Sorel cement (also known as magnesia cement or magnesium oxychloride ) is a non-hydraulic cement first produced by the French chemist Stanislas Sorel in 1867. [1]
In fact, in 1855, before working with magnesium compounds, Stanislas Sorel first developed a two-component cement by mixing zinc oxide powder with a solution of zinc chloride. [2] [3] In a few minutes he obtained a dense material harder than limestone.
Only a decade later, Sorel replaced zinc with magnesium in his formula and also obtained a cement with similar favorable properties. This new type of cement was stronger and more elastic than Portland cement, and therefore exhibited a more resilient behavior when submitted to shocks. The material could be easily molded like plaster when freshly prepared, or machined on a lathe after setting and hardening. It was very hard, could be easily bound to many different types of materials (good adhesive properties), and colored with pigments. Therefore, it was used to make mosaics and to mimic marble. After mixing with cotton crushed in powder, it was also used as a surrogate material for ivory to fabricate billiard balls resistant to shock. [4]
Sorel cement is a mixture of magnesium oxide (burnt magnesia) with magnesium chloride with the approximate chemical formula Mg4Cl2(OH)6(H2O)8, or MgCl2·3Mg(OH)2·8H2O, corresponding to a weight ratio of 2.5–3.5 parts MgO to one part MgCl2. [5]
Quite surprisingly, much more recently, another chemist, Charles A. Sorrell (1977, 1980) – whose family name sounds quite similar to that of Stanislas Sorel – also studied the topic and published works on the same family of oxychloride compounds based on zinc and magnesium, just as Sorel had done about 100 years before. The zinc oxychloride cement is prepared from zinc oxide and zinc chloride instead of the magnesium compounds. [6] [7]
The set cement consists chiefly of a mixture of magnesium oxychlorides and magnesium hydroxide in varying proportions, depending on the initial cement formulation, setting time, and other variables. The main stable oxychlorides at ambient temperature are the so-called "phase 3" and "phase 5", whose formulas can be written as 3Mg(OH)
2·MgCl
2·8H
2O and 5Mg(OH)
2·MgCl
2·8H
2O, respectively; or, equivalently, Mg
2(OH)
3Cl·4H
2O and Mg
3(OH)
5Cl·4H
2O. [8]
Phase 5 crystallizes mainly as long needles which are actually rolled-up sheets. These interlocking needles give the cement its strength. [9]
In the long term the oxychlorides absorb and react with carbon dioxide CO
2 from the air to form magnesium chlorocarbonates. [10]
These compounds are the primary components of matured Sorel cement, first prepared in 1867 by Stanislas Sorel. [1]
In the late 19th century, several attempts were made to determine the composition of the hardened Sorel's cement, but the results were not conclusive. [11] [12] [13] [14] Phase 3 was properly isolated and described by Robinson and Waggaman (1909), [11] and phase 5 was identified by Lukens (1932). [15]
Sorel cement can withstand 10,000–12,000 psi (69–83 MPa) of compressive force whereas standard Portland cement can typically only withstand 7,000–8,000 psi (48–55 MPa). It also achieves high strength in a shorter time. [16]
Sorel cement has a remarkable capacity to bond with, and contain, other materials. It also exhibits some elasticity, an interesting property increasing its capacity to resist shocks (better mechanical resilience), particularly useful for billiard balls.
The pore solution in wet Sorel cement is slightly alkaline (pH 8.5 to 9.5), but significantly less so than that of Portland cement (hyperalkaline conditions: pH 12.5 to 13.5). [17]
Other differences between magnesium-based cements and portland cement include water permeability, preservation of plant and animal substances, and corrosion of metals. [18] These differences make different construction applications suitable. [19]
Prolonged exposure of Sorel cement to water leaches out the soluble MgCl
2, leaving hydrated brucite Mg(OH)
2 as the binding phase, which without absorption of CO2, can result in loss of strength. [17]
In use, Sorel cement is usually combined with filler materials such as gravel, sand, marble flour, asbestos, wood particles and expanded clays. [20]
Sorel cement is incompatible with steel reinforcement because the presence of chloride ions in the pore solution and the low alkalinity (pH < 9) of the cement promote steel corrosion (pitting corrosion). [17] However, the low alkalinity makes it more compatible with glass fiber reinforcement. [20] It is also better than Portland cement as a binder for wood composites, since its setting is not retarded by the lignin and other wood chemicals. [20]
The resistance of the cement to water can be improved with the use of additives such as phosphoric acid, soluble phosphates, fly ash, or silica. [17]
Magnesium oxychloride cement is used to make floor tiles and industrial flooring, in fire protection, wall insulation panels, and as a binder for grinding wheels. [20] Due to its resemblance to marble, it is also used for artificial stones, [20] artificial ivory (e.g. for billiard balls) and other similar purposes.
