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    <title>Transport Research International Documentation (TRID)</title>
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    <atom:link href="https://trid.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Frost heave classification of compacted well-graded gravels: a new perspective based on the revised soil classification system</title>
      <link>https://trid.trb.org/View/2684673</link>
      <description><![CDATA[Frost-induced damage to pavement infrastructure remains a critical engineering challenge. Accurately predicting frost heave in subbase and subgrade materials is essential for ensuring long-term durability of pavements. Determining the frost susceptibility of soils via direct laboratory testing remains the most reliable approach, however, the requirement for specialized equipment and extensive testing time makes it impractical for routine projects. Consequently, there is a need for reliable classification systems that can accurately predict frost behavior using simple index tests. While traditional classification systems like USCS and AASHTO are widely used, they primarily rely on grain size and plasticity, which often fail to differentiate the frost-heave potential of soils with similar fines content but different mineralogy. Hence, these systems are limited in their capacity to constitute a reliable framework for the assessment of frost heave behavior. This paper addresses the difficult problem of assessing the frost susceptibility of subbase and subgrade material focusing particularly on new soil classification parameters that have a potential for improving soil index based frost classification methods. This study utilized a custom-designed frost susceptibility testing system to conduct step-load freeze–thaw tests on twelve gravel-sand mixtures with fines contents ranging from 5.2% to 18%. Three distinct fines were tested: non-plastic silt, kaolinite, and a high plasticity clay. The mixtures were analyzed using the Revised Soil Classification System (RSCS) to evaluate its predictive potential compared to traditional methods. Detailed test results for all twelve mixtures (each with four duplicate samples) are shared including data pertaining to sample index parameters, heave rates and amounts, sample boundary temperatures and residual heave. The results demonstrate that frost heave rates are profoundly impacted by fine mineralogy rather than mass percentage alone, with kaolinite producing the highest heave rates. A significant finding is that RSCS parameters—specifically the liquid limit tested with brine, LLBrineC and electrical sensitivity, SE —successfully differentiate the three fine types into separate soil classes (NI, II, and IL). Furthermore, normalized heave rates were successfully modeled using non-linear regression, revealing that the threshold fines content expected to produce high-frost susceptibility (8 mm/day) varied drastically from about 5% for kaolinite to 74% for YK clay. These findings suggest that the RSCS provides a physics-inspired, data-driven framework capable of improving Level II frost classification. Future work should build on these initial findings by contributing to coupled RSCS and frost-heave databases, refining reference heave rates for fine and coarse soil fractions and addressing post-thaw strength loss.]]></description>
      <pubDate>Tue, 23 Jun 2026 13:52:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2684673</guid>
    </item>
    <item>
      <title>Long-term Hydro-mechanical Behavior and Equilibrium Characteristics of Compacted Soils in Highway Subgrades Under Wetting-drying Cycles</title>
      <link>https://trid.trb.org/View/2690969</link>
      <description><![CDATA[The long-term moisture-density evolution of compacted soil was investigated through field investigations and laboratory experiments. Field investigations were conducted on multiple highway subgrades with service lives up to 20 years. Comparison with construction-stage data revealed a progressive increase in moisture content accompanied by a reduction in compaction degree, indicating long-term degradation of the compacted soil structure. Representative soil from a strong monsoonal region with pronounced capillary rise was selected for laboratory testing. Unsaturated triaxial tests were conducted to examine the hydromechanical response of the soil under controlled wetting-drying cycles involving variations in matric suction. The results demonstrated a linear relationship between moisture content and degree of compaction. Repeated wetting-drying cycles weakened the soil-water retention behavior, induced cumulative volumetric expansion, and reduced the moisture-holding capacity of the soil. To characterize the stabilized state of soil subjected to long-term wetting-drying cycles, the concepts of equilibrium moisture content (15.0%-19.6%) and equilibrium degree of compaction (95.3%-92.1%) were proposed. A critical compression-expansion line was established to distinguish between cumulative swelling and shrinkage behavior.]]></description>
      <pubDate>Mon, 27 Apr 2026 14:58:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/2690969</guid>
    </item>
    <item>
      <title>Settlement Behavior of Compacted Oklahoma Soils</title>
      <link>https://trid.trb.org/View/2669626</link>
