2. Discovering cement

To tell the truth, it was a very long story that lasted millennia.

If early man sheltered in caves or caverns, prehistoric man was already building vast huts with cob walls supported by a wooden frame. Clay, which hardens as it dries, was very probably the first binder used by man, but the reversible nature of its properties, making the cob obtained highly sensitive to water, must have been one of the first headaches faced by our distant ancestors.

Around the 4th millennium BC, the Egyptians used water to mix the first real mineral binder: a coarse plaster obtained by calcining gypsum.

Later, the Greeks and Romans were undoubtedly the first to produce hydraulic binders capable of hardening under water. To do so, they mixed quicklime CaO, obtained by firing limestone, with volcanic ash from the Pozzuoli region. This...