At the end of a construction job, when the last bucket of paint has been closed and the last nail has been pounded in, you are done! Right? Unfortunately, finishing a construction project may not be that easy since cleanup comes next. Worse than that, after all the work has been done, the contractor may find that windows, doors, frames, and other surfaces were damaged in the process. Preventing these surprises and the necessary repair, replacement, or damage control that can follow does not have to be that difficult. With MCI® Peel-Off Coating, temporary protection is easy to spray on and peel off when the project is finished.

Peel-Off Coating for Corrosion and Abrasion Protection
MCI® Peel-Off Coating is an acrylic water-based coating for temporary protection of non-porous surfaces against physical abrasion, weathering, and corrosion. It is low VOC (0.2 lbs/gal [24 g/L]) and may be applied by spray, roll, or dip. When no longer needed, the coating can be peeled off the surface and disposed as solid waste. MCI® Peel-Off Coating can be tinted to several basic colors to blend in with or stand out from the surrounding environment. It offers UV resistance for outdoor applications, in addition to temporary protection from salt and chemical induced corrosion. Although water-based, MCI® Peel-Off Coating will not be softened or penetrated by most solvent-based paints. 

Where to Use MCI® Peel-Off Coating
So, what are some practical ways to use MCI® PeelOff Coating in the field? One of the primary examples is to protect windows, doors, and frames from the time they are installed until the rest of the job is completed. Windows and doors often go into place before the construction work is finished, leaving them vulnerable to drips or splatters from paints or putties or nicks and scratches from tools and equipment being jostled around the construction site. Spraying non-porous surfaces with MCI® Peel-Off Coating before construction proceeds can help the contractor and building owner avoid many regrets later. Instead of a discouraging damage inspection at the end of the day, workers can simply peel the coating off the windows, doors, and frames to reveal the scratch-free surfaces beneath.

MCI® Peel-Off Coating is also a great way to mask off windows, doors, frames, and even floors during a large-scale painting project (indoors or outdoors) or during the application of surface treatments that could cause etching. Metal window frames, beams, or railings that are not designed for outdoor weathering but will be exposed to the elements during construction can also be protected from corrosion and atmospheric damage by temporarily coating them with MCI®
Peel-Off Coating. The list goes on to include light fixtures, ceilings, doorknobs, and many other non-porous surfaces that need temporary masking and protection. Going back one step earlier in the process, manufacturers of windows and doors can even apply MCI® Peel-Off Coating to sensitive areas of their products to avoid physical damage or corrosion during shipping and handling.

A Preemptive Approach to Construction Damage
There is more than one way to approach in-process damage on sensitive fixtures at the construction site. Rather than opting for damage control after scratches or corrosion has been inflicted, make life easier for yourself, construction workers, and facility owners by applying preventative measures from the start. Contact Cortec® to learn more about using MCI® Peel-Off Coating for your application: https://www.cortecmci.com/contact-us/

Keywords: MCI, Peel Off Coating, protect windows, avoid damage or corrosion during shipping and handling, temporary protection from corrosion, protecting windows during construction, masking windows during painting, corrosion protection, abrasion protection, construction damage

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Industry standards are an excellent source of best practices recommended by the experts. Many new construction guidelines exist on the protection of reinforced concrete structures. However, it took almost two decades of preparation before the first standard on surface applied corrosion inhibitors (SACIs) emerged as ICRI Guideline No. 510.2-2019. The resulting document is an excellent resource on why and how to apply SACIs to extend concrete service life. Furthermore, it lends confidence to contractors interested in using chemistries found in Cortec® MCI® SACIs.

A Groundbreaking Standard on SACIs
ICRI Guideline No. 510.2-2019: Guide for Use of Penetrating Surface Applied Corrosion Inhibitors for Corrosion Mitigation of Reinforced Concrete Structures is the culmination of years of expert collaboration among members† of the International Concrete Repair Institute (ICRI). This groundbreaking standard was published in 2019 and defines SACIs as corrosion inhibitors that penetrate through concrete and directly inhibit corrosion on the surface of the metal reinforcement, thus excluding chemistries that act as pore blockers only. It covers known technologies on the market at the time of publication and offers tips on surface prep, application, and detection/assessment.