      <description><![CDATA[Numerous highway embankments experience post-construction settlement problems, such as bridge approach settlement that results in the "bump at the end of the bridge." One of the causes may be wetting-induced collapse settlement or simply, collapse settlement. Collapse settlement is a time-dependent process resulting from post-construction increases in moisture content. The post-construction settlement of numerous Oklahoma highway embankments raised questions as to whether the current Oklahoma Department of Transportation embankment specifications and construction practices are adequate in addressing collapse settlement, and prompted the current study to examine the influence of soil type on collapse potential of Oklahoma soils. One-dimensional oedometer tests were conducted to study the potential for collapse settlement of 22 Oklahoma soils and shales under conditions typically encountered in compacted fills. Results show that factors related to fine composition, such as clay-size fraction, plasticity index, liquid limit, activity, and AASHTO group index can be used for preliminary estimation of collapse index. Statistical analysis of the oedometer test data indicates that variables having the most impact on collapse index are moisture content, dry unit weight, plasticity index, and clay-size fraction. Settlement charts were developed to facilitate the estimation of collapse settlement of fills for different conditions, including fill height, moisture content, and soil type. Three scale centrifuge models compacted at different conditions and a case history of an embankment that has experienced significant collapse settlement are presented. Predictions based on one-dimensional oedometer-based method and settlement charts are compared to measured collapse settlements at the embankment centerlines. Given the uncertainty with field estimates of settlement, the comparison showed a reasonable agreement between predictions and field estimates of collapse settlement at the embankment centerlines; the limited evidence suggests that predictions based on one-dimensional assumptions tend to underestimate actual settlements possibly due to the two-dimensional nature of embankments. The review of literature regarding settlement of compacted fills, the laboratory test results obtained, and the field study of an actual embankment suggest the need for embankment design and specifications that will account for collapse susceptibility of different soil types. Specifications should demand for exceptional quality control and more stringent compaction requirements during embankment construction, particularly for large embankments, collapse-susceptible soils, and embankments susceptible to flooding.]]></description>
      <pubDate>Mon, 09 Mar 2026 16:50:51 GMT</pubDate>
      <guid>https://trid.trb.org/View/2669626</guid>
    </item>
    <item>
      <title>Coarse Biochar Improves the Hydraulic Performance of Compacted Roadside Soil Media</title>
      <link>https://trid.trb.org/View/2592230</link>
      <description><![CDATA[Compacting engineered soil media is necessary to ensure its stability in many urban contexts, such as in road embankments. However, compaction can reduce infiltration rates, increase runoff volumes, and impede vegetation growth. Amending soil media that is to be compacted by mixing it with biochar may largely mitigate the consequences of compaction, effectively helping road embankments and similar areas function as green stormwater infrastructure. Here, the authors report the results of a lab experiment intended to determine how biochar particle size and application rate influence the hydraulic properties of compacted roadside media. Specifically, the authors amended a loamy sand collected from the field with biochar ranging from 0 to 6% (w/w) and that was either unsieved or sieved to remove most coarse particles. The addition of biochar with many coarse particles (&gt;2  mm) improved the saturated hydraulic conductivity (Ksat) of the medium postcompaction, but this effect diminished at biochar dosages above 3% (w/w). In contrast, the addition of biochar with few coarse particles did not improve Ksat postcompaction. These changes likely arose because unsieved biochar facilitated the addition of interconnected pores and did so to a greater extent than particle breakage led to pore restriction. Also, biochar addition improved water retention in the plant available suction range postcompaction, whether the biochar was sieved or unsieved. Amendment with relatively coarse biochar could therefore help compacted roadside soil media manage stormwater while also reducing plant water-stress in a frequently water-limited setting.]]></description>
      <pubDate>Thu, 18 Sep 2025 09:18:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2592230</guid>
    </item>
    <item>
      <title>Scanners, satellites, smart compactors, and drones: Emerging technologies for assessing compacted soil lift thickness</title>
      <link>https://trid.trb.org/View/2549335</link>
