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This paper presents two real case buildings that are redesigned considering the heave of the ground formation. The buildings are evaluated for upward swelling pressure, taking into account dead load, live load, and expansive soil load combinations. The criterion used to evaluate the safety of buildings constructed on expansive soils is first presented. Then, two scenarios regarding soil wetting are examined. In the first scenario, water only reaches the perimeter of the building, causing soil expansion at the outer boundaries. In this case, swelling pressure is only applied to the outer parts of the buildings. In the second scenario, heave occurs beneath the interior part of the building due to leakage from the domestic supply network. The structural integrity of the two buildings is evaluated by observing angular distortion at varying levels of swelling pressure. This assessment aims to determine to what extent the use of traditional foundation systems (spread footing and mat foundation) is feasible to support buildings on expansive soils considering different levels of swelling pressure. The study focuses on performing a detailed structural analysis of the building using the ETABS. The findings of this study have important implications for the design and construction practices in semi-arid regions.

The bentonite material is currently used in a variety of applications ranging from hydraulic barriers and waste-buffer protection to other special uses in industry and underground disposal of high-level nuclear waste. In the deep geological repository for high-level radioactive waste, the clay acting as a buffer material between the host rock and the canister is subjected to thermal load, which could impact its geotechnical properties. Thus this study is aimed at investigating the swell and compressibility of bentonite subjected to heating at 200 °C, 400 °C, and 600 °C. The impact of heating on the index properties, the swell and compression and hydraulic conductivity is explored. The change in temperature due to weather fluctuations was found to have a minor effect on physical behavior, but this effect is found to be significant when the temperature is raised to high levels in the order of 200 °C–600 °C (Celsius). The rate at which swell and hydraulic conductivity is developed is presented in this study. The result indicated an elimination of the swellable clay minerals effect in the bentonite clay upon exposure to a temperature of 600 °C. This study introduces useful information and data for modeling the behavior of bentonite when subjected to elevated temperatures for use in application for deep geological repository for high-level radioactive waste storage and other applications.

The risk posed by expansive soils can be lessened by placing foundations at a more deep level below the surface. Structures are able to withstand uplift forces because overburden pressure partially suppresses swelling pressure. In order to transfer the forces to a sufficiently deep depth, this study suggests introducing shafts of a low-expansion overburden material. Soil improved with cement is chosen for this purpose. This study suggests using sand with added excavated natural clay and cement. The expansive clay is added to sand in ratios of 10, 20, 30, 40 and 60%. The clay–sand mixture is then enhanced by cement of 1, 2, 4 and 8% by the weight of the mixture under four curing periods of 1, 7, 28, and 90 days. This material is recommended for use under lean concrete to transfer the loads to lower levels below the foundation depth. The thickness of this material depends on the stresses exerted, the type and the properties of the subsurface soils. The cement-enhanced clay–sand shaft’s properties are examined in this work with regard to the swelling potential, compressibility, and the unconfined compressive strength for different clay contents and curing conditions. Stiff shafts were formed and found to support stresses from 600 to 3500 kPa at cement additions in the range of 1% to 8%. Clay content above 30% is found to be not suitable for Al-Qatif clay due to the compressibility and low strength of the mixture. When two percent or more of cement is added, the swelling potential is significantly reduced. This is reliant on the pozzolanic interactions of soils and cement as well as the clay mineralogy. Determining how cement affects clay–sand combinations in regions with expansive soils would facilitate the introduction of a novel, inexpensive technology to support loads applied by the superstructure.

The feasibility of using crushed limestone instead of sand in cement grout is examined in this work. This study entails performing several tests, including the Brazilian test, the compressive strength test, and the stress–strain correlation test. The curing times used were 7, 14, and 28 days for mixtures with various proportions of cement to limestone (1:1, 1:2, and 1:4). The conventional sand–cement grout laboratory tests were prepared using a similar methodology to examine the effectiveness of the suggested substitute. The findings show that the limestone-based grout has sufficient strength, but that it is less than that of the typical sand material. The values of the tensile strength and elastic modulus were determined. A focus was made on the tensile strength and stress–strain relationship. A special laboratory set-up was used to look at the progress of failure using strain gauges fitted to the cylindrical samples both vertically and horizontally. The angular shape of the particles’ ability to interlock is responsible for the material’s increase in strength. According to this study, crushed limestone can be used as a substitute for sand in circumstances where sand supply is constrained. The suggested grout can be used in the shotcrete of tunnels and rock surfaces.

