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REVISION OF MANUAL
Since the adoption of a Specification and Tests for Portland Cement in 1917, the allowance of a variation of 1 per cent passing the No. 200 sieve, as provided in the Tests for the Determination of Fineness, has under an agreement by those interested been omitted from the specification.
The specification as amended has been approved on January 15, 1921, as "Tentative Standard" by the American Engineering Standards Committee.
The Committee is recommending that we omit paragraph 36 in order to make our specification identical.
The Progress Report of the Joint Committee on Standard Specifications for Concrete and Reinforced Concrete was submitted to the constituent organizations June 4, 1921, and it has been issued to the members of the American Railway Engineering Association. Under the rules of organization of that committee the discussion of this report will be open for not less than six months nor more than one year from the above date.
A number of discussions have been received from members and your Committee has reviewed the specifications but will defer its report until some time after the Annual Convention, when it is hoped the discussions will all be in. It is then the intention of this Committee to again review the report and make recommendations for presentation to the Joint Committee.
In view of the advancement in the art that has been developed through the work of the Joint Committee, it is the recommendation of the Masonry Committee that certain changes and additions to the Specifications for Plain and Reinforced Concrete and for Steel Reinforcement, as they appear in the Manual, be issued as a supplement in order to keep our specifications up to date as follows: For Paragraph 11, on consistency, substitute the following:
11 (a) The quantity of water used in mixing shall be the least amount that will produce a plastic or workable mixture which can be properly compacted in the forms and around the reinforcement. Under no circumstances shall the consistency of the concrete be such as to permit a separation of the coarse aggregate from the mortar in handling.
(b) The Engineer shall determine and specify the consistency of the concrete for various portions of the work based on test of the materials to be used. The consistency of the concrete shall be measured by the slump test (for description of test and methods of making slump tests, see Vol. 22, Proceedings for 1921, pages 553 to 564 inclusive).
(c) The consistency of the concrete shall be checked at the beginning of each daily run, and at least once a day thereafter during the progress of the concreting, or when the size of any aggregate or its moisture condition changes.
Under the general heading of Materials, Paragraphs 1 to 7 inclusive,
add the following paragraph:
ORGANIC IMPURITIES IN SAND.—Natural sand which shows a color darker than the standard color when tested in accordance with the Colorimetric Test for Sands (see Appendix B) shall not be used unless the concrete made with the materials and in the proportions to be used on the work is shown by tests to be of the required strength. As a footnote to the section on Steel Reinforcement, Paragraph 7,
add the following:
See Appendix C for “Tentative Specifications for Cold-Drawn Steel Wire for Concrete Reinforcement." Include under section on Steel Reinforcement the following:
Standard Sizes of Bars. Reinforced bars shall conform to the areas and equivalent sizes shown in Table I.
Table I-SIZES AND AREAS OF REINFORCED Bars. Size of Bar
Area, sq. in. Inches
Round Square 38
0.196 0.250 58
1.563 The areas of deformed bars shall be determined by the minimum crosssection thereof. Include under Section VI, on Depositing, Paragraphs 23 to 28, the
following provision for Spouting:
SPOUTING.—When authorized by the engineer, concrete may be conveyed by spouting, in which case the plant shall be of such size and design as to insure a practically continuous flow in the spout. The angle of the spout with the horizontal shall be such as to allow the concrete to flow without separation of the ingredients. The spout shall be thoroughly flushed with water before and after each run. The delivery from the spout shall be as close as possible to the point of deposit. When operation must be intermittent, the spout shall discharge into a hopper.
DEVELOPMENTS IN THE ART OF MAKING CONCRETE
J. E. FREEMAN, Chairman; J. C. NAGLE, Noah Johnson, F. W. LEATHER
TENTATIVE SPECIFICATIONS FOR COLD-DRAWN STEEL
WIRE FOR CONCRETE REINFORCEMENT*
Serial Designation: A 82-21 T. These specifications are issued under the fixed designation A 82; the final num. ber indicates the year of original issue, or in the case of revision, the year of last revision.
Issued, 1921. Material Covered.
1. These specifications cover cold-drawn steel wire to be used as such, or in fabricated form, for the reinforcement of concrete, in gages not less than 0.080 in. nor greater than 0.500 in. Basis of Purchase.
2. When wire is ordered by gage number the following relation between number and diameter, in inches, shall apply unless otherwise specified. Gage
Equivalent Gage Equivalent Number
Diameter, Inches Number Diameter, Inches 0000000.
(I) MANUFACTURE Process.
