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<p>Egypt’s flexible pavement network depends heavily on petroleum-derived bituminous materials, creating economic vulnerability to price volatility and supply uncertainties. This study investigates the mechanical performance and stress-strain behavior of cement-treated base (CTB) layers in Egyptian flexible pavement systems through integrated experimental testing and finite element modeling. Aggregates from two major Egyptian quarries—Someed and Hagool—were characterized and used to prepare CTB specimens with cement contents ranging from 1 to 5% by weight. Unconfined compressive strength testing identified optimum cement contents of 1.5% and 1.2% for Someed and Hagool aggregates, respectively, targeting a 7-day strength of 300 psi to balance stiffness benefits against shrinkage cracking risks. Resilient modulus testing conducted at the optimum cement content resulted in values ranging from 63,517 psi to 65,185 psi for the Someed aggregate and from 55,093 psi to 63,607 psi for the Hagool aggregate at both 7 and 28 days of curing, respectively. Nine pavement configurations—including conventional flexible pavements, conventional CTB-reinforced structures, and inverted pavement systems with varying granular aggregate base (GAB) interlayer thicknesses—were modeled using ABAQUS finite element software. The analysis revealed that placing CTB directly beneath asphalt concrete induces high tensile stresses (0.424&#xa0;MPa or 61.5 psi) and strains (51–53 µε) at the AC layer bottom, potentially causing premature bottom-up fatigue cracking. However, incorporating even a thin 5&#xa0;cm GAB interlayer reduced these stresses to 0.29&#xa0;MPa (42 psi) and strains to 32 µε. Mechanistic-empirical performance predictions demonstrated that inverted pavements with 15&#xa0;cm GAB interlayers (Cross Section F) provide optimal fatigue resistance in both AC and CTB layers while preventing premature CTB failure. CTB incorporation reduced subgrade compressive strains by 64–77% and improved rutting resistance significantly compared to conventional pavements when using the aforementioned strains to predict the number of cycles to failure using the mechanistic empirical performance predictions. Based on these findings, the adoption of inverted pavement configurations with CTB layers and appropriately sized GAB interlayers is recommended for Egyptian highway infrastructure to enhance structural performance and reduce dependency on asphalt materials.</p>

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Investigating the mechanical performance of cement-treated base layers in flexible pavement: experimental evaluation and finite element modeling

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月20日

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  • Malek Anas Elmorsi,
  • Ahmed Hassanien,
  • Gamal M. Mabrouk,
  • Ali Zain Elabdeen Heikal,
  • Hassan A. H. Mahdy

摘要

Egypt’s flexible pavement network depends heavily on petroleum-derived bituminous materials, creating economic vulnerability to price volatility and supply uncertainties. This study investigates the mechanical performance and stress-strain behavior of cement-treated base (CTB) layers in Egyptian flexible pavement systems through integrated experimental testing and finite element modeling. Aggregates from two major Egyptian quarries—Someed and Hagool—were characterized and used to prepare CTB specimens with cement contents ranging from 1 to 5% by weight. Unconfined compressive strength testing identified optimum cement contents of 1.5% and 1.2% for Someed and Hagool aggregates, respectively, targeting a 7-day strength of 300 psi to balance stiffness benefits against shrinkage cracking risks. Resilient modulus testing conducted at the optimum cement content resulted in values ranging from 63,517 psi to 65,185 psi for the Someed aggregate and from 55,093 psi to 63,607 psi for the Hagool aggregate at both 7 and 28 days of curing, respectively. Nine pavement configurations—including conventional flexible pavements, conventional CTB-reinforced structures, and inverted pavement systems with varying granular aggregate base (GAB) interlayer thicknesses—were modeled using ABAQUS finite element software. The analysis revealed that placing CTB directly beneath asphalt concrete induces high tensile stresses (0.424 MPa or 61.5 psi) and strains (51–53 µε) at the AC layer bottom, potentially causing premature bottom-up fatigue cracking. However, incorporating even a thin 5 cm GAB interlayer reduced these stresses to 0.29 MPa (42 psi) and strains to 32 µε. Mechanistic-empirical performance predictions demonstrated that inverted pavements with 15 cm GAB interlayers (Cross Section F) provide optimal fatigue resistance in both AC and CTB layers while preventing premature CTB failure. CTB incorporation reduced subgrade compressive strains by 64–77% and improved rutting resistance significantly compared to conventional pavements when using the aforementioned strains to predict the number of cycles to failure using the mechanistic empirical performance predictions. Based on these findings, the adoption of inverted pavement configurations with CTB layers and appropriately sized GAB interlayers is recommended for Egyptian highway infrastructure to enhance structural performance and reduce dependency on asphalt materials.