Direct Shear Box Tests Research Articles

GEOTECHNICAL AND MINERALOGICAL CHARACTERISTICS OF LATERITIC SOIL AND LOCUST BEAN (PARKIA BIGLOBOSA) PODS ASH AS CONSTRUCTION SOIL

African locust bean (Parkia Biglobosa) has been in great demand and consequently yielding large amounts of the pods which could be a potential hazard to the environment. Converting the pods to ash that would be utilized as construction material is another way of handling them properly. The effects of the mineralogy of the soil on its geotechnical characteristics when the soil is treated with locust bean pod ash have been given very little attention. Therefore, this study considered the effects of locust bean pod ash (LBPA) and the mineralogy of lateritic soil on some geotechnical properties necessary for it to be used as subgrade or foundation soil. The determination of the chemical constituents of the LBPA was carried out using Atomic Absorption Spectrometer. The lateritic soil was characterized by identifying the clay minerals as well as non-clay minerals present in the soil using the x-ray diffraction technique and preliminary tests were also carried out to properly rate the soil. The soil was treated by applying dosages of LBPA 0 – 25% at intervals of 5% and the percentages were measured by weight of the dry soil. The tests conducted on the prepared soil samples with LBPA were specific gravity, consistency indices, compaction (British Standard Light), California bearing ratio and direct shear box test. The LBPA was found to be an acceptable pozzolanic material for the treatment of the lateritic soil. The lateritic soil was observed to belong to soil groups A-2-6(0) in the AASHTO and poorly graded sand (SP) in USCS ratings. It was also observed that the non-clay minerals present in the soil were quartz, feldspar and mica whereas the clay minerals present were kaolinite, iolite, vermiculite and chlorite which had a significant influence on the geotechnical characteristics of the soil. The specific gravity of the LBPA was relatively low and the additions of LBPA reduced the specific gravity of the soil. The consistency indices also dropped and subsequently increased with the further addition of LBPA. The increase in LBPA contents caused increments in the optimum moisture content while the maximum dry density and shear strength parameters reduced. The strength characteristics like the California Bearing Ratio of the lateritic soil improved by 173.91% at the addition of 5% LBSA content which was determined to be the optimum dosage.

Characteristics of Sand-Waste Tyre Rubber Composite as Backfill Material

Waste tyre rubber offers an alternative to natural sand as a backfill material, potentially reducing the dependency on natural sand usage in construction. The purpose of this study is to investigate the properties of waste rubber as a potential backfill material for retaining walls and to assess the shear strength characteristics of the sand-rubber composite when used as a backfill for retaining walls, ultimately identifying the optimal sand-rubber composite ratio for effective backfill application. This study employed sieve analysis and specific gravity testing to identify the physical attributes of waste tyre rubber. Subsequently, direct shear box tests were conducted utilizing ratios of 100%, 50%, 75%, and 25%. Two types of rubber were utilized in this study Granulated Rubber (GR) with particle sizes ranging from 1 to 5 mm, and Mulch (MR) with particle sizes exceeding 25 mm. The findings reveal that the Cu value for waste rubber is less than 2.50 and the Gs value is less than 1.5, indicating favourable characteristics. Moreover, the 25% GR and MR compositions exhibit the highest shear stress values at 0.0347 N/m² and 0.0296 N/m², respectively. In conclusion, it has been determined that the optimal proportion of waste rubber for the application of the sand-waste tyre rubber composite as a backfill material is 25%.

