S.I. No. 286/1949 - Standard Specification (Hydrated Lime For Building Purposes) Order, 1949.

S.I. No. 286 of 1949.


I, DANIEL MORRISSEY, Minister for Industry and Commerce, in exercise of the power conferred on me by subsection (3) of section 20 of the Industrial Research and Standards Act, 1946 (No. 25 of 1946), hereby order as follows :

1. This Order may be cited as the Standard Specification (Hydrated Lime for Building Purposes) Order, 1949.

2.—(1) The specification set forth in Part II of the Schedule to this Order is hereby declared to be the standard specification for the commodity described in Part I of the said Schedule.

(2) The said standard specification may be cited as Irish Standard 8 : 1949.






In this specification, the letters I.S., when followed by two sets of numbers, refer to the Irish Standard of which the first is the serial number and the second the year of its promulgation by the Minister for Industry and Commerce.

In this specification, the letters B.S., when followed by two sets of numbers, refer to the British Standard of which the first is the serial number and the second is the year of its publication by the British Standards Institution.


1. Hydrated lime sold under this Specification shall be in the form of a fine dry powder produced by treating quicklime with sufficient water in any suitable form so as to produce a dry, sound product. It shall be suitable for plastering finishing coat, coarse stuff, and building mortar.

The term HYDRATED LIME shall mean a dry hydrated lime in which the magnesium oxide does not exceed 8 per cent. of the ignited sample (See Clause 6).

If the magnesium oxide exceeds 8 per cent. of the ignited sample the lime shall be termed MAGNESIAN HYDRATED LIME andit shall always be so described by the vendor. Magnesian hydrated lime shall be suitable for use for plastering finishing coat, coarse stuff, and building mortar, after it has been mixed wet for a period of two weeks.

The quicklime employed in the production of hydrated lime shall consist essentially, either of calcium oxide, or of calcium oxide together with a smaller proportion of magnesium oxide (See Clause 6), as may have been agreed upon between purchaser and vendor, formed by burning a natural rock or other suitable material at such a temperature that it will slake when brought into contact with water.


2. If tests are required, the hydrated lime shall be sampled at a place and time to be mutually agreed upon between the purchaser and vendor. The size of sample and the method of sampling shall be as described in Appendix A.


3. The manufacturer shall satisfy himself by regular periodical tests that the material shall be capable of conforming to the requirements of this Specification, and a Certificate to this effect in the form set out in Appendix J shall be provided, free of charge, at the request of the purchaser.

When the purchaser requires tests to be carried out the cost of such tests shall be borne as follows :

(i) by the vendor in the event of the results indicating that the material does not comply with the Specification,

(ii) by the purchaser in the event of the results indicating that the material does comply with the Specification.

The test results shall be reported in the form set out in Appendix K.


4. Where references are made to British Standard Sieves, these shall be in accordance with Part 2 of B.S. 410 : 1943, Test Sieves.

The water used in all operations shall be pure and free from more than traces of dissolved salts and, unless otherwise stated, shall be of a temperature between 12° C. and 20° C. (54° F. and 68° F.).


5. The hydrated lime shall be such that the specified requirements are complied with in respect of the following :—

(i) Content of calcium oxide (See Clause 6).

(ii) Content of magnesium oxide (See Clause 6).

(iii) Content of carbon dioxide (See Clause 7).

(iv) Content of insoluble matter (See Clause 8)

(v) Fineness (See Clause 9).

(vi) Soundness (See Clause 10).


6. The calcium and magnesium compounds present in the lime, and calculated as oxides, shall be not less than 80 per cent. by weight of the ignited sample. The remainder shall be essentially composed of silica and alumina, which are soluble when treated in the manner described in Appendix C.


