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Salinity and sodicity greatly influences ongoing physical processes in soils. Organic matter may rehabilitate physical and mechanical properties of soils. Vermicompost as an amendment influences moisture-related parameters including consistency (plastic – PL and liquid limit – LL) and compaction. This study was conducted on soils (sandy-clay-loam) treated with different salinity levels (0.58 (control – irrigation water quality, tap water), 4 and 8 dS m−1) to investigate the effects of different vermicompost doses (0% (control), 2.5% and 5% w/w) on soil consistency limits and compaction. The pot experiment was carried out in a total of 27 pots, i.e. 3 (vermicompost doses) x 3 (salinity levels) x 3 (number of replicates). For Proctor compaction properties, maximum dry bulk density (MDD) reduced and optimum water contents (OWC) increased with increasing vermicompost doses under different salinity levels (p <.01). Increasing vermicompost doses under the lowest salinity level (0.58 dS m−1) yielded increasing optimum water contents for control (LL = 35.93% and PL = 25.85%). Optimum water contents were determined as 42.19% (LL) and 29.93% (PL) for 2.5% vermicompost dose and as 47.33% (LL) and 36.01% (PL) for 5% vermicompost dose under the lowest salinity level. LL, PL, OWC and MDD were significantly affected by vermicompost x salinity interactions. The highest maximum dry bulk density (1.92 g cm3) and the lowest optimum water contents (13.50%) were obtained from 0% vermicompost under the 8 dS m−1 NaCl level. Mean weight diameter (MWD) values ranged from 0.690 mm for 0% VC treatment under high Na salt level (8 dS m−1 NaCl) to 0.821 mm for 5% VC treatment under lowest Na salt level (0.58 dS m−1 NaCl). The correlations between aggregate stability (particle size group 1–2 mm) and optimum water content were 0.647*, 0.587* and 0.598* as compared to correlations of −0.512*, −0.470*, and −0.617** between aggregate stability (particle size group 1–2 mm) and maximum dry bulk density for the 0, 4 and 8 dS m−1 NaCl levels, respectively. MWD was positively correlated with OWC (0.386*) and negatively correlated with MDD (−0.385*). The greatest (2.39%) and the lowest (0.32%) soil organic matter values were respectively observed in 5% VC under the lowest salinity level (0.58 dS m−1) and 0% VC with at high Na salt level (8 dS m−1 NaCl). It was concluded that vermicompost reduced compaction-induced damage in soils. [ABSTRACT FROM AUTHOR]

Liquid and plastic limits are important parameters of soil hydraulic properties and are important in the research of collapsing gullies. To investigate the specific ion effects on the liquid and plastic limits of collapsing gullies, soil samples from three soil layers in a soil profile（red soil layer, sandy soil layer, and detritus layer) of a stable collapsing gully located in Hetian Town of Changting County, Fujian Province, were collected and exchanged with three kinds of electrolyte solutions（Li+, Na+, and K+) to analyze the liquid and plastic limits. The main results were as follows: the red soil layer had the highest plastic limit, liquid limit, and plasticity index, followed by the sandy soil and detritus layers（P＜0.05). Correlation analysis showed that the clay content, organic matter content, cation exchange capacity, and kaolinite content were positively correlated with the plastic and liquid limits（P＜0.05). Clay and organic matter contents were significantly positively correlated with the plastic limit. The plastic limit, liquid limit, and plasticity index of the red soil layer exchanged with K+ were 5.80%, 9.53%, and 12.99% higher than those exchanged with Li+, and 3.50%, 9.77%, and 15.86% higher than those exchanged with Na+, respectively. The plastic limit, liquid limit, and plasticity index of the sandy soil layer exchanged with K+ were 7.22%, 6.69%, and 6.83% higher than those exchanged with Li+, and 4.33%, 5.27%, and 7.32% higher than those exchanged with Na+, respectively. However, the liquid and plastic limits of the detritus layers did not differ significantly. The liquid and plastic limits of the red and sandy soil layers exchanged for K+ were significantly higher than those exchanged for Li+ and Na+. Therefore, compared with Li+ and Na+, K+ could increase the liquid and plastic limits of collapsing gullies. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil Science & Plant Nutrition / Toprak Bilimi ve Bitki Besleme Dergisi is the property of Soil Science Society of Turkey 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.)

