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* Hydraulic mortars for masonry construction of harbor works, etc ... , in contact with sea water.
* Development of strong concretes.
In [[Kingdom of Great Britain|Britain]] particularly, good quality building stone became ever more expensive during a period of rapid growth, and it became a common practice to construct prestige buildings from the new industrial bricks, and to finish them with a [[stucco]] to imitate stone. Hydraulic limes were favored for this, but the need for a fast set time encouraged the development of new cements. Most famous was Parker's "[[Roman cement]]".<ref>A.J. Francis, ''The Cement Industry 1796-1914: A History'', David & Charles, 1977, ISBN 0-7153-7386-2, Chap. 2.</ref> This was developed by [[James Parker (cement maker)|James Parker]] in the 1780s, and finally patented in 1796. It was, in fact, nothing like any material used by the Romans, but was a "Natural cement" made by burning [[Concretion#Septarian concretions|septaria]] - nodules that are found in certain clay deposits, and that contain both [[clay minerals]] and [[
[[John Smeaton]] made an important contribution to the development of cements when he was planning the construction of the third [[Eddystone Lighthouse]] (1755-9) in the [[English Channel]]. He needed a hydraulic mortar that would set and develop some strength in the twelve hour period between successive high tides. He performed an exhaustive market research on the available hydraulic limes, visiting their production sites, and noted that the "hydraulicity" of the lime was directly related to the clay content of the [[limestone]] from which it was made. Smeaton was a [[civil engineer]] by profession, and took the idea no further. Apparently unaware of Smeaton's work, the same principle was identified by [[Louis Vicat]] in the first decade of the nineteenth century. Vicat went on to devise a method of combining chalk and clay into an intimate mixture, and, burning this, produced an "artificial cement" in [[1817]]. [[James Frost (cement maker)|James Frost]],<ref>Francis ''op. cit.'', Chap. 5</ref> working in Britain, produced what he called "British cement" in a similar manner around the same time, but did not obtain a patent until 1822. In 1824, [[Joseph Aspdin]] patented a similar material, which he called Portland cement, because the render made from it was in color similar to the prestigious [[Portland stone]].
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==The setting of cement==
Cement sets when mixed with water by way of a complex series of hydration chemical reactions still only partly understood. The different constituents slowly hydrate and crystallise while the interlocking of their crystals gives to cement its strength. [[Carbon dioxide]] is slowly absorbed to convert the [[portlandite]] (Ca(OH)<sub>2</sub>) into insoluble [[
==Environmental impacts==
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===CO<sub>2</sub> emissions===
Cement manufacturing releases CO<sub>2</sub> in the atmosphere both directly when [[
The amount of CO<sub>2</sub> emitted by the cement industry is nearly 900 kg of CO<sub>2</sub> for every 1000 kg of cement produced.
<ref>
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