Effect of surface roughness on the interface behavior of clayey soils

Abstract This study investigates the effect of surface roughness on the interface behavior between clayey soils and structural materials, aiming to determine the necessary parameters for soil-structural interaction. The research site, located in one of Iraq’s seismically active regions, was selected for its significance. Experimental measurements were conducted using the SRT-6210 Digital Surface Roughness Tester to assess the roughness characteristics of steel and concrete samples. Four distinct roughness parameters were measured, and their correlation with shear parameters was analyzed. The shear behavior of clay-steel and clay-concrete interfaces was successfully described using the average roughness parameter (Ra), which exhibited the strongest correlation with shear parameters. Direct shear box and interface shear box tests were employed to identify soil’s shear strength parameters and evaluate interface shear strength parameters. The experimental findings highlight the significant influence of surface roughness on the shear strength parameters of clay-steel and clay-concrete interfaces. The interface shear strength, friction angle, and adhesion exhibited an increasing trend with roughness. Notably, shear strength increased by approximately 29.76% when concrete sample roughness was below 20 μm and by 32.8% when steel sample roughness was below 30 μm. Moreover, increasing surface roughness improved the interface friction angle of clay-steel and clay-concrete samples by about 37.95 and 36.3%, respectively. Additionally, an increase in roughness led to a rise in the adhesion of concrete and steel samples by approximately 26.24 and 32%, respectively. These findings emphasize the significance of surface roughness in optimizing the interface behavior between clayey soils and structural materials. The results have important implications for enhancing the design and performance of soil-structural systems.

Experimental Study on Physical and Mechanical Properties of Lightweight Cellular Concrete Specimens Cast in Field and Laboratory

This paper presents a series of laboratory tests for evaluating the material properties of Lightweight cellular concrete (LCC) with different cement-to-fly ash ratios and at different ages. LCC specimens used in this study were cast in the field and/or laboratory. Large and small direct shear box tests were used to determine the shear strengths of LCC specimens. The test results show that the average wet densities for the LCC specimens cast in the laboratory ranged from 460 to 491 kg/m3, whereas the average wet densities for the specimens cast in the field ranged from 480 to 578 kg/m3 at the age of 28 days. The permeability values for the LCC specimens cast in the field ranged from 5.4 × 10-7 to 7.7 × 10-6 m/s and the permeability values for the LCC specimens cast in the laboratory ranged from 6.8 × 10-7 to 2.5 × 10-6 m/s. The measured peak friction angles of the LCC specimens from the small direct shear box tests ranged from 19° to 63°, whereas the measured peak friction angles of the LCC specimens from large direct shear box tests ranged from 23° to 79°. The average measured compressive strengths for the LCC specimens cast in the field and laboratory ranged from 0.43 to 1.15 MPa and 1.08 to 1.11 MPa at the age of 28 days, respectively. LCC specimens showed shrinkage behavior when subjected to wet–dry cycles and had good resistance to freeze–thaw cycles following ASTM D560/560M. The paper also compares the material properties of LCC measured in this study with those reported in the literature and the comparison shows good agreement overall.

Utilization of Plastic Waste in Reinforcing Sandy Soil for Sustainable Engineering Applications

Large quantities of polyethylene terephthalate (PET) plastic are discarded into the environment during production, application, and disposal. Although current clean-up strategies aim to mitigate the adverse impacts of PET pollution, efforts struggle to keep up with the escalating amount of PET waste. This accumulation of PET waste poses significant threats to ecosystems worldwide. One recycling method for PET plastic waste involves its utilization in soil reinforcement applications within civil engineering. By incorporating PET plastic waste to reinforce poor-quality sands, sustainable construction practices can be promoted in civil engineering infrastructures, addressing multiple aspects of sustainability, including engineering, economic, social, and environmental considerations. The experimental work conducted in this research involved sieve analysis, proctor compaction test, California Bearing Ratio (CBR) test, and direct shear box test. The sand was reinforced with varying percentages of PET plastic waste flakes, namely 5, 10, and 15 %, with respect to the weight of the soil sample taken for the test, and laboratory tests were performed on the samples. Including PET plastic flakes enhanced various soil properties, such as shear strength and friction angle. It also improved the CBR value of the composite, making it suitable for pavement construction. The reduction in dry density further supports the application of the composite in lightweight structures. In conclusion, the geotechnical material obtained from the soil-PET plastic waste composite can be utilized in various geotechnical projects, including landfills and slope stabilization.

