OasisLMS

Abstract: The durability of structures in aggressive environmental conditions significantly influences their performance and design life. For underground structures and foundations, current practices often prioritize strength over durability, relying on concrete's inherent corrosion protection. However, corrosion can occur when the protective oxide film on embedded reinforcement is compromised by aggressive substances, leading to severe structural deterioration.

This paper presents three case studies highlighting the challenges and protective measures adopted for the pile foundations and the subsurface concrete in diverse geological conditions with high sulfate, chloride, and acidic content in subsoil and groundwater. In one case, highly acidic soil conditions (pH 3– 4) necessitated measures like Sacrificial Anode Cathodic Protection (SACP) using zinc anodes, tanking systems, increased cover, and composite cement. Another case involved extremely high groundwater chloride contents (8, 400– 108, 000 mg/l), requiring dense, impermeable concrete through optimized mix design, superplasticizers, ultrafine additives, and enhanced cover. Additionally, waterproofing systems, including SBS membranes and HDPE liners, were implemented to prevent the intrusion of aggressive substances.

This paper discusses the findings from chemical analyses of soil and groundwater and the protective measures implemented to make concrete dense and impermeable, ensuring that it performs satisfactorily throughout its design life. It also covers secondary protective measures like the Sacrificial Anode Cathodic Protection (SACP) system and the permanent liner adopted for the reinforced concrete piles.

Keywords: durability, aggressive environmental conditions, reinforced concrete piles, corrosion protection, structural performance

Ms. GEETHANJALI KOPPOLU; Mr. SAMPAT RAJ

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