US1604576A - Production by carbonation and the addition of sulphates of plastic materials having an initial quick set - Google Patents

Description

Oct. 26 1926. 1,604,576

F. C. MATHERS ET AL PRODUCTION BY CARBONATION AND THE ADDITION OF SULPHATES OF PLASTIC MATERIALS HAVING AN INITIAL QUICK SET Filed July 25. 1923 QMQQMHW @M @Wmamjj i Hmum Patented @et 26, ih.,

narran stares FRANK C. MATHERS, QF BIJQOMINGTON, INDIANA, .AND RUSSEL L. MEX. Oia" WD- VILLE, OHIO, ASSLGNOBS T0 NATIONAL LIME ASSQCIA'IION, 0E' WSHING'IUN, DIS- TRICT 0F COLUMBIA, A CORPOBATIQN 0F THE DISTRICT OF COLUMBI.

raonncrron er cannonarron ann man AnnITIoN or. sunrnarns orrnasrrc Marnamns HAVING an INI'rIAI.- QUICK enr.

l Application filed .Tuly 25,

Our invention relates to the production of plastic materials which have quickinitial setting properties and which are adapted to be used in the making of mortars, p asters, shaped articles such as blocks, boards and the like. y

The use of calcined gypsum for plastering purposes is well known. Gypsum sets so quickly that it is necessary to add varying proportions of a retarding agent to delay the set suciently to allow the workmen time to get the plaster on the wall. In addition to this objection, gypsum has a number of other serious objections and disadvantages. For example, the material is dimcult to work, owing to its lack ot3plasticity and, as compared to lime, its low sand-carrying capacity. llt has been proposed to use lime for plastering purposes but this material has one serious disadvantage namely-. it is necessary to wait a considerable periodV of time-twenty toV twenty-four hours-for each coat to acquire what may be termed its initial set, by which it becomes suciently strong, firm and dry so that the succeeding coat may be applied. This is quite a serious objection since it requires the removal of scaffolds from one room to another between the application of the various coats, if the workmen are not to suspend work entirely.

The term initial set is used to indicate that condition of the lime plaster which makes it suitable for the application of the second or brown coat. It is not necessarily hard in this condition, but is rm, strong and rigid enough to support the weight of the second coat and withstand the pressure necessary in the application ot the' second coat. This is distinguished romthe term hardening in that the latter refers to the condition of the mortar after it has undergonepractically all the physical and chemical changes that it will undergo and has developed a strength near its maximum strength.

Ordinarily, lime mortar does not harden .1923. serial No. 653,718.

to the nal condition ot hardness for a great many months and in some cases a number of years, whereas the initial set occurs in about 20 hours when using-standard sanded lime mortar, and in our mortar, the time of initial set may be adjusted to take place at any desired time after mixing from five minutes to the, time required for standard sand lime mixtures. 'lhe term setl is sometimes used indiscriminately as synonymous with hardness. l When so used, it is of course clear, that the hnal hardness of the material is referred to.

Unless otherwise stated, in the experiments, set forth herein, we have used the standard Gillmore needle in testing for the set of lime mortar. -We rind that when the large l( Sfrillmore needle penetrates to a distance of 2 mm. in the pat the mortar has assumed its set, that is, it is in a condition to receive the second-coat. We believe that thel Gillmore needle test gives a substantially correct indication of the set; of course, in actual practice, the trowel used in applying the second coat exerts pressure over 'a very large area whereas the Gillmore needle puts the pressure on a minute spot. In many cases the test pieces are hard and tirm when tested with a. medium having a large area, such as the hand, although with the Gillmore needle test, the needle will penetrate perhaps a little more than 2 mm. Testing by diderent methods, as indicated above, there may be some di'erence in results, but on the whole, the results will be found to approm'mately correspond. rlhe relation between the penetration of the needle and the suitability of the mortar to receive-the second coat has been checked up by ractical plasterers.