7. The content of carbon dioxide shall not exceed 5 per cent. by weight.


8. The insoluble matter shall not exceed 1 per cent. by weight when determined in accordance with Appendix C.


9. The hydrated lime, when treated in the manner described in Appendix D, shall leave not more than 5 per cent. by weight on a B.S. Test Sieve No. 72, and, after passing this sieve, not more than 10 per cent. by weight shall remain on a B.S. Test Sieve No. 170. Both calculations shall be based on the weight of the hydrated lime taken. The sieves used shall conform to B.S. 410 : 1943, Test Sieves.


10. When tested for soundness in accordance with Appendix G, the test pats prepared from the hydrated lime shall exhibit no disintegration, popping or pitting on their surface, and when tested for soundness in accordance with Appendix H none of the Le Chatelier moulds shall exhibit an expansion greater than 10 mm.


11. Unless otherwise agreed between the purchaser and the vendor, the hydrated lime shall be delivered in paper bags of suitable type and quality containing 56 lb. or 112 lb. net with the weight and the manufacturer's name or brand clearly marked thereon.


12. The hydrated lime shall be stored in a suitable weather-tight building, and in such a manner as to permit access for the proper sampling and identification of each consignment.


Facilities for Sampling and Identification.

The sample or samples required for the purposes of this Specification shall be taken by the purchaser, or his representative, as he desires, either at the works of the manufacturer, at the stores of the vendor, or as soon as possible after the receipt of the consignment. The purchaser shall himself, or through his testing agent, notify thevendor of intention and location of sampling, so as to give the vendor reasonable opportunity of being represented at the sampling and, where necessary, to make arrangements for the sampling to be carried out. If the vendor be a merchant it shall be his duty to notify the manufacturer of the proposed tests, and the purchaser shall be entitled to understand that this has been done.

The vendor shall afford every facility for efficient sampling and for identifying the hydrated lime sampled.

The sampling shall be carried out as quickly as possible so that the material shall not deteriorate. The total time occupied in mixing (and, if necessary, quartering down) the composite sample, and the preparation (where necessary) of the final sample or samples from this, shall not exceed two hours. The final samples shall be enclosed immediately in clean, dry, airtight containers ; when testing is not to be carried out at once, the sample or samples shall be enclosed, marked and sealed to the satisfaction of all concerned, and special attention shall be paid to the air-tightness of the containers.

The final sample or samples, each of not less than 10 lb. (5 kg.), shall be taken as follows : Sufficient material for the sample or samples shall be taken direct in approximately equal portions selected from at least 12 different positions when the lime is loose, or from not less than 12 different bags or other packages when the lime is not loose, or, where there is a less number than 12 different packages, from each package. Every care shall be taken in the selection so that a fair average sample is obtained.

Material for Tests and Chemical Analyses.—Subsequently, at the time and place at which the tests and chemical analyses are to be carried out, the above described sample shall be thoroughly mixed, and rather more than sufficient hydrated lime for the said tests shall be taken in such a manner as to be as representative as possible.

Of the material finally chosen, sufficient for the chemical analyses, about 1 oz. (30 g.), shall be rapidly ground, with as little exposure to the air and water-vapour as possible, to pass the B.S. Test Sieve No. 52, and placed in a small air-tight container.


Determination of Loss on Ignition.

The loss on ignition shall be determined on a portion of the sample for chemical analysis, ground to pass the B.S. Test Sieve No. 52, described in Appendix A above, by igniting at a temperature not less than 1,000° C. (1,832° F.) to constant weight within a limit of variation of 0·2 per cent.


Determination of Insoluble Matter.

To approximately 5 g. of the sample which has been ground to pass a B.S. Test Sieve No. 52 shall be added at least 150 ml. of 2N hydrochloric acid. The mixture shall then be stirred to break uplumps, heated to boiling point, and allowed to stand for ten minutes. It shall then be washed by decantation through a filter paper which has been dried at 100° C.±10° C. (212° F.±18° F.) and has been weighed, retaining the solid residue as far as possible in the original vessel. Any residue from the filter shall be washed back to the original vessel with 5 per cent. sodium carbonate solution, using about 50 ml., and the whole heated to boiling point. The residue shall be allowed to settle, shall again be washed by decantation through the same filter with similar precautions, and any residue on the filter washed back with the 5 per cent. sodium carbonate solution and heated to boiling point as before. The total residue shall be brought on to the original filter, washed with water, then with 2N hydrochloric acid, and again washed with water until the washings are free from chloride. The tared filter paper and residue shall be dried at 100° C.±10° C. (212° F.±18° F.) and weighed. This weight, less the weight of the tared filter paper, shall be recorded as the insoluble matter when calculated as a percentage of the lime taken.


