Comparison of Different Magnesium Hydroxide Coatings Applied on Concrete Substrates (Sewer Pipes) for Protection against Bio-Corrosion

Several coatings and linings have been examined and used for the protection of sewer concrete pipes, against mainly biogenic-provoked corrosion due to the production of bio-sulfuric acid, leading to the degradation of the pipes’ structure and eventually, to their collapse and need for costly replacement. This study aimed to examine the potential differences between five different magnesium hydroxide coatings, prepared from powders presenting different purity, surface area and pore size distribution, when applied as corrosion protection agents. These coatings were tested by using accelerated sulfuric acid spraying tests, both in dry and wet coating conditions. The coating adhesion ability and their microstructure were examined by the application of pull-off measurements and of SEM analysis, respectively and were found to present certain differences, regarding the adhesion ability and the surface morphologies. During the acid spraying procedure, the surface pH and the mass change of coated concrete specimens were recorded daily. The surface pH was reduced towards acidic values and the mass reduction approached almost −20% in comparison with the initial coating mass for certain cases. Additionally, the hardness and roughness of concrete surface under the coating layer (i.e., the interface between the coating and the surface) after four days of acid spraying, exhibited much smaller changes (due to protection) in contrast to the uncoated concrete specimens (used as blank/comparison experiments), which were found to be highly affected/corroded. The formation of concrete corrosion and coating by-products, as noticed after the respective chemical reactions, was recorded by X-ray diffraction (XRD) measurements and the respective quantification of obtained results. In all the coated specimens only very small amounts of the major by-product (gypsum) was observed, indicating that the concrete surface was sufficiently protected from sulfuric acid attack.

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Properties and Performance of Novel Mg(OH)2-Based Coatings for Corrosion Mitigation in Concrete Sewer Pipes

Materials ◽

10.3390/ma13225291 ◽

2020 ◽

Vol 13 (22) ◽

pp. 5291

Author(s):

Domna Merachtsaki ◽

Georgios Fytianos ◽

Efthimios Papastergiadis ◽

Petros Samaras ◽

Haris Yiannoulakis ◽

...

Keyword(s):

Sulfuric Acid ◽

Magnesium Hydroxide ◽

Low Cost ◽

Concrete Surface ◽

Initial Surface ◽

Acid Attack ◽

Sewer Pipes ◽

Surface Samples ◽

Protected Surface ◽

And Performance

The biological activity occurring in urban sewerage systems usually leads to the (biogenic) corrosion of pipe infrastructure. Anti-corrosion coating technology was developed in an effort to protect sewer pipes from degradation. This study evaluates a new class of relatively low-cost magnesium hydroxide-based coatings, regarding their ability to adhere efficiently onto the concrete surface, and offer efficient corrosion protection. Six magnesium hydroxide-based coatings were prepared with the addition of two different types of cellulose, used as adhesion additives, and these were applied on concrete specimens. Pull-off measurements showed that the addition of higher amounts of cellulose could improve the coating adhesion onto the concrete surface. An accelerated sulfuric acid spraying test was used to evaluate the consumption time of the applied coatings and their efficiency in maintaining over time slightly alkaline pH values (above 8) on the coated/protected surfaces. At the end of spraying test, a mineralogical analysis of surface samples was performed, indicating that the formation of corrosion by-products (mainly gypsum) was increased when the added amount of cellulose was lower. Hardness and roughness measurements were also conducted on the concrete surfaces, revealing that the coatings helped the concrete surface to preserve its initial surface properties, in comparison to the uncoated specimens. A SEM/microstructure analysis showed that aggregates were formed (possibly consisting of Mg(OH)2), affecting the reactivity of the protected surface against sulfuric acid attack.

