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United States Patent (19) 11 4,209,339 Smith-Johannsen 45 Jun

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United States Patent (19) 11 4,209,339 Smith-Johannsen 45 Jun United States Patent (19) 11 4,209,339 Smith-Johannsen 45 Jun. 24, 1980 54 CEMENT COMPOSTIONS 3,667,978 6/1972 Vassilevsky et al. ................ 106/107 3,751,275 8/1973 Oken .................................... 106/104 75 Inventor: Robert Smith-Johannsen, Incline Village, Nev. Primary Examiner-James Poer 73 Assignee: Noreem A/S, Oslo, Norway Attorney, Agent, or Firm-Pennie & Edmonds 21 Appl. No.: 912,837 57 ABSTRACT 22 Filed: Jun, 5, 1978 Water resistant magnesium oxychloride hydrate (Sorel 51) int. Cl? ........................... C04B 9/02; C04B 9/14 cement) compositions and processes for producing the same. The processes comprise the addition of an ethyl 52 U.S. C. .................................................... 106/106 silicate and/or a premix of magnesium chloride and 58 Field of Search ........................ 106/105, 106, 107 magnesium oxide to the magnesium oxychloride hy (56) References Cited drate reaction mixture (MgCl2--MgO) followed by the U.S. PATENT DOCUMENTS subsequent reaction and curing thereof. 2,717,841 9/1955 Biefeld et al. ........................ 106/07 3,573,941 4/1971 Edwards et al. ..................... 106/107 22 Claims, No Drawings 4,209,339 1. 2 material to the standard Sorel cement formula or devel CEMENT COMPOSITIONS oping a formula and processes which will result in greater stability and strength. BACKGROUND OF THE INVENTION To this end, and as concerns the former case, appli Sorel cement is a term used to refer to various com 5 cant has discovered that when an ethyl silicate is added positions having as basic ingredients a combination of to a standard Sorel cement formula there results a mate magnesia (MgO) and magnesium chloride (MgCl2) in an rial whose water resistance and strength properties are aqueous solution. This basic Sorel formula system when considerably improved. Although the exact order of cured is a magnesium oxychloride hydrate. addition of the reactants, the relative amount of reac Sorel cement was discovered almost 100 years ago. It O tants and the condition under which the reaction is to gets harder, and sets faster than Portland cement, but its take place are not critical, it has been found advanta widespread use has been greatly limited because of its geous to first mix and dissolve the MgCl2.6H2O in the inherent poor water resistance. The magnesium oxy water, after which the MgO is dispersed. Subsequent to chloride hydrate crystals that compose the Sorel ce this the ethyl silicate is dispersed therein, preferably ment have been found to have a structure very much 15 under conditions of high agitation. Although, as noted, like gypsum in that the physical properties of the ce the amount of ethyl silicate is...not critical and the same ment depend on an intimate infiltration of the crystals, need only be added in a water stabilizing amount, it has one with another, but with no real bond between the been found advantageous to add from about 0.5-2% by crystals. The Sorel cement product is also somewhat weight of ethyl silicate based upon the total weight of soluble in water with the result that exposure to water the Sorel cement formula. The resulting formula may virtually eliminates the adhesion between the crystals. then be cured under normal and well known conditions Various attempts have been made to overcome this such as at room temperature and over an extended per difficulty such as the addition of materials which have iod of time. the property of forming insoluble magnesium salts, such The other mode of achieving substantially improved as phosphates and aluminates. The results have been 25 only partially successful and in fact usually with the water stability and strength involves improving the further disadvantage that the hardening rate is greatly solution of the MgO in the MgCl2 in accord with the slowed. nucleation theory of this aspect of the invention as the Various fillers have been reported in the literature, same explained in more detail below. The improved but mainly from the point of view of their compatibility 30 results are obtained by first preparing a Premix formula rather than that they impart any special properties to which is comprised of water, a relatively large amount the cement. Glass fibers have been tried with some of MgCl2.6H2O and a relatively small amount of MgO. success, but the bond between the glass fibers and the The Premix formula is thereafter added to a standard Sorel cement is destroyed by exposure to water and Sorel cement formula and acts, in effect, as a seeding thus the structural advantages of the glass fibers are 35 solution. Particularly improved results are obtained only temporary. when the Premix formula is added to a Sorel cement It is obvious from repeated statements in the litera formula which contains ethyl silicate in accord