Required Engineering Properties Research Articles

New and Sustainable Coal Char-Based Paving Blocks for Roadway Applications

Paving blocks are widely used in engineering construction for durable pavement surfaces characterized by their interlocking capability to enhance structural integrity. This study explores the potential use of char as a byproduct from coal pyrolysis and an alternative raw material to natural aggregates in developing paving blocks, aiming to reduce the associated environmental issues associated with the uncontrolled and excessive mining of natural resources. This study finds the paving blocks made from char to have the required engineering properties as mentioned by ASTM standard C936. Trass and trass-lime are added as supplementary cementitious materials (SCMs) to enhance the performance of char-based paving blocks. The incorporation of SCMs as a cement replacement also aims to reduce the carbon footprint arising from increased cement use. The compressive strength increased from 55.7 MPa to 65.71 MPa at 12.5% cement replacement with trass-lime. The water absorption is reduced to 4.63% from 4.95%. Beneficial effects towards freeze–thaw durability and abrasion resistance are also observed on trass-lime-incorporated paving blocks. This study signifies the remarkable potential use of coal-derived char and SCMs in developing light, high-strength, and durable paving blocks, showcasing their competitive engineering performance. These new char-based paving blocks will contribute towards a more sustainable construction environment and advance the current construction and engineering practices.

Hybrid Trefftz finite element method for heat conduction in cylindrical composite laminates

Laminated composites are made of continuous fibers and matrix which can provide required engineering properties. This paper proposed a hybrid Trefftz finite element method for the analysis of conductive heat transfer in cylindrical composite laminates by assuming two independent temperature fields. The non-conforming intra-element field which is approximated by a linear combination of T-complete solutions satisfying the governing equation and undetermined coefficients is defined within the element domain, while the auxiliary conforming frame field which is interpolated by standard one-dimensional shape functions is defined on the element boundary. Due to the fabrication characteristics of laminates, each layer can be treated as an orthotropic medium for which the hybrid functional is employed to enforce the continuity of temperature and heat flux across the interface of adjacent elements. The proposed method is tested on three numerical examples and compared with exact or ABAQUS solutions. It was found that the proposed method exhibits low sensitivity to mesh distortion and achieves more acceptable results compared with ABAQUS.

Bending Analysis of Orthotropic Plate using 5th Order Shear Deformation Theory

A composite material is a combination of different material which can be assembled to provide required engineering properties like bending, buckling, stiffness etc. It can give better properties than those of individual components. A lamina is the building block of modern composite laminated structures. A lamina is also known as a ply, or a layer. A laminate has several layers of lamina, or laminae. Since the early years of engineering, various types of laminated composite materials have been used in various engineering fields, such as in aerospace, military and automotive industries that are subjected to high temperatures. Thermal stress caused due to change in temperature, increase in temperature causes the changes in material properties of a plate which in turn complicates the analysis and design and may affect the structure also. Therefore, the analysis of thermal stress in design of structure is very important. A critical review of available literature for the prediction of the behaviour of laminated composites under thermal conditions is carried out and summarized. This work attempts to review the studies carried out from 2000 on laminated composite plates by representing classification based on Classical laminate plate concept, First order shear deformation theory, Higher order shear deformation theory, Layerwise theory and Thermal stress on laminated plates.

Review on laminated composite plates

A composite material is a combination of different material which can be assembled to provide required engineering properties like bending, buckling, stiffness etc. It can give better properties than those of individual components. A lamina is the building block of modern composite laminated structures. A lamina is also known as a ply, or a layer. A laminate has several layers of lamina, or laminae. Since the early years of engineering, various types of laminated composite materials have been used in various engineering fields, such as in aerospace, military and automotive industries that are subjected to high temperatures. Thermal stress caused due to change in temperature, increase in temperature causes the changes in material properties of a plate which in turn complicates the analysis and design and may affect the structure also. Therefore, the analysis of thermal stress in design of structure is very important. A critical review of available literature for the prediction of the behaviour of laminated composites under thermal conditions is carried out and summarized. This work attempts to review the studies carried out from 2000 on laminated composite plates by representing classification based on Classical laminate plate concept, First order shear deformation theory, Higher order shear deformation theory, Layerwise theory and Thermal stress on laminated plates.