      <description><![CDATA[Effective soil compaction requires sufficient compactor energy penetration. To achieve this goal, soil compaction specifications typically mandate a “not to exceed” lift thickness for a given layer of soil that is placed, spread, and compacted. Traditional techniques for field monitoring of soil lift thickness are personnel dependent, and add cost and time to projects. New and innovative approaches are emerging that have the long-term potential for more effective lift thickness monitoring at reduced cost. Three of these techniques are discussed in the current paper: (1) non-destructive lift thickness scanning using a magnetic pulse induction lift thickness scanner (scanners), (2) continuous real-time kinematic (RTK) global positioning system (GPS) surveying using a global navigation satellite system (GNSS) such as GPS, GLONASS, BeiDou, Galileo, etc in conjunction with local receivers mounted on “intelligent” soil compactors (satellites and smart compactors), and (3) unmanned aerial vehicle (UAV) image acquisition coupled with photogrammetric analysis/surveying techniques (drones). The accuracy of point-specific measurements made using each of these techniques is of critical importance. This paper describes the results from a field study that was conducted to assess the relative accuracy of these three techniques by monitoring the lift thickness of a full-scale earthen test embankment. Measured field results indicated that emerging technologies such as magnetic pulse induction scanning can accurately estimate soil lift thickness within 0.4 cm when compared against physical soil lift thickness measurements. Other emerging technologies, such as UAV-based surveying techniques, also provided reliable estimates of soil lift thickness measurements, which were accurate to within 1.2 cm of physical soil lift thickness measurements. Additionally, some of these emerging techniques (satellites, smart compactors, and drones) offer the advantage of providing near-continuous soil lift thickness measurements along the entire embankment , which can be useful for building spatial maps of compacted soil lift thickness.]]></description>
      <pubDate>Fri, 30 May 2025 15:53:41 GMT</pubDate>
      <guid>https://trid.trb.org/View/2549335</guid>
    </item>
    <item>
      <title>Research on the determination of subgrade gravimetric moisture content under different compactness based on the ground penetrating radar</title>
      <link>https://trid.trb.org/View/2517036</link>
      <description><![CDATA[It is essential for improving the accuracy of subgrade compactness detection to realize the real-time determination of gravimetric moisture content during subgrade compaction. In this study, a subgrade gravimetric moisture content semi-empirical model is established to evaluate the influence of subgrade filling materials types and compactness on the subgrade gravimetric moisture content. The laboratory and field tests for different subgrade types are carried out to collect the subgrade dielectric constant under different compactness. The proposed semi-empirical model is fitted based on the experimental results and the data from the literature. The Ground Penetrating Radar (GPR) technique is then employed to obtain gravimetric moisture content by collecting the dielectric constant of the subgrade in the field test based on the proposed semi-empirical model. The results after removing anomalous data are compared with the results from the time domain reflectometry (TDR) technique. The results show that the subgrade dielectric constant subgrade increases with the gravimetric moisture content growth. And the higher compactness, the higher the dielectric constant with the same gravimetric moisture content. It can be explained that the higher compactness of the subgrade means better water retention. The proposed semi-empirical model obtains the subgrade gravimetric moisture content satisfactorily considering the types and the compactness of the subgrade, as illustrated in comparison with other models in the literature. Based on this, the GPR technique measures subgrade gravimetric moisture content more accurately compared to the TDR technique after removing anomalies. It has the advantages of not disturbing the subgrade, a wide range of applications, and high measurement accuracy, and can realize real-time non-destructive testing. This study provides a basis for determining subgrade gravimetric moisture content in real-time and non-destructive and it is important to improve the accuracy of subgrade quality evaluation.]]></description>
      <pubDate>Thu, 10 Apr 2025 09:21:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/2517036</guid>
    </item>
    <item>
      <title>A Deep Learning Approach for Modelling of Resilient Modulus of Compacted Subgrade Subjected to Freezing-Thaw Cycles and Moistures</title>
      <link>https://trid.trb.org/View/2445176</link>
      <description><![CDATA[This study employs a deep learning approach to determine the resilient modulus of compacted subgrade, which is one of the most important stiffness characteristics in pavement design. The proposed paradigm, i.e., deep neural network (DNN), comes under the category of artificial neural network with several hidden layers and activation functions. A total of 2813 data of subgrade soils, comprising six influencing parameters namely weighted plasticity index, dry unit weight, confining stress, deviator stress, moisture content, and the number of freezing-thaw cycles, were considered for the creation and validation of the model. The results of the employed DNN were compared with those of other benchmark techniques, such as feed-forward neural network, k-nearest neighbour regressor, extreme learning machine, random forests regressor, multivariate adaptive regression spline, and multiple linear regression. As per the determination coefficient (R²) and root mean square error (RMSE) indices, the developed DNN achieved the maximum degree of precision of robust modulus during both training (R² = 0.9947 and RMSE = 0.0094) and testing (R² = 0.9797 and RMSE = 0.0183) phases. The study also employed DNN-based monotonicity analysis to examine the effects of different influencing parameters. Overall, the developed DNN has demonstrated the potential to assist geotechnical and geological engineers in estimating the resilient modulus of compacted subgrade at varying freezing-thaw cycles and moistures during the preliminary phase of the engineering projects. The developed Python code is attached for future research.]]></description>