Expansive clays present serious issues in a variety of engineering applications, including roadways, light buildings, and infrastructure, because of their notable volume changes with varying moisture content. Tough weather conditions can lead to drying and shrinking, which alters expansive clays’ hydro-mechanical properties and results in cracking. The hydro-mechanical behavior of Al-Ghatt expansive clay and the impact of wetting and drying cycles on the formation of surface cracks are addressed in this investigation. For four cycles of wetting and drying and three vertical stress levels, i.e., 50 kPa, 100 kPa, and 200 kPa, were investigated. The sizes and patterns of cracks were observed and classified. A simplified classification based on main track and secondary branch tracks is introduced. The vertical strain measure at each cycle, which showed swell and shrinkage, was plotted. The hydromechanical behavior of the clay, which corresponds to three levels of overburden stress as indicated by its swell potential and hydraulic conductivity was observed. It was found that at low overburden stresses of 50 kPa, the shrinkage is high and drops with increasing the number of cycles. Al-Ghatt clay’s tendency to crack is significantly reduced or eliminated by the 200 kPa overburden pressure. The results of this work can be used to calculate the depth of a foundation and the amount of partial soil replacement that is needed.

The ground surface and subsurface of green parks in arid and desert areas may be subjected to desiccation as a result of weather and hot temperatures. It is not wise to wait until plants are turning pale and yellow before watering is resumed. Given the scarcity of water in typical desert zones, we recommend full control of irrigation water. This study presents a method of recycling irrigation water using 5TE sensors, employing time-domain reflectometry (TDR) technology. A trial test section was constructed along the coast of the eastern province of Saudi Arabia. Water recycling involves using clay–sand liners placed below the top agricultural soils to intercept excess water and direct it towards a collection tank, and then it is pumped out to a major water supply tank. The main properties of soils and clay–sand liners normally taken into account include moisture content, density, and hydraulic conductivity. An assessment of geotechnical properties of clay–sand mixtures containing 20% clay content was conducted. The profiles of moisture and temperature changes were monitored using 5TE sensors and data loggers. The 5TE sensors provided continuous measurements at varying temperatures and watering cycles. Twenty-nine watering cycles were conducted over a six-month period. An additional section was considered with a liner consisting of the same clay but enhanced with bentonite as one-third of the clay content. The volumetric water content was found to vary from 0.150 to 0.565 following changing weather and direct watering cycles. The results indicated that the use of a TDR instrumentation is a cost-effective and time-saving technique to construct a system for saving irrigation water.

Solving the challenges facing the mining industry is crucial for shaping the global attitude towards clean energy technologies associated with critical minerals extracted from depth. One of these challenges is the well-known explosion-like fractures (rockbursts) or spalling failures associated with the initiation of internal cracks. To prevent such catastrophic failure, shotcrete, as a cement grout, is widely used in tunnel support applications. In areas where the tunnels are constructed within the limestone strata using tunnel boring machines (TBM), drilling, and/or blasting, millions of cubic meters of crushed limestone (CL) in powder form are extracted and landfilled as waste. Given the fact that natural sand consumption as a raw material in the construction industry exceeds previous records, recycling of such excavation material is now becoming increasingly needed. From this perspective, this study aims to utilize crushed limestone as a potentially sustainable alternative to natural sand in shotcrete applications in deep tunnels. Accordingly, several strength characterization and crack initiation determinations through various stress–strain-based models were carried out on cylindrical samples containing different proportions of crushed limestone. By increasing the crushed limestone content in the shotcrete mix, the crack initiation stress (as a measure of the in situ spalling strength) increased as well. The results suggest that the crushed limestone has good potential to replace the natural sand in the shotcrete mixture used in tunnel support applications.

Liner-cover layers are top layers normally placed when closing landfill sites. The top layers are commonly subjected to the direct influence of moisture, temperature changes, and erosion. This study proposed the use of a dynamic cone penetrometer as a quick tool to assess the shear strength and density of sand-clay cover liners. Poor areas indicating low shear strength and dry density need to be investigated and identified. Changes in moisture content and dry density affect the soil compressibility and shear strength parameters. A lightweight dynamic probe was found to give reliable shear strength measurements when assessing bentonite sand mixture materials. The impact of the moisture content on the profile of penetration was established and a bilinear relationship between the cone penetration and moisture content is shown. Laboratory fall cone tests were conducted to verify the trends of penetration and the influence of dry density. It was found that a linear function can be established within the wet of the optimum zone of the compaction curve. The tests conducted support the effectiveness of using dynamic cone penetrometers for measurements and evaluation of shear strength and dry density for sand clay cover liners. This will pave the way for using a quick tool for the assessment of compaction uniformity and shear strength of sand clay cover liners.