Cortec® MCIs and the ICRI Standard
Cortec’s MCI® SACI chemistries fall under the ICRI descriptions of ambiodic (mixed) inhibitors. They include MCI®-2018, MCI®-2019, MCI®-2020, and MCI®-2021, to name a few. The best SACI to use for a particular product varies from application to application. Factors such as environmental conditions, budget parameters, and the application of water protection products all figure into the decision-making. For example, those in search of the MCI® SACI with the highest concentration of corrosion inhibitors may opt for MCI®-2020. Those looking for convenient two-in-one corrosion protection and water repellency may select MCI®-2018, which combines Migrating Corrosion Inhibitors with a 100% silane water repellent. MCI®-2019, containing Migrating Corrosion Inhibitors and a 40% silane water repellent, may be preferred by those seeking to stay within a more limited budget. When tested according to the U.S. Bureau of Reclamation M-82 Protocol (one of the few existing test methods for SACIs), these three surface treatments* showed a significant reduction of corrosion and cracking in the presence of high chloride exposure.

Another Reason to Choose MCI®
The limited availability of standard specifications and test methods on SACIs makes ICRI Guideline No. 510.2-2019 even more valuable as an industry guide. While MCI® SACIs have their own intrinsic qualities of convenience and good performance, the fact that their underlying chemistries are also featured in the ICRI guideline is just one more reason to adopt them as a viable and industry-accepted means of corrosion mitigation on existing concrete structures. Contact Cortec® to learn more about MCI® SACI technologies: https://www.cortecmci.com/contact-us/

Keywords: MCI, Cortec, surface applied corrosion inhibitors, SACI, ICRI Guideline, construction industry standards, corrosion mitigation, protection of reinforced concrete structures, concrete industry best practices, extend service life

† Including Jessi Meyer, Cortec® Corp.
*M-82 test setup required use of water repellent over MCI®-2020.

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A good engineer will be careful to consult best practices when designing a new structure. Over the years, many helpful guidelines have been compiled by industry experts to address a range of concerns including rebar corrosion. By taking advantage of these recommendations, contractors, builders, and engineers can find ways to enhance structural durability in the face of corrosive environments. Among these solutions are MCI® admixtures, an exceptional technology with important ties to industry standards.

Standards on Corrosion Inhibiting Admixtures
The following construction industry standards recognize the use of corrosion inhibiting admixtures and contain a wealth of industry best practices to reference:

US Guidelines
• ACI PRC-212.3-16: Report on Chemical Admixtures for Concrete (American Concrete Institute, March 2016)
• ACI PRC-222-19: Guide to Protection of Metals in Concrete Against Corrosion (American Concrete Institute, 2019)
• NACE Publication 21428-2018: Corrosion Inhibiting Admixtures for Reinforced Concrete—A State of the Art Report (NACE International, 2018)
• NRMCA Publication 2PE004-21: Guide to Improving Specifications for Ready Mixed Concrete (National Ready Mixed Concrete Association, 2021)

Canadian Guidelines
• CSA S413-21: Parking structures (CSA Group, 2021)

UK Guidelines
• BS EN 1504-9:2008: Products and systems for the protection and repair of concrete structures (British Standards Institution, 2008)
• TR 61: Enhancing reinforced concrete durability: Guidance on selecting measures for minimising the risk of corrosion of reinforcement in concrete (The Concrete Society, 2004)

Middle East Guidelines
• CS Guide to the Design of Concrete Structures in the Arabian Peninsula (The Concrete Society, October 2008)

Of special interest are those guidelines that specifically reference amine carboxylate (i.e., MCI®) corrosion inhibiting admixtures. These are described in depth in ACI 212.3R-16, which firmly establishes the technology as an accepted industry standard. Even the guidelines that do not specifically name amine carboxylate technology cover MCI® admixtures generically under their corrosion inhibitor definitions, further identifying the use of corrosion inhibiting admixtures as an industry best practice.

Why Choose MCI® Over CNI Admixtures?
Another admixture prominently featured in these guidelines is calcium nitrite (CNI), raising the question of why to choose MCI® over CNI admixtures. The following points help engineers understand what sets MCI® amine carboxylate admixture technology apart as an excellent alternative to CNI:

• MCI® admixtures are dosed independently of chloride loading, whereas CNI dosage can rapidly increase due to heavy chloride exposure.
• MCI® admixtures do not accelerate set time, making them much easier to work with than CNI, which often causes problems for ready-mixers as a set accelerator. CNI can be a nightmare when poured in the heat of summer, and many contractors have seen a stark and welcome contrast on workability when using a normal set version of MCI®-2005 instead of CNI.
• Many MCI® admixtures are certified to meet ANSI/NSF Standard 61 for use in drinking water system components.
• MCI®-2005 is a USDA Certified Biobased Product. Several other MCI® admixtures also include a portion of biobased content, which can help projects earn credit toward LEED certification.

