S.I. No. 35/1953:

STANDARD SPECIFICATION (PORTLAND CEMENT) ORDER, 1953.

STANDARD SPECIFICATION (PORTLAND CEMENT) ORDER, 1953.

I, SEAN F. LEMASS, 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 (Portland Cement) Order, 1953.

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 1 : 1953.

3.--(1) The Standard Specification (Portland Cement) Order, 1949 ( S.I. No. 162 of 1949 ), is hereby revoked.

(2) References in any other standard specification to the order hereby revoked and to Irish Standard 1 : 1949, thereby prescribed, shall be construed, respectively, as references to this Order and to Irish Standard 1 : 1953.

SCHEDULE

PART I

PORTLAND CEMENT

PART II

SPECIFICATION

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.

SCOPE

1. This specification applies to Normal Portland cement and Rapid-hardening Portland cement.

COMPOSITION AND MANUFACTURE

2. Portland cement shall be manufactured by burning to incipient fusion an intimate and properly proportioned mixture consisting essentially of carbonate of lime, silica, alumina and oxide of iron, and by grinding the resultant clinker to a fine powder. It shall contain no additions subsequent to burning other than gypsum or water or both.

CHEMICAL COMPOSITION

3. The chemical composition of the cement shall be such that the ratio of the percentage of lime, after deduction of that necessary to combine with the sulphuric anhydride present, to the sum of 2·8 times the percentage of silica, 1·2 times the percentage of alumina and 0·65 times the percentage of iron oxide as shown in the formula:

shall be not greater than 1·02 and not less than 0·66.

The ratio of the percentage of alumina (A1₂O₃) to that of iron oxide (Fe₂O₃) shall be not less than 0·66.

The content of magnesia (MgO) shall not exceed 4·5 per cent. by weight.

The content of sulphur expressed as sulphur trioxide and calculated as a percentage by weight shall not exceed

for Normal Portland cement, 2·75 per cent.,

for Rapid-hardening Portland cement, 3·20 per cent.

The content of insoluble residue, when determined by the method described in Appendix B, shall not exceed one per cent. by weight.

The loss of weight on ignition at 900°C.±25°C. shall not exceed 4 per cent.

FINENESS

4. The residue by weight on a No. 170 test sieve, when determined as described in Appendix C, shall not exceed

for Normal Portland cement, 10 per cent,.

for Rapid-hardening Portland cement, 5 per cent.

SETTING TIME

5. When tested by the method described in Appendix E, the initial setting time shall be not less than 45 minutes, and the final setting time not more than 12 hours.

SOUNDNESS

6. When the cement is tested for soundness by the method described in Appendix F, the expansion shall be not greater than 5 mm.

In the event of the cement failing to comply with this requirement a further test shall be made using another portion of the same sample, aerated for seven days as described in Appendix F. When so tested, the expansion shall be not greater than 2·5 mm.

TENSILE STRENGTH

7. For Normal Portland cement the tensile strength, determined in the manner described in Appendix G, shall be :

not less than 330 lb. per sq. in. at 3 days (72 hours), and

not less than 430 lb. per sq. in. at 7 days.

The tensile strength at 7 days shall be greater than that at 3 days.

For Rapid-hardening Portland cement the tensile strength, determined in the manner described in Appendix G, shall be :

not less than 300 lb. per sq. in. at one day (24 hours), and not less than 455 lb. per sq. in. at 3 days (72 hours).

The tensile strength at 3 days shall be greater than that at one day.

PACKING AND MARKING

8. Unless otherwise agreed between the purchaser and vendor the cement shall be delivered in paper bags, each containing 112 lb. nett, with the weight and the manufacturer's name or mark clearly marked thereon.

STORAGE

9. The cement shall be stored in a suitable weather-tight building, and in such a manner as to permit access for the proper inspection and identification of each consignment.

CERTIFICATES OF QUALITY

10. The manufacturer shall satisfy himself that the cement conforms to the requirements of this specification, and if requested, shall furnish a certificate to this effect to the purchaser or his representative. Any vendor shall furnish, on request, free of cost to the purchaser, a copy of such certificate with each consignment of one ton or more of cement sold.

SAMPLING

11. Samples for testing shall be taken in the manner described in Appendix A.

The vendor shall give the purchaser or his representative every facility for taking and packing samples and for the identification later of the cement sampled.