Geotechnical investigation of soil bearing capacity a case study of Nile university of Nigeria

Geotechnical investigation was conducted within Nile University soil with the aid of the master plan showing areas awaiting future developments. This is as a result of the university planning for infrastructural expansion due to such in student’s population. Each time a building construction is to be taken place, the university management spent another set of money on conducting geotechnical investigation. There are no comprehensive geotechnical information of the soil bearing capacity that can represent the whole of Nile university space/area of 1,153,208,008?2. In-situ and laboratory test were carried out. Three boring point were established using map at a regular interval and drilled to a depth where basement was encountered. In each test sample were collected at 1.5m interval. The standard penetration procedure consist of split spoon and u-tube as set forth in ASTM-1990. The test involves counting the number of blows required to drive a spoon sampler by 300mm, using a weight of 64kg hammer with a free fall of 76mm on the anvil of a rod arrangement. An initial penetration of 150mm is allowable on the sampler known as sitting blows before counting the subsequent blow for the required 300mm. another six trial pit were evenly spread at regular interval at different location within the university. It was manually excavated by hand, undisturbed and disturbed sample were extracted by hand auger and shovel. Sample were extracted at 1.5m depth, properly labelled and taken to laboratory. The laboratory test of the extracted soil sample include moisture content, grain size distribution, liquid limit, plastic limit, consolidated drained test and unified soil classification system was adopted. It was observed that the results obtained from Standard Penetration test indicates variance in allowable bearing capacity with depth, between 0.0-0.5m is 56??⁄?2, 0.6- 1.0m is 112??⁄?2, 1.5- 2.0m is 215??⁄?2, 3.0 – 3.5 is 279??⁄?2, 4.5 – 5.0m is 273??⁄?2. The soil type were predominantly medium dense to very dense inorganic silty sand with clay content less than 5%. Point of refusal was encounter at 6m depth, boring was then terminated. The Direct shear box test analyses obtained from site BC and CH gave the allowable bearing capacity values of 250??⁄?2 at pit one, 211.2??⁄?2 at pit two, 798.1??⁄?2 at pit three, at pit four, 798.1??⁄?2, at pit five, 918??⁄?2 , at pit six 960.5??⁄?2, but with the results obtained from oedometer test show that we cannot adopt this allowable bearing capacity value due to it high settlement rate beyond the acceptable settlement rate set by Development Control in Nigeria, which is 100mm. therefore based on the result from oedometer test the allowable bearing capacity of 120??⁄?2 was adopted with a safe consolidated settlement of 52mm at site BC. While an allowable bearing capacity of 100??⁄?2 with safe consolidated settlement of 55mm was adopted for site CH. Site BC is predominantly underlain by Sandy Silt. While site CH the predominant soil type was Clayey Sand. Pad footing at 1.5m depth and 210??⁄?2 allowable bearing capacity should be adopted. It is recommended that for both site BC and CH pad foundation at 1.5m having maximum individual column load less than 600??⁄?2 with a ground beam adopted.

Investigating the compressibility and flowability of cocoa powders: A solution for chocolate industry

AbstractThe flowability and compressibility properties were determined for two types of cocoa powders, which are used commercially in chocolate industries; alkalized and natural cocoa powders. Physical and flow properties have a very significant role in the flow behavior, which relates to the handling, transportation, and storage of bulk powders. Throughout the research, it was observed that the properties of both cocoa powders are similar. The objectives of this work are to compare the compressibility and flowability between alkalized and natural cocoa powders and to design the minimum opening size of hopper for mass flow based on their flow properties. Jenike's mathematical methodology is applied during the research for the design of conical hoppers for mass flow. Besides, powder flow analysis using powder flow analyzer is one of the testing methodologies in this research. In addition, direct shear box tests were performed with three different normal stresses. The alkalized cocoa powder needs 1.366 m in diameter for the opening of the hopper, while the natural cocoa powder needs 1.531 m. From the results of the study conducted, it was concluded that both cocoa powders are very cohesive and have poor flow properties. This research reveals that the physical and flow properties of two main types of cocoa powder contributed a lot to the process of hopper design, enhance process understanding, and also applicable for analyzing the powder behavior at any stage in industry.Practical applicationsCocoa powder is the essential ingredient of chocolate manufacturing and other food industry having a chocolate‐like flavor including beverages, biscuits, desserts, and so forth. In chocolate industry, the flow behavior of cocoa powders can affect manufacturing efficiency, which directly affects the production capacity and product quality in terms of its weight and content uniformity. In this study, the critical design parameters such as hopper angle and size of opening were determined to improve the flowability of cocoa powders when passes through hopper. The findings of the present study make it possible for an accurate estimation of a correct intersection with the hopper flow factor line and effective angle of internal friction (δ), extrapolating the powder flow function ff curve to obtain hopper opening size for each cocoa powder for better flowability.

