How to protect FRP laminates from vehicular abrasion 1

[asixth]

Hi guys

I want to use externally bonded Carbon FRP plates in the negative moment region of a carpark slab to strengthen the structure in flexure. The problem with this is that the FRP will be bonded to the slab surface and therefore exposed to vehicular traffic.

How can I protect the FRP laminates from damage?

I was thinking to overlay the FRP with a wearing surface, but this will prevent any future inspection and maintenance of the FRP laminate?

All suggestions or published data on similar projects will be welcomed and appreciated.

 

[rowingengineer]

Asixth,
good question, I have no idea, but i was considering using a heavy meshed epoxy overlay for my slab with saw joints. I think this would provided a highly durable surface, up to a 2.5t braking load. after this, i doubt it would be effective. I never got to doing the calcs as you can see, but i think it would standup. would increase the cost of the overlay by about 2-3 so I would try to put in on the underside it possible, you could use 2 times the product and still be in front.

Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that them like it

 

[abusementpark]

Interesting question?

Perhaps if you do it in a line you can cover it with one of those metal speed bumps.

I am thinking of something like this.

http://cache.gizmodo.com/assets/images/4/2008/12/speed-bump-design.jpg

However, I am not sure how these are connected and if they could be easily removed for inspection.

Are you doing anything for fireproofing?

 

[SkiisAndBikes]

Asixth,

I am not sure ... just throwing ideas around for consideration.

Thin type waterproofing membranes (less than 1/8" thick epoxy and/or polyurethane), with wear surfaces, are used in parking garages all the time. They are relatively cheap, durable and slip resistant. They are thin enough that any potential delamination or deterioration of the FRP would reflect through. They can easily be recoated in 10+ years time if they wear thin. The issue would be compatibility/bond between the two materials.

Another idea would be to consider an extra, sacrificial layer of FRP with silica sand cast into the top course and backrolled, similar to thin waterproofing membranes or possibly just add the silica sand to the top course and hope for the best.

I have always been curious about the fire performance of FRP's in parking garages and how they would withstand high temperatures without failure.

 

[apsix]

The load factors for the fire case will be lower, therefore any FRP added for strength purposes is probably not required in that case.

 

[asixth]

Thanks for the replies

rowingengineer,

how far advanced are you and your company/previous company with research and specification of FRP? It is something I am uncomfortable designing because I am not an expert on the material and we as engineers owe a duty of care to the community.

abusementpark,

is is a good idea and one that I haven't considered although for my example there is a large redistribution of forces, positive moment regions are becoming negative moment regions, so I feel there is going to be a large amount of FRP specified and I don't think it will all be able to be covered by a speed bump.

SkiisandBikes,

Good suggestions, I will look into them. Do you know of any suppliers.

apsix,

I haven't look at fire design but it will need to be considered.

PS: Even as engineers check the turning circles for vehicles, it will save you a lot of headaches.

 

[ImminentCollapse]

Take a look at NCHRP Report 564. It is related to inspection of FRP bridge decks, but may provide someone useful information.

 

[SkiisAndBikes]

Asixth,

A few waterproofing membranes, to name a few:

Tremco Vulkem
TBS Kelmar
Duron

If you are uncomfortable with the design, the FRP suppliers might be a good source of design information. When the FRP products were new and they were trying to increase market share, they offered to have the FRP portion of a project we were contemplating either designed by a local professor and then presented to us for our review or the professor would be made available to us for questions.

 

[asixth]

It's not that I can't design it, I'm actually enjoying researching into this developing material. I just don't feel as confident with it that I would for a reinforced or stressed concrete design which I was educated on and have spent my career designing.

Thanks for the manufacturer list.

 

[rowingengineer]

"Even as engineers check the turning circles for vehicles, it will save you a lot of headaches" sounds like a nice big headache.

As of 6 weeks ago I no longer work for the company which provided engineering services to the FRP manufacture. However when I left you could say that development of bridge both foot and road were completely developed with Mark I and II design complete with Mark III underway. The objective was to develop a range of FRP products for structural applications. We were never involved in repair situations ect but the principles are the same.

I think you should take a look at the RAPT & sika program for design of the FRP, I believe the latest RAPT program supports laminate design. However if I remember correctly it doesn't provided glue line stress's which are more important than the FRP laminate. The laminate itself can be designed however the bond is crucial, and what a lap do you allow for the FRP to the steel reo, all these can be worked out, but the bond is the key. This is why Sika have a carbon fibre range aimed directly at this application, they produce the glue, that makes the system work.

Arguing with an engineer is like wrestling with a pig in mud. After a while you realize that them like it