Unsoaked Conditions Research Articles

Application of Gum Arabic on the Geotechnical Properties of Subgrade Materials

This study investigates the impact of Gum Arabic on the geotechnical properties of subgrade soil materials, a non-traditional soil stabilization technique. Given the need for sustainable and locally available alternatives in road construction, the study aims to assess how different percentages of Gum Arabic affect the physical and mechanical behavior of soil. The research aims to provide sustainable and locally available alternatives in road construction. Three soil samples were treated with varying percentages of Gum Arabic, (1.5%, 3%, 6% and 12%), and standard geotechnical tests were conducted under both soaked and unsoaked conditions. The results showed that the average natural moisture content of the soils was 7.9%, 2.2%, and 4.6%. The addition of Gum Arabic increased the peak maximum dry density of the soil samples by 8.02%, 1.88, and 7.88%. The maximum unsoaked California Bearing Ratio (CBR) values of soil samples were 32.1%, 81.7%, and 48.7%, respectively. Whereas, maximum soaked CBR values of soils S1, S2 and S3 obtained at 1.5%, 6% and 1.5% additions of gum Arabic were 8.4%, 28.7% and 16.9% respectively. The study recommends using 3% Gum Arabic to improve the CBR property of soil samples. The application of Gum Arabic showed significant improvements in soil behavior under both soaked and unsoaked conditions.

Microstructural analysis and prediction of strength response of black expansive soil

Amelioration studies using waste residues are gaining popularity in the construction sector, as they offer dual effective management and utilization of waste residue. This practice is of interest to the growth of any nation due to environmental protection and the economic advantages it offers. For that reason, this present-day study seeks the sustainable utilization of calcium carbide residue (CCR) and palm oil fuel residue (POFR) in expansive soil amelioration. After an in-depth characterization of the parent soil, several number of California bearing ratio (CBR) tests was performed on the parent and additive-treated soil. For this purpose, a total of twenty mixes were prepared possessing various combinations of CCR, POFR, water, and soil. CBR testing for soaked and unsoaked conditions was carried out to assess the strength performance and effectiveness of the additives. Through this approach, optimal California bearing ratio (CBR) values of 41 and 61% were achieved at trial runs designated Y4 for soaked and unsoaked conditions, indicating a strong mechanical performance. These experimental outcomes were subsequently validated using statistical indicators such as ANOVA (F crit > F) and student t-test (t crit > t stat). A step further, microstructural testing such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were performed on the natural soil and soil treated with the optimal level of additives obtained at trial runs designated Y4. The SEM micrographs evidence the transformation of the loosely packed structure of untreated soil into a dense soil composite. Similarly, diverging molecular functional groups were recorded in the FTIR examination with the incorporation of blended CCR-POFR. Finally, the findings suggest that carefully designed mixtures of CCR and POFR can offer a sustainable, efficient approach to soil amelioration, potentially revolutionizing construction practices.

Mineral Identification as an A-7-5 Clay Stability Indicator Using Volcanic Ash

Soil is a building material and the foundation of the structure, it must be considered. There are bumpy roads and collapses on Jalan Elak Lhokseumawe. This study’s primary focus is on road subgrade. Because of its high plasticity index and clay minerals that swell when water is added, the soil cannot be used as a subgrade. Volcanic ash from Burni Telong Bener Meriah was used in this study. The combined volcanic ash content ranges between 7.5% and 15%. The goal is to see if the bearing can be stabilized afterward. Based on XRD analysis, this soil has an illite clay mineral content with a WT value of 0.817%. The Atterberg limit test on soil is classified as A-7-5 by AASHTO and MH by USCS. At a percentage of 12.5% volcanic ash, the CBR test results for soaked and unsoaked conditions yielded optimal values of 5.9% and 9.4%, respectively. The swelling value continued to fall at a percentage of 12.5% volcanic ash. UCS test results in soaked and unsoaked conditions at 12.5% volcanic ash percentage yielded optimum values of 1.46 kg/cm2 and 2.18 kg/cm2, respectively. The soil is found to be usable, but it needs to be stabilized.

