straw biochar (0, 15, and 30 t ha−1) on the Atterberg limits (plastic limit, PL and liquid limit, LL), water-dispersible clay content (WDC), and the aggregate characteristics of an Acrisol. Aggregate characteristics were measured on four size classes (1–2, 2–4, 4–8, and 8–16 mm). The 30 t ha−1 treatment significantly (p < 0.05) increased PL and LL by 27% and 20%, respectively, compared to the control. The plasticity index, WDC and tensile strength were unaffected by biochar addition. For all treatments, there was a decreasing trend in tensile strength with increasing aggregate size. The 15 and 30 t ha−1 treatments increased friability by 21% and 38%, respectively, relative to the control. The 30 t ha−1 treatment significantly increased workability of the smaller aggregates but marginally increased the workability of the larger aggregates. Thus, there is potential for increased optimum water content at tillage (inferred from the PL) and increased workability after biochar application at 30 t ha−1. [ABSTRACT FROM AUTHOR]

Sundri (Heritiera fomes Buch.-Ham.) is an evergreen mangrove tree species found abundantly in the freshwater zone of Sundarbans, Bangladesh and scattered in moderate or strong saline zones of the forest. H. fomes grows well in top canopy having full sunlight and even in full shade under the canopy. This study presents the plasticity of leaf morphological and anatomical characteristics in H. fomes due to variation of light intensity at different canopy depths and of salinity in different saline zones of Sundarbans. This study was conducted in two steps, firstly the light intensity and leaf phenotypic variations at different canopy depths (one-meter interval) in the fresh water zone of Sundarbans, secondly the leaf phenotypic variations in three saline zones having variable light environment at different canopy positions (top, middle and bottom) in each zone. Leaf samples were collected from three different salinity zones and each canopy positions and various morphological and anatomical characteristics were quantified. A wide range of variations were observed in the leaf parameters measured among the salinity zones of the Sundarbans and the canopy positions. The canopy of H. fomes showed an exponentially decreasing light gradient. Leaf plasticity index (PI) of all the parameters was developed for the salinity zones and the canopy positions of the Sundarbans. The ordination plots (PCA) suggested clear morphological and anatomical shift of the samples collected from different saline zones and canopy positions showing relationship to light and salt stresses in natural environment. Our results provide clear evidence on plastic strategy of H. fomes against salinity and light gradients in the Sundarbans.

Geotechnical engineering like any other engineering field has to develop and cope with new technologies. This article intends to investigate the spatial relationships between soil’s liquid limit (LL), plasticity index (PI) and Liquidity index (LI) for particular zones of Sulaymaniyah City. The main objective is to study the ability to produce digital soil maps for the study area and determine regions of high expansive soil. Inverse Distance Weighting (IDW) interpolation tool within the GIS (Geographic Information System) program was used to produce the maps. Data from 592 boreholes for LL and PI and 245 boreholes for LI were used for this study. Layers were allocated into three depth ranges (1 to 2, 2 to 4 and 4 to 6) m. A total of 1396 observations were used for producing the maps for both LL and PI, and 371 data for LI. Based on the results, the IDW method gives reasonable predictions depending on the results of R2 and RMSE. The results also showed that the study area has relatively large zones of high expansive soil that must be taken into considerations before performing any construction activity. These maps are essential for helping geotechnical engineers in making decisions and visualizing soils’ behaviors.

The effect of material properties and surface roughness on the contribution of asperities and sphere bulk displacements to the total displacement of a rough spherical contact is investigated. A dimensionless transition load, above which the contribution of the bulk displacement exceeds the contribution of the asperities displacement, is found as a function of the plasticity index and dimensionless critical interference of the sphere bulk. A criterion is proposed for evaluating the importance of surface roughness in calculating the displacement of a rough spherical contact. Some experimental results with a spherical micro-contact are presented to verify the model.

Article determins a correlation between the values of the plasticity and liquidity index (IP, IL) of cohesive soils achieved by various laboratory methods (on the basis of Casagrande apparatus and cone penetrometer method) and consists research results on natural clayey soils of known origin and strictly defined genetic features, described in detail in terms of particle size and mineralogy (the North Polish ablation boulder clays and varved clays).