Take the Critical Step
When it comes to new construction, following best practices is a critical step to maximizing the longevity and durability of a building. Many existing guidelines demonstrate that corrosion inhibiting admixtures, including amine carboxylates, have become an industry standard for corrosion protection in a variety of situations. Contact Cortec® to learn more about taking advantage of these guidelines and MCI® admixtures to extend service life: https://www.cortecmci.com/contact-us/

Keywords: Cortec, MCI, MCI admixtures, standards for new construction, engineer best practices, rebar corrosion, construction industry standards, corrosion inhibiting admixtures, calcium nitrite alternative, From Grey to Green

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Humans are imperfect, which can be a serious problem when pouring concrete. Concrete contractors have one chance to make the slab or structure turn out right in order to avoid expensive repairs and the possibility of tearing it all up and doing it over again. Fortunately, several concrete application errors can be solved or at least mitigated using Cortec® Migrating Corrosion Inhibitor™ (MCI®) Technology. Some common application errors and their MCI® solutions are outlined here.

Forgot to Add Corrosion Inhibitor

One of the easiest application errors to fix is the failure to add a corrosion inhibiting admixture to the readymix. Although it is ideal to include an MCI® admixture in a concrete structure from the start, MCI® can also be added as a surface applied corrosion inhibitor (SACI) to concrete that has already hardened. Two great versions of MCI® SACI to start with are MCI®-2020 and MCI®-2018. MCI®-2020 contains a high concentration of Migrating Corrosion Inhibitors that penetrate through the concrete pore structure to form a protective molecular layer on the rebar surface. This protective layer delays time to corrosion and reduces the rate of corrosion once started. Wherever high humidity environments or other conditions call for water repellency, MCI®-2018 can introduce Migrating Corrosion Inhibitors along with a 100% silane water repellent. More options exist for different budgets and circumstances.

Insufficient Concrete Cover

Another common worker error is to not apply enough concrete cover and only realize later that it is too thin (e.g., 1 inch [2.54 cm] instead of 2 inches [5.08 cm] as specified). When this issue occurs, it is difficult or impossible to change without destroying the structure. However, a great alternative to protect against the higher risk of early corrosion is to apply an MCI® SACI on top. This type of scenario took place at a desalination plant, where MCI®-2020 was consequently applied to desalinated water reservoirs to help compensate for a concrete cover that was too thin.

Honeycombing

A third problem is honeycombing, a situation where the ready-mix has not been able to thoroughly work its way through the rebar network and fill the concrete forms as one consolidated substance. This leaves behind small air pockets and is known as honeycombing. Usually, MCI®-2020 or MCI®-2018 can be applied to account for the higher risk of corrosion. However, honeycombing is sometimes so bad that it leaves behind exposed rebar and voids large enough to threaten structural integrity. In these cases, CorrVerter® MCI® Rust Primer should be applied directly to the rebar to passivate and protect the metal from further rusting before completing the repair. From there, a product such as MCI®-2044 Self-Consolidating Concrete Mix is a great way to fill void spaces while adding Migrating Corrosion Inhibitors to actively protect against chlorides or other corrosives that may have entered the concrete. Another option is to add an MCI® admixture or MCI® Grenades to the ready-mix or repair mortar. For smaller repairs, Cortec® also offers two MCI® enhanced high performance repair mortars: MCI®-2039 for horizontal repairs and MCI®-2040 for vertical and overhead repairs.

Rebar Shifting

Rebar shifting also causes problems. This happens when rebar chairs fall over before or during the concrete pour, causing rebar to sink down in one area and forcing it up toward the surface in another. Sometimes, the error is so bad that the rebar actually protrudes out of the concrete surface. In less drastic cases, the only concern may be a thinner concrete cover, which raises the risk of early corrosion and can, again, be addressed by the application of MCI®-2020, MCI®-2018, or other MCI® SACIs.