INVESTIGATION OF CALIFORNIA BEARING RATIO VALUE OF BAMA RIDGE SOIL ADMIXED WITH METAKAOLIN

The study focused on assessing the impact of Metakaolin on the properties of Bama Ridge Soil in the Maiduguri region and its environs. Soil samples, collected using a disturbed sampling method from two distinct locations, were transported to the laboratory in polythene bags to prevent moisture loss. According to the American Association of States Highway and Transport Officials (AASHTO) and the Unified Soil Classification System (USCS), the soil was classified as A-3(0) and CL. The California Bearing Ratio (CBR) values ranged from 19.23% to 26.66% for soaked conditions and 25.01% to 32.46% for un-soaked conditions, indicating its suitability as sub-grade material. The study suggested that a 15% Metakaolin content would suffice for lightly trafficked roads. However, caution was advised against using the soil as sub-base material for roads with heavy traffic density, as CBR values slightly exceeded 30%. This implies that while the soil shows promise for specific construction applications, it may not be optimal for handling the substantial loads associated with high traffic volumes.

Engineering properties of clay soil stabilised with glass powder and rubber particles – a comparative study

ABSTRACT Soil improvement is a significant aspect of geotechnical engineering that requires periodic assessment and modification. This study aims to see how glass powder (GP) and rubber particles (RP) affect the shear strength and bearing capacity of clay soil collectively and separately. The soil samples were subjected to direct shear testing and California Bearing Ratio (CBR) tests at various glass powder and rubber particle contents. The CBR test was conducted under soaked and unsoaked conditions. Clay-rubber, clay-glass powder, and clay-rubber-glass powder mixtures were prepared for the tests. It was discovered that adding glass powder and rubber particles improved the soil’s shear strength parameters and bearing capacity. A comparative analysis was conducted on the clay-rubber mixtures and clay-glass powder mixtures. The results indicated much improvement by the rubber particles than the waste glass powder in the direct shear test. In contrast, the glass powder had a better impact than the rubber particles in the CBR test. Furthermore, a correlation analysis was conducted to ascertain the relationship between the CBR values and the shear strength of the soil samples using a single Linear Regression Analysis (SRLA) model. The correlation yielded satisfactory coefficients (R2), indicating a strong link between the engineering properties.

Effect of sandstone slurry waste on the geotechnical properties of clay subgrade

Sustainability in clayey soil subgrade stabilization has become an emerging topic worldwide. The voluminous generation of sandstone slurry waste from the sandstone cutting and processing industries endangers the environment and human health. The present research investigated how such geotechnical characteristics of the clay soil subgrade were impacted by the addition of sandstone slurry waste (SSW) produced during the cutting and processing of sandstone. Sandstone slurry waste was dried for this experimental analysis and added to the clayey soil. Sandstone slurry waste was added in proportion from 0% to 35% (by dry weight) at intervals of 5% in clay soil, and mixtures were assessed based on how well their geotechnical properties have been improved. Atterberg's limits, compaction, and California bearing ratio (CBR) tests were conducted on the untreated clay and SSW-clay composites to evaluate the soil subgrade's physical properties and strength parameters. The experimental results revealed that incorporating 25% sandstone slurry waste by dry weight in clayey soil improves the maximum dry unit weight (MDUW), workability, and strength of clayey soil. The result of the CBR test showed that the CBR values of subgrade material enhanced with the addition of SSW. The improvement in treated composites was 69.79% and 68.27% for soaked and unsoaked conditions, respectively, at 25% SSW dose. The present experimental study shows that SSW-clay composite containing 25% SSW can treat the clayey soil subgrade.