Ve have found that quick initial setting properties may be imparted to plastic materials such as hydrated lime and thereby the latter may be successfully used for plastering purposes and for the production of mortars, blocks `and the like. We have A foundl that when hydrated lime or lime putty that has been exposed to the proper proportion of carbon dioxide is mixed with a compound having a sulphate radical to form a plastic mass, the latter acquires quick in itial setting properties. Either organic or inorganic sulphate compounds may .be used. Among the organic sulphates, aniline sulphate and dimethyl sulphate have given excellent results. However, in the preferred embodiment of our invention, we contemplate the use of the metal sulphates. The proportion of carbon dioxide necessary in the plastic mass for the best results is of paramount importance as will be hereinafter set forth.

In the accompanying gure the curve shows the time of set of mixtures containing carbon dioxide and an inorganic sulphate. The ordinates show the time of set and the abscissae the amount of carbon dioxide present by Weight. This specific curve was plotted from the results obtained by mixing 60 grams of hydrated lime containing varying amounts of carbon dioxide and l gram of ferric sulphate and a suitable amountof Water. Using different mixtures the curve will, of course, vary somewhat, but in general,` the curves will be similar.

Hydrated lime will, on exposure to carbon dioxide, absorb this gas. For the purpose of preparing a quick setting plastic. mass in conjunction with the use of an inorganic sulphate, we have found that the percentage of carbon dioxide must-be controlled. It is quite easy to introduce too much carbon dioxide and, when this occurs, the hydrated lime loses its capacity to take on an initial quick set lwhen used as an ingredient in a plastic mix, such as a plaster mix. Referring to the accompanying gure, it is seen that when the percentage of carbon dioxide present in the hydrated lime is between 1 and 51/2 per cent, the time of set varies through a considerable range from less than one-half hour to less than l1 hours. When the percentage of carbon dioxide is between 1% and 3% per cent the time of set varies between 4 hours and less than a half an hour. The quicklime from which the results set forth in the curve were derived had the following composition:

' Per cent. Calcium oxide 98.00 Iron oxide 0.02 Alumina 0.30 Magnesia 0.45 Silica 0.44

Using different limes, having different physical and chemical characteristics, the percentages of CO2 absorbed by the hydrated lime and periods of set, will, of course, be somewhat diiferent and We do not desire to be limited by any definite percentages. The

results are obtained with a carbon dioxidecontent between 21/2 and 4% per cent.A The percentage of carbon dioxide referred to includes the carbon dioxide in the lime from air-carbonation.

The carbonation of the hydrated lime may be carried out as follows: 'The hydrated lime is placed in a cylindrical vessel provided with battle plates and containing an o ening adapted to receive a tube leading rom a source of carbon dioxide. The vessel containing the hydrated lime is rotated by a motor which insures that the hydrated lime flowing over thev balile plates is thoroughly mixed and therefore uniformly treated by carbon dioxide. The carbon dioxide may be introduced with or withoutthe application of external heat. If the gas is introduced into the hydrated lime without` the external application of heat, a period of 20 or 40 minutes is required in order to get suthcient absorption of the carbon dioxide to give satisfactory results. The absorption of the carbon dioxide by the hydrated lime usually evolves sufficient heat to accelerate the reaction. In small-scale operations, the radiation of the heat is usually suiiiciently rapid to prevent any undesirable overheating and still allow the absorption of the carbon dioxide to occur quickly. However, if the radiation proceeds faster than the generation of heat by the absorption of the carbon dioxide, the absorption may practically cease. ln such cases, the heat-content of the hydrated lime may be maintained by external heating to a suitable temperature. ln some cases we have found 50o C. satisfactory. The carbon dioxide necessary for the carbonation may be prepared in any desired'manner, but at a lime plant the kiln exit gases are conveniently used as a source of carbon dioxide. Limes, which have been exposed to the air until the required quantity of carbon dioxide has been absorbed may be used, in conjunction with a sulphate, to produce a plastic having quick initial setting properties.

The addition of ground calcium carbonate i f inname change but occurs throughout the mass. A.

broken block will show approximately the same hardness in the interior as on the surfac-e.