      <pubDate>Mon, 09 Dec 2024 09:56:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/2445176</guid>
    </item>
    <item>
      <title>Estimating the compacted dry density of gravelly soil with oversized particles</title>
      <link>https://trid.trb.org/View/2440372</link>
      <description><![CDATA[The compacted dry density of gravelly soils containing particles that are too large for ordinary laboratory compaction tests is usually estimated by measuring the dry density of the base sample obtained by removing over-sized particles then correcting the measured value by the Walker-Holtz Equation (W&H Eq.). It is known that the W&H Eq. overestimates the dry density of gravelly soils and this trend becomes stronger as the mass ratio P of oversized particles increases. It seems that a satisfactory solution is not yet available. A comprehensive series of laboratory compaction tests was performed on a wide variety of gravelly soil samples with different particle sizes, grading uniformities and particle shapes. The followings were found. The ratio, X, of the maximum dry density predicted by the W&H Eq. to the measured value increases linearly from unity as P increases from zero up to approximately 0.75. The slope of the X-P relation, (X − 1.0) / P, increases as the coefficient of uniformity or the fines content of the base sample increases and as the gravel particles become more angular in a synergistic manner. It is proposed to estimate the maximum dry density of compacted gravelly soil containing oversized particles by dividing the value predicted from the W&H Eq. by X obtained from the substitution of P into the relevant X-P relation. Proposed based on the above is an effective and efficient compaction method for gravelly soils containing oversized particles that controls the degree of saturation and the compaction energy.]]></description>
      <pubDate>Wed, 30 Oct 2024 11:08:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/2440372</guid>
    </item>
    <item>
      <title>Small-strain stiffness of compacted loess upon wetting, drying and loading: Experiments and model interpretation</title>
      <link>https://trid.trb.org/View/2425805</link>
      <description><![CDATA[Stiffness of soil at very small strains G₀ is mainly affected by void ratio, effective stress and suction. Empirical equations considering those factors have been proposed to estimate G₀. However, for collapsible soil like loess, variations in suction might induce changes in void ratio of soil. The combined effect of these two factors poses challenges in accurately estimating of G₀. This paper first presents an experimental study on the G₀ of collapsible loess under various conditions, including as-compacted states, wetting/drying and K₀ loading. G₀ is estimated from shear wave velocity obtained with bender element technique. The changes of G₀ with respect to void ratio, suction, effective stress, and wetting under K₀ stress conditions are evaluated. Test results reveal that power relationships can be defined between G₀ and void ratio, suction and effective stress, respectively. The changes in G₀ along wetting/drying shows an “S” shape due to the different dominant effects on soil structure, as well as the induced non-uniform volume changes when suction change at different zones. Under K₀ loading, G₀ decreases upon wetting at stresses below the compaction stress, while it increases upon wetting at stresses above the compaction stress, due to the combined effects of densification caused by volume collapse during wetting and softening induced by suction decrease. Finally, a G₀ model considering net stress and suction as independent stress variable is proposed. This model could effectively capture the change of G₀ during wetting, drying and loading, as well as upon wetting under K₀ loading for collapsible loess.]]></description>
      <pubDate>Mon, 07 Oct 2024 16:55:11 GMT</pubDate>
      <guid>https://trid.trb.org/View/2425805</guid>
    </item>
    <item>
      <title>Evaluating Subgrade Compaction for Different Soils Using Nondestructive Lightweight Deflectometer</title>
      <link>https://trid.trb.org/View/2344596</link>
      <description><![CDATA[Insufficient compaction of the subgrade can result in nonuniform deformation, leading to severe subgrade distress. To address this issue and find a new method for rapid detection and evaluation of subgrade compaction, the lightweight deflectometer (LWD) was used to analyze the dynamic deformation modulus (Eͮvd) of subgrades filled with four types of soils—silt (ML), well-graded gravel (GW), lean clay (CL), and poorly graded sand (SP)—in different regions of Gansu province, China. Concurrently, the degree of compaction (Doc) was measured using the sand replacement method (SRM) to establish its correlation with dynamic deformation modulus (Evd). A strong correlation between the degree of compaction and dynamic deformation modulus was established for soils ML, GW, CL, and SP, and suitable formulas were selected based on curve variations. The developed formulas enabled back-calculation of the dynamic deformation modulus requirements corresponding to different degrees of compaction ranging from 90 to 100, facilitating direct queries and quick field checks. Results demonstrated that the LWD, as a reliable rapid detection method, effectively controlled subgrade compaction quality in field construction. Moreover, it extended the testing area and increased measurement frequency, thus providing a practical means for quickly evaluating the qualification rate and uniformity of subgrade compaction.]]></description>
