They certainly can. They're competing with dirt, because you can dig up dirt and use it as filler in construction. So either they need to have some favourable properties compared to dirt, or the "crushing/grinding" process has to be really cheap, or the alternatives for disposing of the blades have to be expensive.

If dirt was scarce, we'd find an economic way to recycle turbine blades. We should be happy to have so much dirt, not sad that we can't reuse our end-of-life turbine blades. The same goes for the other suggestion mentioned in the article, of using them to put roofs on homeless shelters - there are other materials which are cheaper and more suitable, and no homeless shelters are going unbuilt because evil energy companies won't donate their old blades.

The article talks about a startup that is crushing them for into pellets.

>Global Fiberglass Solutions, developed a method to break down blades and press them into pellets and fiber boards to be used for flooring and walls. The company started producing samples at a plant in Sweetwater, Texas, near the continent’s largest concentration of wind farms. It plans another operation in Iowa.

https://www.globalfiberglassinc.com/

Fibrous things like fiberglass and carbon fiber get their strength from the length of the fibers distributing force across the assembly. Ground fiberglass is basically worthless after you account for supply compared to demand. It would be better to cut them up into strips/sheets and use them to build retaining walls or something (using them whole is not practical because they are big enough to make transport expensive). The inertness of fiberglass in the presence of most common things makes it an attractive building material for things that are expose to the weather but it is expensive when new and until now there has never been much supply of used fiberglass in any consistent form factors so it is rarely used and construction techniques are not very mature (read: common enough to be cost competitive).

Honestly we can probably just let old turbine blades pile up. If there's one thing the free market is good at it's finding creative uses for expensive materials that are waste products as far as their original use is concerned.

Composite turbine blades are a suitable fuel and feedstock for cement kilns. The challenge is logistical, to have enough feedstock in inventory to keep the kiln fed. Pyrolysis is also an option (similar to plasma gasification), and is how scrap automobile tires are disposed of, although you're then landfilling the resulting ash (although it might perhaps also be used in cement or asphalt).

My quick read of it lands on them not being toxic, just large and difficult to manage. Seems like they could be used as aggregate in road construction or fill or just about whatever. Likewise, its not like they break down into some shockingly toxic biproduct, so burying them is a fine solution unless refurbishment becomes a real possibility.