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Choosing your Water Repellent and Corrosion Inhibitors for construction

When it comes to selecting water repellents and corrosion inhibitors for both construction and repair projects, Cortec® MCI® recommends preparing a list of considerations.

New Construction or Concrete Repair?

Corrosion inhibiting admixtures followed by a waterproofing membrane on concrete surfaces are typical for new structures. In contrast, water repellents, waterproofing membranes, and MCI® surface applied corrosion inhibitors (SACIs) are used for existing structures.

State of the Structure

If the concrete shows cracks and leaks, the underlying problem needs to be addressed first. This may include evaluating the depth of carbonation, the concentration of chlorides present, and the degree of metal loss on the rebar.

Signs of carbonation or chlorides could imply removing the problem concrete and using a SACI like MCI®-2020 ahead of the waterproofing membrane. Without it, the corrosion may remain underneath the membrane, and continue to deteriorate the structure from the inside.

Reinforcement bars affected by corrosion may require replacement, or if enough metal remains, it can be cleaned or chemically treated with CorrVerter® MCI® to passivate the rebars.

Expected Water Exposure

Concrete structures in direct contact with water such as high water table, may require an MCI® admixture or SACI and a waterproofing membrane. In other cases, structures might simply need a dual water repellent / SACI such as MCI®- 2018 or MCI®-2019. These would provide adequate protection with exposure to moisture but not constant hydrostatic pressure.

Service Life and Maintenance Schedule

MCI® admixtures such as MCI®- 2005 can extend the service life predictions in new structures for a lower cost when compared to other methods, such as an epoxy coated rebar solution.

Using an SACI such as MCI®-2020 followed by a waterproofing membrane can offer a 20 year maintenance free as membrane systems typically carry 20+ year warranties. Other DOTs reapply water repellents every 5 years as part of their maintenance and the 7-10 year reapplication recommendation for MCI®-2018 or MCI®-2019 two-in-one SACI water repellents works well in those instances.

Current Specification

Another helpful consideration is to investigate previously used products. If a water repellent has been used in the past, a water-based SACI such as MCI®-2020 will not be able to penetrate the concrete pores and MCI®-2019 should be used instead, over the remaining silane water repellents.

Identifying what products have been used in the past can also prevent potential waste. In certain cases MCI®-2018 is really all that is needed instead of both MCI®-2020 and a waterproofing membrane.

Source: Cortec Corporation “Five Questions to Optimize MCI® / Water Repellent Selection!”

Interested in our Corrosion Inhibitor products? Read more here.


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