A mortar or plaster whichA will have a quick initial set may be prepared b mixing carbonated hydrated lime'fand a su pliate in suitable proportions. Hair, sand, or .hair and sand maybe added with the sulphate to .the carbonated hydrated lime and the entire 'mass mixed. with the `required amount of water. .What is known as a 1:3 mix, that is, one part of. carbonated hydrated lime to three parts-.of sand may be used butother `v pro ortions are suitable and we do not desire to e limited to a .mix having any specific composition. lt is not necessary that the sul hate be in avery ne state of division or uniformly mixed' with the `hydrated lime but we have found that the best results are ob-l l tained when the sulphate is added ina 'nely divided-i condition and is `unitormly mixed with thev carbonated hydrated lime. Various organic or inorganic sulphates oitl the type referred to may bevused, butwe have secured the best' results with aniline sulphate and manganese, ferrie, and `ferrous sulphates. Other sulphates which maybe used are those of magnesium, nickel, cobalt, chromium, cadium, andl zinc. rlhese sulphatesare typical of those which do not produce an eorescing compound in reaction with vliime.. Sodium sulphate is typical of those which produce eforesccnceand for this reason is not very desirable. 1

As a specific example illustrative ci our invention the following is given: lift hydrated lime containing from 117/2 to 6 per cent of carbon dioxide by weight with or without sand or other usual ingredients is treated with" an e ual weight of water containing one 'of the a ove-mentioned sulphates, such as magnesium, manganese or iron su]- phate in solution in such amount that the ratio of the dissolved salt to the dry hydrate is one gram to sixty grams, a plaster is obtained which is of normal consistency but which in a few minutes, that is in 5 to 15 minutes yafter being mixed, takes on an initial stiii'ening which when subjected to an indentation test by a one-pound GillmoreA needle gives a reading of 2 nim. lf the ratio of the metallic sulphate to the dry hydrated lime is 1:60 by weight, it is obvious that the resulting plaster sets too quickly, but if the concentration of the metallic sulphate is cut down to 1 :120, a plaster is obtained which acquires an initial set in forty minutes or somewhat longer after being -mixed lt is therefore obvious that by proper regulation of the quantity of metallic sulphate in the carbonated hydrated lime containing from 1.5% to 6% carbon dioxide by weight, a

' in any desired time. ofthe metallic sulphate is gradually reduced limit 'set plaster may be obtained which will set withto zero the time required for set isfcorrespondingly y4 the hydrated lime containing nothing but carbon dioxide.

The carbonated hydrated lime may be mixed with the finely divided sulphate in a dry state in which case there is no reaction between the `mix-constituents until after. the water is added. Proceeding as outlined, the sulphate, carbonated hydrated lime, and other ingredients may be mixed at the place oi manufacture and thereby a prepared dry plaster mix sent to the trade which requires only the addition of water to be immediately available for use. ln a mix prepared as set forth above there is no substantial reaction between theconstituents until the water is drated lime and sulphate progresses slowly,

and consequently no setting action is appar ent within such a time esto permit the placlf the concentration reduced until it approaches the iii) Ving oit the mortar or plaster in place in the joint or on the surface to be plastered. Ultimately, however, after the plaster is in place,

the reaction does progressV to such an extent as to produce the setting action.

The following table shows the eiiect on the time of set of varying amounts of carbon dioxide and sulphate:

Per cent Addition anni addition P9536 'rime ofset agent Era. Min. MuSOi 1.64 3.56 1 20 MnSOi. 8.20. l 3. 56 2 30 Mns 04. 25 3. 7a 3 45 MnSO4. 5.00 2.00 4 40 MnSO4 2 l 3.5 2 30 FeSOi 2 3.5 5 Fe2(SO4); 1.64 3.58 9% Fez ($04)i 2 3. 5 18 .Amlme sulphate i 3.35 set to finger l K in 10 min. Hydrated lime alone--. 20 Prepared gypsum plaster 9 In the above table the percentage of addition agent, and carbon dioxide is figured on the combined weight of the hydrated lime, addition agent, and carbon dioxide. For example, 5% manganese sulphate and 2% carbon dioxide means 5 parts manganese,- 2 parts carbon dioxide and 93 parts of hydrated lime. i l

The test pieces prepared from the above mixtures were molded almost immediately. that is within a minute or two, after water was added to the mix to form the mortar.

instead of using carbonated'hydrated lime as heretofore set forth, putty may also be carbonated by saturating activated cai'- bon with carbon dioxide and distributing the carbon together with a sulphate through the putty mass. It is preferable to use the carbonated hydrate, but as stated,`t-he putty may also be used.