Laterite soil stabilization using cellulose biopolymer

Laterite soil stabilization is a promising technique that aims to enhance the engineering properties of this naturally occurring soil, Cellulose are one of the potential bio-polymer stabilizers that have been widely employed. The effectiveness of Cellulose (CL) biopolymer in stabilizing laterite soil is shown in this study. In various proportions of 0%, 1%, 2%, 3%, and 4% by dry soil mass, cellulose biopolymer is treated with laterite soil. The engineering parameters of soils treated with cellulose biopolymer were determined using modified proctor tests, direct shear tests, and CBR tests. The treated soil's dry density increases slightly up to 3% cellulose content, but the optimum moisture content decreases. The addition of cellulose biopolymer greatly increased the strength and cohesiveness of laterite soil mixtures. The CBR value increases with increasing the cellulose dose up to 3%; however, with addition of dose, the CBR value decreases slightly in both soaked and unsoaked conditions. The examination of the microstructure through field emission scanning electron microscopy (FESEM) examinations revealed the emergence of novel cementitious substances as a consequence of chemical interactions between cellulose and laterite soil components at the microscopic scale. These reactions led to the enhancement of soil composition by fusing soil particles and occupying the voids within the soil framework. The use of cellulose as a material for the stabilization of laterite soil is therefore a solution for an environmentally benign soil stabilizing material.

Investigating the advantage of copper and steel slags as partial replacement material in a sand compaction column in stabilizing the soft clay

ABSTRACT The current study aims in finding the utilization of Industrial waste such as copper and steel slags as a partial replacement material for sand in Sand Compaction Pile (SCP) in proportions of 5%, 10%, 15%, 20%, 30%, and 40% by weight. From the direct shear tests, it is observed that the angle of internal friction increases from 27.59° to 40.1° and 34.82° for copper and steel slags, respectively. The tests are done by installing the SCP in a soft clay in California Bearing Ratio mould and it is tested under soaked and unsoaked conditions. The optimum percentage found from the study for both the slag material is 30%. Tests were also done by air-curing the composite soil within the mould for 7 days and water-curing the sample under soaked conditions for 4 days for the optimum replacement percentage.

EVOLUTIONARY POLYNOMIAL REGRESSION FOR PREDICTING THE UNCONFINED COMPRESSIVE STRENGTH OF LIME-STABILIZED

Peat has a lack of strength, making it unsuitable for foundations or road construction. The results of 104 unconfined compressive strength (UCS) on peat stabilized with various lime percentages are presented in this article. The strength performance of peat soils stabilized with lime in soaked and unsoaked conditions was also evaluated. Evolutionary Polynomial Regression (EPR) models are constructed to predict the UCS values using the data obtained from the tests. After evaluating the various functions, the EPR model with a hyperbolic tangent function is the best model for predicting the UCS. The proposed EPR models may benefit practitioners when determining the optimal amount of stabilizers to utilize in soft-ground improvement projects. In this section, we show and expand on applying the suggested models to the design of soft ground mixing. Additionally, by applying the created relationships to a new instance, the comprehensiveness of the established relationships is shown, as is the practicality of the suggested relationships for usage during the preliminary design stage. The findings of this study have important implications for estimating the quantity of lime required in ground peat improvement work.

Compaction and bearing characteristics of untreated and treated lateritic soils with varying moisture content

