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TECHNICAL PAPER

PERFORMANCE OF ORGANIC

AND INORGANIC FUNCTIONAL

GROUPS AS CORROSION

INHIBITORS IN CONCRETE

EXPERIENCING EXTREME HIMANSHU GULERIA,

CORROSIVE ENVIRONMENT PURNIMA,
ASHISH KUMAR TIWARI,
SHWETA GOYAL*

Abstract For a better representation of in-service modern concrete
itself, characterizing the realistic exposed deteriorating
Reinforcement corrosion is the major durability issue causing environments is however more challenging. Most RC structures
premature failure of reinforced concrete structures. Ingress of are experiencing multi-deteriorating actions simultaneously
chloride and atmospheric CO 2 are two important phenomena over their entire service life; the combination of them may be
promoting the corrosion, but combined effect of these two even more detrimental than any single deterioration process
causes even more severe damage than individual environment. alone. For instance, when chloride attack is accompanied with
The corrosion inhibition mechanism of various compounds carbonation under wetting-drying cycles, it may even further
depends upon the presence of functional group in their increase the risk of corrosion in RC structures. Recently, there
molecular structure. The present study deals with determination are several studies regarding the influence of carbonation on
of the inhibition efficiency of organic and inorganic based chloride penetration in concrete. For instance, Tumidajskiand
compounds in combined chloride and carbonated environment. Chan (1996) found that carbonation has a minor effect on
[1]
The aggressive environment was achieved by subjecting the chloride diffusivity of ordinary portland cement-based
specimen to alternate wetting-drying-carbonation cycles. concrete, but increases the chloride diffusivity for concrete with
Specimen was wetted by ponding in 5% NaCl solution followed blast-furnace slag. However, Lee et al. (2013) found that the
[2]
by air drying and exposed to carbonation by using environment ratio of water-soluble chloride (i.e. free chlorides) to the acid-
chamber. The results show that compound containing organic soluble chloride (total chlorides) content is higher for the case
functional group was able to reduce corrosion rate in combined of accelerated carbonation than that of natural air exposure.
environment, while inorganic inhibitor was unable to perform Hailong et al. (2016) also observed that with the increase in
[3]
in aggressive conditions. Chloride and carbonation profile also the carbonation front, both free and total chloride content
shows that organic functional group-based inhibitor blocks the decreases.
pores and resists the movement of aggressive chloride ions and To have longer and durable RC life, some preventive measures
carbonation front.
against the corrosion should be taken. Some of these methods
Keywords: Carbonation, Chloride, Corrosion inhibitors, Half- includes: design as per standard codes, protective coating, use
cell potential (HCP), Linear polarization resistance, Reinforced of sealant, use of non-corrosive steel and corrosion inhibitors.
concrete. .Among all the available preventive measures, inhibitors seem
to be the most significant preventive measure in terms of usage,
economy, easy handling and overall effect on durability of
1. INTRODUCTION
concrete structures [4-6] . Inhibitor is defined as a substance made
Corrosion of reinforced concrete (RC) structure is the major up of chemicals which decrease the rate of corrosion when
durability issue for infrastructure, such as offshore and harbour present at suitable concentration in system without affecting
structure, pavement and bridges. The methodical increase of the concentration of any other corrosion agent [7,8] . Inhibitors can
pollutants in the environment has led to inflation in chloride ions be either used as admixed or migratory in concrete system. For
and carbon dioxide (CO 2 )leading to corrosion process which is a fresh concrete, admixed inhibitors have been used since 1970s
major concern for reinforcement in concrete. whereas; in repair work migratory corrosion inhibitors have come

THE INDIAN CONCRETE JOURNAL | APRIL 2021 29
*Corresponding author : Shweta Goyal, Email: shweta@thapar.edu