The mixtures set forth should be applied tc the wall .within a few minutes after mixing with water. If the mortar is reworked or retelnpered and it has started to stiifen or set,` it will not set again except after many hours. In order to delay the setting action it is usually necessary to add a retarder in sufficient quantities t0 delay the set and thereby allow the Workmen sufficient sults set forth in the following table were obtained, the hydrated lime contained 4.2 per 'cent of carbon dioxide. Each test piece was made by dissolving the quantity of sugar given in the table and one gram of manganese sulphate in 35 oc. of water. This solution was then added to 30 grams of hydrated carbonated lime and grams of standard sand, after which the whole mass was thoroughly mixed, allowed to stand for 30 minutes, mixed again, and then made into test blocks.

Time otset in hours Grams from maksugar ing of used test piece The time of set, given inthe last column, clearly shows the valuable action of the retarder. Without the retarder, the mixes would have stifi'ened or set inside of 30 minutes. The breaking up of this set by the reworking and forming of the test pieces would have prevented any new set except after several hours. With the quantity of sugar below 0.020 grams, the initial set which had started before the end of thirty minutes was broken up and the new set did not occur until after 7.5 hours. With sugar present in a quantity ranging from 0.03 to 0.1 grams, the initial setl did not start .during the period of standing and, therefore, a set was Obtained in the test blocks in 3.5

hours. With more sugar, 0.12 to 0.14 grams, the final set was delayed to 5.5 hours. Using 60 grams of lime containing 3.35% of carbon dioxide, on the addition of 1% of aniline dissolved in cc. of water and containing 60 milli ams of sugar, the test piece set to the nger in twenty-five minutes.

From the above it is clear that the time of set may be increased or decreased by regulating the quantities of carbon dioxide,

Per cent Time of carbon set in dioxide hours 0.52 20 1. 88 18 g lita 4.48 2% 4. 72 2% 5.19 9 9. 91 19 10. 3 1 20 The term hydrated lime. as used inthe specilication and claims includes various kinds of commercial hydrated lime which may vary considerably in its composition. It is intended to include thereunder both calcium and dolomitic hydrated lime. In addition, we intend to cover with this term dry hydrated lime which is a definite article of commerce or lime putty which may be made from dry hydrated lime or from quick lime.

In the claims, the term carbonated hydrated lime is intended to include any of lthe above described forms of hydrated lime which have been treated with carbon dioxid, the latter being present either inthe combined state or the free state or both.

The elements, sodium, potassium, magnesium, aluminum, chromium, manganese, iron, cobalt and nickel appear in series 3 and 4 of the periodic table as devised b Mendeleef, (see page 2,'Van Nostrands hemical Annual, 5th ed., 1922). In the claims, by the phrase a soluble sulphate o-f a metal in series 3y and 4 of Mendeleefs periodic table, we intend t0 cover any soluble sulphate appearing in series 3 and 4.

We claim:

1. A plastic material having quick initial setting properties consistingof the reaction products of carbonated hydrated lime and a maarre soluhle compound havin a sulphate radical. i

lsetting pro erties consisting of the reaction products o carbonated hydci'ated lime and a soluble sulphate of a metal in series 3 and 4l ci Mendelees periodic table.

A. A plastic material having uick initial setting properties comprising t e reaction products of carbonated hydrated lime and manganese sulphate.

5. A plastic material having quick initial setting properties com rising the reaction products oit a mixture oi a soluble com @und having a sulphate radical and hydrate' lime containing sumcient carbon dioxide as'to aid in imparting to the mixture quick setting properties.

6. A plastic material having nick initial setting properties comprisin t. e reaction products of a mixture of a so uble inorganic sulphate and hydrated lime containing sumcient carbon dioxide as to aid in imparting' to the mixture quick setting properties.