Shear behaviour of peat at different stress levels

Consolidated undrained triaxial compression tests were conducted from 1.65 m depth subjected to stress levels of 10.4–40.5 kPa. The results showed that most test data failed to reach the tension cut-off line (q/p′ = 3). For peat, the membrane correction effect on peat shear resistance was strain dependent – generally small within 10% shear strain, but significant above 10% shear strain. A critical state line for peat was determined based on the maximum curvature approach. Of the data recorded for peat, 78% fell within the range 30–60°, increasing to 90.4% when ignoring points lower than 10 kPa. Organic content (OC) also had an effect on the shear behaviour. For OC > 75%, the deviator stress behaved like an organic soil; otherwise, the peat behaved more like a mineral soil. In peat samples with OC > 75%, the direct shear box test gives higher estimates of shear strength than the triaxial shear test, but which are not necessarily accurate – the mechanism of direct shear acts only at the centre of a specimen, while triaxial shear can shear throughout the specimen.

Bearing Capacity of Shallow Foundations on Unsaturated Silty Soils

In general, the ultimate bearing capacity (UBC) of shallow foundations on unsaturated soils is characterized by the conventional shear strength (SS) parameters in which saturated theories are applied. However, in this case, it is clear that the foundations designed using the obtained values from the saturated cases not be economical. In recent years, procedures have been developed to estimate the UBC of foundations on unsaturated soils, that take into account drained and undrained loading conditions. However, these studies generally concentrate on sandy soils. The validity of the results proposed in the literature should be tested for other soils. Therefore, this paper includes a conventional direct shear box (DSB) test to determine the unsaturated SS of statically compacted silty soil, and a series of model tests were performed to determine the foundation’s UBC. In the experimental model setup, the UBC values of different types and sizes of model foundations on silty soil layers with a different soil saturation degrees (SSDs)/matric suctions (MSs) and different void ratio values were measured. In addition, the soil-water characteristic curves (SWCCs) and SS parameters of unsaturated silt were obtained. Using the experimental results, a new equation is proposed for the characterization of the UBC of shallow foundations on unsaturated silty soils. Using this equation, the UBC of unsaturated soils can be determined based on the results of unconfined compressive strength tests (UC) measured on unsaturated soil samples and based on the degree of saturation and the fitting parameter. The results indicate that the measured bearing capacity values obtained via the model footing test, shows a good consistency with those obtained by the proposed equation.

Determination of shear strength parameters of compacted high plasticity clay soils based on different laboratory tests

In civil engineering projects, soils are compacted to improve their engineering behavior and properties. Compacted soils are widely used in dams, embankments and road infrastructure. Compacted fine-grained soils, especially clay-containing soils, are frequently used as barriers to water and pollutant movement in landfills. Shear strength parameters of compacted high plasticity clay soils depend on many variables such as consistency limits, dry density, and degree of saturation. In this study, 20 high plasticity clay soil samples were used and geotechnical identification tests were performed on each of them. Direct shear box and unconfined compression tests were carried out to determine the shear strength parameters of the samples prepared by compression in their compaction characteristics. As a result of this study, the relationships between the geotechnical properties of soil samples and both the effective shear strength parameters and total shear stress parameters were evaluated.

