Proportions for 4000 lb.

per sq.

in. Concrete

Based on 28-day compressive strength of 6x12 in. cylinders.

Proportions are expressed by volume as follows: Portland Cement: Fine Aggregate : Coarse Aggregate.

Thus 1:2.6:4.6 indicates 1 part by volume of portland cement, 2.6 parts by volume of fine aggregate and 4.6 parts by volume of coarse aggregate.

Quantities of Materials for 1 cu. yd. of 4000 lb. per sq. in. Concrete

The volume of cement is expressed in barrels and of aggregates in cubic yards. F= fine aggregate; C coarse aggregate.

Quantities are net, no allowance being made for waste; for average conditions, the following additions are suggested: Cement, 2%; fine aggregate, 10%; coarse aggregate, 5%.

JOINT COMMITTEE ON SPECIFICATIONS FOR CONCRETE

PIPE

JOB TUTHILL, Chairman; A. F. ROBINSON, Joint Committee.

The Joint Concrete Culvert Pipe Committee was formed to prepare Standard Specifications for Concrete Pipe for railroad and highway use and is composed of representatives of the following societies:

American Society for Testing Materials:

Chairman, Anson Marston, Dean, Engineering Department, Iowa State College, Ames, Iowa.

A. E. Phillips, Sanitary Engineer Washington, D. C. American Society Civil Engineers:

T. L. D. Hadwen, Masonry Engineer, C. M. & St. P. Ry., Chicago, Ill. Geo. H. Tinker, Bridge Engineer, N. Y. C. & St. L. Ry., Cleveland, Ohio

American Concrete Institute:

A. B. Cohen, Consulting Engineer, New York City.

B. S. Pease, Engineer, American Steel & Wire Company, Chicago, Illinois.

American Concrete Pipe Association:

C. F. Buente, Manager, Concrete Products Company, Pittsburgh, Pa. Paul Kircher, Western Manager, Massey Concrete Products Company, Chicago, Ill.

American Association of State Highway Officials:

Prof. T. R. Agg, Iowa State College, Ames, Iowa.

J. N. Mackall, Chairman, Maryland State Road Commission, Baltimore, Md.

Bureau of Public Roads, U. S. Department of Agriculture:

Thos. H. MacDonald, Chief of Bureau.

A. T. Goldbeck, Engineer of Tests.

American Railway Engineering Association:

A. F. Robinson, Bridge Engineer, Atchison, Topeka & Santa Fe Rail

way.

Job Tuthill, Assistant Chief Engineer, Pere Marquette Railway.

The first meeting of the Committee was held at Atlantic City, June 27, 1919, when Mr. H. T. Shelly, then representing the American Society for Testing Materials, was elected Chairman and the following sub-committees were appointed:

No. 1-Classification and Loading Requirements.

No. 2-Design.

No. 3-Methods and Requirements of Tests.

No. 4-Workmanship and Installation.

The representation at this meeting was but one member from each association and it was decided to ask that a second representative be appointed. This was subsequently done, bringing the membership to its present numbers.

Professor Agg advised the meeting that the Iowa State College would extend its experimental work in its investigation of pressures of earth on pipes to include larger sizes and greater height of fills, conforming to conditions of railroad and highway work and that the information obtained would be available to the Committee for determining the loading that should be considered in designing concrete pipe.

Several meetings of sub-committees and two of the general committee have been held since and more or less preliminary work done awaiting more definite information as to the actual pressures coming on pipes from fills. Last spring Mr. Shelly resigned and Dean Marston was appointed in his stead as representative for the American Society for Testing Materials and elected by the Committee as its chairman.

The investigation at the Engineering Experiment Station of the Iowa State College to determine the pressures of earth on pipes under conditions similar to those of railroad and highway work has been in progress and two experiments completed. The details of these and the results obtained will be published in a Bulletin at an early date by the Engineering Experiment Station. A pipe 42 inches in diameter was used and the embankment carried to a height of twenty feet. In a general way the results indicate considerably greater pressures than have heretofore been assumed or considered probable and that the pressure increases in proportion to the increase in the height of the fill above the pipe. The Engineering Experiment Station intends to continue this investigation, as it is not felt that the results so far obtained are sufficient to afford an authoritative answer to the question, and that considerable more experimental work is neces

sary.

The information gained has been made available for the immediate use of the Committee and will be a valuable help in its work.

Appendix D

OUTLINE OF WORK FOR THE ENSUING YEAR

C. C. WESTFALL, Chairman; R. ARMOUR, T. L. CONDRON, RICHARD L HUMPHREY, Sub-Committee.

The following outline of work is recommended for next year's work:

1. Study the Manual and submit proposed revisions thereof. 2. Continue representation on Joint Committee on Standard Specifications for Concrete and Reinforced Concrete and report progress and recommendations thereon.

3. Continue representation on Joint Committee on Specifications for Concrete Pipe and report progress and recommendations thereon.

4. Study and report on factors causing deterioration of concrete

structures.

5. Report on distribution of loads and impacts through ballast and embankments as affecting the design of masonry structures.

6. Study and report on the developments in the art of making con

crete.

7. Recommend a carefully considered outline of work for the ensuing year.