A study on the effect of sisal fibre and waste plastic strips on tropical black clay (also called Black cotton soil, BCS) was carried out. Tests piloted on the natural and treated soil consist of California bearing ratio (CBR), Atterberg limits and compaction for different percentages inclusion of sisal fibre (0, 0.5, 1, 1.5 and 2%) and waste plastic strips (0, 0.5, 1, 1.5 and 2%) by dry weight of soil. Results obtained showed that the liquid limit of BCS initially fluctuated between 43.4% and 55.9% at 1% sisal fibre content, then dropped to 49.4% at 2% sisal fibre content. In the case soil treated with waste plastic strips, liquid values increased from 43.4% for the natural soil to a highest value of 58% at 1% waste plastic strips and thereafter decreased to 49.15% at 2% waste plastic strips content. Plastic limit for both BCS-sisal fibre/waste plastic strips initially decreased from its natural value of 25.78 to 15.55 and 14.77% when treated with sisal fibre and waste plastic strips respectively at 0.5% admixtures content. In the case of plasticity index, values initially increase from its natural value of 17.66% to peak values of 35.39 and 43.23% for sisal fibre and waste plastic strips treated soil respectively, and thereafter decreased. Maximum dry density (MDD) initially increased from 1.55 mg/m3 at 0%, to 1.60 mg/m3 at 0.5% and thereafter decreased to 1.53 mg/m3 at 2% of fibre content. In the case of samples treated with waste plastic strips. The MDD progressively increased as the amount of waste plastic strips increased. OMC show an overall trend of increase for BCS treated with sisal fibre, and a general trend of decrease for soil treated with waste plastic strips. The CBR values initially lessened from their natural value of 13.59% to 4.76% at 1% sisal fibre and subsequently increased to 10.57% at 2% sisal fibre. Similar behaviour was observed for soil modified with waste plastic strips. Based on the results, BCS/waste plastic strips improved the soil more than BCS/sisal fibre treated soil and is recommended at optimal 2% waste plastic strips for geotechnical engineering application such as road payment. [ABSTRACT FROM AUTHOR]

Copyright of Investigación e Innovación en Ingenierías is the property of Universidad Simon Bolivar 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.)

This article presents a discussion of the paper by Akbay Arama et al. (2021) published in the Arabian Journal of Geosciences, Vol. 14, No. 7, Article 534. Using simple and multiple regression analyses, as well as soft computing artificial neural network (ANN) methods, Akbay Arama et al. (2021) investigated a large database comprising of 1253 Atterberg limits test results for high and very high plasticity clay (CH) soils that are dominant on the European side of Istanbul Province, Turkey. Stated objectives included querying the attainment of the plasticity index (PI) for these soils directly from only liquid limit (LL) test results. Based on regression analyses results, Akbay Arama et al. (2021) produced various correlations relating the PI to LL. Then, employing the Noe (2005) experimental PI–LL dataset, Akbay Arama et al. (2021) reported that their proposed correlations have superior predictive performance compared to those of eight previously reported PI–LL correlations selected (by them). The authors of the present discussion article are of the views that (i) the produced PI–LL correlations for the Istanbul CH soils may not be sufficiently reliable, (ii) it does not seem intuitive to compare the predictive capabilities of these proposed correlations against those previously reported in the literature and deduced for diverse groups of fine-grained soils sourced from geographically different regions, and (iii) since PI–LL correlations cannot definitively and consistently establish the water content corresponding to the experimental plastic–brittle transition point, the thread-rolling test for plastic limit (PL) determination (and hence by association for PI calculation) needs to be retained. Each of these views is elaborated in this article. [ABSTRACT FROM AUTHOR]

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]

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]