Effects of Crumb Rubber on the Shear Strength of Sand: An Experimental Study

The application of waste rubber tires for ground improvement helps to improve the environment by recycling and reusing it as admixtures. This research aims to investigate the shear strength parameters of rubber-sand mixtures. By using crumb rubber with a constant size (425μm), the sand is replaced by different percentages (0, 2.5, 5.0, 7.5, and 10%) of crumb rubber by weight. A direct shear box test is used to determine the shear strength parameters of rubber-sand mixtures with two different controlled densities. The samples were loaded with normal stresses of 20, 40 and 80kPa and were sheared at a rate of 1mm/min. Although, this experiment discovered that crumb rubbers improve the shear strength parameters in loose sand, however, a reduction in shear strength parameters was found in dense sand. Moreover, it was observed that the inclusion of crumb rubbers into sand greatly improve the strain energy of both loose and dense sand. Likewise, rubber has a low unit weight which makes it suitable for lightweight backfill materials. The surface properties of rubber should be further studied to understand the contribution of shear strength in the rubber-sand mixture.

An experimental study on strength improvement of expansive subgrades by polypropylene fibers and geogrid reinforcement

The rapid development of infrastructure often encounters the loose subgrades and is becoming difficult to carry to construction activities. Numerous counteracting methods are developed to control the swelling-shrinkage behavior of the expansive subgrades. The mechanical stabilization of the expansive subgrades by reinforcing with the polypropylene fiber and geogrid is sustainable. Geogrids and polypropylene fibers have been used extensively to strengthen the expansive subgrade and foundations as individuals. The polypropylene fiber reinforcement enhanced the reinforced expansive subgrades's tensile strength capacity, wherein the geogrid reinforcement is the quick fix mechanical stabilization technique, which reduces the pavement failures. In this research, the polypropylene fiber and geogrid reinforcement’s combined effect has been evaluated to stabilize the pavement subgrades. The various mechanical strength test such as unconfined compressive strength (UCS) and large direct shear box test was conducted to evaluate the mechanical interaction between expansive subgrades, polypropylene fiber, triaxial geogrid, and biaxial geogrid at the interface. The polypropylene fiber of 12 mm length was used in the proportion of 0.25%, 0.5%, and 1.0% and single geogrid layer at mid-depth. The result shows that reinforced subgrades’ shear strength with a layer of biaxial/ triaxial geogrid and polypropylene fiber increases by 177%. It is also observed that the unconfined compressive strength of the expansive subgrades increased ranging 3.8–139.6% with the inclusion of polypropylene fiber with geogrid in different combinations. The combined reinforcement method shows an effective treatment methodology to improve the property of expansive subgrades.

Large Scale Direct Shear Box Tests on Gravels

The determination of shear strength characteristics of gravelly soils is difficult through the use of conventional small scale, triaxial or simple shear testing devices in the laboratory due to membrane compliance and boundary effects; or due to inconsistent penetration resistances measured as part of standard or cone penetration testing in the field. These limitations require the use of available empirical or semi-empirical relationships or the execution of large scale laboratory or field tests. In the literature there exists inconsistent, and large range of recommendations for shear strength parameters. Within the confines of this study, direct shear box test results performed on poorly- (GP) and well-graded (GW) gravel samples with initial void ratio ranging from 0.42 to 0.53 are presented, which are tested under effective normal stresses ranging from 77 to 205 kPa. The estimated peak secant-angles of shearing resistances vary in the range of 49 to 54 degrees. On the basis of volumetric change vs. shear strain responses, the peak angle of dilation and elastic Poisson’s ratio are estimated to vary in the range of 10-16 degrees and 0.28-0.39, respectively. These estimated values are compared with available literature.