If All Else Fails

It is a fact of life that mistakes happen. When it comes to construction projects, the best that can be done is to prevent problems whenever possible, follow up with proper inspection, and correct application errors that do occur. The last step can be much easier thanks to the versatile forms of MCI® that allow Migrating Corrosion Inhibitors to be applied to the structure even after it is completed. Contact Cortec® for further help correcting application errors with MCI®: https://www.cortecmci.com/contact-us/

Keywords: honeycombing, rebar shifting, insufficient concrete cover, MCI, corrosion protection, forgot to add corrosion inhibitor, common concrete application errors, Migrating Corrosion Inhibitors, From Grey to Green, Cortec

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The famous Zagreb Cathedral is the tallest and one of the most beautiful buildings in Croatia that attracts thousands of tourists worldwide. As the most impressive gothic-style sacral building southeast of the Alps, it is characterized by great architectural and historical value. Its construction dates back to 1093 with continued enrichment of the cathedral by famous architects during the following centuries.

Reconstruction of the cathedral in the late 1800s was led by Hermann Bollé, who brought the cathedral to its most recent architectural form in which it stood until the earthquake of March 22^nd, 2020, damaged the cathedral’s southern spire. Over the last 30 years, extensive restoration work has been undertaken on the cathedral, with ongoing repairs to this day. During reconstruction work on the south tower of the cathedral in 2012, damaged steel joints were found surrounding the tower 10 cm (4 in) below the surface at approximately every 3 m (1.1 yd) between the first and 25^th rows. Most of the joints were only partially exposed in order to replace the surface layer of stone on the bell tower, while the back of the joints remained embedded in stone and lime mortar. The joints were covered with a layer of rust and in drainage areas corroded all the way through the cross-section. In order to define the optimal solution for maintaining or improving the mechanical resistance and structural stability of the tower, the Faculty of Mechanical Engineering and Naval Architecture of Zagreb was called in to examine the joints. At their laboratory, they performed experiments on steel joints removed from the cathedral. They recommended doing the following:

• Remove corrosion from accessible joint connections
• Apply corrosion protection to accessible joint connections
• Strengthen the joint connections where damage had occurred

It was suggested that a minimal range of intrusion be used to keep the mechanical resistance and stability of the tower structure at their existing level while keeping costs at a minimum. Cortec’s CorrVerter® MCI® Rust Primer was recommended for cor­rosion protection. CorrVerter® is a water-based product that quick­ly converts rust into a protective layer and is capable of penetrat­ing into corroded surfaces. It contains a novel chemical chelating agent that modifies surface rust into a hydrophobic passive layer. A metal brush was used to remove loose rust from the joints. Then, two layers of CorrVerter® MCI® Rust Primer coating were ap­plied directly onto the metal. A brush was used for CorrVerter® MCI® application on smaller metal joint surfaces, while spray ap­plication was used for larger areas. The first coat was applied at a thickness of 100 microns (4 mils). A second coat was applied at a thickness of 75 microns (3 mils). During application, the coating temperature was 13 °C (55 °F). The joints were then reinforced with steel fishplates that were welded onto the joints and also pro­tected with CorrVerter® MCI® Rust Primer. The final step was to replace the stones around the joints. With the help of a skilled team and good project management, the entire project was completed successfully with minimal cost and intrusion as specified. The coating penetrated into the metal and stopped further advancement of the corrosion process.

Renovation of Medieval City Walls

The town of Ilok, Croatia, is a place of rich history and cultural heritage. The medieval long fortress and royal castle of Ilok are protected historical and cultural treasures of the highest degree, enabling visitors to step into ages long past. The tower walls have a square floor plan and rest on foundations made of broken stone. These walls are exposed to damaging atmospheric influences, and the binding material between the bricks has washed away, leading to brick deterioration. Renovation work on “tower three” includes strengthening of the foundations, restoration of collapsed parts, and injection of cracks. The project involves the use of corrosion inhibitors to prolong the life of the structure. Cortec’s corrosion inhibitor, MCI®-2005 is added into concrete being used to reinforce the foundation. This amine-carboxylate based corrosion inhibitor additive will be used to protect embedded metallic reinforcement from corrosion in order to extend the lifetime of the walls. MCI®-2005 is a water-based, organic corrosion inhibiting admixture with set-retarding effects. When incorporated into concrete, it migrates towards reinforcement to form a molecular layer that inhibits the corrosion reaction on both anodic and  cathodic components of the corrosion cell. In new construction, this protection is quantified by subsequent reduction in corrosion rates when corrosion does initiate. When used with repair mortars and grouts, MCI®-2005 not only protects rebar within the patch, but can also help protect embedded reinforcement already in place in undisturbed concrete adjacent to the repair. MCI®-2005 is a USDA Certified Biobased Product.