Comparative effectiveness of fibers in enhancing engineering properties of Earth as a building Material: A review

Earth is becoming increasingly popular as a building material to promote sustainability, considering environmental impacts and economic aspects. Recent studies have focused on enhancing the engineering properties of earth and earthen construction using different types of fibers, which is considered one of the suitable options for soil reinforcement. A comprehensive review considering the effectiveness of different fibers, their dosages, and their relationship with various engineering properties of stabilized earth is missing in the literature. Therefore, this study aims at providing a state-of-the-art review of research on the effectiveness of fiber reinforcement techniques in overcoming the limitations of the earth and enhancing the engineering characteristics of the reinforced earth. Based on 96 existing studies, the properties and types of fiber and soil, sample-making processes, and engineering properties of fiber reinforced earth, including physical, thermal, mechanical, and durability properties, are reviewed and presented in recapitulative tables. The review demonstrates that there is no specific fiber that showed the best performance considering all the properties; rather, different fibers proved to be best at improving different properties. The present study should aid in the selection of superior fibers and their suitable contents depending on the required engineering properties of earth for being used in construction. Furthermore, this study provided directions for future studies, which should focus on soil mineralogy, the effectiveness of combinations of different fibers, microstructural analysis, and the development of a widely accepted code to promote earthen construction.

Nanotechnology Incorporation into Road Pavement Design Based on Scientific Principles of Materials Chemistry and Engineering Physics Using New-Age (Nano) Modified Emulsion (NME) Stabilisation/Enhancement of Granular Materials

The use of naturally available materials not conforming to traditional specifications or standards in the base and sub-base layers of road pavement structures and stabilised with New-age (Nano) Modified Emulsions (NME) have been tested, implemented and successfully verified through Accelerated Pavement Testing (APT) in South Africa. This was made possible through the development and use of a materials design procedure addressing fundamental principles and based on scientific concepts which are universally applicable. The understanding and incorporation of the chemical interactions between the mineralogy of the materials and an NME stabilising agent (compatibility between the chemistry of the reactive agents and material mineralogy) into the design approach is key to achieving the required engineering properties. The evaluation of the stabilised materials is performed using tests indicative of the basic engineering properties (physics) of compressive strengths, tensile strengths and durability. This article describes the basic materials design approach that was developed to ensure that organofunctional nano-silane modified emulsions can successfully be used for pavement layer construction utilising naturally available materials at a low risk. The enablement of the use of naturally available materials in all pavement layers can have a considerable impact on the unit cost and lifecycle costs of road transportation infrastructure.

Case Study on Applications of Lime–Cement Grouting to Strengthen Soil Characteristics

Formulating solution to obtain the required engineering properties by means of stabilizing the soil for placing infrastructural unit without undergoing large settlement, grouting is widely used restoration method for improving the relative density of the soil strata. This paper has analyzed two case scenarios about soil stabilization to accommodate reinforced cement concrete (RCC) structure to facilitate production units. Considering the soil characteristics and to avoid further collapse of the nearby establishment, injecting lime–cement composition to strengthen the loosen earth bearing capacity at certain depth has been followed. Accordingly, researchers have shown to mend on the discrepancy happened in both cases regarding strengthening of disturbed soil strata up to 2 to 2.5 times with respect to Standard Penetration Test-Number of Blows (SPT-N) values after carrying out pre- and post-dynamic cone penetration tests (DCPT) up to an average depth of 6 to 6.5 m from finished ground level (FGL), by using of grout injection procedure. Following methodology has been emanated and after conducting several trials resulted in appreciable improvement in soil consistency. Researchers believe that the study will be comparatively more suitable for improving problematic soils in South-Asian continent. In both cases, desired soil bearing capacity has been attained in most economical way and within stipulated time frame.

Appraisal of Bearing Capacity and Modulus of Subgrade Reaction of Refilled Soils

Soil is remoulded, replaced, or improved in place to meet the required engineering properties. Relative compaction is the measure of the resulting engineering improvement. But design engineers need the allowable bearing capacity while the modulus of subgrade reaction is the primary input of modern foundation design software. The current research appraised a correlation between Relative Compaction ( ), Moisture Content ( ), and allowable bearing capacity ( ) and another correlation between , RC, MC, and modulus of subgrade reaction ( ). The test samples were extracted from each trial of the standard proctor test using purpose-built extraction tubes. Allowable bearing capacity has been determined by performing unconfined compression tests on the extracted tubes. The relationships have been established employing statistical analysis. It was noticed that soil samples at the lower moisture content (6-9%) show brittle failure before reaching the allowable strain. The soil samples having a moisture content of 10-14% exhibited shear failure, nearly simultaneous to the allowable strain. The soil samples having higher moisture content undergone a strain of 15% without showing the shear failure. A simple equation has also been appraised to determined Ks involving the three-input variable, i.e., , , and . Moderate correlations have been found to exist between the studied parameters, owing to some other variables' influence. Recommendations for future studies have been drawn to quantify the effect of identified parameters. Doi: 10.28991/cej-2020-03091606 Full Text: PDF

