Papers by Dr. Bishwajit Bhattacharjee
Current science
Occurrence of corrosion in rebars of reinforced concrete (RC) structures is a very common problem... more Occurrence of corrosion in rebars of reinforced concrete (RC) structures is a very common problem faced by the ageing infrastructure across the world. This paper presents a new approach for detecting and quantifying corrosion of steel bars via a piezoelectric ceramic (PZT) patch surface-bonded on the rebars using equivalent structural parameters extracted from PZT sensors via the electro-mechanical impedance (EMI) technique. The EMI technique utilizes the electro-mechanical coupling property of piezoelectric materials for damage diagnosis. Through tests on three steel rebars, empherical relations are derived to relate the corrosion induced mass and stiffness loss to the loss in the equivalent mass and stiffness identified by the PZT patch. The equivalent mass loss and stiffness loss correlates well with the actual mass loss and stiffness loss and provides an alternative corrosion assessment paradigm suitable for diagnosing corrosion in steel rebars.
Moisture imbibed in structural concrete during the course of service plays a critical role in the... more Moisture imbibed in structural concrete during the course of service plays a critical role in the initiation and propagation of rebar corrosion in reinforced concrete (RC) elements. The provision of an adequate cover depth is thus essential to restrain the ingress of moisture up to the layer of embedded steel, mitigating thereby the evolution of the corrosion process. A prediction of moisture penetration depth in concrete, under the given conditions of exposure, facilitates the rational determination of cover thickness. The present work relates to the numerical simulation of moisture distribution in concrete subjected to rainfall exposure. Based on one dimensional nonlinear finite element (FE) analysis of unsaturated flow in porous medium, the study investigates the influence of rainfall intensity and duration on the extent of moisture penetration in concrete. The study is extended to analyze the effect of intensity-duration combinations corresponding to a fixed quantity of incident...
Computers and Concrete
A rational estimation of moisture distribution in structural concrete is vital for predicting the... more A rational estimation of moisture distribution in structural concrete is vital for predicting the possible extent and rate of progression of impending degradation processes. The paper proposes a numerical scheme for analysing the evolution of moisture distribution in concrete subjected to wetting-drying exposure caused by intermittent periods of rainfall. The proposed paradigm is based on the stage wise implementation of non-linear finite element (FE) analysis, with each stage representing a distinct phase of a typical wet-dry cycle. The associated boundary conditions have been constituted to realize the influence of various meteorological elements such as rain, wind, relative humidity and temperature on the exposed concrete surface. The reliability of the developed scheme has been demonstrated through its application for the simulation of experimentally recorded moisture profiles reported in published literature. A sensitivity analysis has also been carried out to study the influen...
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The scarcity of freshwater in densely populated urban centres has necessitated conservative utili... more The scarcity of freshwater in densely populated urban centres has necessitated conservative utilisation of depleting water resources. The prospect of using reclaimed wastewater for concreting operations in lieu of the conventionally tapped municipal, surface and ground water sources bears a great potential in this regard. The present study compares the influence of four different surface curing agents, viz. (i) treated wastewater, (ii) tap water and commercially available (iii) water based and (iv) resin based curing compounds on the compressive strength and water absorption characteristics of ordinary concrete. The observations establish the suitability of wastewater curing in achieving better strength and water tightness at 28 days.
The paper numerically analyses the phenomenon of moisture penetration in concrete subjected to th... more The paper numerically analyses the phenomenon of moisture penetration in concrete subjected to the action of intermittent I events -an exposure type typical of tropical monsoon climate. The rainfall scenario considered in this study pertains to the posite tropical climate ofNew Delhi (India) and have been quantified based on the statistical analysis of 15 years' rainfall data. The isture transport process in unsaturated concrete medium has been represented with a modified form ofRichard's equation stated using a of dimensionless terms corresponding to space, time and moisture variables. Analysis of the modified model has been carried out using a non-linear, one dimensional finite element scheme coded into a computer program. Mix design data and associated moisture properties for a typical ordinary concrete have been adopted from published literature to demonstrate a simulation of the moisture phenomena. The observations reveal the influence of intermittent rainfall events on...