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Evaluation of the Protection Ability of a Magnesium Hydroxide Coating against the Bio-Corrosion of Concrete Sewer Pipes, by Using Short and Long Duration Accelerated Acid Spraying Tests

Materials ◽

10.3390/ma14174897 ◽

2021 ◽

Vol 14 (17) ◽

pp. 4897

Author(s):

Domna Merachtsaki ◽

Eirini-Chrysanthi Tsardaka ◽

Eleftherios Anastasiou ◽

Anastasios Zouboulis

Keyword(s):

Sulfuric Acid ◽

Magnesium Hydroxide ◽

Xrd Analysis ◽

Sem Analysis ◽

Health Issues ◽

X Ray Diffraction ◽

Corrosion Properties ◽

Sewer Pipes ◽

Adhesion Ability ◽

Long Duration

The Microbiologically Induced Corrosion (MIC) of concrete sewer pipes is a commonly known problem that can lead to the destruction of the system, creating multiple public health issues and the need for costly repair investments. The present study focuses on the development of a magnesium hydroxide coating, with optimized properties to protect concrete against MIC. The anti-corrosion properties of the respective coating were evaluated by using short and long duration accelerated sulfuric acid spraying tests. The coating presented satisfying adhesion ability, based on pull-off and Scanning Electron Microscopy (SEM) analysis measurements. The surface pH of the coated concrete was maintained at the alkaline region (i.e., >8.0) throughout the duration of all acid spraying tests. The consumption of the coating, due to the reaction (neutralization) with sulfuric acid, was confirmed by the respective mass and thickness measurements. The protection ability of this coating was also evaluated by recording the formation of gypsum (i.e., the main corrosion product of concrete) during the performed tests, by X-ray Diffraction (XRD) analysis and by the Attenuated Total Reflectance (ATR) measurements. Finally, a long duration acid spraying test was additionally used to evaluate the behavior of the coating, simulating better the conditions existing in a real sewer pipe, and the obtained results showed that this coating is capable of offering prolonged protection to the concrete substrate.

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Study of Corrosion Protection of Concrete in Sewage Systems with Magnesium Hydroxide Coatings

Environmental Sciences Proceedings ◽

10.3390/environsciproc2020002027 ◽

2020 ◽

Vol 2 (1) ◽

pp. 27 ◽

Cited By ~ 1

Author(s):

Domna Merachtsaki ◽

Eirini-Chrysanthi Tsardaka ◽

Evangelia Tsampali ◽

Konstantinos Simeonidis ◽

Eleftherios Anastasiou ◽

...

Keyword(s):

Sulfuric Acid ◽

Corrosion Protection ◽

Magnesium Hydroxide ◽

Low Cost ◽

Methyl Cellulose ◽

X Ray Diffraction ◽

Sewer Pipes ◽

Surface Ph ◽

Time Period ◽

Concrete Blocks

The purpose of the present work was to study the corrosion protection that relatively low-cost magnesium hydroxide coatings offer to concrete by stabilizing the surface pH. To facilitate the material’s adhesive ability, methyl-cellulose and carboxymethyl-cellulose were used as environmentally friendly additives in three different concentrations, 1, 0.4 and 0.1 wt.% of solids, respectively. The coatings were applied on the surface of concrete blocks, in two different coating thicknesses. A sulfuric acid solution was used to simulate the biologically produced acid in sewer pipes. Sulfuric acid was sprayed on the specimens, while the total amount of acid sprayed was calculated, in order to correspond to a specific reaction’s stoichiometry daily. The surface pH of coated specimens was monitored daily with a surface pH meter. The gypsum production was studied with X-ray diffraction, to evaluate the coatings’ protection. The experimental time period that coatings were consumed was compared with the theoretically consumption time.