Determination of Fineness.

100 g. of the hydrated lime shall be placed on a B.S. Test Sieve No. 72 superimposed on a B.S. Test Sieve No. 170 and washed on and through the sieves with a moderate jet of water from a flexible tube, the whole operation taking not over thirty minutes. The residues shall not be rubbed through the sieves. The actual residue on each sieve shall then be dried at 100° C.±10° C. (212° F.±18° F.) to constant weight and weighed, the amounts being recorded as " residue on B.S. Test Sieve No. 72 " and on " No. 170 " respectively, when calculated as a percentage of the weight of the hydrated lime taken.


Description of Gauging Plaster.

The plaster of Paris used for gauging in the soundness test for hydrated lime (See Appendix G), shall be of good quality fine white calcium sulphate plaster, obtained by calcining gypsum at a low: temperature ; it shall contain not less than 90 per cent. by weight of calcium sulphate (CaSO4), and show a loss of between 5 and 7 per cent. by weight when heated at 160° C. (320° F.) with free access of air until the weight is constant. It should substantially all pass a B.S. Test Sieve No. 72. When gauged with 50 per cent. of its own weight of distilled water at a temperature between 12° C. and 20° C. (54° F. and 68° F.) it shall show an initial setting time, as indicated by the Vicat needle, of not less than four and not greater than fifteen minutes.


Standard Sand.

Description.—The standard sand shall be obtained from Leighto Buzzard, shall be of the white variety, and shall be thoroughly washe and dried. Its loss of weight on extraction with hot hydrochloric acid shall be not more than 0·25 per cent.

The sand shall pass through a B.S Test Sieve No. 18 and be retained on a B.S. Test Sieve No. 25.

Test for Loss of Weight.—To carry out the test, dry the sand at 100 C.± 10° C. (212° F.±18° F.) for one hour, weigh out 2 g. into a porcelain dish, add 20 ml. of hydrochloric acid of specific gravity 1·16 and 20 ml. of distilled water. Heat on the water bath for one hour, filter, wash well with hot water, dry and ignite in a covered crucible.


Determination of Soundness. Pat Test.

For the purposes of the soundness test, Clause 10, four test specimens shall be separately prepared in the following manner :

70 g. of the hydrated lime under test shall be thoroughly mixed with 70 ml. of clean water at a temperature between 12° C. and 20° C. (54° F. and 68° F.) and allowed to soak for two hours.

At the expiration of two hours, the lime putty thus obtained shall be thoroughly mixed and " knocked up " with a trowel, with, if necessary, a small additional amount of clean water, so as to obtain a plastic mass ; it shall then be spread out on a non-porous surface. 10 g. of plaster of Paris (as described in Appendix E) shall then be added, the plaster being scattered evenly over the putty, and the whole shall be mixed with the trowel rapidly and thoroughly for two minutes.

A flat pat shall then be formed by pressing the gauged material into a ring mould 100 cm. (4 in.) in diameter and 5 mm. (¼ in.) deep, greased inside and resting on a well-greased non-porous plate. (One gramme of petroleum jelly per pat is suitable for greasing when renewed each time.)

The gauged putty shall be pressed in small quantities at a time, with the aid of a broad palette-knife or spatula, in such a manner as to avoid air bubbles. It shall then be smoothed off level with the top edge of the ring with not more than 12 strokes of the knife, any excess material being removed in this process. The total time shall not exceed five minutes from the time of adding the plaster of Paris to the last stroke of the knife for any one pat.

