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Fiberglass in concrete?

Fiberglass in concrete?

Fiberglass in concrete?

We recently had the coping poured for an in-ground pool and were suprised to find that the contractor had added PPG short strand fiberglass to the concrete.  The strands are visible throughout the concrete and some can be pulled off the surface.  We now have two concerns:

1)Is it safe?  We have young children and are concerned about it injuring their feet or coming loose and being in the pool water itself.

2) Are the strands supposed to be this visible?  I've never seen concrete with fibers in it before and our contractor didn't mention that he was using them or that they'd be visible.

Thanks in advance.


RE: Fiberglass in concrete?

The surfaceappearance of fiber concrete can be a problem, especially when fresh. Some of the exposed fibers will wear off or weather off. Fiber concrete is becoming more common on floor slabs in an attempt to minimize cracking.

They are not inherently dangerous, but huge amounts, if inhaled, could be.

There are many types of fibers that are used ranging from steel, fiberglass to various "plastic" compounds. If fiberglass was used is should be an alkalai-resistant glass, since common fiberglass will deteriorate over time in concrete.

In some cases, I have seen the protruding fibers singed off with a butane torch to accelerate the natural process.


RE: Fiberglass in concrete?

How about you cover up the surface by applying thin layer of mortar mix. You may have to use shrinkage compensating concrete in the mortar mix.

RE: Fiberglass in concrete?

Fiberglass has to be coated else the alkali in concrete can deteriorate it.


RE: Fiberglass in concrete?

Fibres (steel, fibreglass or polypropylene) are used in concrete to minimise cracking, especially at the surface.  I've only ever seen fibre reinforced concrete (FRC) used in slabs-at-grade and in sprayed concrete ("shotcrete"); not in formed items such as beams, walls and columns.

I've seen some disastrous outcomes with FRC slabs-at-grade - with the fibres "balling" and the concrete mix becoming unworkable -- and would never specify it again.

FYI, see these industry links regarding glass fibre reinforced concrete:
- International Glassfibre Reinforced Concrete Association, http://www.grca.org.uk/
- National Precast Concrete Association Australia, http://www.npcaa.com.au/html/RESOURCES-GRC.html

RE: Fiberglass in concrete?

I would be very unhappy with fibreglass in a concrete pool coping, especially if I didn't know about it beforehand.  Did you have a specification?  How do you stand contractually?  Is there an association of swimming pool builders that you can complain to?  I would consider exposed fibres to be hazardous, and your builder should rectify his poor work.

RE: Fiberglass in concrete?

Are you sure it is fiberglass and not plastic?

RE: Fiberglass in concrete?

These folks do precast for cell phone equipment shelters ect. I think they have a proprioritory fiberglass component. http://www.fibrebond.com/

RE: Fiberglass in concrete?

I have done pools and pool buildings and always specifically prohibited use of fibers for the same reason that you mention....bare feet! They will wear off but I would require the contractor to burn them off with a torch (as concretemasonry suggested). I would then have the Owner view it and walk on it to see if that remedy is acceptable to him.

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