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Study of Magnesium Hydroxide Protective Coating against Corrosion, Applied on Poly(methyl methacrylate) Plates, By Using the Sulfuric Acid Attack Acceleration Test

Materials Proceedings ◽

10.3390/materproc2021005004 ◽

2021 ◽

Vol 5 (1) ◽

pp. 4

Author(s):

Domna Merachtsaki ◽

Eirini-Chrysanthi Tsardaka ◽

Eleftherios Anastasiou ◽

Anastasios Zouboulis

Keyword(s):

Sulfuric Acid ◽

Methyl Methacrylate ◽

Magnesium Hydroxide ◽

Concrete Surface ◽

X Ray Diffraction ◽

Acid Attack ◽

Poly Methyl Methacrylate ◽

Concrete Pipes ◽

Custom Made ◽

Microbiologically Induced Corrosion

Microbiologically induced corrosion (MIC) leads to the degradation/deterioration of concrete pipes, due to the formation of gypsum. Magnesium hydroxide powders may protect the concrete surface by maintaining alkaline pH values at the surface, or by neutralizing the biogenic produced sulfuric acid. An accelerated sulfuric acid spraying test in a custom-made spraying chamber used to examine the consumption of magnesium hydroxide coating, which was applied on poly (methyl methacrylate) plates, instead of applying it on concrete substrates. In that way, only the magnesium hydroxide coating can interact with the acid and can be examined separately. Surface pH measurements and the mass changes were daily conducted, during the four-day accelerated spraying test. The mineralogical phases of the surface were determined by using X-ray Diffraction (XRD) measurements.

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Accelerated performance evaluation of repair mortars for concrete sewer pipes subjected to sulfuric acid attack

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2020.09.124 ◽

2020 ◽

Vol 9 (6) ◽

pp. 13635-13645

Author(s):

Han Byeol Chang ◽

Young Cheol Choi

Keyword(s):

Performance Evaluation ◽

Sulfuric Acid ◽

Acid Attack ◽

Sewer Pipes ◽

Repair Mortars

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Biogenic sulfuric acid attack on different types of commercially produced concrete sewer pipes

Cement and Concrete Research ◽

10.1016/j.cemconres.2009.10.002 ◽

2010 ◽

Vol 40 (2) ◽

pp. 293-301 ◽

Cited By ~ 66

Author(s):

Ma. Guadalupe D. Gutiérrez-Padilla ◽

Angela Bielefeldt ◽

Serguei Ovtchinnikov ◽

Mark Hernandez ◽

Joann Silverstein

Keyword(s):

Sulfuric Acid ◽

Acid Attack ◽

Sewer Pipes ◽

Different Types

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Sulfate Attack on Different Types of Concrete in Media Simulating Sewer System

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.714.122 ◽

2016 ◽

Vol 714 ◽

pp. 122-127

Author(s):

Martin Vyšvařil ◽

Markéta Rovnaníková ◽

Patrik Bayer

Keyword(s):

Waste Water ◽

Sulfuric Acid ◽

Sewage Water ◽

Sulfate Attack ◽

Acid Attack ◽

Bottom Part ◽

Sewer Pipes ◽

Fine Grained ◽

Different Types ◽

One Year

The degradation of concrete due to ingress of sulfate ions from the environment plays an important role in the durability of concrete constructions. Microbiologically induced concrete corrosion (MICC) damages especially sewage collection systems. The most rapid cases of deterioration always occur in areas with elevated H2S concentrations, moisture, and oxygen in the atmosphere. During the MICC, the pH of the surface of concrete sewer pipes is reduced and it may lead to the steel depassivation and results in the corrosion of steel reinforcement. Damage due to a sulfate interaction can result in a cracking and softening, with a loss of strength of concrete. The formation of ettringite (AFt) from gypsum (forming by reaction of sulfate anion with calcium hydroxide) and C3A via monosulfate (AFm) is the main chemical reaction of sulfate attack on concrete. Ettringite and gypsum have considerably larger volume than initial compounds, which leads to increased pressure in concrete. This paper is focused on the sulfate attack on fine-grained concrete where the effect of 0.5% sulfuric acid, simulating MICC, and a solution simulating sewage water has been investigated on changes of the pH, content of sulfates and the porosity in various types of concrete. The aim of this study is to compare the changes in different types of concrete during the sulfate attack in two kinds of medium represented the bottom part of pipelines (waste water) and the sewer crown (0.5% H2SO4). It was found, that after 1 year in 0.5% H2SO4, a visible degradation of surface occurs in all investigated types of concrete. Samples over the year in waste water became dark. Concentration of sulfates in all studied types of concrete increased six times at least after one year sulfuric acid attack and also the reduction of the pH of their aqueous leaches was determined. The solution simulating sewage water did not cause such changes.