CBR behavior of sandy soil reinforced by geofiber material

Abu Dhabi sand lacks the required engineering properties to suffice as pavement base course, subbase course, subgrade and as a foundation-support layer under buildings and various structures. Low bearing capacity is manifested on the roadways as differential settlement, waviness and undulations. Stabilization of this type of sand is one of the major geotechnical challenges in practice. In this study the sandy soil was improved by mixing with geofiber. Three different levels of geofiber was added to the sandy soil; 0.1, 0.2 and 0.4% by dry weight of sand. The results showed great increase in shear strength as indicated by the CBR values. The CBR values have increased from 19 to 55 for 0 and 0.4% geofiber content respectively.

Effect of Mixing of Rice Straw to Enhance the Characteristics of Soil

The foundation should have sufficient strength to support any land based structure. The soil surrounding the foundation plays a very important role. The strength of soil should be maintained according to the loading conditions. The soil reinforcement process helps to attain the required engineering properties in soil for the construction purpose. The necessity of enhancing soil properties came to the light from the beginning of construction work. Soil reinforcement was used in India in 1970’s but proper techniques and skilled labour was not available that's why in India ancient methods for soil reinforcement was using, show the soil reinforcement lots lost its importance. Recently, the demand for infrastructure, raw materials and fuel is improving show the process of soil reinforcement rising its importance up again. According to the better research, materials and equipment, soil reinforcement is the cost effective and popular method for improving the soil properties. Here, in this paper, soil reinforcement analysis completed with the mixing of soil with the powder produced from burning of rice straws fibers (parali) by an specific method. The main motive of this analysis is to find out the utilization of waste rice straw fiber materials in foundation construction without open burning of waste so we can reduce the pollution which create by the open burning of rice straw in the fields.

Stabilization of black cotton soil and loam soil using reclaimed asphalt pavement and waste crushed glass

Stabilization of soil to attain required engineering properties can be done either by mechanical or chemical stabilization. Most of these methods are relatively expensive to implement in practice and the best way is the usage of locally available materials. The present paper reports the stabilization of black cotton soil and loam soil with varying percentages of Reclaimed Asphalt Pavement (RAP) and waste crushed Glass (WCG). Various properties such as maximum dry density, optimum moisture content, and California Bearing Ratio (CBR) are analysed and the results are compared with red soil. Investigations are performed using percentages of Reclaimed Asphalt Pavement (RAP) at 30%, 50%, 55%, 60%, 65% and Waste Crushed Glass (WCG) at 5%. The results showed that there was an appreciable increase in strength and CBR values by the addition of RAP and WCG. The paper proved the effectiveness of proposed method for construction of pavements in village roads with reduced thickness.

Performance of stabilized adobe blocks prepared using construction and demolition waste

This paper presents an experimental investigation into product based research, in preparation of stabilized adobe blocks (SAB) by attempting to utilize construction and demolition waste (CDW) in the form of excavated natural soil (NS) and crushed demolished brick masonry. SAB are energy efficient sustainable variety of masonry units. A detailed study on strength, durability and elastic properties of SAB produced in different combinations were carried out, to determine the optimum combination and gradation, to achieve the required engineering properties. The experimental results were evidenced at a micro-level through microstructure analysis using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). When excavated natural soil was replaced in the order of 60–80% by crushed demolition brick masonry waste, the test results indicated better strength and durability characteristics. The experimental program indicates suitability and potential of utilizing crushed demolished brick masonry waste as partial replacement to excavated natural soil in preparation of stabilized adobe blocks. This attempt of experimental research studying performance of masonry units is one of the ways to address the disposal of construction and demolition waste.

Study on Strength Characteristics of Soil with Agro Waste

Background/Objectives: Soil stabilization is one of the methods used when the given site conditions does not have desirable strength characteristics to support structures, railways and roads. It is the process for improving the soil properties by methods of mechanical or chemical, to produce an soil material which has all the required engineering properties. Application of solid waste disposal (Industrial or Agro waste) for soil stabilization is a significant which serves various benefits to the environment. Methods/Statistical Analysis: In this study the properties of weak soil is improved with the addition of Rice Husk Ash (RHA) of varying percentages of 3, 6, 9 and 12%. The sample was compacted at maximum dry density with the addition of OMC. A series of laboratory experiment has been conducted on expansive soil blended with Rice Husk Ash in 3%, 6%, 9%, 12% and 15% by weight of dry soil. Findings: Unconfined compressive and CBR values of soil increased with the addition of rice husk ash. From the UCC test result, showing that the percentage increase in UCS is 242% and the decrease in swell value from 75 to 45 for the addition of 12% RHA. The study giving the most relevant results by addition of Rice Husk Ash (RHA) upto12% in soil sample. Variations in mineralogical composition analysed by SEM and XRD studies clearly indicate the variation in soil structure formation, due to the chemical reactions initiated by the agro waste mixed in soil. Application/ Improvement: The Rice Husk Ash has a potential to improve the strength characteristics of expansive soil and it reduces the swelling potential of soil. Use of RHA in soil stabilisation is economic; eco friendly and it also solve the disposal problem.