Compaction and bearing characteristics are important factors in evaluating the quality of subgrade construction, and the compaction moisture content has a significant effect on both characteristics. In this paper, the lateritic soils were taken from three locations: the Guangxi Zhuang Autonomous Region, Hunan Province, and Fujian Province. The lateritic soils from the Guangxi Zhuang Autonomous Region were treated with 0%, 1%, 3%, 5%, and 7% cement. The effects of variable moisture content (ω) on the dry density (γd), California bearing ratio (CBR) values, and resilient modulus (MR) of untreated and treated lateritic soils were investigated by compaction tests, soaked/unsoaked CBR tests, and soaked/unsoaked MR tests. The variation in the microstructure of lateritic soils was analysed by scanning electron microscopy, X-ray fluorescence, X-ray diffraction, and mercury intrusion porosimetry tests. The results show that the optimum moisture content (ωopt) of lateritic soil decreases significantly with increasing cement content, while the maximum dry density (γd,max) increases. Moreover, ωopt and γd,max are exponential functions of the plasticity index (IP). The CBR of lateritic soil showed an obvious decrease after soaking, and the CBR values of the soaked samples were approximately 1.5 times lower than the unsoaked samples under the same conditions. Some of the soaked samples had CBR values lower than the specification values, and the CBR values of lateritic soils increased by 10 times using cement treatment. The moisture content corresponding to the maximum CBR value (ωCBR,max) is higher than ωopt. The empirical relationship of the difference between ωCBR,max and ωopt with IP was established, and the proposed ωCBR,max is used as the compacted moisture content of the subgrade filler. The MR of the soaked samples decreased faster than that of the unsoaked samples, and with the increase in moisture content, the MR of the soaked and unsoaked conditions decreased by 57% and 34%, respectively. With increasing moisture content, the CBR index and MR index, which are the ratios of the test results under unsoaked and unsoaked conditions, decreased by 0.45. With increasing cement content, the moisture sensitivity of the treated soil decreased, while the bearing characteristics are slightly influenced by the varying moisture content. The main reason for the increase in γd, CBR value, and MR of the treated lateritic soils was the increase in the content of elemental calcium and calcium-based compounds. Based on the analysis of the test results, the prediction models between CBR and MR with ω, γd, and IP were established by multiple regression analysis. The prediction model between MR and CBR was established with a correlation coefficient of 0.99. Finally, the procedure of material selection, construction control, and treatment of expressway upper roadbed filler was proposed. The practical application in a test section of an expressway verified that the suggested procedures applied to subgrade construction.

Potential Usage of Rice Husk Ash-Cement Based Soil in Subbase and Base Courses in Road Construction

This paper presents an experimental study of rice husk ash-cement-based soil for layers in roadway construction. Rice husk ash (RHA) used in this study is a by-product of rice milling. In this work, twelve proportion mixes were used with varying quantities of RHA (0-30%), and Portland cement blended amounts of 4, 6, 8%. The specimens were prepared by the Proctor mould method, conditioned at room temperature, and tested in soaked and unsoaked conditions. Specified curing periods of 7, 14, 28 days were applied for all types of specimens. Some engineering tests were carried out, such as proctor compaction, unconfined compressive strength, splitting tensile strength, and the stiffness of stabilized soil. Test results indicated a general decrease in the maximum dry density (MDD) and increased optimum moisture content (OMC) with an increase in RHA content. Adding cement and RHA significantly improved the geotechnical properties of stabilized soils, including compressive strength, splitting tensile strength, elastic modulus. In addition, the combination of 80% soil and 20% RHA and 6% cement can be used as the optimum proportion, which satisfied grade 3 of soils stabilized with inorganic adhesive substances, chemical agents, or reinforced soil for road construction, as indicated in the current Vietnamese standard.

Engineering behavior of municipal solid waste incinerated bottom ash with the addition of lime

The paper identifies the physio-chemical properties of incinerated bottom ash procured from waste incineration and treatment facility. The key factors responsible for its limited use as raw material have been identified. The stabilization process can successfully control these limitations using lime as the stabilizing agent. The properties of the stabilized product for 3, 5, and 7 % of lime addition have been compared with the untreated bottom ash. A series of Unconfined Compressive Strength (UCS), Split Tensile Strength (STS), and California Bearing Ratio (CBR) tests were performed for the experimental investigations on the improvement of strength characteristics. The specimens were prepared at the Optimum moisture content (OMC). Maximum dry density (MDD) values were calculated using Indian Standard light compaction tests and kept under curing for 3,7,14, and 28 days. The results suggest better strength in the stabilized specimen with higher lime contents as the pozzolanic action results in 124 kPa for STS value for 7 % lime content under curing for 28 days. The best results for UCS were also produced, where an increase of more than 3859 % strength was noticed. The soaked CBR values showed well-stipulated results with more comparative strength gain than in unsoaked conditions. The analysis of Mineral and Microstructure in Municipal solid waste incinerated bottom Ash (MSW-IBA) is carried out through FESEM and XRD testing.