Among the multitude of alternate plasticity index (PI) estimation proposals, empirical correlations based on the linear shrinkage (LS) test, originally proposed in the 1967 edition of the British BS 1377 standard, seem to be gaining increased attention. This study has two main aims: (i) re-examining LS-based correlations for PI estimation to better understand their true potentials and/or limitations; and (ii) investigating the possibility of employing LS, as a proxy for the standard PI, for fine-grained soil classification. To this end, comprehensive statistical analyses were performed on the largest and most diverse database assembled of its kind, entailing PI:LS measurements for 265 different fine-grained soils [pertaining to the 'soft' base percussion-cup liquid limit (LL = 17–134%) and the Australian standard LS = 0.5–32.0%]. It was demonstrated that the LS can generally only provide a rough approximation of the actual PI. At best, only those predictions produced by PI = 1.86 × LS for low-plasticity soils (i.e., LL ≤ 35%) included in the database may be deemed acceptable, specifically when difficulties are encountered in executing the standard plastic limit (PL) thread-rolling test for such soils. The second/novel aim of this study found that the agreement level between the Casagrande-style plasticity-chart classification (based on the measured PI = LL − PL) and that performed using the PI deduced from a newly introduced multivariable correlation involving LS and LL, as inputs, was obtained as 95%. Hence, in the absence of measured PI, the multivariable PI:LS:LL correlation may be deemed suitable for preliminary soil classification purposes. • Examine linear shrinkage (LS) – liquid limit (LL) correlations for plasticity index (PI) estimates. • Statistical analysis of large PI:LS database for 265 different fine-grained soils with measured PL. • LS can generally only provide guesstimate of actual PI [= LL − thread-rolling plastic limit (PL)]. • For low-plasticity soils (i.e., LL ≤ 35%), predictions by PI = 1.86 × LS may be deemed acceptable. • New multivariable PI:LS:LL correlation deemed suitable for preliminary soil classification purposes. [ABSTRACT FROM AUTHOR]

Atterberg limits and indices, for example liquid limit ( LL), plastic limit ( PL), linear shrinkage ( LS) and plasticity index ( PI), are important soil properties in engineering and land evaluation for predicting soil mechanical behaviour. This study was conducted to develop and evaluate pedotransfer functions ( PTFs) to predict Atterberg limits using measured and morphological soil properties from a large data set in South Africa covering a vast range of soils, geologies and climates. Five PTFs were developed; the first four using measured properties from 2330 soil horizons including extractable Fe, Al, Mn, Na, K, Mg and Ca; organic carbon ( OC); pH (H2O); cation exchange capacity ( CEC); and sand, silt and clay fractions to predict LL, PL, LS and PI. Morphological descriptors such as colour, structure (grade, size and type), consistency, occurrence of slickensides and cutans and abundance of roots were included in the second PTF using data from 717 horizons to predict PI. For all PTFs, two-thirds of the data were randomly selected and used for model development and the remainder for validation. Prediction accuracies of R2 between 0.49 and 0.77 comparable to other studies on large data sets but underperformed when compared to localized data sets. For engineering purposes, site-specific PTFs for prediction of Atterberg limits should be developed. [ABSTRACT FROM AUTHOR]

In order to ensure the bearing capacity and durability of road pavement in cold climate areas, it is necessary use materials which are resistant to harmful frost impact, known as frost-heaving. Frost heave cause adverse volume changes, the upwards swelling of the pavement after freezing and deterioration of the bearing capacity of the structure after thawing. In winter, road carriageway temperatures may reach t min = -30̊C under Polish conditions, which results in the freezing of the structural pavement and subgrade layers. Due to frost penetration into the pavement and the subgrade, heaves may form in soils and in structural layers (unbound mixtures), and during the thaw period a high level of moisture is maintained in the frozen layers, and therefore the structure has a low bearing capacity. The aim of this research was to evaluate frost susceptibility of aggregates mixtures based on content of fine-grain fractions and plasticity index I P . Potential frost susceptibility of road materials and soils is determined by laboratory testing. Frost susceptibility is connected directly with the content and quality of fines, which is why the basic test is that material grading. The criterion based on fines content is the most frequently used indicator in determining frost susceptibility for soils. The article shows whether the limit values adopted for this criterion are also applicable to aggregates. The results of frost-heaving properties are presented of 14 typical natural aggregate road mixtures, continuously graded 0/31.5 mm. Frost susceptibility was determined based on laboratory testing of the following features: content of fine-grain fractions, smaller than 0.002 mm, 0.02 mm, 0.075 mm, 0.125 mm, plasticity index I P and the value of the actual frost-heave of a compacted aggregate mixture frozen in a cylinder. The article shows the test results and their analyses according to the frost susceptibility evaluation criteria for unbound mixtures in road construction. The tests presented in the article were carried out at the Road and Bridge Research Institute in Warsaw. [ABSTRACT FROM AUTHOR]