Utilization of ferrochrome wastes such as ferrochrome ash and ferrochrome slag in concrete manufacturing.

Solid waste management is one of the subjects essentially addressing the current interest today. Due to the scarcity of land filling area, utilization of wastes in the construction sector has become an attractive proposition for disposal. Ferrochrome ash (FA) is a dust obtained as a waste material from the gas cleaning plant of Ferro alloy industries. It possesses the chemical requirements of granulated slag material used for the manufacture of Portland cement. Ferrochrome slag (FS) is another residue that is obtained as a solid waste by the smelting process during the production of stainless steel in Ferroalloy industries. FS possesses the required engineering properties of coarse aggregates. The possibility of using FA with lime for partial replacement of ordinary Portland cement (OPC) and FS for total replacement of natural coarse aggregates is explored in this research. The combined effect of FA with lime and FS-addition on the properties of concrete, such as workability, compressive strength, flexural strength, splitting tensile strength and sorptivity, were studied. Results of investigation revealed improvement in strength and durability properties of concrete on inclusion of FA and FS. Concrete mix containing 40% FA with 7% lime (replacing 47% OPC) and100% of FS (replacing 100% natural coarse aggregate) achieved the properties of normal concrete or even better properties at all ages. The results were confirmed by microscopic study such as X-ray diffraction and petrography examination. Environmental compatibility of concrete containing FA and FS was verified by the toxicity characteristic leaching procedure test.

Influence of processing parameters on the impact strength of biocomposites: A statistical approach

Injection molded biocomposites from a new biodegradable polymer blend based matrix system and miscanthus natural fibers were successfully fabricated and characterized. The blend matrix, a 40:60wt% blend of poly(butylene adipate-co-terephthalate), PBAT and poly(butylene succinate), PBS was chosen based on their required engineering properties for the targeted biocomposite uses. A big scientific challenge of biocomposites is in improving impact strength within the desired tensile and flexural properties. The stiffness–toughness balance is one of the biggest scientific hurdles in natural fiber composites. Thus, the key aspect of the present study was in investigating an in-depth statistical approach on influence of melt processing parameters on the impact strength of the biocomposite. A full factorial experimental design was used to predict the statistically significant variables on the impact strength of the PBS/PBAT/miscanthus biocomposites. Among the selected processing parameters, fiber length has a most significant effect on the impact strength of the biocomposites.

STUDY ON STRENGTH CHARACTERISTICS OF SOIL USING SOIL STABILISER RBI – 81

Stabilization of soil is the moderation of one or more soil properties, by chemical or mechanical means, to create an improved geo material possessing the required engineering properties. Soils may be stabilized to increase strength and durability or to prevent erosion and dust generation. The present paper describes a study carried out to check the improvements in the properties of expansive soil with RBI grade 81 in varying percentages and different curing periods. Unconfined Compressive Strength (UCS) tests, XRF and SEM analysis were carried out on untreated and treated soils for different curing periods of 3 days, 14 days and 28 days. An increasing trend in UCS was observed with the increase in the percentage of chemical and curing period.

Utilization of sepiolite materials as a bottom liner material in solid waste landfills

Landfill bottom liners are generally constructed with natural clay soils due to their high strength and low hydraulic conductivity characteristics. However, in recent years it is increasingly difficult to find locally available clay soils that satisfy the required engineering properties. Fine grained soils such as sepiolite and zeolite may be used as alternative materials in the constructions of landfill bottom liners. A study was conducted to investigate the feasibility of using natural clay rich in kaolinite, sepiolite, zeolite, and their mixtures as a bottom liner material. Unconfined compression tests, swell tests, hydraulic conductivity tests, batch and column adsorption tests were performed on each type of soil and sepiolite–zeolite mixtures. The results of the current study indicate that sepiolite is the dominant material that affects both the geomechanical and geoenvironmental properties of these alternative liners. An increase in sepiolite content in the sepiolite–zeolite mixtures increased the strength, swelling potential and metal adsorption capacities of the soil mixtures. Moreover, hydraulic conductivity of the mixtures decreased significantly with the addition of sepiolite. The utilization of sepiolite–zeolite materials as a bottom liner material allowed for thinner liners with some reduction in construction costs compared to use of a kaolinite-rich clay.