The major problematic soils in semi-arid regions include expansive soils and collapsible soils. These two types of soils cause problems and are hazardous for buildings when moisture is introduced following a dry or semi-dry season. In order to assess the risk and damage likely to occur, a protocol of investigation needs to be considered by geotechnical engineers to quantify and assess the possible heave or collapse that may occur. The characterization and prediction of unsaturated soil behavior in semi-arid areas can now be enabled following the advancement of unsaturated soil mechanics. Heave is associated with the wetting of expansive soils, while excessive settlement or the sudden loss of support may occur when water is introduced to collapsible soils. This work calls for more than one parameter for the assessment of problematic soils to avoid misleading predictions based on a single test. This study presents an investigation of two sets of soil samples obtained from semi-arid areas in Saudi Arabia known for their collapsible or expansive nature. Tests under controlled suction and variable effective stress were conducted. The air entry values, inflection points, and residual points were established and compared for the two problematic soils. A series of oedometer tests was conducted for typical soils, and settlement and collapse were measured and assessed. The swell potential for the tested clays varied from 4% to 22%. It is possible to integrate the data from the soil–water characteristic curve (SWCC) and compressibility tests with any project specification and applied stresses to produce reliable recommendations for the construction and protection of structures in hazardous soils.

The near-surface soils are generally exposed to environmental changes and can be influenced by water, humidity, temperature, and other factors related to erosion or physical changes. It has been reported that serious distress occurred in the ground surface and below ground for many areas subjected to seasonal weather changes. The gypsum rich material is often linked to the cavity formation, uplift, and cracking of road surfaces due to the high solubility of gypsum in water and acidic media. Electrical resistivity techniques along with the advanced method of identifications (Scanning electron microscope; SEM and X-ray diffraction: XRD) were utilized to detect cavities and gypsum rich subsurface soils. A site where many cavities were formed as a result of dissolving gypsum and anhydrite was considered for this study. Syscal R1 electrical resistivity equipment (IRIS instrument) was used for several cross-sections established within the site. Several electrical resistivity tomography lines were constructed and studied. The SEM (scanning electron microscope) was used to examine and compare forms and fabrics of gypsum and minerals containing sulfates. The chemical analysis (EDAX) using an electron beam was conducted to establish elements present within tested samples. Quantitative chemical tests for some parameters including sulfate ions were carried out. A prediction model based on statistical correlations between sulfate ion content and the electrical resistivity is presented. Electrical resistivity is found to be inversely proportional to the sulfate content for concentrations of 0 to 5%.

The ground surface of green parks in arid and semi-arid areas may not be comfortable at specific times during the day and night due to the sun and the rate at which the subsoil gains or loses heat. Knowledge of the subsurface soil’s thermal properties can provide designers with convenient and comfortable settings. Design focus is generally directed toward stability, density, and hydraulic conductivity. An assessment of the thermal properties of clay–sand mixtures of 10%, 20%, and 30% clay content is conducted. The proposed clay–sand layers are subjected to three different thermal gradients of 30, 20, and 10 degrees of magnitude. The profile of temperature changes was monitored using 5TE sensors and data loggers. The mixtures were also subjected to cooling at room temperature. The results indicate that the clay type and the clay content govern the response of subsurface clay–sand liners to temperature gain and loss. Two field sections with clay–sand layers of 15% and 20% clay were examined for temperature changes over an extended period. In winter, green areas rich in clays were found to keep heat for several hours and provide relatively warm evenings. In summer, the mixture retains a cool temperature for some time during the day.

A method to predict the swellability of clay-sand mixtures is proposed. This model is a modified form of the Studds (1997) prediction model for clay-sand mixtures. The new proposed model uses the laboratory fall cone penetration technique to produce a characterization chart. This chart presents slope levels that can be used to obtain an equation for the final clay void ratio versus the vertical effective stress for clays. The porosity of the clay-sand mixtures was worked out based on a correction factor obtained from compression and porosity measurements in the laboratory. The porosity of the mixture was merged into the clay profile equation to compute the final clay void ratio at a specified stress level, which made it possible to predict the swelling behavior for different and variable stress levels. The swellability slope was obtained using fall cone tests conducted on the fine portion. Mixtures of kaolinite and bentonite were introduced to represent soils with different swell potentials. The fall cone measurements of a few points can be used to establish the swellability relationships for natural clay. Merging fall cone points with the swellability slope chart can define the profile of the vertical effective stress versus the clay void ratio.