You can learn more about Migrating Corrosion Inhibitors (MCI^®) here: https://www.cortecmci.com/

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Two priorities exist when restoring historical structures that have deteriorated from corrosion: (1) Mitigate corrosion to extend service life and minimize future repairs. (2) Do so without changing the appearance of the structure. This is especially difficult with historical concrete structures, as the addition of new materials could alter the color or texture of the concrete. Fortunately, Cortec® MCI® products have proven to be excellent resources for both maintaining and repairing heritage structures.

Rebar and Concrete Surface Prep

Rebar rust is typically the leading cause of concrete deterioration, and good surface prep is therefore integral to a successful repair. Traditionally this involves labor-intensive sandblasting and cleaning of the rusted rebar to white metal. CorrVerter® MCI® Rust Primer offers a convenient alternative to treat and passivate rusted rebars. A single component, fast drying water based primer, CorrVerter® MCI® can be applied to layers of tight rust, converting it into a hydrophobic passive layer. This method reduces labor and makes re-rusting less likely in the near future. Ash Hasania, Technical Sales & Product Manager for Cortec® MCI®, explained the consequences of overlooking this convenient surface prep method: “You can basically sandblast and not choose any corrosion inhibitor on the steel, but rust is going to come back fairly quickly, and [repair workers] will have to open it up again and clean it and . . . do the same cycle.”

Another important aspect of surface prep is making sure the concrete is clean. For example, concrete contaminated with oils or greases can be cleaned with MCI®-2061 or MCI®-2062. These cleaners contain microorganisms for extended cleaning power. Left overnight, the microorganisms degrade and digest greasy substances within the concrete. They also continue to provide residual cleaning even after the surface has been rinsed off.

Adding Migrating Corrosion Inhibitors to Repair Mortars

One of the most difficult parts of a historical concrete repair can be matching new repair mortars or concrete mixes to the old surface where patching is needed. Sometimes this requires highly specialized historical or decorative concrete mixes. MCI® Mini Grenades can be added directly to these specialty mixes to introduce Migrating Corrosion Inhibitors to the repair. These concrete corrosion inhibitors have been successfully used in historical preservation jobs to extend service life without changing the color or look of the final repairs. They may also discourage the progression of the ring anode effect in areas adjacent to the repair by migrating and evening out the corrosion potential between existing concrete and repaired areas.

Surface Applied Corrosion Inhibitors in Historical Restoration

Surface Applied Corrosion Inhibitors (SACIs) are another important tool in historical restoration and preservation. SACIs can be applied at any stage of a structure’s lifecycle, extending time to subsequent repairs. MCI®-2018 is an excellent option for preventative maintenance because it contains Migrating Corrosion Inhibitors with a 100% silane water repellent to slow the ingress of moisture and chlorides. MCI®-2020 is ideal for heritage structures where corrosion problems have already begun. It contains a higher concentration of corrosion inhibitors, minus the water repellent. Both SACIs are clear and do not change the color of the concrete while allowing Migrating Corrosion Inhibitors to penetrate into the concrete, slow the corrosion process, and extend service life.

Past MCI® Heritage Projects

Cortec® MCI® Technology has been used in many historical restoration projects or heritage structures where minimal change in appearance was as critical as corrosion mitigation.

• Zagreb Cathedral: Steel joints reinforcing the south tower at regular intervals were coated with CorrVerter® MCI® Rust Primer to arrest the corrosion while minimizing cost and intrusiveness of the repair.
• Pentagon: Corrosion due to carbonation that extended 3.5 inches (9 cm) deep prompted a major repair on the Pentagon lightwell walls. After 200,000 ft² (18,581 m²) of hand patches were made (using specially cut boards to mimic the pattern created by forms during original construction), MCI®-2020 V/0 was applied over 1,000,000 ft² (92,903 m²) of surface area, along with a silane sealer and mineral-based coating to provide a minimum 20-year design life with the hopes of extending service life by 50 years.
• New York Hall of Science: The cast-in-place concrete façade of this unique structure had a shallow concrete cover, a common characteristic of brutalist architecture (often coinciding with high porosity) that makes such buildings more prone to corrosion. Repair work included application of MCI®-2020 and a water repellent. Probes were embedded during the repair and subsequently confirmed effective corrosion protection.
• Memorial University, St. John’s, Newfoundland: The entrance of the education building was adorned with a decorative design in brutalist architectural style. Rebar corrosion took place beneath a very shallow concrete cover. CorrVerter® MCI® was used to passivate the rebar. MCI®-2020 was surface applied to protect the decorative entrance from further corrosion and extend the service life of the repair.