Wheat straw direct shear simulation using discrete element method of fibrous bonded model

A discrete element method (DEM) calibration for a flexible wheat straw model for simulating direct shear test of wheat straw was investigated. The calibration process uses DEM simulated Design of Experiment (DOE) of a three-point bending test, DEM parameters initialised from previous cantilever beam test, and uniaxial compression test of wheat straw. Wheat straw samples from physiologically matured Winter wheat straw (Triticum aestivum) material were used to estimate shape of a flexible wheat straw model and to obtain material testing data. Using the DEM simulated DOE of a three-point bending test, a regression meta-model was established between particle contact Young's modulus, and bond Young's modulus and Poisson's ratio. An optimisation procedure that minimised a global error relative to the test data was utilised to determine the DEM parameters of particle contact Young's modulus, bond Young's modulus, and Poisson's ratio. From the three-point bending test of wheat straw (length of 55 mm, a diameter of 2.81 mm, and a thickness of 0.35 mm), and DOE based optimisation procedure, the DEM predicted Young's modulus of flexible wheat straw at a percent relative error (RE) of 3.11% compared to test data. Using the optimised DEM parameters of the flexible wheat straw model, the direct shear box test was simulated using the flexible fibre DEM model, as a validation experiment. DEM successfully simulated the direct shear behaviour of wheat straw from the ASTM laboratory direct shear box test, predicting wheat straw angle of internal friction (RE of 1.67%) and apparent cohesion close to zero.

Shear behaviour of sandy soil from Chlef river reinforced with different types of fibres

Direct shear box tests were carried out in order to evaluate the effect of different types of randomly distributed fibres; two synthetic fibres (Polypropylene and Glass fibre) and one natural fibre (Sisal fibre) on the improvement of Chlef sandy soil shear strength. All of the inclusions were randomly distributed in the soil mass with a length of 12 mm and fibre contents of (0, 0.25, 0.5, 0.75 and 1% by dry soil mass). Samples were prepared at a relative density of 50% representing medium dense state and performed at normal stresses of 50, 100 and 200 kPa. The present work is conducted in order to study the effect of material properties and fibre content on the shear strength of sand. The experimental results show that all types of fibre greatly improved the shear strength, cohesive intercept and friction angle of Chlef sand. However, samples reinforced with sisal fibres have shown a more pronounced increase in strength parameters than those reinforced with glass or polypropylene fibres. The effect of the soil initial state was also discussed.

Effect of Waste Tire Reinforcement with and without Cement Additives on Peat Strength Improvement

This paper presents the peat ground improvement techniques using waste-tire as a fibre reinforced material. In this study, two sizes of the waste-tire are chosen, which are 0.05 mm and 1-3 mm, respectively. The collected peat is classified as Sapric peat with the degree of decomposition of H7 based on von Post classification with high moisture content of 400% was recorded. The Sapric peat is treated with the waste-tire at designated percentages of 5%, 10% and 15% with the addition of 5% of cement acting as a binder. The untreated and treated peat without and with cement content are compacted at the optimum moisture content for both the Unconfined Compressive Strength (UCS) test and Direct Shear Box Test. The specimens were air-cured for 7, 28, 56, and 90 days. Hypothetically, higher percentages of rubber improve the shear stress value of the treated peat. According to the results the finer size (0.05mm) of the tire produces a higher shear stress, which may due the finer sizes of the waste-tire filled the void between the soil particles. Further, from the 90 days of curing UCS results, there is a significant increase in compressive strength with the increase percentage of the waste-tire peat mixed samples. In summary, soil stabilized by the scrap-tire is believed to decrease the optimum moisture content and the maximum dry densities, but it helps in increasing the unconfined compressive strength value. Stabilizing by using the tire wastes not only increasing the strength of the soil, but it also helps in reducing the disposal problems.

