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Tobermorite is a
''''Ancient lessons: Roman concrete durable, green'', Jim Destefani, ed., Ceramic Tech Today, The American Ceramic Society, June 7, 2013
/ref>
Tobermorite in the American Mineralogist Crystal Structure Database
{{commonscat, Tobermorite Calcium compounds Calcium minerals Cement Crestmore Heights, California Geology of Riverside County, California 4.5 Inorganic compounds Inosilicates Minerals in space group 20 Orthorhombic minerals
calcium silicate hydrate
Calcium silicate hydrates (CSH or C-S-H) are the main products of the hydration of Portland cement and are primarily responsible for the strength of cement-based materials. They are the main binding phase (the "glue") in most concrete. Only well de ...
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...
with chemical formula:
Ca5Si6O16(OH)2·4H2O or
Ca5Si6(O,OH)18·5H2O.
Two structural varieties are distinguished: tobermorite-11 Å and tobermorite-14 Å.
Tobermorite occurs in hydrated cement
A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi ...
paste and can be found in nature as an alteration mineral in metamorphosed
Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism. The original rock (protolith) is subjected to temperatures greater than and, often, elevated pressure of or more, causi ...
limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
and in skarn
Skarns or tactites are coarse-grained metamorphic rocks that form by replacement of carbonate-bearing rocks during regional or contact metamorphism and metasomatism. Skarns may form by metamorphic recrystallization of impure carbonate protoliths, ...
. It has been reported to occur in the Maqarin Area of north Jordan
Jordan, officially the Hashemite Kingdom of Jordan, is a country in the Southern Levant region of West Asia. Jordan is bordered by Syria to the north, Iraq to the east, Saudi Arabia to the south, and Israel and the occupied Palestinian ter ...
and in the Crestmore Quarry near Crestmore Heights, Riverside County, California
California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...
.
Tobermorite was first described in 1880 for an occurrence in Scotland
Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...
, on the Isle of Mull
The Isle of Mull or simply Mull ( ) is the second-largest island of the Inner Hebrides (after Skye) and lies off the west coast of Scotland in the Council areas of Scotland, council area of Argyll and Bute.
Covering , Mull is the fourth-lar ...
, around the locality of Tobermory.
Use in Roman concrete
Aluminum-substituted tobermorite is understood to be a key ingredient responsible for the longevity of ancient undersea Roman concrete. The volcanic ash that Romans used for construction of sea walls contained phillipsite, and an interaction with sea water caused the crystalline structures in the concrete to expand and strengthen, making that material substantially more durable than modern concrete when exposed to sea water.Ancient Romans made world’s ‘most durable’ concrete. We might use it to stop rising seas''
Washington Post
''The Washington Post'', locally known as ''The'' ''Post'' and, informally, ''WaPo'' or ''WP'', is an American daily newspaper published in Washington, D.C., the national capital. It is the most widely circulated newspaper in the Washington m ...
'', Ben Guarino, July 4, 2017. Retrieved July 5, 2017./ref>
Cement chemistry
Tobermorite is often used in thermodynamical calculations to represent the pole of the most evolved calcium silicate hydrate (C-S-H). According to itschemical formula
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...
, its atomic Ca/Si or molar CaO/SiO2 (C/S) ratio is 5/6 (0.83). Jennite
Jennite is a calcium silicate hydrate mineral of general chemical formula: Ca9Si6O18(OH)6·8H2O.
Jennite occurs as an alteration mineral in metamorphosed limestone and skarn. It typically occurs as vein and open space fillings as a late minera ...
represents the less evolved pole with a C/S ratio of 1.50 (9/6).
See also
* Othercalcium silicate hydrate
Calcium silicate hydrates (CSH or C-S-H) are the main products of the hydration of Portland cement and are primarily responsible for the strength of cement-based materials. They are the main binding phase (the "glue") in most concrete. Only well de ...
(C-S-H) minerals:
**
**
**
**
**
**
**
* Other calcium aluminium silicate hydrate, (C-A-S-H) minerals:
** Hydrogarnet
** Hydrogrossular
** Hydrotalcite
** Katoite
** Tacharanite ()
References
Further reading
* American Mineralogist (1954) 39, 1038. * * * * * * * * * * *External links
Tobermorite in the American Mineralogist Crystal Structure Database
{{commonscat, Tobermorite Calcium compounds Calcium minerals Cement Crestmore Heights, California Geology of Riverside County, California 4.5 Inorganic compounds Inosilicates Minerals in space group 20 Orthorhombic minerals