Can FRP Be Recycled? Cement Kiln, Mechanical and Pyrolysis Routes

In short: Yes, FRP can be recycled, but not like steel. The resin in most FRP is a thermoset, so it cannot be melted down and reshaped. Today the route that works at scale is cement kiln co-processing: the resin burns as fuel and the glass fiber becomes part of the cement clinker. Mechanical grinding turns scrap into short fibers and filler for new products. Pyrolysis and chemical routes recover cleaner fibers, but with lower strength or at small scale. The best lever a buyer has is a long service life, plus clean, sorted scrap at the end. FIBROVX builds each item to order.

How this guide fits with our others

This guide covers what happens to FRP at end of life. For the carbon side of the story, see lifecycle carbon of FRP vs steel: how to read an EPD. For what FRP is made of, see what is FRP. Sectors we serve are on our industries page.

Why FRP is harder to recycle than metal

FRP is glass fiber held in a cured resin such as polyester, vinyl ester or epoxy. Once a thermoset resin cures, it does not melt again. That is why FRP grating keeps its shape and why it resists corrosion. It is also why you cannot simply melt it and pour a new part.

The European composites association EuCIA puts it plainly: composites cannot easily be separated into their fiber and matrix, which is the basis of their success but also makes them inherently difficult to recycle. EuCIA estimates that 40–70% of composite waste still ends up in landfill or is incinerated without energy recovery.

So "can FRP be recycled" really means three questions:

1. Can the material value (glass and minerals) be used again?
2. Can the energy in the resin be used?
3. Can fibers come back as reinforcement in a new composite?

Each route answers these differently.

Route 1: Cement kiln co-processing

How it works

Cement clinker is made in rotary kilns at temperatures up to about 1,400–1,500 °C, according to an LCA study that SGS INTRON carried out for EuCIA. In co-processing, end-of-life glass fiber composite is shredded near a cement plant into a fine, fluffy material. In the kiln:

• the resin (the organic fraction) burns, and its energy is used to make clinker, replacing part of the fossil fuel;
• the glass fiber and mineral fillers such as calcium carbonate become part of the clinker, replacing part of the virgin raw material.

What the studies say

• A joint position paper from the composites value chain and cement makers calls co-processing a recycling solution that uses 100% of the end-of-life material and can be deployed at large scale now, unlike routes that are not yet technically or economically ready.
• The SGS INTRON LCA for EuCIA found that co-processing saves 213 to 411 kg CO2-eq per ton of waste (weighted average 335 kg), while incineration with energy recovery generates 347 to 719 kg CO2-eq per ton (weighted average 496 kg). The average combined difference is about 0.83 t CO2-eq per ton of waste.
• The same groups ask EU policymakers to recognize co-processing as recycling under the Waste Framework Directive 2008/98/EC, create dedicated waste codes and set up separate collection.

Results by material type

The LCA modeled three waste types, labeled GF50, GF70 (two glass fiber composite compositions) and SMC (sheet molding compound). The aggregated difference between co-processing and incineration was 1,130 kg CO2-eq per ton for GF50, 782 kg for GF70 and 560 kg for SMC. The resin share changes the result, because the resin is what supplies the fuel value and the direct CO2 in the kiln. The study notes that it focused on greenhouse gas emissions, but co-processing also reduced the need for virgin mineral raw materials and fossil fuels.

Why it beats incineration

In a waste incinerator with energy recovery, only the energy content is put to use. In a cement kiln, both the energy and the mineral fraction are used. That is the basis for calling co-processing material recycling, not only energy recovery.

Limits

• No fiber comes back as fiber. The value is recovered as fuel and cement raw material.
• A review in the journal Materials lists potentially hazardous dust from shredding and rising gate fees as challenges.
• It depends on a cement plant that accepts the waste stream. Ask your local waste contractor.

Route 2: Mechanical grinding

How it works

Scrap is cut, shredded and milled into smaller fractions. The Materials review describes the result as a mix of resin, filler and fibers of different lengths that may need sieving.

Where the output goes

The ground material can be used as filler or partial replacement in new composites such as SMC and DMC, or in polymer concretes and mortars. Commercial operations exist.

Limits

• Fiber properties drop, and only short fibers and fillers are recovered.
• The output has a low market value, so transport distance matters.

Route 3: Pyrolysis and other thermal or chemical routes

How it works

Pyrolysis heats the composite in an inert atmosphere. The resin breaks down into gas and oil, which can feed the process, and the fibers and fillers are left behind.

What comes back

• Recovered glass fibers lose much of their strength. Researchers at DTU who compared mechanical, burn-off, pyrolysis and glycolysis routes noted that a process able to recover the original fiber properties at a limited cost is still under investigation.
• A study on sheet molding compound, published through the US DOE OSTI repository, found that glass fibers are already damaged before recycling, during manufacturing, service and shredding. That pre-existing damage limits what any recovery process can give back.
• Chemical routes (solvolysis) can recover fibers with higher strength retention, but the Materials review lists them as laboratory scale only.