Evaluation of the Bearing Capacity of the Board Pile in Collapsible Soil using A Laboratory Model

The pile’s ultimate capacity or failure load must be computed by some criteria using load-settlement curve data gathered during the pile load test. Many scholars have proposed several approaches for evaluating the pile’s ultimate capacity in the past. This study compared different failure criteria to predict the ultimate load capacity for piles with two different lengths-to-diameter ratios embedded in gypseous soil with gypsum content of 60% under soaked and unsoaked conditions. Two types of piles were used. Floating pile and end-bearing pile. Davisson, Brinch Hansen’s 80 percent, Chin-Kondner, Mazurkiewicz’s, and Brinch Hansen’s 90 methods that were used in this study predict a higher value of the ultimate pile capacity, whereas the Decourt Extrapolation method gave fluctuated value. Fuller and Hoy’s, Butler and Hoy’s methods give far away value from realistic. On the other hand, Shen’s, ASTM, Terzaghi, and DeBeer’s methods predicted an acceptable and realistic value. The failure criterion of (15%D) where (D) is pile diameter according to(ASTM D-1143) was adopted in this type of soil.

Influence of cohesion on California bearing ratio of clay–gravel mixtures

An understanding of the behavior of cohesive sediment is required to solve various engineering problems such as scour around bridge elements, mitigation of soil erosion, pavement design, river bed degradation, stable channel design. Pavement foundation designers principally use the California bearing ratio (CBR) to describe the subgrade and subbase materials and their strength. Several laboratory experiments were done to study the variation in the CBR of cohesive mixtures comprised of clay–gravel mixtures. Nine different clay–gravel mixtures were used in which the clay content varies from 10% to 50% by weight. The variation of the CBR with clay percentage, moisture content, and undrained shear strength parameters was studied. The CBR value reduces with the increase in the moisture content and clay fraction in the mixtures and increases with an increase in the dry density of the mixture under unsoaked conditions. The CBR also increases with the increase of the angle of internal friction of clay–gravel mixtures. A functional relation has been identified to estimate the CBR of clay–gravel mixtures. Using multiple linear regression analysis (MLRA), a relation is proposed to estimate the CBR of clay–gravel mixtures under unsoaked conditions. A statistical analysis was done to judge the behavior of the pertinent variables on the CBR. The proposed relation predicts the CBR of clay–gravel mixtures very well. Artificial neural network (ANN) analysis using R programming was also done to determine the effects of the pertinent variables on the CBR. ANN methodology was applied to predict the contribution of each variable. Three different methods: Garson algorithm, Olden algorithm, and Lek's profile model are used to assess the influence of variable parameters. The Olden algorithm and Lek's profile both show positive association of cohesion with CBR in an unsoaked condition. The role of moisture content was found to be marginally negative in the Olden algorithm and Lek's profile results. It is found that both the ANN and MLRA models are accurate in predicting the CBR of clay–gravel mixtures. It was further found that the MLRA and ANN models are reliable and rapid tools for correct assessment of the CBR of cohesive soil mixtures using the basic soil properties.