      <pubDate>Fri, 29 Mar 2024 16:58:30 GMT</pubDate>
      <guid>https://trid.trb.org/View/2344596</guid>
    </item>
    <item>
      <title>Implementing the LWD for MoDOT Construction Acceptance of Unbound Material Layers: Phase II</title>
      <link>https://trid.trb.org/View/2289620</link>
      <description><![CDATA[Modulus-based quality assurance (QA) methods with Light-Weight Deflectometer (LWD) can easily measure the critical engineering properties of compacted soil in the field. The Phase I project has concluded that the LWD is a promising tool for construction acceptance evaluation of unbound material layers such as well graded sands and clay soils. However, limited number sites were tested since LWD could not be used on clay soil sites with much higher moisture content than optimum. In this Phase II project, more types of soils from different sites to develop representative testing specifications. The project will develop testing specification for field compaction QA using LWD. The existing testing procedure will also be simplified to improve the testing efficiency and will be ready to implement. In addition, the highway agency will obtain important data of resilient behavior of typical Missouri unbound materials from lab LWD on mold, lab triaxial test, and field LWD and significant influencing factors for future design, construction, and management.]]></description>
      <pubDate>Tue, 14 Nov 2023 20:28:42 GMT</pubDate>
      <guid>https://trid.trb.org/View/2289620</guid>
    </item>
    <item>
      <title>Impact of drying-wetting cycles on the small strain behaviour of compacted clay</title>
      <link>https://trid.trb.org/View/2216001</link>
      <description><![CDATA[Small strain shear modulus (Gmax) is an important parameter for assessing the performance of compacted soils that underlie typical transport infrastructure assets such as railway tracks. This is particularly important when considering changes in climate patterns, which are expected to yield larger seasonal soil-atmosphere moisture fluctuations. This in turn results in the progressive variation of the small strain properties of compacted soils during their service life (i.e. drying and wetting). In this study, the small strain shear behaviour was evaluated for an intermediate plasticity clay (i.e. kaolin) in a series of drying and wetting cycles . Four different dying and wetting boundaries were considered to explore a wide range of moisture amplitudes during 10 drying-wetting cycles. Drying and wetting was controlled using gravimetric water content in order to mimic realistic field conditions typically observed at substructure level. An ultrasonic pulse transmission method was used to capture the change in small strain stiffness and volume at discrete points during the drying-wetting cycles. The results reveal clear distinctions in behaviour for all four boundaries considered, with wetting boundaries having the greatest influence on behaviour. In this instance, specimens brought to full saturation during wetting exhibited an increase in the small strain shear modulus during progressive drying-wetting cycles. However, a reduction was observed when the wetting boundary was restricted to the compacted state. Measured volume changes were also in agreement with these findings, however there was some evidence of volume increase when drying to residual conditions. The results suggest that this is associated with the formation of the partial pendular state where a loss of capillary contacts between particles occurs. Furthermore, when all data for 10 drying-wetting cycles is plotted in the e-Gmax space, a linear relationship is observed for different constant water content levels. Remarkably, this trend is shown to be independent of the boundary conditions considered in this study or number of drying-wetting cycles.]]></description>
      <pubDate>Mon, 28 Aug 2023 09:34:04 GMT</pubDate>
      <guid>https://trid.trb.org/View/2216001</guid>
    </item>
    <item>
      <title>A Study on Pore Size Distribution of Compacted Expansive Soils</title>
      <link>https://trid.trb.org/View/2113542</link>
