The Study of Half-cell Potential Behaviour of Reinforced Concrete in Marine Environment

Corrosion of reinforcement in concrete affects the strength and durability of reinforced concrete structure. Monitoring and maintenance of concrete structure throughout the service life prevent the ingress of corrosion at the initial stage. Half-cell potential meter was developed and fabricated to monitor the corrosion potential of reinforcement in a M25 grade concrete. Half-cell potential test and accelerated corrosion test has been carried out in marine environment of 3.5% of NaCl solution. The potential behaviour of specimen subjected to accelerated corrosion is studied throughout the test period. The results were obtained in terms of current flow behaviour and weight loss. Obtained results has been analyzed graphically and a comparative analysis has been carried out to know the rate of corrosion occurred in the specimen by accelerated corrosion test and half-cell potential test. Obtained results clearly indicates that the potential behaviour value increases with increase in time from 160 mV on day 1 to 949 mV on day 5. In the other way the compressive strength value for corroded specimen is lesser than the controlled specimen subjected to accelerated corrosion.

A Novel Accelerated Corrosion Test for Supporting Devices in a Floating Photovoltaic System

Recently, countries from around the globe have been actively developing a new solar power system, namely, the floating photovoltaic (FPV) system. FPV is advantageous in terms of efficiency and cost effectiveness; however, environmental conditions on the surface of water are harsher than on the ground, and the regulations and standards for the long-term durability of supporting devices are insufficient. As a result, this study aims to investigate the durability of supporting devices through a novel type of accelerated corrosion test, copper-accelerated acetic acid salt spray (CASS). After an eight-day CASS test, the results demonstrated that only a small area of white protective layer on the SUPERDYMA shape steel was fully corroded and rusted. Moreover, five types of screw, fastened solidly on the SUPERDYMA shape steel, namely a galvanized steel screw capped with a type 316 stainless steel (SS) nut, a type 304 SS screw, a type 410 SS screw, a chromate-passivated galvanized steel screw, and a XP zinc–tin alloy coated steel screw, achieved varying degrees of rust. In general, the corrosion degree of the eight-day CASS test was more serious than that of the 136-day neutral salt spray (NSS) test. Therefore, the CASS test is faster and more efficient for the evaluation of the durability of supporting devices.

An experimental study on the shear capacity of corroded reinforced concrete beams without shear reinforcement

The effect of corrosion on the structural behavior of reinforced concrete (RC) beams without stirrups was experimentally investigated. A total of eight medium-scale RC beams were constructed without stirrups. The beams were 150 mm in width, 200 mm in depth, and 1100 mm in length. Test variables included three distinct degrees of corrosion (0%, 3.13%, 4.11%, and 4.93% by mass loss of steel rebar). Six beams were subjected to an accelerated corrosion test, while two beams served as non-corroded control beams. All beams were tested under four-point loading failure after the corrosion stage. The effect of various small degrees of corroded longitudinal reinforcements has been observed for the shear capacity. Test findings found that all tested beams had a brittle failure with tested corrosion degrees. Moreover, corroded beams that are exposed to 3% and 4% average corrosion degree reported having a larger shear capacity of approximately 7% compared to control beams. Lastly, beams with a corrosion degree of about 5% showed a decrease of 10% shear strength and a different failure mechanism with distinguished cracking patterns due to the formation of corrosion cracks along the longitudinal reinforcements. Keywords: reinforced concrete beam; reinforcement corrosion; shear strength; no stirrups.

Physicochemical characterization and rheological properties of magnetic elastomers containing different shapes of corroded carbonyl iron particles

Carbonyl iron particles (CIPs) is one of the key components in magnetic rubber, known as magnetorheological elastomer (MRE). Apart from the influence of their sizes and concentrations, the role of the particle’ shape is pronounced worthy of the attention for the MRE performance. However, the usage of CIPs in MRE during long-term applications may lead to corrosion effects on the embedded CIPs, which significantly affects the performance of devices or systems utilizing MRE. Hence, the distinctions between the two types of MRE embedded in different shapes of spherical and plate-like CIPs, at both conditions of non-corroded and corroded CIPs were investigated in terms of the field-dependent rheological properties of MRE. The plate-like shape was produced from spherical CIPs through a milling process using a rotary ball mill. Then, both shapes of CIPs individually subjected to an accelerated corrosion test in diluted hydrochloric (HCl) at different concentrations, particularly at 0.5, 1.0, and 1.5 vol.% for 30 min of immersion time. Eight samples of CIPs, including non-corroded for both CIPs shapes, were characterized in terms of a morphological study by field emission scanning electron microscope (FESEM) and magnetic properties via vibrating sample magnetometer (VSM). The field-dependent rheological properties of MREs were analyzed the change in the dynamic modulus behavior of MREs via rheometer. From the application perspective, this finding may be useful for the system to be considered that provide an idea to prolong the performance MRE by utilizing the different shapes of CIPs even when the material is fading.

Influence of nano-modification on mechanical and durability properties of cement polymer anticorrosive coating

In the present study performance evaluation of nano-modified cement polymer anticorrosive coating (CPAC) was undertaken by conducting the Chemical Resistance Test (CRT), Applied Voltage Test (AVT), Bond Strength Test (BST), Accelerated Corrosion Test (ACT) and Coating Flexibility Test (CFT). The site oriented coating comprises of nitrite, styrene-butadiene polymer and other additives. The anticorrosive polymer solution is compatible with concrete or cement when uniformly mixed with fresh ordinary portland cement (OPC). Totally forty-five specimens were subjected to various performance evaluation tests. In CRT observations were made on drilled and undrilled specimens after 45 days test period in liquid and vapour phase. The coating did not blister, soften and lose bond in all the tested medium during CRT and meet the requirement of BIS 13620-1993 and ASTM A775/A775M.The coating has the ability to withstand the electrochemical stresses during one-hour AVT. In the BST, single and double coated rebars showed +126.96% and +46.08% greater usable bond strength respectively than uncoated rebar. In the ACT, there is a significant escalation in time of cracking of specimens of double-coated reinforced rebars by 2 times as compared to uncoated rebars. Cracking time for single coated reinforced rebars was found 1.6 times more than uncoated rebars. In the CFT, coating completely in the inner and the outer radius of the 180° bend rebar fails to meet the requirements of BIS and ASTM standards. Thus the coating has to be applied subsequent to cutting and rebar twisting is finished.

Monitoring internal corrosion in steel pipelines: a two-step helical guided wave approach for localization and quantification

This article presents a two-step approach for the assessment of internal corrosion in cylindrical structures using helical guided ultrasonic waves. The approach consists of two steps such as (1) localization and (2) estimation of the size of the corroded area. Localization is performed with the algebraic reconstruction technique where the energy ratio of the two fundamental Lamb modes S0 and A0 is used as input damage coefficient. Using the output of the localization step, the size of the corroded area is estimated by iteratively solving the eikonal equation using a finite-difference approach. The proposed approach is validated by an accelerated corrosion test. Furthermore, numerical simulations are carried out to study the interaction of the energy ratio and the phase velocity travel time with various thickness profiles acquired from the experiment. The proposed approach is validated against the experimental data up to approximately 50% thickness loss.