Investigating the Relationship Between Moisture Content and Dry Density on Different Gradations for Road Base Granular Materials

California Bearing Ratio (CBR)in granular materials is the key technical characteristic of layers in flexible pavement. The CBR value is a way to measure the material stiffness used in the pavement design procedure for the road base layer depending on the aggregate types. Road base layers’ ultimate role in the flexible pavement is to spread loading evenly over the sub-grade from the loading of vehicles throughout the design life. Among the factors affecting the material's bearing capacity, aggregate gradations are one of the most important parameters that give a considerable result. This study was carried to evaluate the effects of different aggregate gradations using granite, basalt, and quartzite aggregates on the bearing capacity of the granular materials. Further analysis on the base course layer’s upper and lower gradation limit were conducted to identify the bearing capacity of the layer, through a series of aggregates physical tests and strength tests. The results indicated that physical properties of the selected aggregates complied to the Public Works Department (PWD) Specifications (2008) for soaked and un-soaked condition. For both soaked and un-soaked conditions, the samples with lower limit gradations showed higher stress values compared to upper limit gradations for all three types of aggregates. Granite showed higher CBR values for both, soaked, and un-soaked conditions, followed by basalt and quartzite at upper and lower limit gradation. Un-soaked granite samples with lower limit gradation showed 60.5% increment in strength compared to un-soaked upper limit gradation, followed by quartzite 53.6% and basalt 9.94% respectively. The results indicated that strength is highest in the lower limit gradations where the use of coarse-grained aggregates could significantly increase the strength.

Improvement of the California Bearing Ratio of Peat Soil Using Soybean Crude Urease Calcite Precipitation

Due to its high organic matter, moisture content, and low bearing capacity, peat soil needs to be stabilized for use as a subgrade. The soybean crude urease calcite precipitation (SCU-CP) method is a grouting technique using carbonate precipitation and soybean as a biocatalyst. This study aims to analyze the effect of the SCU-CP method and soil density on the California bearing ratio (CBR) value to obtain the best stabilization alternative for reducing the field’s compaction energy. The CBR test was conducted in both soaked and unsoaked conditions. The study was conducted with variations of 50%, 70%, and 90% density of Standard Proctor and used grouting treatment with a combination of optimum SCU-CP solution for the treated samples. The results showed a significant increase in CBR, with an average increase of more than two times compared to untreated samples. In terms of compaction effort, a density of 70% Proctor in unsoaked conditions with SCU-CP treatment is the best alternative. However, considering the soil saturation level and the swelling of the subgrade layer, 90% proctor density with SCU-CP treatment can be recommended as a stabilization method without dewatering. This research concluded that the SCU-CP method could improve the CBR value of peat soil.

Engineering properties of marginal lateritic soil stabilized with one-part high calcium fly ash geopolymer as pavement materials

This research investigated the engineering and microstructure properties of marginal lateritic soil (MLS) stabilized with one-part high calcium fly ash geopolymer. High calcium fly ash (FA), a by-product of an electrical power plant in Thailand was used as a starting material and solid sodium hydroxide (NH) in flake form was used as an alkali activator. The influences of NH content, soaking conditions, and curing time were studied. The unconfined compressive strength (UCS), indirect tensile strength (ITS), and microstructure were investigated. Test results showed that the use of one-part high calcium FA geopolymer (OP-G) to stabilize MLS can improve the engineering properties noticeably. The samples with 20% NH content yielded the maximum 7-day UCS of 1930 kPa and 2800 kPa under soaked and unsoaked conditions, respectively, corresponding to the maximum 7-day ITS of 270 kPa and 400 kPa. The 28-day UCS and 28-day ITS of MLS samples stabilized with OP-G were higher than the 7-day UCS and 7-day ITS of samples. This indicated the continued reaction of the OP-G stabilized MLS. The 7-day soaked UCS of the stabilized MLS was higher than 689 kPa required for subbase materials according to the Department of Highway (DOH), Thailand. The total cost, cost/UCS ratio, and CO2 emission of OP-G were lower than those of two-part geopolymer stabilized MLS samples. The outcomes of this research thus support the utilization of OP-G as an alternative to Portland cement in treating MLS for use as pavement materials.

