Properties of self consolidating concrete for prestressed members
Compressive strength is widely used for specification requirement and quality control of concrete.
Engineers know their target tensile (flexural) requirements and will express these in terms of compressive strength.
without compensating, concrete would almost always fail from tensile stresses – even when loaded in compression.
The blocks appeared to use an aggregate of steel fibres and quartz – a mineral with a compressive strength of 1100 MPa, much higher than typical high-strength aggregates such as granite (100–140 MPa or 15,000–20,000 psi).Reactive powder concrete, also known as ultra-high-performance concrete, can be even stronger, with strengths of up to 800 MPa (116,000 PSI).These are made by eliminating large aggregate completely, carefully controlling the size of the fine aggregates to ensure the best possible packing, and incorporating steel fibers (sometimes produced by grinding steel wool) into the matrix.All concrete structures will crack to some extent, due to shrinkage and tension.
Concrete which is subjected to long-duration forces is prone to creep.Plastic shrinkage cracks can occur soon after placement but if the evaporation rate is high they often can actually occur during finishing operations, for example in hot weather or a breezy day.