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How did John Smeaton improve hydraulic lime for the Eddystone Lighthouse in 1756?

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Cement The cement-making process, from crushing and grinding of raw materials, through roasting of the ground and mixed ingredients, to final cooling and storing of the finished product.

While planning the construction of the third Eddystone Lighthouse in 1756, John Smeaton conducted research to identify the most effective mortar for underwater use. Through his investigations, he discovered that limestone containing a high proportion of clay produced the best mortar for construction exposed to water.1

By recognizing that this specific composition was essential for creating a durable bond in wet conditions, Smeaton became the first person to identify the properties that constitute hydraulic lime. This breakthrough allowed him to develop a superior mortar that could withstand the constant pounding of waves, a technique that proved vital for the stability of his all-masonry lighthouse design. His work on this project is considered a significant precursor to the development of portland cement.12