Engineering Properties of Silty Clay Stabilized with Calcium Carbide Residue

Calcium carbide residue (CCR) is a waste product from acetylene gas factories, which is rich in calcium hydroxide (CaðOHÞ2). Because clayey soils contain high amount of natural pozzolanic materials (silica and alumina), CCR can be used as a soil stabilizer. This article presents the engineering properties of CCR-stabilized silty clay to ascertain its performance in pavement base and subbase appli- cations. The input of CCR, which reduces the plasticity index of the clay, increases the optimum water content (OWC) and decreases the maximum dry unit weight (γd;max) of the stabilized clay. The CCR fixation point, simply obtained from the index test, is proved as a practical indicator for determining the CCR content to obtain the required engineering properties at a particular molding water content. The state of water content controls the densification, chemical reaction, and water absorption capacity. The soaked engineering properties are thus de- pendent upon the state of water content. For a particular CCR content, the optimum water content is the most appropriate in terms of strength, swelling and collapse behaviors, and bearing capacity. The lower water content is not sufficient for the chemical reaction, while the higher water content yields a higher water/binder ratio. The water absorption is smallest for the CCR-stabilized samples compacted at the OWC. To conclude, the optimal mix proportion is the CCR fixation point at OWC. CCR stabilization is more effective than lime stabilization in terms of engineering, economic, and environmental viewpoints. DOI: 10.1061/(ASCE)MT.1943-5533.0000618. © 2013 American Society of Civil Engineers. CE Database subject headings: Calcium; Soil stabilization; Clays; Silts; Material properties. Author keywords: Calcium carbide residue; Engineering properties; Pozzolanic reaction; Soil stabilization.

Review of soft soils stabilization by grouting and injection methods with different chemical binders

Soil stabilization has become one of the useful solutions to treat the soft soils to achieve the required engineering properties and specification so that structures can be placed safely without undergoing large settlements. Soil stabilization by admixture was developed in Japan during 1970s and 1980s. The treated soil has greater strength, reduced compressibility and lower hydraulic conductivity than the original soil. The use of admixture such as lime, cement, oils and bitumen is one of oldest and most widespread method for improving soil. When mixed with soil, it forms a material called soil-cement. The original technique known internationally as the deep mixing method (DMM) was developed simultaneously in Sweden and Japan in the mid-1970s. It is an in-situ soil treatment technology whereby the soil is blended with cementitious and/or other materials. Jet grouting is suitable to be used as the injection method for the DMM. It utilizes a fluid jet (air, water and/or grout) to erode and mix the in-situ soft or loose soils with grout. The grouting method is one of the ground improvement methods suitable for the soft soil. Chemical stabilization is the effective method to improve the soil properties by mixing additives to soils. Usually the additives are cement, lime, fly ash and bituminous material. The chemicals usually used are sodium silicate, acrylamide, N-methylolacrylamide, polyurethane epoxy resins, aminoplasts, phenoplasts, lignosulfonates, among others. The choice of a particular chemical for soil stabilization will depend upon many factors like, purpose, soil strength desired, toxicity, rheology among others. Key words: Injection, jet grouting, chemical grouting, deep mixing method.

Utilization of Local Available Materials to Stabilize Native Soil (Earth Roads) in Tanzania—Case Study Ngara

The native soil behavior of unpaved low volume roads and their mode of failure were studied to establish proper method of stabilizing native soils using local available materials. The use of lime and its positive effect to modify and stabilize Ngara soil in Tanzania is presented in this paper. There are many methods of stabilizing soil to gain required engineering specifications. These methods range from mechanical to chemical stabilization. Most of these methods are relatively expensive to be implemeted by slowly developing nations and the best way is to use locally available materials with relatively cheap costs affordable by their internal funds. Tanzania is a country having abundantly amount of Lime. Ngara native soil roads (unpaved rural roads) was studied under preliminary investigation and found to have higher plasticity, tendency of swelling and shrinking, low bearing capacity when wet, compressive strength of soil to have higher sensitivity to moisture and lower shear strength when wet. These soil behaviors deny road access to about 32 million people in Tanzania (80% of population) during rainy season. The detailed investigations is still going on at China university of Geosciences but other results from similar researches show that Ngara soils can be stabilized by lime and gain the required engineering properties.