In landfills, due to their low hydraulic conductivity, compacted clays (CC) are commonly used in multilayered structures as base liners and cover systems. Nevertheless, the hydraulic performances of the CC layer can be affected by temperature alterations. The CC barrier of cover systems is exposed to heating caused by waste degradation processes as well as by the air temperature fluctuations, including freezing and thawing and high temperatures. Exposition occurs especially during transitory configurations when the final cap is not completed with the protective soil layers. In the present work, four clayey soils of varying plasticity all suitable for landfill barriers according to the international standard requirements are tested with respect to their sensitivity to thermal stresses in terms of hydraulic conductivity changes. For each material, experimental tests are performed on compacted specimens comparing the values obtained soon after compaction with the ones obtained after exposition to freezing–thawing or drying processes, the latter caused by heating up to 60 °C. The results show that freezing–thawing is more detrimental than heating, since the first can increase the hydraulic conductivity by up to about 20 times, while the second by less than 10 times. The soils of medium plasticity are the most affected, while the ones with high plasticity show the ability to partially withstand the effects of the investigated thermal alterations. This behavior seems related to the water absorption capacity of the material. The results suggest that the optimum water content acquired from the Proctor Standard curve seems to be a suitable indicator of this partial recovery potential. [ABSTRACT FROM AUTHOR]

Platanus acerifolia (Aiton) Willd was generated spontaneously around the beginning of the 1600s in Spain between Platanus orientalis L. and Platanus occidentalis L. The study was carried out on P. acerifolia trees in different sites in Rome in the period April-July 2019. Trees comparable for size were selected in A sites (historical parks), B sites (high traffic density streets) and in C sites (high traffic density avenues along the Tevere River characterized by a large water availability). At the morphological level, leaf area (LA) was significantly higher in A and C sites and leaf tissue density (LTD) in C sites. At anatomical level, the total leaf thickness (LT). the palisade parenchyma thickness (Pt), the spongy parenchyma thickness (St) and the abaxial epidermis thickness (Abet) were significantly higher in A sites, while the adaxial cuticle thickness (Adct) and the adaxial epidermis thickness (Adet) in B sites. The ratio between palisade and spongy parenchyma thickness (P/S) was significantly higher in C sites. The plasticity index (PI, 0.42) was calculated on all the considered leaf traits. Among the morphological traits, LTD had the highest plasticity (0.49) and among the anatomical traits, trichomes density (TD) and Adet (0.74 and 0.54, respectively). Overall, the results highlight the large adaptability of P. acerifolia to grow in different sites in Rome through several changes in leaf morphological and anatomical traits. [ABSTRACT FROM AUTHOR]

In this work, thermal conductivity and mechanical strength of a commercial epoxy resin were improved by incorporating an amine-terminated oligoimide modified graphene oxide (ATO-GO). For this purpose, the surface of GO was modified with flexible/stable imide backbone and amine terminals. The ATO-GO was incorporated in epoxy proportion to prepare series of nanocomposites. The terminal amino group of ATO-GO also acted as curing moiety for epoxy resin leading to good interfacial compatibility and dispersion in the epoxy matrix resulting in improved properties. The epoxy resin was cured with hardener Aradur-22962 and ATO-GO separately and the results of curing behavior were compared with each other, which clearly showed the curing action of ATO-GO. In the prepared ATO-GO-epoxy nanocomposites, the filler enhanced the thermal conductivity, hardness and elastic modulus without decrease in thermal stability even at higher filler loading. In previous studies, it is reported that at higher GO, filler-loading properties like elastic modulus, hardness values, and glass transition temperature (T g) were decreased. An enhancement of 59.5% in thermal conductivity was achieved for 5 wt% loading of ATO-GO filler as compared to neat epoxy. Along with this, thermal analysis revealed that the nanocomposites with 5 wt% filler loading have high T g and thermal strength. Nanoindentation results revealed that elastic modulus and hardness values enhanced by 104% and 147%, respectively, for the same nanocomposites. The enhanced thermal conductivity and good elastic behavior of the ATO-GO-epoxy nanocomposites demonstrated that these can be used as high-performance materials in electronic packing and electronic devices. [ABSTRACT FROM AUTHOR]