Sorel cement is also studied as a candidate material for chemical buffers and engineered barriers (drift seals made of salt-concrete) for deep geological repositories of high-level nuclear waste in salt-rock formations (Waste Isolation Pilot Plant (WIPP) in New Mexico, USA; Asse II salt mine, Gorleben and Morsleben in Germany). [21] [22] [23] Phase 5 of the magnesium oxychloride could be a useful complement, or replacement, for MgO (periclase) presently used as a CO2 getter in the WIPP disposal chambers to limit the solubility of minor actinides carbonate complexes, while establishing moderately alkaline conditions (pH: 8.5–9.5) still compatible with the undisturbed geochemical conditions initially prevailing in situ in the salt formations. The much more soluble calcium oxide and hydroxide (portlandite) are not authorized in WIPP (New Mexico) because they would impose a too high pH (12.5). As Mg2+
is the second most-abundant cation present in sea water after Na+
, and that magnesium compounds are less soluble than those of calcium, magnesium-based buffer materials and Sorel cement are considered more appropriate backfil materials for radioactive waste disposal in deep salt formations than common calcium-based cements (Portland cement and their derivatives). Moreover, as magnesium hydroxychloride is also a possible pH buffer in marine evaporite brines, Sorel cement is expected to less disturb initial in situ conditions prevailing in deep salts formations. [24]
Sorel cement is usually prepared by mixing finely divided MgO powder with a concentrated solution of MgCl
2. [17]
In theory, the ingredients should be combined in the molar proportions of phase 5, which has the best mechanical properties. However, the chemical reactions that create the oxychlorides may not run to completion, leaving unreacted MgO particles and/or MgCl
2 in pore solution. While the former act as an inert filler, leftover chloride is undesirable since it promotes corrosion of steel in contact with the cement. Excess water may also be necessary to achieve a workable consistency. Therefore, in practice the proportions of magnesium oxide and water in the initial mix are higher than those in pure phase 5. [20] In one study, the best mechanical properties were obtained with a molar ratio MgO:MgCl
2 of 13:1 (instead of the stoichiometry 5:1). [20]
Periclase (MgO) and magnesite (MgCO
3) are not abundant raw materials, so their manufacture into Sorel cement is expensive and limited to specialized niche applications requiring modest materials quantities. China is the dominant supplier of raw materials for the production of magnesium oxide and derivatives.[ citation needed ] Magnesium-based "green cements" derived from the more abundant dolomite ((Ca,Mg)(CO
3)
2) deposits (dolomite), but also containing 50 wt. % calcium carbonate, have to be not confused with the original Sorel cement, as this latter does not contain calcium oxide. Indeed, Sorel cement is a pure magnesium oxychloride.
Magnesium is a chemical element; it has symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals it occurs naturally only in combination with other elements and it almost always has an oxidation state of +2. It reacts readily with air to form a thin passivation coating of magnesium oxide that inhibits further corrosion of the metal. The free metal burns with a brilliant-white light. The metal is obtained mainly by electrolysis of magnesium salts obtained from brine. It is less dense than aluminium and is used primarily as a component in strong and lightweight alloys that contain aluminium.
The term chloride refers either to a chloride ion, which is a negatively charged chlorine atom, or a non-charged chlorine atom covalently bonded to the rest of the molecule by a single bond. Many inorganic chlorides are salts. Many organic compounds are chlorides. The pronunciation of the word "chloride" is.
Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions held together by ionic bonding. Magnesium hydroxide forms in the presence of water (MgO + H2O → Mg(OH)2), but it can be reversed by heating it to remove moisture.
Magnesium hydroxide is an inorganic compound with the chemical formula Mg(OH)2. It occurs in nature as the mineral brucite. It is a white solid with low solubility in water (Ksp = 5.61×10−12). Magnesium hydroxide is a common component of antacids, such as milk of magnesia.
Magnesium sulfate or magnesium sulphate is a chemical compound, a salt with the formula MgSO4, consisting of magnesium cations Mg2+ (20.19% by mass) and sulfate anions SO2−4. It is a white crystalline solid, soluble in water but not in ethanol.
