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).

Facebook Tips for Structural Engineers

facebook-logoIn our last social media–related blog post, I shared the Top 5 LinkedIn Groups to Follow for Structural Engineers. Following groups on LinkedIn allows you to share content, post or view job openings, network and help establish yourself as a key opinion leader in your industry. But what about critical design questions or help? How do you deal with office dynamics or a difficult client as a structural engineer?

LinkedIn groups may assist with questions like these, but there are other social media platforms that might make it easier to have a more in-depth discussion about issues that you face. While LinkedIn is certainly an important social media platform for professionals such as structural engineers, it is not the largest social media platform. That title goes to the social media giant Facebook. Facebook has the social advantage of engaging more than 1.7 billion active users.

You are probably using Facebook already for personal social networking. However, there are some professional applications for structural engineers on Facebook that you may not have heard about. Here are some Facebook tips for structural engineers that you can use to jumpstart your professional social media arsenal:

Follow Industry-Related Pages

There are a variety of pages that you can follow on Facebook to give you an idea of what is happening in the industry. Following and engaging with pages like Structural Engineering World for design inspiration or Civil + Structural Engineer magazine for project management ideas allows you to have a more professionally focused newsfeed around content that matters to you (while still allowing time for cat memes and Buzzfeed quizzes if you want those, too). One useful page for engineers is the Autodesk Revit page, because it has things like tips on how to share large BIM files.

Join Structural Engineering Groups

Groups are a great way to connect with other Facebook users. As a structural engineer, you are bound to come across an issue that you would like some advice on. By joining a group of other structural engineers, you can ask design questions, questions about calculations and get tips on the best tools for your profession. I would ask your colleagues which groups they recommend joining.

Jumpstart Your Job Search

If you are looking for a new position, I am sure that you already know about LinkedIn. But did you know that there are things like the Career Center App on Facebook pages like the ASCE? The app works for employers looking to hire, too!

Do you have Facebook tips that would you recommend for structural engineer? Let us know in the comments below.