An experimental study on controlled low strength material (CLSM) for utilization as sustainable backfill

Disposal of ash produced by coal-based power plants is a global problem because of its fineness and lack of space for its pondage. In recent years, efforts have been made to reutilize ash for different applications, viz., manufacturing of cement, bricks, tiles, in concrete, for soil stabilization, construction material for roads and bridge abutments, etc. However, there is a need to find more applications for the complete utilization of ash. In this direction, the present work explores potential of fly ash and pond ash for development of controlled low strength material (CLSM), an alternative material for backfilling applications. The performance of different compositions of CLSM have been studied, by partially replacing sand and cement, with pond ash and fly ash, respectively. Experimental studies have been performed to obtain flowability, hardening time and compressive strength (soaked and unsoaked conditions) for different CLSM combinations. In the present study, 20% binder content and 80% filler content has been considered, with a water/binder (w/b) ratio of 1.7 based on initial trials. Further, variation in percentage of fly ash and pond ash as partial replacement of cement and sand, respectively, have been evaluated. From the test results, it can be concluded that upto 75% replacement of sand by pond ash (60% of overall mix) is possible for development of CLSM with desired properties. Furthermore, the 28-days average compressive strength observed for CLSM varies from 0.4 MPa to 1.8 MPa for the studied combinations. This range of strength is favourable for backfilling applications, wherein, excavation in future may be necessary. Though the study results are quite encouraging towards development of CLSM using pond ash and fly ash, further studies on durability properties and minimizing the variation in properties would help towards developing sustainable CLSM for environmentally friendly infrastructure development.

A Novel Technique to Utilize Second Waste of Plastic Bottle as Soil Reinforcement: A Comparative Study on Mechanical Properties with Natural Black Cotton Soil

Black cotton soils, which are expansive, are present in abundance in Ethiopia. This type of soil possesses expansion when saturated with water and contraction during hot seasons, due to which it is labelled as “weak soil.” They may remain a threat to the structures if they are constructed over them without precautions. The quality of such soils can be improved by treating them with suitable stabilizers or soil reinforcers. This paper discusses the chances of using the second waste of plastic bottles as a reinforcer to strengthen weak black cotton soils in Ethiopia. Second, plastic bottle waste was added at 1%, 2%, 3%, 5%, 7%, and 9% to the soil, and numerous trials were conducted to ensure the reliability of the results. The effects were analyzed based on the results from the Atterberg limit tests, compaction tests, unconfined compression strength (UCS) tests, and the California bearing ratio test (CBR) for soaked and unsoaked conditions. The results were compared against the natural soil results, and the optimum usage percentage of second waste plastic required to reinforce the soil was reported. The results indicate that among the various properties used, the mix with 2% second waste plastic is effective with numerous trials being conducted to ensure the reliability of the results and decreased values of OMC by 18.5%, increased MDD by 1.9%, increased CBR by 50.9%, and increased UCS by 10.1%. Thus, the research provides a novel technique to recycle plastic waste once again as soil reinforcement, thereby saving the environment from dumped waste.

Stabilised sulfate-rich clay with magnesium oxysulfate cement

ABSATRACT Magnesium oxysulfate cements are modern green air-hardening magnesia-based cementitious materials that were produced using the chemical reaction of magnesium sulphate (MgSO4), magnesium oxide (MgO), distilled water and a small number of additive materials. In this paper, the influences of thawing and freezing cycles on the chemical-mechanical and microstructural properties of stabilised sulphate-rich clay with MOSC using a triaxial cell set-up, scanning electron microscopy and X-ray diffraction were investigated. The sulphate-rich clay specimens with various dosages of Magnesium Oxysulfate Cement (MOSC) and different curing times were exposed to one, two and three thawing and freezing cycles in soaked and un-soaked conditions. The consequences showed that the compression strength and behaviour of the stress and strain samples significantly depend on the amount of MOSC. The durability index which was described as the ratio of the resistance before and after stabilising revealed that the durability augments by the increase of MOSC. In addition, increasing curing times in the MOSC stabilised specimens leads to an increase in their compression resistance.