with the ture that had it not been for the water sensitivity of first aspect of this invention. Sorel cement products, their use would have been much More particularly, it is preferred that the Premix more general and wide spread. It is exactly because of 40 formula be prepared under such conditions that MgCl2 this drawback of these cement products that there re concentration in solution is maximized, this will in turn mains a large potential for these materials if the water increase the solubility of MgO and the resulting forma sensitivity problem could be solved. The superior hard tion of magnesium oxychloride hydrate. To this end, it ening rate, greater strength and excellent fire retardant is preferred that a near saturated solution of MgCl2 and properties of Sorel cement could then be taken advan 45 water, preferably dionized water, be prepared at or near tage of in a host of building materials where its use is the boiling point (about 120° C). This will insure that presently not considered. there results a concentrated solution of MgCl2 and in creased solubility of MgO so that when a small amount SUMMARY OF THE INVENTION of the MgO is added to the solution, preferably under The present invention relates to water/moisture resis 50 conditions of vigorous stirring, the same will quickly tant magnesium oxychloride hydrate (Sorel cement) and almost completely react with the MgCl2 to form the formulae compositions and processes for producing the magnesium oxychloride hydrate. As can be seen from same. The processes comprise the addition of an ethyl the foregoing, the relative amounts of the MgCl2, MgO silicate and/or a Premix formula of magnesium chloride and water reactants in the Premix formula, as well as and magnesium oxide to the magnesium oxychloride 55 the reactive conditions, are not critical, it being only hydrate reaction mixture (MgCl2--MgO) followed by required that substantially all of the MgO react to form the subsequent reaction and curing thereof. The inven the magnesium oxychloride hydrate. tion further comprises the addition of various sub The order in which the ingredients of the Sorel ce stances, reinforcing materials or fillers such as glass ment formula of this aspect of the invention are ad fibers to the compositions of this invention. mixed, including the Premix formula constituent thereof, as well as the relative amounts of each such DETALED DESCRIPTION OF THE ingredient and the conditions under which admixture is INVENTION to take place, are not critical. The same applies also in Applicant has discovered that the aforediscussed the case wherein the Sorel cement formula contains disadvantage of present day Sorel cement formulae, and 65 ethyl silicate in accord with the first aspect of this in especially as relates to the very poor stability in and vention. It is, however, preferred to first dissolve all of sensitivity to water of the resulting cement products, the MgCl2.6H2O in all of the water that is to be used, can be largely overcome either by addition of a certain preferably at room temperature, and to thereafter add 4,209,339 3 4. the Premix formula. As noted, the amount of Premix of crystals of magnesium oxide, magnesium chloride formula that is added is not critical, it only being re hydrate and magnesium oxychloride hydrate. This ma quired that the Premix formula be added in an amount terial would be weak because the residual MgO cannot sufficient to effectuate nucleation. It has been found, contribute to the new crystal entanglement, and hence however, that the Premix formula may advantageously to the strength and stability of the cement, and it would be added in an amount of from about 1-5% by weight be very sensitive to water exposure since the magne based on the total weight of the Sorel cement formula. sium chloride is soluble and is easily leached out, elimi After the Premix formula is added, the entire amount of nating the necessary intimate contact between the mag MgO that is to be used is added. In the case where ethyl nesium oxychloride hydrate crystals which is responsi silicate is to be employed, the same is finally added. The 10 ble for the stability and strength of the end-product resulting Sorel cement formula may then be cured cement material. under normal and well known conditions such as at If this physical picture is correct, it would suggest the room temperature and over an extended period of time. possibility of a greatly improved Sorel cement formula It should be observed that the Sorel cement formulae provided that these reactions could be controlled and of the present invention may contain other ingredients 15 residual MgCl2 eliminated-that is, if the solution of the besides MgCl2.6H2O, MgO and H2O, as these other MgO can be completed before the hydration reaction ingredients are customary and well known in the art. starts. The foregoing would appear to depend on the These include ferrous chloride, feltspar, a release agent, phenomenon of nucleation.
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