Browsing by Author "Orji, Francis"

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    Experimental assessment of subgrade stiffness of lateritic soils treated with crushed waste plastics and ceramics for pavement foundation
    (International Journal of Low-Carbon Technologies, 2019) Chibuzor Onyelowe, Kennedy; Bui Van, Duc; Nguyen Van, Manh; Ezugwu, Charles; Amhadi, Talal; Sosa, Felix; Wu, Wei; Ta Duc, Thinh; Orji, Francis; Alaneme, George
    The assessment of subgrade stiffness of four test soils treated with crushed waste ceramics (CWC) and crushed waste plastics (CWP) has been experimented on under laboratory conditions. There have been recorded failures of pavements resulting from inadequate subgrade formations and the use of weak and expansive soils as subgrade materials. The changes in the behavior of these foundation materials affect the performance and overall behavior of the entire pavement or foundation structure. The aim of this work was to assess the behavior of test soils commonly used as subgrade materials and treat same with selected solid waste based geomaterials to enhance their ability to withstand dynamic and cyclic loads. The selected solid waste based geomaterials were crushed waste ceramic and crushed waste plastics. The test materials including the soils were tested for characterization procedure. The preliminary test results showed that the test soils were classified as A-2-7, A-2-6, A-7 and A-7-5, respectively according to AASHTO classification system and poorly graded soils according to USCS. They were also classified as highly plastic soils and expansive with plasticity indexes of above 17%. The oxide composition test on the CWC and CWP shows that the materials possess pozzolanic properties with high aluminosilicates. The test soils were treated with these geomaterials in the proportion of 10% to 120% by weight. The treatment protocol showed that the CBR, resilient modulus, and r-value improved consistently with increased CWC and CWP. Lateral deformation observed from the modified triaxial compression also reduced consistently with increased proportions of CWC and CWP. It is novel to have achieved improved California bearing ratio characteristics, resilient modulus, resistance value and lateral deformation properties of the test soils with a solid waste based geomaterial. It is also promising that beyond the proportion utilized in the laboratory, the CWC and CWP treated soils will resist both axial and lateral deformation or failure when compacted to the maximum dry density and optimum moisture.
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    Generalized Review on EVD and Constraints Simplex Method of Materials Properties Optimization for Civil Engineering
    (Civil Engineering Journal, 2019) Onyelowe, Kennedy; Alaneme, George; Bui Van, Duc; Nguyen Van, Manh; Ezugwu, Charles; Amhadi, Talal; Sosa, Felix; Orji, Francis; Ugorji, Benjamin
    Extreme vertex design (EVD) has been adapted to be used in the modeling of the behavior of mixture experiments in civil engineering. This method has been in use since the 1970s and has be prevalent in the field of medical science. Various other methods of design of experiments have been used in engineering but neither has EVD being used particularly in civil engineering. This review is presented to serve as a hub or guide for subsequent exercise where concrete production, asphalt production or modification, soils stabilization and concrete improvement or water treatment would be studied with the help EVD. Its ability to fix design points and centroids has been reviewed in this work. EVD operates with various algorithms and depends on the order or condition of problems to be solved. The XVERT algorithm working on Minitab and Design Expert platform was adopted in this review work because of its efficiency in handling quadratic model problems like the four cases reviewed in the present work. From the four special cases, it can be asserted that there is a confidence in the use of EVD to develop the constraints, design the experimental factor space, design the mix proportions, and validate the models resulting from these procedures after experimental specimens are tested to determine the responses.
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    Scheffe optimization of swelling, California bearing ratio, compressive strength, and durability potentials of quarry dust stabilized soft clay soil
    (Materials Science for Energy Technologies, 2019) Onyelowe, Kennedy; Alaneme, George; Igboayaka, Clifford; Orji, Francis; Ugwuanyi, Henry; Bui Van, Duc; Nguyen Van, Manh
    Scheffe’s second degree polynomial was used to formulate models for predicting the swelling potential, California bearing ratio, unconfined compressive strength and loss of strength on immersion durability of quarry dust treated soil. These models could predict the swelling potential, California bearing ratio, unconfined compressive strength and loss of strength on immersion durability of treated soil if the mix ratios are known and vice versa. The response predicted by the models are in good agreement with the corresponding experimentally observed results. The result of these tests shows the feasibility of using quarry dust in soil stabilization. The student t-test and the analysis of variance (ANOVA) test were used to check the adequacy of the models, and the models were found to be adequate at 95% confidence level. With the optimized equations, the properties’ design, behaviour, and performance of treated soft clay soil as a pavement subgrade material will be appropriated and monitored. This will be for any possible volume changes, shear failures, strength failures and durability failures when the material used as a hydraulically bound material is in contact with moisture beyond its optimum and subjected to dynamic load beyond its design value.
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    Sorptivity, swelling, shrinkage, compression and durability of quarry dust treated soft soils for moisture bound pavement geotechnics
    (Journal of Materials Research and Technology, 2019) Onyelowea, Kennedy; Onyelowe, Kennedy; Bui Van, Duc; Eberemu, Adrian; Xuan, Man Nguyen; Salahudeen, Bunyamin; Ezugwu, Charles; Nguyen Van, Manh; Orji, Francis; Sosa, Felix; Ta Duc, Thinh; Amhadi, Talal; Ikpa, Chidozie; Ugorji, Benjamin
    The failure of pavement foundation materials as hydraulically bound materials is a worri-some condition facing pavement infrastructures in the developing world. Capillary action leads to swelling and shrinkage, compressive strength and durability problems, which result from sorptivity as a function of hydraulic exposure conditions. Pavement infrastructures a constantly interfaced with rise and fall of ground water level and capillary action hence a study on the sorptivity behaviour of quarry dust (QD) treated soft clay soils was carried out. Preliminary tests were conducted on the test materials for the purpose of charac-terization. The basic test results show that the test soils S1, S2 and S3 were classified asA-2-7, A-2-6 and A-7 soil groups respectively according to AASHTO classification system.Also, they were classified as poorly graded soils but test soils S1 and S2 were observed to be of high clay content (CH) according to USCS. The test soils were equally observed to be of highly plasticity and contains high free swell index properties, hence are expansive.
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    Triaxial and density behaviour of quarry dust based geopolymer cement treated expansive soil with crushed waste glasses for pavement foundation purposes
    (International Journal of Pavement Research and Technology, 2019) Onyelowe, Kennedy; Igboayaka, Clifford; Orji, Francis; Ugwuanyi, Henry; Bui Van, Duc
    The effect of quarry dust based geopolymer cement (QDbGPC) and crushed waste glasses (CWG) on the triaxial and density characteristics of expansive test soil was investigated under laboratory conditions. Quarry dust is a solid waste the management of which poses a big problem to construction and environmental experts. So also is the management of waste glasses. Then again, the use conventional cement poses everyday threat to the environment as its utilization releases huge amount of CO2 to the environment thereby causing increased global warming. However, the utilization of quarry dust in the synthesis of geopolymer cements which is an eco-friendly geomaterial and by extension its use in the soil treatment protocol is the aim of this work. The test soil was observed to be a poorly graded A-2-6 soil according to USCS and AASHTO classification systems respectively. The treatment exercise showed that the shear characteristics of the treated soil improved consistently. The poisson ratio, porosity and submerged density i mproved with increased additives. The stress-strain relationship improved to a very stiff consistency which satisfies the requirements for subgrade and subbase materials in pavement construction. Finally, the utilization of QDbGPC proved to be a good replacement for conventional cement in terms of environmental issues resulting from CO2 emission, resistant to moisture, heat, sulphate attacks, etc on hydraulically bound materials.