This study presents the results of in-situ field stabilization of clay soil using lime, dolerite and quartzite powders. The rock samples were collected from Oghi village and Misri Banda village of Khyber Pakhtunkhwa Province, Pakistan. A 415m2 site comprised of loose clay in Haripur district of Khyber Pakhtunkhwa was selected for field stabilization. In order to implement the experimental plan, eight test pits were dug and soil samples were collected from each pit to determine their major geotechnical properties. The raw soil contained kaolinite, illite and montmorillonite and hence characterized as CH type according to the Unified Classification System. The addition of 6% lime was found to produce the most positive impact on soil properties. Following a steady augment by 10%, a maximum of 30% dolerite and quartzite powders were separately mixed with each of the 6% lime-added soil samples. The resulting mixed soils were placed back into their respective pits and compacted using compaction vibrator. Standard penetration, field density and plate load tests were performed on each test pit. Finally, soil samples were extracted from all the test pits and the values of their direct shear box and Atterberg limits were measured. The results demonstrate that the addition of dolerite and quartzite leads to a significant increase in the bearing capacity, dry density, penetration resistance and angle of internal friction and thus improves the performance of the formerly lime-stabilized soil by drastically decreasing its compressibility. The resulting improvement is mainly due to the denser and less hydrophilic character of the constituents of the added rock powders as compared with the lime and raw soil. It has also been found that the magnitude of impact on the soil properties by dolerite and quartzite is notably different owing to the difference in mineralogical composition and physical characteristics of individual minerals present in both rock types. This study would help construction engineers for better soil treatment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Consistency limits and soil plasticity are the basic parameters that represent the physical properties of fine-grained soils and provide important information about their engineering properties, such as the compressibility and shear strength. These parameters are the standard input for all soil investigation programs, so their correct definition and usage in the design have great importance. The liquid limit value, which is one of the parameters that determine the consistency properties of the soils, can be obtained by standardized mechanized experiments that minimize operator effects. Meanwhile, the plastic limit is calculated by an experiment that is not standardized and can be affected by the operator's experience. In this case, the important parameters that affect the soil behavior are obtained in a wide range of values, and the reliability of the results is debatable. Thus, this paper aims to develop a new correlation, where the plasticity index can be directly calculated based on the liquid limit obtained from standardized experiments. Thus, the effect of the operator on the plastic limit test is eliminated. The effect of mineralogy is also considered in the newly developed correlation in addition to previous studies in the literature. A comprehensive experimental program was applied to 301 high-plastic clay samples, which were taken from the Bakırköy region of Istanbul city (Turkey), and the results were used to obtain liquid limit values using the Casagrande cup method. [ABSTRACT FROM AUTHOR]

This study presents the effect of high plasticity on swell potential, swelling pressure and micro-structural characteristics of kaolinite-bentonite mixed clays. Five different mix ratios of kaolinite bentonite mixture of 100:0, 90:10, 75:25, 50:50 and 25:75 in % by weight of dry kaolinite were used. All five synthesised soils were then mixed with 0%, 5% and 8% of cement by weight of dry soil, cured for 28 days and subjected to the Atterberg limit, one-dimensional oedometer and scanning electron microscope test. The inclusion of 5% and 8% cement reduces the plasticity index of the treated soils as the percentage of bentonite increases. The effects on plasticity of treatment with 5% and 8% cement after a 28-day curing period was evaluated, and the results show that reduction in plasticity index resulted in decreased swell potential and swelling pressure of the kaolinite-bentonite mixed clays. The results of microstructural analysis of 5% cement-treated soils show formation of flocculated fabric and cementation of soil particles, and filling with cementitious compounds of the voids of flocculated fabric in the soil. The reduction in swell can be attributed to the resulting compacted and dense mass of treated soils due to cementation of soil particles and cation exchange. The complex swell behaviour of high-plasticity kaolinite-bentonite mix is explained using the one-dimensional oedometer test, by further experimental study and examination of the microstructure of treated soils. [ABSTRACT FROM AUTHOR]

Structural failure of buildings, roads, and other infrastructures has led to the loss of lives and monumental damage to the economy. In developing countries such as Nigeria, the failures are always attributed to the nature/type of soils in the area without considering other factors. With the increase in civil engineering constructions and the scramble for a limited portion of competent soils for such constructions, land, therefore, is becoming man's most priced commodity for agriculture, residential and industrial purposes. No works of such have been done in the area, it is, therefore, imperative to study the cause(s) to prevent further loss of lives and the negative effects of such on the economy. The study was carried out at Panyam and some surrounding localities on latitudes N9021′ and N9026′ and longitudes 9011′E and 9016′E an area of 72 km2. A total of forty samples were collected out of which twenty were selected for swelling potentials determination due to their cohesive nature within the 1.5 m depth. To characterize the swelling of the soils, inferential testing methods; direct method comprising Liquid Limit and Plasticity Index with values ranging from 30% – 70% and 10% – 27% respectively, and the indirect method (Free Swell Index, FSI) whose values range from 9.1% – 90% were used. Most of the soils analyzed based on the geotechnical standards were categorized relatively safe for civil infrastructure. Structural studies employed the direct measurements of surface structures to get the orientations of structures measured. Landsat image and Total Magnetic Intensity (TMI) map of the area was acquired from the Nigerian Geological Survey Agency (NGSA) for subsurface structural analysis. The RTP-TMI (reduce to pole) grid data of the area were processed to improve magnetic anomalies associated with edges of surface/near-surface geological structures using the MAGMAP two-dimensional fast fourier transform (2D-FFT) filters package in Oasis Montaj v7.2 software. Geophysical studies using aeromagnetic data at a near-surface depth of 40 m and fractures measured on the surface both revealed a major trend in the NNE – SSW. It was observed that structures constructed across the major trend suffered little to moderate damage while those constructed along the major fractures trend suffered severe damage. It was concluded that both soils and fractures played individual roles in the collapse of infrastructure in the area. [ABSTRACT FROM AUTHOR]