Journal of Structural Engineering (Madras)
Degradation of concrete is largely a moisture dependent phenomenon. Predicting the durability per... more Degradation of concrete is largely a moisture dependent phenomenon. Predicting the durability performance of structural elements therefore necessitates the estimation of moisture penetration depth in concrete under the action of prevailing service environment. The present paper relates to the study of rainfall exposure pertaining to the composite tropical climate of New Delhi, India and the numerical simulation of concomitant moisture movement in concrete. Statistical analysis of fifteen years’ rainfall data has been carried out to identify the rainy spell of the year, to ascertain the associated characteristics of average rainfall intensity and duration corresponding to wet days, manifestation pattern of wet and dry days in the identified spell and the total duration of rainfall over the spell. The moisture transport phenomena has been represented using a modified form of Richards’ equation constituted using a set of dimensionless terms corresponding to space, time and moisture var...
Structural Engineering International, 2014
The simulation of moisture movement in concrete is vital for estimating its durability performanc... more The simulation of moisture movement in concrete is vital for estimating its durability performance under the given conditions of service. A robust analysis of the nonlinear phenomenon relies on the implementation of an efficient numerical algorithm. This entails a comprehension of the underlying mathematical models, the numerical analysis scheme and the related issues of stability and convergence. This paper describes a computational scheme to facilitate the estimation of moisture distribution in concrete subjected to wetting-drying exposure due to intermittent rains, an exposure type which severely impairs the durability performance of structural concrete under tropical climatic conditions. Beginning with a brief review of the conventional moisture transport models for concrete, this paper proposes a modified model using dimensionless parameters, which enhances the computational efficiency of the delineated scheme. This paper also describes the formulation of a one-dimensional, nonlinear finite element scheme for the modified model and discusses the issue of numerical oscillations concomitant to the numerical analysis of the problem. The suitability of the first-order element in providing stable convergence when implemented in conjunction with a lumped-mass scheme has been mathematically interpreted. The validity of the delineated proposition has been illustrated using a test problem.
Advances in Structural Engineering, 2014
Moisture imbibed within the porous matrix of concrete during the course of service plays a critic... more 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 fifteen years' rainfall data obtained from the archives 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 properties which serve as inputs to the analysis have been adopted from published experimental literature.
Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2014, 2014
ABSTRACT Reinforced concrete (RC) is an economical, versatile and successful construction materia... more ABSTRACT Reinforced concrete (RC) is an economical, versatile and successful construction material as it can be moulded into a variety of shapes and finishes. In most cases, it is durable and strong, performing well throughout its service life. However, in some cases, it does not perform adequately due to various reasons, one of which is the corrosion of the embedded steel bars used as reinforcement.. Although the electro-mechanical impedance (EMI) technique is well established for damage detection and quantification of civil, mechanical and aerospace structures, only limited studies have been reported of its application for rebar corrosion detection in RC structures. This paper presents the recent trends in corrosion assessment based on the model derived from the equivalent structural parameters extracted from the impedance spectrum of concrete-rebar system using the lead zirconate titanate (PZT) sensors via EMI technique.
Concrete Solutions 2014, 2014
In this experimental and analytic research, the effect of curing regime on various combinations o... more In this experimental and analytic research, the effect of curing regime on various combinations of silica fume and fly ash was investigated in terms of development of compressive strength. Over 24 mixes were prepared with the water-to-binder ratios of 0.45, 0.35 and 0.25 and with differing percentage of additives used as a combination of 2 or 3 binders. The specimens
Journal of Advanced Concrete Technology, 2009
... E-mail:[email protected] 2Professor and Head, Civil Engineering Department, Thapar University... more ... E-mail:[email protected] 2Professor and Head, Civil Engineering Department, Thapar University, India. ... One particular observation that is unique to hydro-chloric acid attack is the identification of brownish belts on the surface of specimens (Chandra 1988; De Ceuke-laire ...
Cement and Concrete Research, 2004
Permeation quality of laboratory cast concrete beams was determined through initial surface absor... more Permeation quality of laboratory cast concrete beams was determined through initial surface absorption test (ISAT). The pore system characteristics of the same concrete beam specimens were determined through mercury intrusion porosimetry (MIP). Data so obtained on the measured initial surface absorption rate of water by concrete and characteristics of pore system of concrete estimated from porosimetry results were used to develop correlations between them. Through these correlations, potential of MIP in assessing the durability quality of concrete in actual structure is demonstrated.
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Papers by Dr. Bishwajit Bhattacharjee