MCI® products are an excellent companion to heritage repairs because they mitigate corrosion without affecting structural appearance. Contact Cortec® to consult on which products may be ideal for your historical or heritage restoration project: https://www.cortecmci.com/contact-us/

Keywords: historical concrete restoration, concrete repair, brutalist architecture, Cortec, MCI, Migrating Corrosion Inhibitors, rebar rust, concrete corrosion, rusted rebar in concrete, From Grey to Green

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Cortec^® Corporation, the home of MCI^® Technology, is pleased to announce its new, improved MCI^®-2040 High Performance Vertical/Overhead Repair Mortar. This is yet another component of Cortec’s High Performance Repair System (HPRS^®), which helps concrete repairs last longer by inhibiting corrosion and reducing the risk of the insidious ring-anode effect. With MCI^®-2040, Cortec^® has extended the protective qualities of MCI^®-2041 (horizontal repair mortar) to vertical and overhead surfaces, giving concrete contractors an MCI^® repair mortar for any angle!

Extend Service Life of Concrete Repairs

MCI^®-2040 is a single-component, fast-setting, high-strength, cement-based repair mortar that is enhanced with Migrating Corrosion Inhibitors (MCI^®). MCI^®-2040 offers corrosion protection to reinforcing metals both in the patch and in the surrounding areas. Migrating Corrosion Inhibitors in the concrete repair mortar penetrate the substrate and even out corrosion potentials between patched areas and nearby concrete. This slows down the ring-anode/halo effect in surrounding concrete. Once applied and hardened, MCI^®-2040 provides a high level of adhesion and durability, as well as resistance to water and carbonation attack. This increases the quality and extends the service life of the repair and surrounding structure.

More Flexibility for Vertical and Overhead Repairs

MCI^®-2040 is an easy-to-handle patching material for fast-paced repair jobs. It offers quick turnaround due to high early strength and can be applied like normal repair mortars, but without the need for bonding agents. MCI^®-2040 is specifically designed for vertical and overhead repairs, greatly increasing the potential use for MCI^® repair mortar and offering enhanced flexibility for contractors. Possible applications for MCI^®-2040 include the following:

• Undersides of bridge decks, parking ramps, balconies, and ramps
• Concrete columns, retaining walls, building facades, and soffits

 MCI^® High-Performance Repair System (HPRS^®)

For best results, MCI^®-2040 should be applied following the five steps of the MCI^® HPRS^®:

1. Prepare the substrate.
2. Treat and clean rusted rebar in concrete.
3. Apply repair materials (e.g., MCI^®-2040) to reinstate concrete and mitigate rebar rust.
4. Apply surface applied corrosion inhibitors (optional for added protection).
5. Apply final coating (optional for added protection).

The HPRS^® guide promotes maximum repair mortar success through best practices for surface prep (critical to good adhesion) and additional protection options.

Building and Resource Conservation

Sustainability has become a buzzword in today’s construction market with practical implications for building owners as well as the environment. Engineers are looking for ways to make buildings last longer to meet increasing service life demands and preserve an aging infrastructure. However, in spite of the strength of concrete as a durable building material, repairs are an inevitable part of the concrete life-cycle. The good news is that the proper use of MCI^® Technology to mitigate concrete corrosion can help concrete structures and repairs last longer, ideally lengthening intervals between repairs and thus saving substantial time, labor, and money. Contact Cortec^® to learn more about the benefits of MCI^®-2040 for vertical and horizontal repairs: https://www.cortecmci.com/contact-us/

Keyword: rusted rebar in concrete, rebar rust, Migrating Corrosion Inhibitor, concrete corrosion, corrosion inhibitors in concrete, MCI concrete, repair rusted rebar concrete, Cortec, From Grey to Green, sustainability

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September 1, 2022

The ubiquitous problem of rebar rust is hard to escape in the construction industry, but there is a practical answer. As part of Cortec’s High Performance Repair System (HPRS^®), CorrVerter^® MCI^® Rust Primer simplifies surface prep by passivating corrosion on steel surfaces. It is an exciting tool to help the construction industry tackle a recurring challenge.

