Abstract

The marine environments reduce the working life of the concrete structures owing to the severe exposure to the chemical ingress, and continuous contact with the humid air, and saline soil conditions. A scientific investigation and the conditional assessment of the existing structures may be helpful to learn the damage mechanism. This article represents the scientific conditional assessment of some existing old concrete structures in the coastal areas of Jamnagar and Dwarka of Gujarat. The objective of the study was to collect information on the types and severity of the damagesin the existing structures and preparing an assessment rubric mentioning the significance of modes of marine environment resulting in a specific damage type. To evaluate the severity of the damages, the parametric approach and a root cause analysis including the experimental investigations on the collected samples has been utilized. The outcomes revealed several interesting observations those have been classified into three major attributes namely material limitations, structural design and third as the gross environmental impacts. The study encouraged the authors to dig deeper in the area of work and showed potential of the methodology to understand the damages caused by the marine environments to the on-shore concrete structures.

Introduction

The marine exposure condition imposes a challenging environment on concrete as a material, structures and member. The long-term performance of concrete in marine environment is observed to be subjected on a complex integrated physical and chemical mechanisms [1]. The marine environment is not always regarded as the sea water, but it is the combination of the marine sand /ground, air and temperature at and around the coastal regions and the shallow as well as deep sea water together. In such cases, the damage occurred on the concrete structures needs to be evaluated or assessed for the damage with a systematic approach. Therefore, conditional assessment of the marine structures is merely not similar to the other structures. In fact, how to assess the damages of concrete in marine environments is a challenge because the nature of degradation and skill of damage varies with the location of marine structure. The concrete in the marine environment along with the reinforcements of steel bars shows damages namely corrosion, efflorescence, staining, erosion, cracking, mortar spalling and surface losses, lump mass losses, and many others. Regarding reinforced concrete in particular, chloride ingress by diffusion is probably the most important mechanism of deterioration, leading to corrosion of the embedded reinforcing steel. However, the overall situation is complicated by concomitant deterioration of the material itself by sulfate attack and physical effects such as salt crystallization and mechanical action of the waves.There are references available to refer on the topic of assessment of damage in marine environments. Use of common methods of assessment includes use of rebound hammers, porosity meters, carbonation tests on the samples [1] providing preliminary damage information, use of non-destructive tests methods and visual inspections [2], [3], on site assessment of the strength parameters of the concrete [4], use of permeability apparatus for fluid ingress, destructive tests on samples at the site and chemical analysis of the samples in laboratories [5], [6], assessment of the degree of the distresses in the concrete due to marine environment by visual and analytical inspections of the sites [7], applications of electromagnetic methods on the existing structures [8], the corrosion detection of the damages structures in the repaired structures by.

Conclusion

From the case study and the proposed systematic assessment methodology, the authors have observed that the conditional assessment of a marine structure requires a panoramic perspective on the investigations. The site survey remains the key factor for obtaining the exact details of the structural conditions, however the pre-assessment survey and related inquiries supports the process significantly. The laboratory tests and results contributed to a significant extent in ascertaining the scientific reasons for the damage. The study encouraged the authors to propose an overall severity rubric based on the systematic assessment process suggested in the present study. Table 4 indicates the overall rating to be utilized for declaring the damage scenario of the structures impacted by the marine environment.