What it is and the problem it solves
Prestressed concrete is a composite structural material that solves concrete’s weakness in tension. It does this by embedding or surrounding concrete with tensioned high-strength steel tendons, generating internal compression that offsets tensile stresses from loading.
How it works
It works by tensioning high-strength tendons—inside or adjacent to the concrete—to induce controlled compression before service loads are applied. Freyssinet used jacks to raise and connect arches, introducing prestress mechanically. He recognised that only high-strength wire could counteract creep and relaxation, and developed anchorages to make the system adaptable.
What works
The planned introduction of internal stresses counteracts imposed loads as intended. The resulting behaviour matches the claim: high-strength concrete under compression, ductile high-strength steel under tension. Freyssinet demonstrated this in practice—132 m hollow arches completed in 1923, prestressed beams used in shipyard building consolidation.
What does not
It does not eliminate creep. Freyssinet discovered creep in concrete—the time-dependent deformation under stress—and his system was designed to compensate for it, not prevent it. The 1928 patent came after years of observing its effects; the method mitigates but does not abolish the phenomenon.
What it changes
It changes how concrete carries tension. Instead of relying solely on passive reinforcement, it pre-emptively compresses the section so that service loads must first overcome that compression before tensile stress develops in the concrete itself. This enables longer spans, thinner sections, and reduced cracking.
Is it worth your time
Yes—if you work with long-span concrete structures, foundations on compressible ground, or retrofits requiring minimal added weight. It demands precise control of material behaviour over time, not just at installation.