Experimental assessment of subgrade stiffness of lateritic soils treated with crushed waste plastics and ceramics for pavement foundation

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Date
2019Author
Chibuzor Onyelowe, Kennedy
Bui Van, Duc
Nguyen Van, Manh
Ezugwu, Charles
Amhadi, Talal
Sosa, Felix
Wu, Wei
Ta Duc, Thinh
Orji, Francis
Alaneme, George
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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.