Determination of Shear Strength Parameters by Multistage Triaxial Tests in the Long-Term Analysis of Slopes

Accurate determination of soil parameters is of great importance in the analysis of landslides, which is a common type of natural disaster. In the solution of landslide problems, the direct shear box test is generally preferred as a laboratory test type for the determination of the shear strength parameters of soils. However, the need for drained parameters in long-term problems reveals a disadvantageous aspect of this experiment, especially in clayey soils, because pore water pressures cannot be measured in the direct shear box test, which is widely used in the laboratory to determine the shear strength of the soils.Multistage triaxial compression tests used to obtain shear strength parameters in the laboratory are advantageous compared to conventional triaxial compression tests because of the time and financial concerns, as well as the avoidance of differences between the samples to be tested. In this study, a new method was tried in addition to the methods used to obtain shear strength parameters with consolidated-drained multistage tests in normally consolidated clayey soils and the results were promising. Thus, since it increases the usability of multistage tests, it will be helpful in terms of preventing possible disasters by enabling analysis in many more sites.

Improvement of shear strength and compressibility of soft clay stabilized with lime columns

Soft clay improvement using lime columns is an effective and economic method; which used mainly for enhancing the engineering properties of soft soil, reducing settlement and increasing shear strength. Improvements in engineering properties of soft clay can be achieved instantaneously with small additions of lime to soft soils. However, the effectiveness of this improvement depends on the quantity and type of lime as well as the mineralogical composition of soil. In this paper, the behavior of soft clay improved with lime columns has been studied. A series of large scale direct shear box tests were carried out with different number of lime columns, diameter, and different curing periods. Experimental study was carried out on both single and a group of lime columns. The results showed that the group of columns increased the shear resistance of soft clay soil with lesser horizontal deformation. Shear strain decreased by 28% and 47% in case of using 1 and 4 lime columns respectively after 7 days curing. Meanwhile, increasing the lime column diameter was found to increase the shear strength of soft clay and improve its compressibility. Finally, the shear strength was found to be increased by 53% when using a single lime column, while when using a group of 4 lime columns with diameter/length (D/L) ratio equals 0.28, the shear resistance is duplicated compared to the case of soft clay without lime columns.

Shear strength parameters of sand-tire chips mixtures

Used tires are unwanted wastes especially in urban areas and their extent is growing every year. With the development of human societies and the increasing use of automobiles, every year millions of used tires are collected as garbage around the world and leave the consumption cycle. However, they can be used by mixing with soil, one of the basic building materials, to improve their mechanical properties. This article discusses the effect of adding tire chips on the shear strength properties of high-friction sand. Different mixing ratios of the sand-tire chips mixture by weight (100: 0, 97.5: 2.5, 95: 5, 92.5: 7.5 and 90:10) were used. The Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) of sand and different sand-tire chip mixtures were determined by the standard Proctor test. Samples were prepared under OMC and MDD conditions and direct shear box test was performed on sand and sand-tire chip mixtures under three different axial stresses. The results showed that when the percentage of tire chips reaches 5%, the internal friction angle was increased by 13.8% and cohesion was decreased by 66.4%. After this point internal friction angle was decreased and cohesion increased slightly.

The Role of Soil Stabilisation in Mitigating the Impact of Climate Change in Transport Infrastructure with Reference to Wetting Processes

Cost efficient and robust transport systems are of critical importance to future economic prosperity as well as for the society’s social and environmental well-being. However, current performance shortcomings in the transport infrastructure formations induced by extreme climatic events cause excessive maintenance requirements with increased costs and disruptions to commuters and loss of productivity in the freight services. This is particularly important in locations where soils are sensitive to moisture changes caused by extreme climatic events. In this paper the role of soil stabilisation in halting volumetric deformation and associated reduction in shear strength derived from the wetting processes (e.g., rainfall periods) is examined for an expansive soil. Two stabilizers commonly used in road construction are examined, i.e., hydrated lime and Portland cement. An additional non-traditional stabiliser composed of a blend of ground granulated blast furnace slag and hydrated lime is also considered. A series of one-dimensional swelling and direct shear box tests were conducted adopting vertical stresses relevant for pavements and simulate wetting process that can take place after a period of rainfall. Results indicate that while all stabilizers contribute to a reduction of swelling and smaller losses in shear strength upon wetting, the blend of blast furnace slag and hydrated lime is the most favourable in terms of carbon footprint.