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Sulfuric Acid Attack on Various Types of Fine Grained Concrete

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1100.101 ◽

2015 ◽

Vol 1100 ◽

pp. 101-105

Author(s):

Martin Vyšvařil ◽

Markéta Rovnaníková

Keyword(s):

Sulfuric Acid ◽

Acid Corrosion ◽

Sulfate Attack ◽

Steel Reinforcement ◽

Acid Attack ◽

Sewer Pipes ◽

Sulfate Ions ◽

Fine Grained ◽

Ph Values ◽

Sulfuric Acid Corrosion

Sulfate corrosion is one of the major threats for durability of concrete constructions and it becomes a major destructor in sewage collection systems where the concrete sewer pipes are exposed to sulfates from wastewater as well as from biogenic activity of bacteria. During this process the pH of the surface of concrete sewer pipes is reduced and it may lead to steel depassivation and results in the corrosion of this steel reinforcement. This paper is focused on the sulfate attack on fine grained concrete where the effect of 0.5% sulfuric acid, simulating biogenic sulfuric acid corrosion, on changes of pH and content of sulfates in various types of concrete has been investigated. After 3 and 6 months of the corrosive treatment, the content of sulfate ions and pH values in several layers of specimens were determined. It was found that the sulfate ions penetrate into concrete to the maximum depth of 20 mm and the pH of the aqueous leaches of particular layers of the samples was reduced to 11.4 at the most. Thus, the conditions for the depassivation of reinforcement were not met. The GL and GBFS concrete samples showed the least changes of their pH and therefore they had the best resistivity to the six months sulfate attack.

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Flammability, morphological and mechanical properties of sugar palm fiber/polyester yarn-reinforced epoxy hybrid biocomposites with magnesium hydroxide flame retardant filler

Textile Research Journal ◽

10.1177/00405175211008615 ◽

2021 ◽

pp. 004051752110086

Author(s):

MJ Suriani ◽

SM Sapuan ◽

CM Ruzaidi ◽

DS Nair ◽

RA Ilyas

Keyword(s):

Tensile Strength ◽

Surface Morphology ◽

Flame Retardant ◽

Tensile Properties ◽

Magnesium Hydroxide ◽

Building Materials ◽

Epoxy Composite ◽

Sem Analysis ◽

Palm Fiber ◽

Sugar Palm Fiber

This paper aims to study the surface morphology, flammability and tensile properties of sugar palm fiber (SPF) hybrid with polyester (PET) yarn-reinforced epoxy composite with the addition of magnesium hydroxide (Mg(OH)2) as a flame retardant. The composites were prepared by hybridized epoxy and Mg(OH)2/PET with different amounts of SPF contents (0%, 20%, 35% and 50%) using the cold press method. Then these composites were tested by horizontal burning analysis, tensile strength testing and scanning electron microscopy (SEM) analysis. The specimen with 35% SPF (Epoxy/PET/SPF-35) with the incorporation of Mg(OH)2 as a flame retardant showed the lowest burning rate of 13.25 mm/min. The flame took a longer time to propagate along with the Epoxy/PET/SPF-35 specimen and at the same time producing char. Epoxy/PET/SPF-35 also had the highest tensile strength of 9.69 MPa. Tensile properties of the SPF hybrid with PET yarn (SPF/PET)-reinforced epoxy composite was decreased at 50% SPF content due to the lack of interfacial bonding between the fibers and matrix. Surface morphology analysis through SEM showed uniform distribution of the SPF and matrix with less adhesion, which increased the flammability and reduced the tensile properties of the hybrid polymeric composites. These composites have potential to be utilized in various applications, such as automotive components, building materials and in the aerospace industry.

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