Appendix A

SAMPLING AND SIZE OF SAMPLE

One sample shall be taken from each 100 tons or part thereof. The sample shall consist of approximately equal portions selected from at least five separate bags or from at least five different positions in the heap or heaps when the cement is loose. The sample shall weigh approximately 10 lb. and shall, immediately after taking, be packed in a clean air-tight tin.

Appendix B

METHOD FOR THE DETERMINATION OF INSOLUBLE RESIDUE

One gram of cement shall be weighed into a 250-400 ml. beaker and stirred with 40 ml. of water ; 10 ml. concentrated hydrochloric acid (sp.gr.1·16) shall be added and the mix stirred again. The mix shall be warmed, any lumps present being broken up, and boiled for 10 minutes with stirring if necessary, the volume being maintained constant. The contents of the beaker shall then be filtered, the beaker rinsed out five times with hot water and the residue on the filter washed about ten times with hot water. The residue shall then be washed from the filter paper back into the same beaker with about 30 ml. of hot distilled water and boiled for 10 minutes with 30 ml. of 2N sodium carbonate solution and the volume maintained constant.

The contents of the beaker shall then be filtered through the same filter paper, care being taken that all the residue is transferred to the paper. The residue shall then be washed at least five times with water, then with a little 2N hydrochloric acid solution, and finally with water until free from chlorides. The filter paper with the residue shall be dried and ignited to constant weight. This weight shall be taken as the weight of insoluble residue.

Appendix C

TEST FOR FINENESS

The sieve to be used shall be such that its wire cloth complies with the requirements for the wire cloth of test sieve No. 170 specified in I.S. 24:1950. The wire cloth shall be carefully mounted on the frame without distortion. The sieving surface shall be not less than 50 sq. in. and the depth of the frame shall be not less than 2¾ in. measured from the surface of the wire cloth.

One hundred grams of cement shall be placed on the sieve and continuously sifted for a period of 15 minutes. Air-set lumps in the sample may be broken down with the fingers, but nothing shall be rubbed on the sieve.

Appendix D

DETERMINATION OF NORMAL CONSISTENCY OF CEMENT PASTE

The determination shall be made with a Vicat apparatus having a 10 mm. diameter brass plunger, 50 mm. long with flat lower end, and loaded so that the plunger and load together weigh 300 g. The mould used shall be 80 mm. diameter and 40 mm. deep.

Five hundred grams of cement shall be gauged with a measured quantity of clean fresh water, and the time from the moment of adding the water to commencing to fill the mould shall be not less than three minutes or more than five minutes. The mould resting upon a non-absorbent plate shall be completely filled, the operator's fingers and an ordinary gauging trowel (weighing about 200 g.), only being used. The surface of the paste shall be smoothed off level with the top of the mould. The temperature of the room and of the cement and water at the time the operations are being performed shall be from 58°F. to 64°F. The mould, immediately it is filled, shall be placed, resting on its plate, under the 10 mm. diameter brass plunger. The plunger shall be lowered gently until it comes in contact with the surface of the cement paste and then shall be suddenly released and allowed to sink into it.

Trial pastes shall be made up of varying percentages of water until the paste is such that the plunger comes to rest 5 to 7 mm. above the bottom of the mould. The amount of water used to obtain this result expressed as a percentage by weight of the dry cement shall be taken as the amount required to produce cement paste of normal consistency.

Appendix E

TESTS FOR SETTING TIME

The tests shall be made with a Vicat apparatus. The needle for the initial setting test shall be 1 mm. square in cross-section and have a flat end and shall be loaded so that the needle and load together weigh 300 g. The needle for the determination of the final setting time shall be of the same cross-section but with a metal attachment 5 mm. in diameter hollowed out to form a sharp circular edge and with the needle projecting 0·5 mm. below it. The mould shall be 80 mm. diameter and 40 mm. deep.

The initial and final setting time shall be determined on a test block of cement paste of normal consistency, made in the manner and under the conditions described in Appendix D. The test block shall be kept, during the whole time of the test, at a temperature of 58°F. to 64°F., in an atmosphere of not less than 90 per cent. relative humidity and away from draughts.

Initial setting time : For the determination of initial setting time the mould shall be placed resting on its plate under the 1 mm. square needle. The needle shall be lowered gently until it is in contact with the surface of the test block and then suddenly released and allowed to sink into it. This process shall be repeated until the needle does not pierce it within 5 mm. of the bottom of the mould. The time elapsing between the moment when water is added to the cement and the moment at which the needle stops about 5 mm. from the bottom of the mould shall be taken as the initial setting time.