The current research is focused on the static liquefaction and effective stress path characteristics of soils of the high seismicity Kutch region, India. In previous studies, the effects of the fines content and the plasticity of the fines on the undrained behavior were explored in a controlled and systematic manner with either non-plastic or plastic fines added to standard or river sands. The undrained characteristics of natural soil deposits having the simultaneous presence of both silt and clay fractions have not been explored. In the present study, the effects of a varying fines content and the nature of the fines on the static liquefaction and effective stress path characteristics of various soil deposits in the Kutch region at their in-situ densities have been studied. Various liquefaction indices were determined to quantify the static liquefaction, namely, the undrained brittleness index, the collapse potential, the liquefaction potential, and the resistance to further deformation. The variation in these parameters was analyzed in the context of the fines content, silt content, clay content, and plasticity. The effective stress paths of the Kutch soils exhibited a strain softening, limited strain softening or strain hardening response and their behavior was controlled by the fines content and its nature. Due to the presence of non-plastic fines, and irrespective of the content, the silty sands exhibited intense strain softening which was captured by the liquefaction indices. [ABSTRACT FROM AUTHOR]

To establish the evaluation method of intrinsic compressibility, oeodemter test was performed on Zhuozi clay and Wuqing clay and some other test data of various kinds of reconstituted clays were collected from the previous literatures. The compressibility constants (void ratio at vertical stress of 100 kPa) and (compression index) are widely recognised as indicators of intrinsic compressibility. Therefore, the influencing mechanisms of index properties can be investigated by establishing correlations with and. It has been found that and have linear relationships with liquid limit and normalised initial water content. Therefore, and can be quantitatively evaluated in terms of liquid limit and initial water content. Since plasticity index is the third factor that can slightly affect intrinsic compressibility, it can be used to modify the calculated value of and. It is indicated that liquid limit, initial water content and plasticity index are all index properties that can affect intrinsic compressibility, based on which and can be calculated and finally the compression curves can be evaluated based on the intrinsic concept. [ABSTRACT FROM AUTHOR]

Site investigations of the soils are considered very important for evaluation of the site conditions, as well as the design and construction for the project built in it. Taihu tunnel is thus far the longest tunnel constructed in the lake in China, with an entire length of over 10 km. However, due to the very insufficient site data obtained for the lacustrine clay in the Taihu lake area, a series of self-boring pressuremeter (SBPM) field tests was therefore carried out. Undrained shear strengths were deduced from the SBPM test, with the results showing generally higher than those obtained from the laboratory tests, which may be attributed to the disturbance to the soil mass during the sampling process. Degradation characteristics of the soil shear modulus (Gs) were mainly investigated, via a thorough comparison between different soil layers, and generally, the shear modulus would cease its decreasing trends and become stable when the shear strain reaches over 1%. Meanwhile, it was found that a linear relationship between the plasticity index and the shear modulus, and between the decay rate of the shear modulus and the plasticity index as well, could be developed. Further statistical analysis over the undrained shear strength and shear modulus distribution of the soils shows that the undrained shear strength of the soils follows a normal distribution, while the shear modulus follows a log-normal distribution. More importantly, the spatial correlation length of the shear modulus is found much smaller than that of the undrained strength.

This study has been prepared as a reply to the discussion written by O'Kelly and Soltani (2021). [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Materials / Revista Romana de Materiale is the property of Foundation for Materials Science & Engineering Serban Solacolu and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao is the property of Chinese Journal of Applied Ecology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