The Problem of Rebar Rust
Rebar and other reinforcing metals play an integral role in providing the strength necessary to make concrete a viable building material. It is also one of the major causes of concrete deterioration. Although the high initial pH of concrete creates a naturally passive environment that protects metal reinforcement in new concrete, carbonation and cracking can lead to the formation of corrosion products on embedded reinforcement. As rebar rusts, it expands, putting pressure on the concrete cover. This causes more cracking and concrete spalling, deteriorating the structure and eventually requiring repair.

Effective Concrete Repair
For a repair to be effective, exposed reinforcement is typically sandblasted to remove corrosion and promote good surface adhesion to the new repair material. The ICRI 310.1R-2008 “Guide for Surface Preparation for Repair of Deteriorated Concrete Resulting from Reinforcing Steel Corrosion,” states that exposed reinforcing steel should be free of any materials such as concrete, dirt, and corrosion products that could interfere with repair material adhesion, although tightly bonded light rust is usually not detrimental to the bond of patch materials. This opens the door to a completely different level of surface prep convenience using CorrVerter^® MCI^® Rust Primer.

How CorrVerter^® MCI^® Works
CorrVerter^® MCI^® is a unique formulation of chelating agents combined with a high-solids waterborne latex with extremely low water vapor permeability. This fast drying, single-component primer converts surface rust into a hydrophobic passive layer and offers excellent protection against re-rusting of metal surfaces. These characteristics are ideal for repairs, making surface prep extremely simple. When using CorrVerter^® MCI, the first step is to wire brush loose rust off the metal surface. This requires much less labor than blasting and no special equipment. The next step is to remove the excess salt, dust, and contamination by rinsing with water. CorrVerter^® MCI^® can then be applied by spray or brush and left to cure for 12 hours before applying repair products. CorrVerter^® will turn visibly black by the time it dries to touch in about two to three hours.

A Convenient Solution for the Construction Industry
CorrVerter^® MCI^® is an exciting labor- and time-saving tool for contractors and engineers to be aware of. In addition to increasing the convenience of concrete repairs, CorrVerter^® MCI^® is also useful for construction delays where some concrete was already poured, leaving rebar partially exposed to the elements until the project can resume. When the project starts again, CorrVerter^® MCI^® is a good way to passivate any rust that has begun in the meantime, thus forestalling additional corrosion problems that could develop as a result. Contact Cortec^® to learn more about these great alternatives to sandblasting during concrete repair and rusty surface prep: https://www.cortecmci.com/contact-us/

Keywords: rusted rebar in concrete, surface prep, rebar rust, construction industry, concrete deterioration, concrete repair, Cortec, MCI, concrete spalling, alternative to sandblasting

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August 22, 2022

When it comes to sustainability, the most important thing Cortec^® MCI^® Technology can do is to help extend the service life of reinforced concrete structures by mitigating corrosion. Because concrete is a major producer of greenhouse gas, the very act of helping concrete last longer means less new concrete is needed to replace the old concrete, thus reducing overall CO₂ output from cement production. Furthermore, MCI^® helps contractors and building owners steward resources wisely by repurposing existing structures and sometimes even using renewable materials for construction.

Challenges to Concrete Service Life

To understand MCI’s impact on sustainability, it is necessary to look at one of the major challenges to concrete longevity: corrosion. The two main sources of corrosion in concrete are chlorides and carbonation. For example, a structure with high chloride exposure from proximity to the sea or frequent exposure to deicing salts is likely to corrode much sooner than a reinforced concrete structure in the middle of a dry, landlocked environment. However, even structures in this latter environment can deteriorate over the years as carbonation sets in from exposure to CO₂ in the air. Carbonation reduces the naturally high pH of the concrete so that reinforcement is no longer in the zone of passivity and can corrode more easily. In either case, concrete cracking can make matters worse by allowing corrosives to enter and reach reinforcing steel more quickly.

Helping Concrete Structures Last Longer

MCI^® Technology can protect against both types of corrosion by forming a protective molecular layer on the surface of the steel reinforcement. By interfering with the natural corrosion reaction between oxygen, steel, and an electrolyte, MCI^® delays time to corrosion and reduces corrosion rates once started. MCI^® can be applied as a concrete admixture to new structures or as a surface applied corrosion inhibitor (SACI) to existing structures. It can also be combined with repair mortars or water repellents for dual benefit and application convenience. In this way, both specifying engineers and repair contractors can help their work last longer and be more efficient, reducing the time and labor normally needed for repair. This weighs strongly in favor of earning credits toward LEED certification, a prominent sustainability rating system overseen by the U.S. Green Building Council.