'i'. A plastic material having quick initial setting properties comprising the reaction products or' a mixture of manganese sulphate. and hydrated lime containing sufficient carhon dioxide, as to aid in imparting to the mixture quick setting properties.

8. A plastic material having quick initial setting properties comprising the reaction products oit a mixture of a soluble sulphate of a metal in series 3 and l of Mendeleels per iodio table, and hydrated lime containing a suci-ent quantity or" carbon dioxide, as to aid in imparting to the mixture quick setting properties.

9. A plastic material having quick initial setting properties comprising the reaction products of a mixture of a soluble inorganic sulphate and hydrated lime containing 11/2 to 6 per cent ot carbon dioxide. i

10. A plastic material having quick initial setting properties comprising the reac` tion products of a mixture of a soluble suliliate oit a metal in series 3 and 4 of Mendeleeis periodic table, and hydrated lime coiitaining Ill/2 to 6 per cent carbon dioxide.

11. A plastic material having quick initial setting properties com rising the reaction products ot a mixture o manganese sulphate and hydrated lime containing 11/2 to 6 per cent carbon dioxide.

titl

12. A prepared plaster mix having quick initial setting properties consisting of a mixture oi' a soluble compound having a sul- 14. A prepared plaster mix havin quick initial setting properties consisting o a mixture of a soluble sulphate ot a metal iny series 3 and l of Mendeleeds periodic table, and

carbonated hydrated lime.

15. A prepared plaster mix having quick initial setting properties comprising a mix-fture or manganese sulphate and carbonated hydrated lime.

16. A prepared plaster mix having quick initial settin properties comprisin a mixture orta solu le compound having asulphate radical and hydrated lime containin sumcient carhon dioxide, as to aid in -imp rting to the mixture quick setting properties.

- 1'?. A prepared plaster mix having quick initial setting properties comprisinga mixture oit e soluhle inorganic sulphate and hydrated lime containing sucient carhon dioxide, as to aid in imparting to the mixture quick setting properties.

18. A prepared plaster mix having quick initial setting properties comprising mani ganese sulphate and hydrated lime containing sucient carhon dioxide, as to aid in imparting to the mixture quick setting properties.

19. A prepared p aster mix having quick initial settin properties comprising va mixture ot a solu le compound having a sulphate radical and hydrate lime containing 1% to 6 per cent carbon dioxide.

20. A prepared plaster mix having quick initial setting properties comprising a mixture or a solulole inorganic sulphate and h drated lime containing 11/2 to 6 per cent cadhon dioxide.

ltlll 21. A prepared plaster mix having quick initial setting properties comprising a mixture of manganese sulphate and hydrated lime containing 1V?4 to 6 per cent carbon dioxide.

22. rlhe rials having quick initial setting properties conipiisinf carbonating h drated lime and treating the reaction-Dro uct with a coxnpound having a sulphate radical.

23. The process ot producing plastic mateprocess of producing-plastic materials having quick initial setting properties comprising carbonating hydrated lime until it contains from 11/2% 'to 6% of carhon dioxid and treating the reaction-product with a compound having a'sulphate radical, v

24. The process of producing plastic materials having quick initial settlng properties V", y

comprising carhonating hydrated lime and treating the reaction-product with a soluble inorganic sulphate.

25. The process of producing plastic materials having quick initial setting properties comprising carbonating hydrated lime until it contains from 11/2 to 6 per cent of carbon dioxide and treating the reaction-product with a soluble inorganic sulphate.

26. The process of producing plastic materials having quick initial setting properties ico comprising carbonating hydrated lime and treating the reaction productwith a soluble sulphate of a metal in series 3 and 4 of Me11- deleefs periodic table. y

27. The process of producing plastic materials having quick initial setting properties comprising 'carbonating hydrated lime until it contains from 11/2 to 6% of carbon dioxid K and treating the reaction product with a soluble sulphate of a metal in series 3 and 4 .10 of Mendelees periodic table.

vIn testimony whereof they hereunto afiix their signatures.

FRANK C. MATHERS. RUSSEL L. HARDY.

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