Final setting time : For the determination of final setting time, the 1 mm. square needle of the Vicat apparatus shall be replaced by the 1 mm. square needle with the 5 mm. diameter metal attachment, which is gently lowered to the surface of the test block. The cement shall be considered to have finally set when the needle makes an impression on the surface of the test block but the attachment fails to do so. In the event of a scum forming on the surface of the test block, the underside of the test block may be used for determining the final set.

Appendix F

TEST FOR SOUNDNESS

The test for soundness shall be made by the " Le Chatelier " method. The apparatus consists of a split cylinder, of metal 0·5 mm. thick, forming a mould of 30 mm. internal diameter and 30 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 cement shall be gauged to form a paste of normal consistency as described in Appendix D. The mould shall be placed on a glass plate and filled with the paste, the edges of the mould being kept gently together during the operation. The mould shall be then covered with another glass plate and a small lead weight placed on top, and the whole immersed in water at a temperature of from 58°F. to 64°F., for 24 hours.

The distance between the indicator points shall then be measured and the mould again immersed in water, within the temperatures mentioned above. The water shall then be brought to boiling point in from 25 to 30 minutes and kept boiling for 1½ hours. The mould shall then be removed from the water and allowed to cool and the distance between the indicator points again measured.

The difference between the two measurements shall be taken as the expansion of the cement.

Aeration of the cement if required shall be carried out by spreading it to a depth of 70 mm. in a room at a temperature of from 58°F. to 64°F., and a relative humidity of not less than 50 per cent.

Appendix G

TEST FOR TENSILE STRENGTH

The sand used in this test shall be a natural quartz sand, of the white variety from Leighton Buzzard, thoroughly washed and dried. It shall pass through a No. 18 test sieve conforming to I.S. 24 : 1950 and not more than 10 per cent. by weight shall pass through a No. 25 test sieve conforming to I.S. 24 : 1950. Its loss of weight on extraction with hot hydrochloric acid shall be not more than 0·25 per cent., when determined as follows :

Dry the sand at 100°C. for 1 hour, weigh out 2 g. into a porcelain dish, add 20 ml. of hydrochloric acid (sp. gr. 1·16), and 20 ml. of distilled water. Heat on a water bath for one hour, filter, wash well with hot water, dry and ignite in a covered crucible.

The moulds used in this test shall be such that briquettes made with them shall have the dimensions and shape shown in Figure 1.

The spatula used in filling the moulds shall be of steel with a wooden handle. It shall have a total length of approximately 355 mm., a weight not exceeding 340 g., and the centre of gravity shall be practically in the centre of the length of the spatula. The flat portion of the spatula shall be about 73 mm. long, 46 mm. wide, 5·6 mm. thick at the centre, tapering to the edges.

Cement and sand in the proportion of one part by weight of cement to three parts by weight of sand shall be gauged with clean fresh water, the percentage of water to be used being determined from Table 1. The mould shall be placed on a non-absorbent or metal plate and filled with the mortar. After filling the mould, more mortar shall be placed on the top and beaten down with the spatula until the mortar is level with the top of the mould. The mould shall then be turned over and the operation repeated on the other side, the mortar being beaten down until water appears on the surface. The flat portion only of the spatula shall be used, and no other method or apparatus shall be used for ramming the mortar in this operation. The briquettes shall be finished off in the moulds by smoothing the surface with the blade of a trowel.

The moulds containing the briquettes shall be kept in a damp box or chamber, at a temperature of from 58°F. to 64°F., and not less than 90 per cent. relative humidity, for 24 hours after gauging. The briquettes shall then be taken out of the moulds and immediately immersed in clean fresh water, at a temperature of from 58°F. to 64°F., and kept there until required for testing.

The briquettes shall be tested for tensile strength at the specified ages reckoned from the filling of the moulds. The briquettes shall be held centrally in metal jaws of the shape shown in Figure 2 and oiled paper or other suitable material shall be placed between the surfaces of the briquette and the jaws so as to distribute the load uniformly. The load shall be uniformly applied commencing at zero and increasing at the rate of 100 lb. per sq. in. in 12 seconds.

The average of the values of the tensile strengths of four briquettes of the same age shall be taken as the tensile strength for that age.

TABLE 1.

PERCENTAGE OF WATER FOR GAUGING 3 TO 1 SAND AND CEMENT MORTAR.

"

GIVEN under my Official Seal, this 26th day of January, 1953.

(Signed) SEÁN F. LEMASS.

Minister for Industry and Commerce.