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  2. Roman concrete - Wikipedia

    en.wikipedia.org/wiki/Roman_concrete

    Roman concrete, also called opus caementicium, was used in construction in ancient Rome. Like its modern equivalent , Roman concrete was based on a hydraulic-setting cement added to an aggregate . Many buildings and structures still standing today, such as bridges, reservoirs and aqueducts, were built with this material, which attests to both ...

  3. Scientists Finally Solved the Mystery of Roman Concrete’s ...

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    Calcium is a binding agent in Roman concrete, which makes it remarkably strong. Figuring out where it came from was the key to solving this architectural mystery.

  4. Properties of concrete - Wikipedia

    en.wikipedia.org/wiki/Properties_of_concrete

    Engineers usually specify the required compressive strength of concrete, which is normally given as the 28-day compressive strength in megapascals (MPa) or pounds per square inch (psi). Twenty eight days is a long wait to determine if desired strengths are going to be obtained, so three-day and seven-day strengths can be useful to predict the ...

  5. Pantheon, Rome - Wikipedia

    en.wikipedia.org/wiki/Pantheon,_Rome

    No tensile test results are available on the concrete used in the Pantheon; however, Cowan discussed tests on ancient concrete from Roman ruins in Libya, which gave a compressive strength of 20 MPa (2,900 psi). An empirical relationship gives a tensile strength of 1.47 MPa (213 psi) for this specimen. [52]

  6. Scientists Finally Solved the Mystery of Roman Concrete’s ...

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  7. 2,000 years later, ancient Roman concrete still stands — and ...

    www.aol.com/2-000-years-later-ancient-222152484.html

    Modern concrete crumbles in decades, but the concrete Colosseum still stands — a mystery that puzzled scientists. 2,000 years later, ancient Roman concrete still stands — and experts finally ...

  8. Pozzolanic activity - Wikipedia

    en.wikipedia.org/wiki/Pozzolanic_activity

    Compressive strength testing is carried out at fixed moments, typically 3, 7, and 28 days after mortar preparation. A material is considered pozzolanically active when it contributes to the compressive strength, taking into account the effect of dilution.

  9. Types of concrete - Wikipedia

    en.wikipedia.org/wiki/Types_of_concrete

    High-strength concrete has a compressive strength greater than 40 MPa (6000 psi). In the UK, BS EN 206-1 [3] defines High strength concrete as concrete with a compressive strength class higher than C50/60. High-strength concrete is made by lowering the water-cement (W/C) ratio to 0.35 or lower.