In this study, the chemical stabilization of moderately to highly plastic expansive soil using calcium chloride with added cement is introduced as an effective alternative to the conventional approaches using a single additive such as lime, cement, or a by-product of industrial processes. Using only calcium chloride may lead to its leaching or dissolution over time, leaving a collapsing skeleton with weak bonds. The chemical effect produced by additives is dependent on the constituents of the stabilized soil and the curing period considered. Herein, calcium chloride concentrations of 2%, 4%, and 8% with the addition of 2% cement by dry weight of the soil were considered. The main objective of this study is to investigate the addition of a low amount of cement as a binder to improve the strength and durability of a chemically treated expansive soil. The engineering properties were investigated at 3 curing times: 3 days, 7 days, and 28 days. A laboratory investigation was carried out to investigate the effect of the addition of calcium chloride with cement on the swell potential, swell pressure, compression index, suction, and unconfined compressive strength. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) testing was conducted. The X-ray diffraction patterns were recorded to observe the mineralogy of the material. The results confirmed that calcium chloride with cement is very effective for stabilizing the expansive soil. A reduction in the swell potential by 8% and 25% and a reduction in swelling pressure by 28% and 37.4% were observed for 4% and 8% calcium chloride with cement addition. The compression index decreased with the increase in the calcium chloride content.

The ASTM D6951 suggests a test method using the dynamic cone penetrometer (DCP) for the assessment of shallow pavement strength. This study is dedicated to evaluating a similar test method to be used for fine-grained clay–sand mixtures, which are commonly used to construct liners and fluid barriers. The liner layers include clay, which is water-sensitive. The shear strength of the liners depends mainly on the composition and proportions of the mixtures adopted. A series of tests were conducted in the laboratory for compacted clay–sand mixtures, including 5% and 10% bentonite material. The responses to advancing a dynamic probe into compacted material at three various moisture conditions—namely, the optimum, dry of optimum, and wet of optimum water contents—are investigated. The penetration profiles are compared for the two clay content levels selected and for three moisture state conditions. The clay–sand liners support vehicles and vibratory compactors during construction and when waste material is placed. The shear strengths of the mixtures are evaluated in the laboratory using direct shear tests. From the results obtained in this investigation, general guidelines and recommendations are presented to help with the efficient assessment of liners consisting of clay–sand mixtures. A cheap and quick approach to assess the density and shear strength of landfill liners or clay–sand layers can be achieved using a hand-held dynamic cone penetrometer. The state of moisture during compaction was found to influence the DCP results. The compaction of layers in a wet of optimum state is not expected to be an ideal alternative.

Tunnel boring machine (TBM) materials are usually crushed powder obtained during tunnel excavations for subways and transportation networks. Huge quantities of crushed rock powder are generally treated as waste. This study is aimed at assessing proposed mixtures of TBM and granular material for use in construction. This approach will help in a greener environment and reduce the need for crushed aggregates used in sub-base and subgrade layers of pavements. Assessment is executed using dynamic and static strength tests, including the modulus of resilience and the California bearing ratio (CBR). The TBM-crushed material can be sorted and screened on site to optimize its use as a construction material. The blending ratios for the 3/8-inch aggregate (G1) to the material-passing sieve number 4 (P4) were found to influence the pavement design parameters. This study recommends sorting the TBM-crushed limestone by an on-site sieving operation. A guide to optimizing the quality of the material is suggested by blending 3/8-inch aggregate with the crushed limestone fine-powder material at a specified percentage ranging from 5 to 10% by weight. The stability and durability tests conducted on the TBM-crushed powder material confirmed its suitability as a pavement construction material for subgrade and sub-base layers. Modulus of resilience, CBR values and compressive strength tests were carried out for different suggested mixtures.

