SewperCoat®

SewperCoat is a ready-to-use premix mortar, composed almost entirely (both cement binder and aggregate) of calcium aluminate materials. It is specifically designed for spray-applied installation methods to provide a protective lining for structures exposed to abrasion and biogenic corrosion resulting from the hydrogen sulfide (H₂S) cycle that occurs in municipal wastewater environments. Its unique properties result from its particular mineral phases and hydration process. PDS available in documentation center.

Biogenic corrosion is a bacterially mediated process of forming hydrogen sulfide gas and the subsequent conversion to sulfuric acid that attacks concrete and steel within wastewater environments. The hydrogen sulfide gas is biochemically oxidized in the presence of moisture to form sulfuric acid. The effect of sulfuric acid on concrete and steel surfaces exposed to severe wastewater environments can be devastating.

Through a combination of many factors, but primarily through its neutralization capacity and its inhibiting effect on the thiobacillus bacterial strains present in the wastewater environment.

Imerys is the world leader in the manufacture of calcium aluminates. Calcium aluminate cements were developed and first manufactured by the group in 1908 (J. Bied patent).

Calcium aluminates have been successfully used for more than 80 years in extreme wastewater applications worldwide. The first U.S. application was in 1959 located at the Los Angeles County Sanitation District's Hyperion Treatment Plant in Southern California.

The components of SewperCoat are manufactured by a fusion process. The raw materials for this process are bauxite and limestone. The limestone and bauxite are proportionately fed into a reverbatory furnace where they are melted into a liquid. The composition of the finished calcium aluminate is dependent upon the purity and proportions of the raw materials. SewperCoat mortars are composed of both calcium aluminate cement and manufactured calcium aluminate aggregates. The unique mineralogy of the cement and aggregate are key to the ultimate performance of SewperCoat.

When both the calcium aluminate cement and aggregate are of the same chemical and mineralogical nature, upon hydration, a superior physical and chemical bond is achieved between the cement and aggregates. This, coupled with the hardness of the manufactured calcium aluminate aggregates, allows SewperCoat mortars to have excellent abrasion resistance as well as superior corrosion resistance properties. But the essential benefit of the 100% calcium aluminate composition is the chemically uniform shielding obtained opposing the same "bacteriostatic effect" to the biogenic corrosion process in every single point.

SewperCoat can be used for the rehabilitation of existing wastewater structures, as well as in new construction. Typical applications for SewperCoat include the lining of manholes, wet wells, lift and pump stations, piping systems, and treatment plant structures. It can be used almost anywhere in a municipal wastewater network where biogenic corrosion exists.

SewperCoat is formulated for a spray-applied installation in wastewater structures, and can be applied with a low-pressure, wet-spray process, or with the traditional high-velocity, dry-gunite process.

It is an installation method that uses low air-pressure, wet spray equipment to apply SewperCoat. The material is mixed with water and conveyed through a hose with a progressive cavity (rotor-stator) or piston type (swing tube) pump system. There is an atomizing nozzle on the hose that uses air pressure to propel the wet material, spraying it onto the surface at a low velocity.

It is an installation method that uses high-velocity, dry-gunite equipment to apply SewperCoat. The material is blown dry through a hose with high pressure air. There is a nozzle on the hose that contains a water ring, which injects water into the dry material as it passes through. SewperCoat is mixed as it hits the sub-surface. The nozzleman uses a circular application pattern that shears the material and mixes it through displacement.

The typical substrate for structural wastewater applications is generally Portland cement concrete. There are several industry guidelines available regarding surface preparation for concrete repair materials. In general, all sub-surfaces should be clean and free of laitant, loose material, residue and all existing coating and lining materials and should be thoroughly dampened. Inflow and infiltration prevention measures should also be undertaken. For a detailed explanation of the surface preparation requirements please see ACI RAP-3 "Spall Repair by Low Pressure Spraying" page 2. ACI 546R "Concrete Repair Guide", chapter 2 also provides a good reference for important considerations for repairing concrete surfaces using mortar.

A newly cast Portland cement concrete structure may require a significant amount of surface preparation to achieve the desired degree of surface roughness and typically requires a surface roughening process such as a thorough sand grit blasting. A severely corroded, existing structure may be well in excess of the desired degree of surface roughness at the time of rehabilitation and may require only high-pressure water cleaning. Regardless, SewperCoat must be applied to clean, sound, rough, damp surfaces. Any unsound concrete or contaminated surface materials must be removed and all active and potential leaks must be addressed prior to installation.

SewperCoat is generally applied at an installation thickness ranging from ½" to 1", but can be installed up to a 4" thickness depending upon the application. The minimum installation thickness however, is nominally ½".

With SewperCoat being a specialty construction product having very specific installation methods and equipment requirements, Imerys is very selective in our assessment of any contractor interested in gaining our "competent and qualified installer" designation. This designation is typically required in project specifications, along with other exhaustive experience and volume of similar work requirements. Imerys maintains a listing of competent and quality contractors that have demonstrated requisite skill and training to be considered qualified installers of our materials.

Applicators, agents, and manufacturer's reps are continually being developed as there are attractive market areas available throughout the world. If you are interested in becoming a part of the team, the first step is to contact your local Imerys sales person.