The four pats thus formed shall be left to set for half an hour. They shall then be transferred on their base-plates with or without their ring-moulds to a well-ventilated drying-oven maintained at a temperature between 35° C. and 45° C. (95° F. and 113° F.) to be well dried. A period or periods amounting to a total of sixteen hours should be ample for this purpose, but a minimum of four hours suffices in many cases.

The pats may be left in the cool oven either before drying or between the periods of drying.

Any test pats which show shrinkage cracks before steaming shall be rejected and replaced by fresh pats.

The four pats, still on their base-plates, shall be placed horizontally in a suitable steam boiler in which the water is already boiling, and subjected to the action of saturated steam at atmospheric pressure for a period of three hours. The steamer shall be so arranged that condensed water cannot drip back on to the face of the pats.

The pats shall then be examined in a good light for disintegration, popping or pitting.


Determination of Soundness. Le Chatelier Test.

The standard " Le Chatelier " apparatus consists of a split cylinder of spring brass, or other suitable metal, 0·5 mm. in thickness forming a mould 13 mm. internal diameter and 13 mm. deep. Two indicators with pointed ends are symmetrically attached to the mould, one on each side of the split. The distance from the centre of the mould to the line joining the points of the indicators is 165 mm. The moulds shall be kept in good condition, having the jaws not more than 0·5 mm. apart. Three moulds shall be used for the test and the expansions recorded.

The mortar shall be prepared and gauged in the following manner :

A suitable amount of hydrated lime shall be mixed with one-third its weight of normal Portland cement conforming to I.S. 1 : 1949, and four times its weight of the standard sand specified in Appendix F. The whole shall first be well mixed dry and then gauged and well mixed with 12 per cent. by weight of water, calculated on the dry mix. The three Le Chatelier moulds, previously well greased internally, shall be immediately filled as described, and tested simultaneously.

In conducting the test each mould shall be placed upon a small non-porous plate and filled with the mortar gauged in the manner described, care being taken to keep the edges just visibly opened when this operation has been performed and to avoid the introduction of air-voids. The mould shall then be covered with another non-porous plate, upon which a small weight shall be placed. The whole shall then be left undisturbed for one hour. At the expiration of this period the distance separating the indicator points shall be measured and the whole transferred to a damp air cupboard for a period of forty-eight hours.

The whole shall then be removed, with covers in place, from the damp air cupboard and placed in a suitable steam boiler, in which the water is already boiling vigorously, and subjected to the continuous action of saturated steam at atmospheric pressure for a period of three hours, but not immersed in the water.

At the expiration of this period, the moulds shall be removed from the steamer and allowed to cool and the distances between the indicator points again measured. The increases, if any, over the former measurement shall in no case exceed 10 mm. after the deduction of 1 mm. (to allow for the expansion of the added cement) from the measured expansion. The figure so obtained shall be recorded as the net lime expansion.


Certificate as to Compliance with Irish Standard 8 : 1949.

We............................................................ .................................................hereby certify that the/images/si286y49p1807a.gif lime supplied by us to your order No.. and referred to in Delivery Note No........ complies with Irish Standard 8 : 1949.

(Signed):............................................................ .....


Form of Test Certificate.

Certificate No...................

Name and Address of.....................

Testing Laboratory



Sample received from.............................................

Date received..............................

Identification marks....................................

Result of test

Specification limits

Chemical Analyses :

Content of Calcium Oxide, CaO.


Content of Magnesium Oxide, MgO.


(If percentage exceeds 5%, product shall be termed Magnesian Hydrated Lime)

Content of CaO + MgO.



Content of Carbon dioxide, CO2



Content of Insoluble Matter



Fineness :

Residue on B.S. Test Sieve No. 72



Residue on B.S. Test Sieve No. 170 after passing B.S. Test Sieve No. 72



Soundness :

Disintegration, popping or pitting on four pats


Net expansion of three Le Chatelier moulds



None over 10 mm.


Remarks :



GIVEN under my Official Seal this 4th day of November, 1949.


Minister for Industry and Commerce.