3. (a) The steel shall be made by either or both the following processes: Bessemer or open-hearth. Drawing.
(b) The wire shall be cold drawn from rods hot-rolled from billets.
•Criticisms of these Tentative Specifications are solicited and should be directed, preferably before January 1, 1922, to F. M. Waring, Chairman of Committee Al on Steel, Pennsylvania System, Altoona, Pa.
(II) PHYSICAL PROPERTIES AND TESTS Tension Tests.
4. (a) The wire, except as specified in paragraphs (b) and (c), shall conform to the following minimum requirements as to tensile properties : Tensile strength, lb. per sq. in..
.80,000 Reduction of area, per cent.
30 (b) For wire to be used in the fabrication of mesh a minimum tensile strength of 70,000 lb. per sq. in. shall be permitted.
(c) For wire testing over 100,000 lb. per sq. in. tensile strength the reduction of area shall be not less than 25 per cent. Bend Tests.
5. The test specimen shall withstand being bent cold through 180 deg. without cracking on the outside of the bent portion, as follows: For wire 0.3 in. in diameter or under a pin the diameter of which
is equal to the diameter of the specimen.. For wire over 0.3 in. in diameter, around a pin the diameter of
which is equal to twice the diameter of the specimen. Test Specimens.
6. Tension and bend test specimens shall be of the full-size section of the wire as drawn. Number of Tests.
7. (a) One tension and one bend test shall be made for each 10 tons or less of each size of wire.
(b) If any test specimen shows defects or develops flaws, it may be discarded and another specimen substituted.
(III) PERMISSIBLE VariaTIONS IN GAGE 8. The diameter of the wire shall not vary more than 0.003 in. from the size ordered.
(IV) WORKMANSHIP AND FINISH 9. The finished wire shall be free from injurious defects and shall have a workmanlike finish with smooth surface.
(V) INSPECTION AND REJECTION Inspection
10. The manufacturer shall afford the inspector, without charge, all reasonable facilities to satisfy him that the wire is being furnished in accordance with these specifications. All tests and inspection shall be made at the place of manufacture prior to shipment, unless otherwise specified, and shall be so conducted as not to interfere unnecessarily with the operation of the works. Rejection.
11. Wire which shows injurious defects subsequent to its acceptance at the manufacturer's works will be rejected, and the manufacturer shall be notified.
ABRAMS' SELECTIVE CONCRETE STRENGTH TESTS
Giving Proportions and Quantities of Materials,
as measured by the slump test. The following tables were prepared by Prof. Duff A. Abrams, based on experimental studies of concrete carried out at the Structural Materials Research Laboratory, through the cooperation of the Portland Cement Association and Lewis Institute. The investigations on which these tables are based covered a period of about seven years and included nearly one hundred thousand tests.
Separate tables of Proportions and Quantities of Materials have been prepared for concrete of compressive strengths of 1,500, 2,000, 2,500, 3,000, 3,500 and 4,000 lb. per sq. in. at the age of 28 days, using fine and coarse aggregate of different sizes and a wide range of consistencies as measured by the slump test.
The proportions are based on the compressive strengths of 6 by 12-in. cylinders made and stored in accordance with the Tentative Methods of Making Compression Tests of Concrete of the American Society for Testing Materials. The principal features of this method are: Aggregates dry and of known sieve analysis, proportion by volume, concrete handmixed, puddled in metal cylinder forms, generally 6 by 12 in. in size. Plasticity of concrete controlled by slump test, specimens cured in damp sand and tested in compression at 7 and 28 days.
The quantities of materials per cubic yard of finished concrete given in the tables are net quantities, no allowance being made for waste. The conditions peculiar to each job should govern waste allowances which the estimator should base on experience or other data available; for average conditions, the following allowances for waste are suggested:
Cement 2 per cent, fine aggregate 10 per cent, coarse aggregate 5 per cent.
The above percentages do not include any allowance for grouting, patching, washing or replacements.
The purpose of the tables is threefold:
(1) To furnish a guide in the selection of mixtures to be used in preliminary investigations of the strength of concrete from given ma terials.
(2) To indicate proportions which may be expected to produce concrete of a given strength under average conditions where control tests are not made.
(3) To furnish à correct basis for comparing the relative economies of concretes made from aggregates of different sizes when the plasticity and strength of the resulting concrete are taken into account.
The chief value of the tables of Quantities of Materials is in comparative studies of different aggregates and combinations, but they should also prove useful in estimating. The quantities are based on laboratory