Numerical estimation of moisture penetration depth in concrete exposed to rain-towards the rationalization of guidelines for durable design of reinforced concrete in tropics

Abstract

Moisture imbibed within the porous matrix of concrete during the course of service plays a critical role in causing its degradation. Under tropical climatic conditions structural concrete elements often get exposed to spells of rainfall which result in a conspicuous ingress of moisture and subsequently to conditions amenable for corrosion of embedded steel reinforcement-the most prevalent cause of premature durability failure of reinforced concrete (RC) elements. The estimation of associated moisture penetration depth in concrete is thus pivotal for delineating the near surface zone of a RC element which remains susceptible to durability damage.Such an estimate also enables in ascertaining rationally the cover depth to be provided to RC elements intended to serve under tropical conditions which is otherwise adopted as per to the prescriptive standards currently in vogue. The present work numerically investigates the aspect considering the probable extremes of rainfall scenarios pertaining to the composite tropical climate of New Delhi (India). The associated exposure traits have been ascertained by statistically analyzing 15 years’ rainfall data obtained from thearchives of Indian Meteorological Department. The moisture transport phenomenon in concrete has been represented using a modified form of Richards’ equation constituted using dimensionless terms to achieve computational efficiency. The material propertieswhich serve as inputs to the analysis have been adopted from published experimental literature.