Valid meaning.....? Its insulative value is low, however its thermal properties are such that it would make a great flooring material for a south facing room with large windows that receive solar gain in the winter. Fiber-filled concrete is stronger than other forms of concrete. It also has the potential to last far, far much longer than steel-rebar filled concrete since most fiber fill is fiber glass or other 'stable' materials.. Concrete and rebar structures tend to 'fall apart' over long periods, decades or centuries depending on the climate that the structure is built. Steel corrodes, granted embedded in concrete that process is slowed, however it does rust and the process of rusting leads to its expansion, that breaks apart the concrete surrounding it. Fiber-filled does not go through this process (unless it is also strengthened with rebar). and potentially could last as long as granite or other 'hard' rocks, subject to the other processes of erosion. Due to the problems of steel companies are developing fiber-filled and carbon mesh and even carbon composite 'rebar' technologies to make stronger, longer lasting concrete. For foundations and slabs (floors) rebar is not really needed on most soil types. Rebar is needed in spans of concrete since concrete has nearly no span strength, although has great compression strength. In some areas building code is now allowing mesh and fiber composite concretes instead of rebar strengthened concrete in house pours (foundation, footings and slabs) depending on the stability of the soils. Sand is considered 'unstable' and leads to uneven setting of a slab, clay however is considered stable. in areas where the bed rock is high or just below the ground surface they allow fiber-fill concrete pours to take place in smaller applications for SLABS only. Footings, foundations are load bearing, holding the walls of the structure, thus need the extra binding of a cage (steel, or carbon-carbon composite material). I understand that a "new" plastic is coming out that is extremely light, but very durable, it is formed much like steel rebar- circular with 'rings' however the rings are larger. It is not a pure plastic like a milk jug, instead it is laced with fiberglass or carbon fibres. I personally would use a mesh screen wire with a slab and of course would pour a thicker slab - The design for our future home has 2 'levels' Kitchen, bath(s), pantry and laundry room are over a shallow cellar (5 feet deep) and raised (30 inches) above the rest of the slab pour floor. I decided to go with 8 inch slabs for living, dining and bedrooms composed of fiber-filled concrete, inlaid with inert plumbing materials (the "newer" CPVC) for hot water heating via solar heating and of course solar gain where the slab becomes the thermal mass.