Effect of Organic and Inorganic Corrosion Inhibitors on Strength Properties of Concrete

V Srinivasa Reddy,P Prashanth,Thoodi Prashanth,S P Raju V,S Tummala,S Kosaraju,P Bobba,S Singh

doi:10.1051/e3sconf/202018401112

Abstract

In the current study, the M25 grade concrete mixes are admixed with various locally available organic and non-organic corrosion inhibitors such as Calcium Nitrite, Sodium Nitrite, Hexamine and Di-ethanolamine to understand the influence of these organic and non-organic corrosion inhibitors on the strength and corrosion resistance properties of concrete. The percentage dosage of admixed inhibitors vary from 1 to 5% by the weight of cement. For M25 grade concrete the optimum percentages of corrosion inhibitor admixture was found to be 4% for Calcium Nitrite, 3% for Sodium Nitrite, 2% for Hexamine and 3% for Di-ethanolamine. Calcium Nitrite corrosion inhibitor admixture imparts increased compressive, split- tensile and flexural strength than other corrosion inhibitors at 28 days. All the corrosion inhibitors used in the study have enhanced the compressive strength, split tensile strength, and flexural strength of concrete. The initial gain of early strength decreased due to anodic process of inhibitors. Measured electrical resistivity and half-cell potential values of all corrosion inhibitors admixed M25 grade concrete mixes directs that calcium nitrate and Di-ethanolamine have shown high electrical resistance indicating their superior corrosion inhibition ability than sodium nitrite and hexamine. Accelerated corrosion test on reinforced concrete beams admixed with corrosion inhibitors confirmed that possible inception of corrosion in calcium nitrate admixed reinforced concrete beams is very low when compared to other corrosion inhibitors used for the study.

Highlights

The most commonly adopted approaches to enhance the service life of rebars in concrete structures are epoxy or zinc coating on the rebars, applying waterproofing agents, controlling the water/cement ratio, increasing the concrete cover thickness, application of chemical coats, cathodic protection etc [1]
7.1 Compressive Strength The table 3 and Fig. 8 displays the compressive strengths of M25 concrete made with calcium nitrite
It is very evident that the gain of compressive strength in corrosion inhibitor admixed M25 concrete mix at 3 days is very slow when compared to normal concrete mix due to anodic process

Summary

Introduction

The most commonly adopted approaches to enhance the service life of rebars in concrete structures are epoxy or zinc coating on the rebars, applying waterproofing agents, controlling the water/cement ratio, increasing the concrete cover thickness, application of chemical coats, cathodic protection etc [1]. IS Code propose usage of various supplementary cementitious materials in the form of mineral admixtures provides a good solution for prevention of rebar corrosion, but whenever cracks appear in concrete rebars are exposed to corrosion. The most cost-effective and newly used practices to defer the corrosion of rebars in concrete is the usage of corrosion inhibiting admixtures in concrete [2]. It is hypothesized that the corrosion inhibiting admixtures delays the onset of corrosion and impacts the other important properties of concrete [3]. There are various corrosion inhibitors that are in usage in the market [4]. The corrosion inhibitive properties can be appraised in the laboratory using accelerated corrosion test based on impressed voltage technique in saline medium and supplemented by electrical resistivity and half-cell potential measurements [6]

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Results

Conclusion