Atterberg limits are broadly used for engineering and geology purposes as well as in agricultural and environmental applications. Laboratory methods used for their determination are, however, laborious, destructive and tool dependent. The aim of this study was to test the feasibility of using visible near-infrared spectroscopy (vis–NIRS) as a fast and accurate alternative to the conventional measurements of Atterberg limits (LL and PL) and the PI for 229 geographically diverse soil samples originating from 24 countries. Three types of calibration techniques including Partial Least Squares (PLS) regression, Artificial Neural Networks (ANN) and Support Vector Machines (SVM) were applied to the spectral data. The performance of the best vis–NIRS models was validated using 45 independent samples and compared with two existing and one newly developed pedotransfer functions (PTF). The application of SVM yielded marginally better predictive ability than PLS and ANN for all modelled properties. The SVM models estimated LL, PL, and PI with root mean squared error (RMSE) of 7%, 5% and 7%, respectively. The newly developed PTF gave slightly better estimations than the existing ones, with RMSE values of 8%, 6%, and 6%, respectively for LL, PL, and PI. Furthermore, in terms of the sample swelling class, the SVM model correctly classified 31 of the 45 samples, compared to 34 samples for the best PTF. The results indicate a great potential of vis–NIRS for reliable estimates of Atterberg limits for soil samples of large geographical and mineralogical diversity. [ABSTRACT FROM AUTHOR]

• Standard methods for measuring the Atterberg limits (ALs) is tedious and costly. • Hygroscopic water content (w h) is intimately linked to the ALs. • We propose regression models to estimate ALs from w h accounting for hysteresis. • Models based on w h were superior to models based on clay, silt, organic carbon or CEC. • Hysteresis had no effect on accuracy of estimating the ALs. A number of environmental, agronomic and engineering applications require knowledge of the Atterberg limits (liquid limit, LL; plastic limit, PL) and the plasticity index, PI of soils. The tedious and costly nature of standard experimental methods, as well as challenges with measurement repeatability motivated the development of regressions as well as more sophisticated techniques to estimate the Atterberg limits from other properties such as clay content, cation exchange capacity (CEC), and soil specific surface area. The amount of water adsorbed to particle surfaces at relative humidity (RH) < 95% is intimately linked to these soil properties, which suggests that hygroscopic water content (w h) may be a better predictor of the Atterberg limits. The present study (i) proposes regression models that estimate the LL, PL, and PI from w h at different relative humidity values ranging from 10 to 90% and considering water sorption hysteresis, and (ii) compares the performance of the models to other models that comprise clay, silt and organic carbon contents and CEC. For model development, w h was measured by water adsorption and desorption for 168 soil samples that varied widely in terms of geographic origin, clay mineralogy, and soil organic carbon content. The LL and PL were determined with the drop cone penetrometer and rolling device, respectively. Regression models were developed for both sorption directions for nine RH values between 10 and 90%. For 44 independent soil samples, the models estimated LL, PL and PI accurately (e.g., for desorption w h measured at 90% RH , RMSE and r 2 values were 6.43% & 0.89; 3.95% & 0.83 and 6.69% & 0.79, respectively). There was no clear effect of sorption direction on the estimation accuracy. The w h determined at higher RH tended to better estimate the Atterberg limits compared to that measured at lower RH. The w h models were superior in estimating LL and PL compared to models that were based on clay content and organic carbon or CEC. For the PI, the models based on CEC performed slightly better than the w h models. Thus, a single measure of w h can provide reliable estimates of the Atterberg limits and PI. [ABSTRACT FROM AUTHOR]