      <description><![CDATA[Compacted expansive soils, characterized with very low hydraulic conductivity and good contaminant retention capacity, have been widely used as barriers in landfills. They exhibit a double porosity structure with discrete interaggregate pores (macropores) and intra-aggregate pores (micropores) when compacted at optimum and dry of optimum water contents. The distribution of these macropores and micropores varies for different expansive soils depending on their grain size distribution and compaction characteristics, and thus, an in-depth study is necessary. This paper focuses on pore size distribution analysis using X-ray computed tomography (X-ray CT) and mercury intrusion porosimetry (MIP) tests on four expansive soils collected from different parts of Tamil Nadu, India. X-ray CT test gave the 2D image slices from top to bottom for all the specimens, and the acquired CT images of each soil specimen were segmented to separate the pores from the soil solids. The most probable threshold numbers for image segmentation were obtained using a newly developed methodology. The threshold numbers obtained decreased with increase in coarser fractions present in the soils. The thresholded binary images illustrated the pattern of larger pores in different expansive soils considered for the study. The MIP results showed a lower volume of macropores and a higher volume of micropores for soils with more clay content and higher dry density. A general insight into the range of macropores and micropores size distribution of compacted expansive soils with different gradation and compaction characteristics was achieved.]]></description>
      <pubDate>Tue, 18 Jul 2023 15:15:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113542</guid>
    </item>
    <item>
      <title>Behavior of Compacted Collapsible Soil After Adding Calcium Chloride</title>
      <link>https://trid.trb.org/View/2113040</link>
      <description><![CDATA[The collapse behavior of subgrade soil presents stability problems on road construction in collapsible soil region due to its sudden reduction in volume when encountering an increased soil moisture. Compaction is widely accepted as a densifying method for collapsible soil. Recent studies pretreated the loess soils by mixing with chemical agents to obtain an enhanced mechanical behavior. However, studies in stability properties (e.g., under compaction) of chemically modified soils are limited. This study aims to evaluate the behavior of compacted collapsible soils by mixing with chemical agents. This paper presents the first stage results of the study: Behavior of soil treated by calcium chloride (CaCl2) subjected to compaction. Experiments including liquid/plastic limit, oedometer, unconfined compression and hydraulic conductivity tests were conducted to evaluate the engineering behavior of compacted collapsible soil treated at different CaCl2 concentrations. Results indicate that soil treated with higher CaCl2 concentration exhibits an overall enhanced performance in resisting wetting-induced collapse. The addition of CaCl2 could reduce the modified collapse ratio and show less sensitivity to molding water content. Scanning electron microscopy (SEM) was used to visually capture the size of soil aggregates due to enhanced cementation, which was formed by the dual effect of salt concentration and compaction effort. Unconfined compression strength (UCS) of treated soils generally increases with increasing water content at dry of optimum conditions and decreases as water content increases toward wet of optimum conditions. The preparation method for sampling soil from compaction has an essential influence on the measured soil strength. Hydraulic conductivity decreases with increasing CaCl2 concentration. Studies on the mechanism of cementation in compacted collapsible soil treated by chemical agents are ongoing.]]></description>
      <pubDate>Wed, 14 Jun 2023 17:09:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/2113040</guid>
    </item>
    <item>
      <title>Effect of Static and Dynamic Methods of Compaction on Mechanical Properties of Silt</title>
      <link>https://trid.trb.org/View/2155070</link>
      <description><![CDATA[Engineered fills, such as roads, earthen dams, embankments, and earthen sites, are enhanced by compaction to increase strength and decrease compressibility. Static and dynamic compaction are the most popular and important methods in geotechnical engineering practice with different compaction mechanisms. However, the significant differences in the physical and mechanical properties between both compaction methods that have been reported in the literature were limited to clay or sand. Limited attempts have been made to quantify the variations in silt’s mechanical attributes that were caused by the sample preparation method. A series of consolidated drained triaxial shear tests and some mercury intrusion porosimetry (MIP) tests were constructed to interpret this. The results showed that static and dynamic compaction had a significant influence on the mechanical properties of the silt coupled with the molding water content. The shear strength of the dynamically compacted samples was higher than those of the statically compacted samples, as was cohesion (c), and the sample preparation method had little effect on the internal friction angle (φ). Furthermore, samples that were compacted at optimum water content (wot) had greater strength than those compacted on the dry or wet side of the optimum. Compared with the static compaction sample, the pore size distribution curve of the dynamic compaction sample shifted to the left with the peak pore size, distribution density, and the interaggregate pores proportion decreased. The strength discrepancy could be traced to differences in the silt structure features, for example, pore size distribution and particle orientation between statically or dynamically compacted specimens.]]></description>
      <pubDate>Fri, 21 Apr 2023 09:51:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2155070</guid>
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