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<p>Full Depth Reclamation (FDR) is widely used for rehabilitating low-volume rural roads in India. It offers advantages such as material reuse, cost efficiency, and sustainability. However, the heterogeneous nature of field-reclaimed materials affects strength development, shrinkage, and mechanical behaviour. These properties differ from conventional cement-treated bases prepared with virgin aggregates. Current practices often use early-age strength criteria derived from conventional base layers. This may result in excessive cement usage and higher susceptibility to drying shrinkage. The issue is more pronounced in low-traffic road applications. This study evaluates the mix design, shrinkage behaviour, strength development, durability, and microstructural evolution of FDR mixtures. The mixtures were stabilized using Ordinary Portland Cement (OPC) and Portland Pozzolana Cement (PPC). Achieving an early-age UCS of 4.5&#xa0;MPa required high cement content. This significantly increased the risk of shrinkage cracking. The results indicate that selecting the optimum cement content based on 28-day UCS is more appropriate. This approach reduces cement demand while meeting strength and durability requirements. It is especially beneficial for mixtures with higher subgrade fines. The performance of FDR mixtures is influenced by binder type, fines content, and aggregate gradation. OPC-stabilized mixtures showed strength stabilization by 90&#xa0;days. In contrast, PPC-stabilized mixtures exhibited continued strength gain beyond this period. This indicates better long-term efficiency. Aggregate blending improved gradation and reduced cement demand by more than 40%. It also enhanced durability performance. Microstructural analysis showed lower early-age formation of portlandite and ettringite in FDR mixtures. However, consistent development of C–S–H gel was observed by 28&#xa0;days. Overall, the findings support the adoption of a 28-day strength-based design approach. The study provides practical guidance for optimizing FDR mix design. These insights are useful for road authorities, pavement engineers, and contractors.</p>

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Mechanical and microstructure characterization of cementitious full depth reclamation mixtures

  • 期刊论文

  • 发表日期：

    2026年4月22日

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  • Ammu B Crusho,
  • Vishnu Radhakrishnan,
  • K. Sridhar Reddy,
  • Veeraragavan Amirthalingam,
  • Harisankar Asadevi

摘要

Full Depth Reclamation (FDR) is widely used for rehabilitating low-volume rural roads in India. It offers advantages such as material reuse, cost efficiency, and sustainability. However, the heterogeneous nature of field-reclaimed materials affects strength development, shrinkage, and mechanical behaviour. These properties differ from conventional cement-treated bases prepared with virgin aggregates. Current practices often use early-age strength criteria derived from conventional base layers. This may result in excessive cement usage and higher susceptibility to drying shrinkage. The issue is more pronounced in low-traffic road applications. This study evaluates the mix design, shrinkage behaviour, strength development, durability, and microstructural evolution of FDR mixtures. The mixtures were stabilized using Ordinary Portland Cement (OPC) and Portland Pozzolana Cement (PPC). Achieving an early-age UCS of 4.5 MPa required high cement content. This significantly increased the risk of shrinkage cracking. The results indicate that selecting the optimum cement content based on 28-day UCS is more appropriate. This approach reduces cement demand while meeting strength and durability requirements. It is especially beneficial for mixtures with higher subgrade fines. The performance of FDR mixtures is influenced by binder type, fines content, and aggregate gradation. OPC-stabilized mixtures showed strength stabilization by 90 days. In contrast, PPC-stabilized mixtures exhibited continued strength gain beyond this period. This indicates better long-term efficiency. Aggregate blending improved gradation and reduced cement demand by more than 40%. It also enhanced durability performance. Microstructural analysis showed lower early-age formation of portlandite and ettringite in FDR mixtures. However, consistent development of C–S–H gel was observed by 28 days. Overall, the findings support the adoption of a 28-day strength-based design approach. The study provides practical guidance for optimizing FDR mix design. These insights are useful for road authorities, pavement engineers, and contractors.