• ANN model has been developed to predict fly ash based geopolymer abrasion resistance properties. • Plasticity index of the fly ash based geopolymer is determined from nanoindentation load-displacement curve. • Plasticity index properties of fly ash based geopolymer is related to increase of compressive strength, degree of activation and also abrasion resistance. This study presents the investigation of the abrasion resistance of fly ash based geopolymer via the application of nanoindentation. Nine fly ash based geopolymer mixes with four variables: silica fume (SF), sand to cementitious ratio (s/c), liquid to solid ratio (l/s) and superplasticizer (SP) were investigated with statistical methods to obtain the plasticity index of the four fly ash based geopolymer phases. The results suggest that the pure fly ash based geopolymer paste with no SF, no SP, no sand and l/s ratio of 0.60 provides the highest abrasion resistance. Artificial neural network (ANN) is also adopted to predict the abrasion performance of the fly ash based geopolymer where good correlation is found. With the application of deconvolution method, it is reported that the plasticity index of N-A-S-H, partly activated slag and non-activated slag phases show a decreasing trend of plasticity index with increasing hardness or modulus. The non-activated compact slag phase shows no clear trend with changes in hardness and modulus. The relationship between degree of activation versus plasticity index (PI) is also studied, it was found that high degree of activation leads to formation of high volume fraction of N-A-S-H which this correlates with increased compressive strength and improved abrasion resistance. The application of nanoindentation with deconvolution method is suitable in quantifying the PI of the phases and abrasion resistance of the fly ash based geopolymer mortar. [ABSTRACT FROM AUTHOR]

In this study, we utilize acceleration time histories data at eight KiK-net vertical arrays in Japan, recorded between January 2009 to June 2014, to analyze nonlinear seismic site response. Ground motion records provided by seismic vertical arrays allow estimation of in situ soil dynamic parameters. First, the shear modulus is computed from the shear wave velocity using seismic interferometry by deconvolution. Considering each record as an in situ cyclic test under seismic loading, the shear strain is computed as the velocity ratio between two sensors and the shear stress is assumed as a spatial function of accelerations. Using classic hyperbolic regression models, we quantitatively assess the relationships between the in situ soil dynamic parameters and the level of ground motion. We found nonlinearity starts at a quite low level of shear strain of 5 × 10−6–5 × 10−5, and becomes much more significant beyond a relatively high level of strain of 1 × 10−4. The threshold strains from ground motion observations are well consistent with those from previous laboratory tests. Finally, a parametric analysis is presented to discuss the influence of plasticity index on nonlinear soil behavior evaluations. It is concluded that the threshold acceleration of soil nonlinear behavior (generally ranging from 20 to 100 cm/s2) is mainly controlled by the stiffness and plasticity index, and the degree of soil nonlinear behavior is mainly controlled by the stiffness, plasticity index and the level of ground motion. [ABSTRACT FROM AUTHOR]

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An investigation into the effects of steel slag and saw dust ash on index properties of selected subgrade soils is here presented. The influence of various percentages by weight of steel slag and saw dust ash on index properties i.e. liquid limit, plastic limit, plasticity index and linear shrinkage of subgrade soils were deduced from the results of laboratory analysis conducted in accordance with standards. The results obtained showed that values of the index properties decreased as the quantities of steel slag and saw dust ash added to the soils increased and vice versa. [ABSTRACT FROM AUTHOR]

Due to its low permeability, a clay liner is the main material used in solid waste disposal landfills. These liners exposed to various chemical, biological and physical events and would be affected by the resulting leachate which will change the shear strength parameters of compacted clay-bentonite liner (CCL). In this paper, the effect of four types of inorganic leachate's components at concentrations of 2, 5 and 10%, leachate and deionised water on shear strength parameters of three CCLs with different plasticity index was investigated by performing a series of direct and vane shear tests. The experimental results show that in both direct and vane shear tests, by addition of soluble salts of single-valence cations and leachate provided from them up to 2%, the undrained shear strength of clay-bentonite liners increased. With further increase in contaminants, the shear strength decreased. The variation of undrained shear strength for clays by the addition of soluble salts of bivalence cations is more intricate. Also, it can be found that, the effect of contaminants on shear strength of clays is more significant in clays with medium plasticity index. [ABSTRACT FROM AUTHOR]

Morphological and ecophysiological traits showed by male and female Populus tomentosa Carr. trees were studied under various degrees of water and alkaline stresses. The results showed that different adaptations to drought and alkaline stresses were adopted by each gender; males possessed a much higher tolerance to both stresses compared to females. In contrast to females, the males exhibited a lower inhibition in total biomass, total leaf area, net photosynthetic rate, stomatal conductance, leaf carbon and nitrogen concentrations as well as water- and nitrogen-use efficiency in response to drought and alkaline stresses. Nevertheless, compared to the males, the females showed a higher plasticity in root biomass/shoot biomass ratio, fine root/coarse root ratio, and intrinsic water-use efficiency, indicating that the males and females differed in some of trade-offs between growth and stress defence to maximize water and nitrogen gains under both stress conditions. [ABSTRACT FROM AUTHOR]