Manganese dioxide is the inorganic compound with the formula MnO
2. This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for MnO
2 is for dry-cell batteries, such as the alkaline battery and the zinc–carbon battery. MnO
2 is also used as a pigment and as a precursor to other manganese compounds, such as KMnO
4. It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. MnO
2 has an α-polymorph that can incorporate a variety of atoms in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in α-MnO
2 as a possible cathode for lithium-ion batteries.
Magnesium carbonate, MgCO3, is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals.
Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca(OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed with water. It has many names including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime. Calcium hydroxide is used in many applications, including food preparation, where it has been identified as E number E526. Limewater, also called milk of lime, is the common name for a saturated solution of calcium hydroxide.
Magnesium chloride is an inorganic compound with the formula MgCl2. It forms hydrates MgCl2·nH2O, where n can range from 1 to 12. These salts are colorless or white solids that are highly soluble in water. These compounds and their solutions, both of which occur in nature, have a variety of practical uses. Anhydrous magnesium chloride is the principal precursor to magnesium metal, which is produced on a large scale. Hydrated magnesium chloride is the form most readily available.
Zinc chloride is the name of inorganic chemical compounds with the formula ZnCl2·nH2O, with x ranging from 0 to 4.5, forming hydrates. Zinc chloride, anhydrous and its hydrates are colorless or white crystalline solids, and are highly soluble in water. Five hydrates of zinc chloride are known, as well as four forms of anhydrous zinc chloride. This salt is hygroscopic and even deliquescent. Zinc chloride finds wide application in textile processing, metallurgical fluxes, and chemical synthesis. No mineral with this chemical composition is known aside from the very rare mineral simonkolleite, Zn5(OH)8Cl2·H2O.
Iron(III) oxide-hydroxide or ferric oxyhydroxide is the chemical compound of iron, oxygen, and hydrogen with formula FeO(OH).
Magnesium compounds are compounds formed by the element magnesium (Mg). These compounds are important to industry and biology, including magnesium carbonate, magnesium chloride, magnesium citrate, magnesium hydroxide, magnesium oxide, magnesium sulfate, and magnesium sulfate heptahydrate.
Stanislas Sorel was a French civil engineer, inventor, and chemist, raised the son of a poor clock-maker.
Friedel's salt is an anion exchanger mineral belonging to the family of the layered double hydroxides (LDHs). It has affinity for anions as chloride and iodide and is capable of retaining them to a certain extent in its crystallographical structure.
Magnesium oxide, more commonly called magnesia, is a mineral that when used as part of a cement mixture and cast into thin cement panels under proper curing procedures and practices can be used in residential and commercial building construction. Some versions are suitable for general building uses and for applications that require fire resistance, mold and mildew control, as well as sound control applications. Magnesia board has strength and resistance due to very strong bonds between magnesium and oxygen atoms that form magnesium oxide crystals.
Concrete degradation may have many different causes. Concrete is mostly damaged by the corrosion of reinforcement bars due to the carbonatation of hardened cement paste or chloride attack under wet conditions. Chemical damages are caused by the formation of expansive products produced by various chemical reactions, by aggressive chemical species present in groundwater and seawater, or by microorganisms. Other damaging processes can also involve calcium leaching by water infiltration and different physical phenomena initiating cracks formation and propagation. All these detrimental processes and damaging agents adversely affects the concrete mechanical strength and its durability.
Calcium nitrite is an inorganic compound with the chemical formula Ca(NO
2)
2. In this compound, as in all nitrites, nitrogen is in a +3 oxidation state. It has many applications such as antifreeze, rust inhibitor of steel and wash heavy oil.
Magnesium hydroxychloride is the traditional term for several chemical compounds of magnesium, chlorine, oxygen, and hydrogen whose general formula xMgO·yMgCl
2·zH
2O, for various values of x, y, and z; or, equivalently, Mg
x+y(OH)
2xCl
2y(H
2O)
z−x. The simple chemical formula that is often used is MgClOH, which appears in high school subject, for example.Other names for this class are magnesium chloride hydroxide, magnesium oxychloride, and basic magnesium chloride. Some of these compounds are major components of Sorel cement.
Calcium hydroxychloride is the inorganic compound with the formula CaOHCl. A white solid, it forms by the reaction of hydrogen chloride with calcium hydroxide According to X-ray crystallography, it adopts a layered structure related to brucite (Mg(OH)2).