Earning LEED Credits

Earning LEED credits with MCI^® can take a two-pronged approach. The main area in which MCI^® can help in LEED v4.1 Building Design + Construction is under the credit category of “Building Life-Cycle Impact Reduction,” which looks at “Building and Material Reuse,” as well as the “Whole-Building Life-Cycle Assessment.” By specifying MCI^® admixtures in new structures, engineers can reduce the need for concrete repairs and reconstruction to achieve the same service life, thus reducing overall CO₂ output over time. In a similar vein, MCI^® repair products can help existing structures last longer, thus making it possible to reuse resources that have a high embodied carbon output (carbon emissions from building the structure) instead of demolishing and replacing them. Another way that contractors can earn credits toward LEED certification is by using MCI^®-2005, a corrosion inhibiting concrete admixture that protects against both chloride- and carbonation-induced corrosion. MCI^®-2005 is a USDA Certified Biobased Product derived from corn. It contains 67% USDA certified biobased content and can contribute to the “Responsible Sourcing of Raw Materials” LEED credit category.

Building for Coastal Resilience

There are many examples of how MCI^® has been used in efforts to extend service life by delaying or mitigating corrosion on rusted rebar in concrete. The Lodge at Gulf State Park is an excellent model. Replacing the original lodge that was destroyed by Hurricane Ivan, the new lodge was designed with special goals for sustainability and resilience. A corrosion mitigation strategy was especially important given the corrosive location of the hotel on the Gulf Coast. In addition to MCI^®-2005 being a biobased product in line with the project’s overall goal of LEED certification, MCI^®-2005 was also shown to outperform the service life of epoxy-coated rebar (intended for corrosion protection) in service life prediction modeling. Furthermore, it provided significant direct cost savings to the project.

Structural Reuse vs. Concrete Demolition

The Höganäs County Water Tower is an excellent example of how MCI^® repair materials can be used to restore and prolong the service life of existing structures rather than demolishing them. Although built for a service life of 50 years, the water tower was already deteriorating at age 42, with chunks of concrete falling off due to chloride- and carbonation-induced corrosion. The concern was that additional damage could develop quickly and affect structural integrity. The municipality therefore requested a repair strategy that would provide 20 additional years of service life. The project owners settled on a repair plan that included MCI^®-2020 V/O for corrosion mitigation over other proposals that had a shorter expected service life or required demolition.

Meeting Longer Service Life Demands

The sustainability trend is evidenced in the fact that more and more projects are demanding structural service lives of 100 years or more. This is the case of the new Pelješac Bridge, which creates an important link between two separate parts of Croatia. The bridge was designed to have a 130-year service life and therefore incorporated multiple corrosion mitigation strategies to counteract concrete corrosion in the harsh saltwater environment. One of these strategies was the application of MCI^®-2018 onto the concrete pylons. This supplied the concrete surfaces with a 100% silane water repellent (to block intrusion of corrosives) and Migrating Corrosion Inhibitors to penetrate and protect embedded steel reinforcement.

An Important Key to Sustainable Construction

The need for concrete corrosion solutions will only get stronger as service life demands increase and sustainability requirements get stricter. MCI^® Technology provides a convenient, efficient, and effective method of corrosion protection for both new and existing structures, providing an important key to sustainable construction and the long-term reduction of one’s carbon footprint. Contact Cortec^® to learn more about MCI^® and sustainable construction: https://www.cortecmci.com/contact-us/

Keywords: extend service life, From Grey to Green, sustainable construction, Cortec MCI, LEED credits, sustainability, concrete admixture, concrete corrosion, carbon footprint, rusted rebar in concrete

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Cortec^® Corporation is the global leader in innovative, environmentally responsible VpCI^® and MCI^® corrosion control technologies for Packaging, Metalworking, Construction, Electronics, Water Treatment, Oil & Gas, and other industries.  Our relentless dedication to sustainability, quality, service, and support is unmatched in the industry. Headquartered in St. Paul, Minnesota, Cortec^® manufactures over 400 products distributed worldwide.  ISO 9001:2015, ISO 14001:2015, & ISO/IEC 17025:2017 certified. Cortec^® Website: http://www.cortecvci.com Phone: 1-800-426-7832   FAX: (651) 429-1122

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