Fluidized bed

A related thermal route uses a hot stream of air to break down the resin in a bed of silica sand. The Materials review notes that contaminated material can be processed without pre-treatment and that energy or precursor chemicals can be recovered, but fiber degradation is higher than with solvolysis or pyrolysis.

Limits

Long processing times, char on the fibers, and economics that only work at large volumes.

What the rules say (EU example)

The EU Waste Framework Directive 2008/98/EC sets the waste hierarchy: prevention, reuse, recycling, other recovery such as energy recovery, and disposal last. The Materials review points out that the directive does not ban landfill; it tells member states how to manage waste streams to reduce the impact of landfill. The review expects recycling technology to mature as rules on end-of-life export and landfill of composites become stricter.

For a buyer, the hierarchy gives a simple order of preference:

1. Prevent: a longer service life means less waste.
2. Reuse: grating panels, covers and profiles in good condition can be reused in a less demanding duty after inspection.
3. Recycle: co-processing or grinding.
4. Recover energy: incineration with energy recovery.
5. Dispose: landfill only as a last resort.

Rules differ by country and region. Check what your local regulations and waste contractor allow.

Routes side by side

What this means for a buyer

1. Service life is the biggest lever

The greenest FRP part is one you do not replace. Pick the right resin for the chemicals and temperature, protect outdoor parts from UV, and inspect on a schedule. See UV degradation of FRP and FRP temperature limits by resin type.

2. Keep scrap clean and sorted

Co-processing and grinding work best with known material. Keep FRP offcuts apart from metal, wood and general waste. Remove metal fixings and clips before sending grating or profiles for recycling.

3. Ask the right questions

• What is the resin type and glass content? (This affects fuel value and mineral share.)
• Are there fillers, fire retardants or coatings?
• Are there metal inserts or embedded parts?
• Is there a local cement plant or recycler that accepts glass fiber composite?

4. Ask a recycler these questions

• Do you accept glass fiber composite, and in what size pieces?
• Must metal, coatings or contaminated parts be removed first?
• What is the final route: cement kiln, grinding, or energy recovery?
• Can you provide a record of where the material went?

5. Design for disassembly

Bolted connections and clips are easier to take apart than bonded joints. When you design an FRP platform, ask whether parts can be bolted rather than glued where the design allows.

End-of-life planning checklist

1. Choose resin and surface for the longest service life.
2. Prefer bolted or clipped joints where the design allows.
3. Keep a record of resin type, glass content and fillers for each item.
4. Sort FRP scrap from metal and general waste; remove fixings.
5. Ask your waste contractor for a co-processing or grinding outlet.

How we customize

FIBROVX makes molded grating, pultruded profiles, tanks and other FRP items to your drawings. We can tell you the resin type, glass reinforcement and fillers used in the items you order, so your end-of-life plan starts with real data. Recycled-content products are custom / available on request and depend on your performance needs; we confirm what is possible with each quotation. See custom FRP manufacturing.

FAQ

Is fiberglass recyclable?

Yes, but not by melting. The main routes are cement kiln co-processing, mechanical grinding into filler, and pyrolysis.

What is cement kiln co-processing?

Shredded composite is fed to a cement kiln. The resin burns as fuel and the glass fiber becomes part of the clinker.

Can recycled glass fiber be used to make new FRP grating?

Recovered fibers are short and weaker, so they are mostly used as filler. Ask us about recycled content for your project.

Is co-processing better than incineration?

The SGS INTRON study for EuCIA found about 0.83 t CO2-eq lower emissions per ton of waste on average, because the glass replaces raw material as well as fuel.

Does FRP go to landfill?

Some does. EuCIA estimates that 40–70% of composite waste still goes to landfill or incineration without energy recovery.

Sources

• EuCIA and partners, Joint position: Cement co-processing is a sustainable solution for recycling end-of-life composite materials (2023): https://eucia.eu/wp-content/uploads/2023/07/230623-Joint-position-Co-processing-Composites.pdf
• SGS INTRON for EuCIA, LCA of Composite Waste Processing through cement co-processing (kiln 1,400–1,500 °C; 213–411 vs 347–719 kg CO2-eq per ton; about 0.83 t average difference): https://eucia.eu/wp-content/uploads/2024/10/LCA-of-Composite-Waste-through-Cement-Co-Processing.pdf
• EuCIA, Circularity of Composite Materials position paper (40–70% landfill or incineration without energy recovery): https://eucia.eu/wp-content/uploads/2023/05/221020-POSITION-PAPER-EuCIA-2022-revision-002.pdf
• Recycling of Reinforced Glass Fibers Waste: Current Status, Materials (2022), PMC8876600 (route comparison table): https://pmc.ncbi.nlm.nih.gov/articles/PMC8876600/
• DTU, Thermoset composite recycling: properties of recovered glass fiber (ICCM20, 2015): https://orbit.dtu.dk/en/publications/f48d18f2-055e-4f65-9f42-d86239ac9921
• OSTI, pre-existing glass fiber damage in sheet molding compound before pyrolysis recycling: https://www.osti.gov/pages/servlets/purl/1607062