Q&A About Fabric-Reinforced Cementitious Matrix

On February 14, we hosted the third interactive webinar in the Simpson Strong-Tie Composite Strengthening Systems™ Best Practices Series: “Introducing Fabric-Reinforced Cementitious Matrix (FRCM).”

Simpson Strong-Tie engineering manager Brad Erickson, S.E., P.E., and Simpson Strong-Tie senior product manager Mark Kennedy, PMP, conducted an informative discussion of this new product solution. You can view the webinar in our Training Center and take a course to earn one hour of CEUs, PDHs and AIA LU/HSW credits. The course and webinar discuss installation steps, identify projects where FRCM would be ideal, and cite testing and industry standards associated with FRCM.

At the end of February’s webinar, we asked participants to submit further questions about this innovative product. We’ve answered some questions below and you can review all the FRCM webinar questions and answers here.

What is the cure time for overhead applications? When FRCM is applied to bridges and train tracks, how do we account for the vibrations’ effects on the cure process?

The initial set of the matrix takes approximately five hours, with the final set taking less than eight hours. For a project with potential vibration issues, it would be best to eliminate vibrations for the CSS-CM to achieve final set. If this closure would be an issue, a small field trial demo on this particular structure may be prudent to check how the vibrations affect the strength of the FRCM’s bond to the substrate.

If FRCM was used to strengthen a residential concrete foundation, could a two-part elastomeric coating be sprayed over it, and if so, how long should the FRCM be allowed to cure before being sprayed over?

Yes, an elastomeric coating could be placed on top of an FRCM installation. We would recommend waiting at least 28 days to allow the FRCM mortar to cure before applying the elastomeric coating. We would also recommend allowing the moisture content of the mortar to drop below 5% prior to applying elastomeric coating.

In practice how does one obtain the CSP profile? We find this difficult to obtain in the field.

Sandblasting, shotblasting and water-blasting could all provide a CSP 6-9 profile.

Could this be used in a soil nail wall in lieu of a shotcrete wall, or is it typically too thin? Anchoring the soil nails to the grid could be an issue, too.

FRCM should not be used as the primary structural system but could be used in combination with a reinforced concrete wall as a retrofit.

How many hours of training will the technician need to spray the matrix safely and properly, and what’s the cost associated with this training?

Training is provided at no cost and typically lasts about half a day.

What are the thickness limitations when using FRCM?

FRCM applications could be as thin as 1/2″ for one-layer grid installations or as thick as 3″ from the face of the substrate for up to four layers of grid. These dimensions do not include rock pockets or other voids in the substrate that can also be repaired with CSS-CM.

In view of the no-cover restrictions, how does this product meet fire-protection requirements?

We have a four-hour UL rating on our FRCM system. The matrix will also help the fire cover requirements of the rebar in the element being strengthened.

If surface preparation exposes existing reinforcement materials, or substantially reduces concrete cover for existing reinforcements, how do you provide the required concrete cover for the existing reinforcement?

The matrix of the FRCM system replaces the cover concrete removed during surface prep.

What surface preparation is required for fire-damaged concrete prior to FRCM application?

Demo to solid concrete and remediation to damaged rebar would be required prior to FRCM application.

Can’t you just prerake surfaces between layers?

That’s not required. Additional layers of matrix can simply be sprayed onto grid installed into previous layers of matrix.

Learn more: Webinar – Introducing Fabric-Reinforced Cementitious Matrix (FRCM)

In this free webinar we dive into some very important considerations including the latest industry standards, material properties and key governing limits when designing with FRCM.

Continuing education credits will be offered for this webinar.
Participants can earn one professional development hour (PDH) or 0.1 continuing education unit (CEU).

New CSS Product Launch — FRCM Strengthening Products

The new FRCM Composite Strengthening Systems™ repair and reinforcement solution from Simpson Strong-Tie combines high-performance sprayable mortar with a carbon-fiber grid that creates a thin structural layer that repairs and strengthens without significantly increasing the structure’s weight or volume. FRCM stands for fabric-reinforced cementitious matrix. Its advantages are similar to those of FRP (that is, strength, low weight and ease of application), but it may also be used to repair, resurface, strengthen and protect in one application, along with providing greater resistance to heat and better long-term durability.

Significant flexural, axial or shear strength gains can be realized with an easy-to-apply composite providing a low-impact, low-weight alternative to traditional concrete strengthening and retrofit methods. Typical applications include tanks, silos, tunnels, pipes, parking garages and marine infrastructure.

• Projects that also require a surface repair and leveling in addition to strengthening
• Projects with large, overhead or vertical surface areas where shotcrete applications may afford the highest production rates
• Repair applications that cannot afford significant member enlargement
• Composite strengthening applications that require an increased level of abrasion and fire resistance

American Concrete Institute (ACI) provides a design guide for FRCM materials titled ACI 549.4R-13 Guide to Design and Construction of Externally Bonded Fabric-Reinforced Cementitious Matrix (FRCM) Systems for Repair and Strengthening Concrete and Masonry Structures. While our Designers sit on this committee, we also provide no-cost design services based on the recommendations in this guide.

Simpson Strong-Tie Can Help
We recognize that specifying Simpson Strong-Tie Composite Strengthening Systems is unlike choosing any other product we offer. Leverage our expertise to help with your FRP and FRCM strengthening designs. Our experienced technical representatives and licensed professional engineers provide complimentary design services and support – serving as your partner throughout the entire project cycle. Since no two buildings are alike, each project is optimally designed to the Designer’s individual specifications. Our pledge is to address your specific condition with a complete strengthening plan tailored to your needs, while minimizing downtime or loss of use, at the lowest possible installed cost.

Your Partner During the Project Design Phase
During the Designer’s initial evaluation or preparation of the construction documents, Simpson Strong-Tie can be contacted to help create the most cost-effective customized solution. Simpson Strong-Tie Engineering Services will work closely with the Designer to provide all the information required to design the system. The solution we deliver will include detailed design calculations for each strengthening requirement and design drawings with all the necessary details to install the CSS.

Why Use Simpson Strong-Tie Design Services?

  • To assess feasibility studies that will help ensure suitable solutions for your application
  • To receive customized FRP and/or FRCM strengthening solutions
  • To work with our trained contractor partners to provide rough-order-of-magnitude (ROM) budget estimates
  • To collaborate during the project design phase
  • To receive a full set of drawings and calculations to add to your submittal
  • To maintain the flexibility to provide the most cost-effective solution for your project
  • To gain trusted technical expertise in critical FRP and FRCM design considerations

For complete information regarding specific products suitable to your unique situation or condition, please visit strongtie.com/frcm or call your local Simpson Strong-Tie field engineer or RPS specialist at (800) 999-5099.

If you are interested in learning more about FRCM and how it compares to other strengthening methods visit our Training Center now. The course discusses installation steps, identifies projects where FRCM would be ideal, and cites testing and industry standards that are associated with FRCM. You can view at your convenience and earn 1 hour of CEUs, PDHs and AIA LU/HSW credits.

Learn more: Webinar – Introducing Fabric-Reinforced Cementitious Matrix (FRCM)

In this free webinar we dive into some very important considerations including the latest industry standards, material properties and key governing limits when designing with FRCM.

Continuing education credits will be offered for this webinar.
Participants can earn one professional development hour (PDH) or 0.1 continuing education unit (CEU).