Commonly due to the presence of calcium hydroxide, a passivating iron-oxide film will form on unprotected steel CPP joints, resulting in almost complete corrosion inhibition. Grout Diapers protect against corrosion as well as leaching– which reduces the pH of the cement grout surrounding the joint steel, while simultaneously resisting the intrusion of salts, chlorides, acids, and sulfates that can affect the inhibitive properties of the grout. Grout Diapers also isolate the protective grout from aggressive soils that correlate with highly corrosive electrical current.
Features & Benefits
- Protects against leaching, which leads to reduction of pH in the joint grout cement.
- Defends against intrusion of salts, chlorides, acids and sulfates that can affect the inhibitive properties of the joint grout cement.
- Guards the protective joint grout cement from aggressive soils that can cause high corrosive electrical current.
STANDARD Grout Diaper
Typar® Cement Form
MarMacʼs Standard Grout Diaper provides the best method of applying Portland cement grout into pipe joints. When mixed to a freely pouring consistency, the Portland cement grout penetrates into every opening of the joint. Because it bonds to and becomes part of the pipe itself, it is the most compatible material that can be used to seal concrete pipe joints.
Standard Grout Diapers are manufactured with Typar®; a tough, non-woven material made of polypropylene fibers. This durable, mildew-proof fabric stands up to almost all chemicals and works to add strength to the joint once it is in the ground.

Foam Grout Diaper
Polyethylene Foam-Lined Cement Form
STRETCH-COTE Grout Diaper
Mastic Moisture Barrier Cement Form

Polypropylene fabric (Typar®) is made with bonded, continuous filaments of polypropylene. It works as an exceptionally strong, dimensionally stable form that molds and holds the weight of the fresh grout. Specialized closed-cell polyethylene foam (Foam Grout Diapers only) is produced according to pipe joint Grout Diaper specifications. This specific foam is resistant to water and most chemicals, including acids, alkalines, and solvents. A thin membrane (0.07”) consisting of layers of polyfilm and rubberized asphalt provide a continuous isolation seal and moisture barrier, protecting the cured grout from exterior elements (Stretch-Cote Grout Diapers only). Steel straps are sewn into the diaper hem to securely tie the diaper to the pipe.
The width of the Grout Diaper will be governed by the width of the joint space and the type of pipe being used. The width should be sufficient to bridge the joint space and be secured to the pipe walls on each side of the joint without failure due to slippage.
The length of the Grout Diaper will be governed by the circumference, with extended tab lengths to accomplish overlapping of the ends once the joint has been filled with grout.
| FABRIC | |
|---|---|
| Material | Non-woven polypropylene |
| Minimum Weight | 3 oz/yd2 |
| STRAPS | |
| Straps | Heat-treated or hot-rolled steel |
| Standard | Class 1, Type I |
| Thickness | ≥ 0.020″ |
| Coating | Waxed or painted/waxed |
| FOAM (Foam Grout Diapers only) | |
| Material | Closed-cell polyethylene |
| Density | 1.9 – 2.2 lbs/ft2 |
| BARRIER MEMBRANE (Stretch-Cote Grout Diapers only) | |
| Material | Polyfilm (0.01″), Rubberized Asphalt (0.06″) |
| Thickness | 0.07″ |
Store Grout Diapers in a dry, cool place.
- Position the Diaper: Wrap the grout diaper around the pipe joint with the foam-lined side facing inward against the pipe wall.
- Secure & Tighten: Fold back the fabric tab at the top. Tighten and crimp the steel straps securely so the diaper can support the weight of the liquid grout without sagging.
- Pour the Grout: Keep the fabric tab folded back to maintain a pour opening at the top of the joint. Pour portland cement joint grout into the opening, rotating from side to side so it fills the bottom and sides evenly until completely full.
- Seal the Opening: Fold the fabric tab back over the filled opening, press it firmly into the wet grout, and weigh it down to keep it sealed during backfilling.
VERSIONS
AVAILABILITY
* Refer to version section for widths.
APPLICATIONS
Concrete-Coated Pipe (CWC)