The technique of using clay-sand mixtures as liners has been widely used in several geotechnical projects where hydraulic barriers or waste-buffer layers are required. During weather fluctuations and below-zero temperature conditions, these layers can be subjected to successive freeze-thaw cycles. The serviceability of such liners needs to be examined during their lifetime for efficiency and function under such suspected weather conditions. The hydraulic conductivity over the long run needs to remain within the acceptable design ranges. In this study, the efficiency of two different clay-sand liners were examined under the effect of freeze-thaw cycles for extended serviceability. The hydraulic conductivity under a continuous discharge rate of these layers was measured before and after applying 15 successive freeze-thaw cycles for more than half a year. The results indicate dramatic changes in the hydraulic conductivity parameter for the specimens subjected to freeze-thaw cycles depending on their mineralogical composition and applied stress. These changes were found to be related to the sealed material composition and placement conditions. The data obtained were found of interest and can be utilized for evaluating the efficiency of the liners in areas subjected to extreme environmental exposures including freeze conditions over extended periods.

The sand-expansive clay liners have a wide application in geoenvironmental and geotechnical projects as hydraulic barriers or cover layers in waste management systems. The flow and mass variations have a significant effect on the hydraulic conductivity of sand-expansive clay liners during their lifetime. This study suggests the use of flooding and/or standing water as a technique to ensure adequate long-term performance. The placement conditions and environmental exposures do have a major effect on the lifetime of liners. The performance of liners is influenced by the size of fluid flow, mass stability, and applied vertical-stresses. This study aimed at investigating the effect of flow and mass variations on the hydraulic conductivity of sand-expansive clay liners during their lifetime. A series of permeability tests were conducted for compacted specimens of sand-expansive clay mixtures with 15 and 20% clay content and sand with 15%-bentonite. The influence of two different vertical stresses (7 and 30 kPa) on the hydraulic conductivity of sand-expansive clay mixture with 20% clay content is monitored and compared over 100 days period, applying a continuous flow of water. The effect of temperature variations and volume-changes were also observed. It was found that the hydraulic conductivity initially measured would not remain stable when subjected to continuous flow for an extended time. The mass loss contributed initially to increasing the hydraulic conductivity until a certain stage where the hydraulic conductivity improves due to soil-structure collapse. The outcome of this work suggests the use of flooding and/or standing water as a technique to ensure adequate long-term performance to accommodate the influence of placement and environmental exposure.

The hydraulic conductivity is known as the soil properties that mostly vary over an order of magnitude. There are many laboratory test methods to determine the hydraulic conductivity of the soil. Each test has its own merits, drawbacks and limitations. One of these methods is the measurement using a rigid wall permeameter (RWP), which is a common practice to obtain the fluid transmissibility characteristics of the soil matrix. This type of permeameter has the advantages of low cost, simplicity of test equipment, and adaptability to many different types of permeant liquids. Another method is the measurement through a flexible wall permeameter (FWP). The hydraulic conductivity measured using the FWP is conducted in a confined cylinder in which water flow is forced into one direction. The main disadvantage of this type is being relatively more expensive and needs more time to perform the test compared to the RWP. This study is aimed at comparing three testing conditions to obtain an adjustment factor for the hydraulic conductivity test normally carried out in practice in order to cut down the time needed to perform the test as well as its cost. Different mixtures of sand and expansive clay addition were considered to examine the effect of expansive clay content on the values of the hydraulic conductivity. Tests results revealed that the clay content had a significant effect on the swelling potential, which was attributed to structural changes in the mixtures. The hydraulic conductivity of mixtures decreases with the increase in clay content. The hydraulic conductivity of mixtures tested using FWP was observed to be lower than that of mixtures tested using RWP at similar clay contents. The tests conducted enabled establishing a correction factor to adjust the hydraulic conductivity normally obtained in practice using rigid wall cells.

This research is aimed at investigating the influence of ambient air temperature on the moisture content and electrical conductivity of clay sand mixtures. Volume changes as a result of shrinking or swelling are very much related to the moisture content and the electrical conductivity for liners consisting of sand and clays. The laboratory tests carried out for clay sand mixtures subjected to drying indicated a bilinear trend for 15, 20, 25, and 30% clay content. Moisture content measurements are influenced by the ambient temperature and exposure time. Watering a clay sand layer at a regular frequency in a field site revealed useful information on the trends of moisture gain and loss. Suction fluctuation associated with these changes is responsible for absorbing variable amounts of water. Moisture/Temp/EC sensors (5TE) were utilized to survey a sand clay liner section over 30 day’s period. A metrological station installed within the site was used to observe temperature, humidity, and rain fall. The drop of moisture and electrical conductivity was found to be nonlinear with temperature changes and reflecting the bimodal nature of the soil. The general trends of repeated wetting and drying were found similar in shape.