A treatise on concrete, plain and reinforced:materials, construction, and design of concrete and reinforced concrete,
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A o> r' *<• 'Cr* c>* v <> >. ° ° : ,4.^ '.wf- aV-** - r 'o , i * A v. . -. v ^ X^rs / "v^P' o^ \;-^'\, Oa ^ v% * »aV1^ C\ > v^ Frontispiece Harvard Stadium A TREATISE ON CONCRETE PLAIN AND REINFORCED MATERIALS, CONSTRUCTION, AND DESIGN OF CONCRETE AND REINFORCED CONCRETE WITH CHAPTERS BY R. FERET, WILLIAM B. FULLER, FRANK P. McKIBBEN AND SPENCER B. NEWBERRY BY FREDERICK W. TAYLOR, M.E., Sc.D. <1 AND SANFORD E. THOMPSON, S.B. M.Am.Soc.C.E. Consulting Engineer SECOND EDITION TOTAL ISSUE, FOURTEEN THOUSAND > * ^ > « 0 4 NEW YORK JOHN WILEY & SONS London: CHAPMAN & HALL, Limited 1911 Copyright, 1905, 1909, bt FREDERICK W. TAYLOR All rights reserved om Mishas? ■Alt 31 IS11 IF aver iy Press , % alii more, Md. PREFACE TO FIRST EDITION This treatise is designed for practicing engineers and contractors, and also for a text and reference book on concrete for engineering students. To broaden the scope of the work and avoid personal inaccuracies, each chapter has been submitted for critcism to at least one, and, in some cases, to three or four specialists in the particular line treated. We have aimed to refer by name to all authorities quoted, and where the data is taken from books or periodicals, to give the original publication, so that each subject may be investigated further. Proof clippings have also been submitted for approval to those whose names are mentioned. Numerous cross refer¬ ences will be found as well as many repetitions, inserted for the purpose of emphasizing important facts. The chapters are arranged for convenience in reference, and therefore are not always in logical order. The Concrete Data in Chapter I presents a list of definitions of words and terms relating distinctively to cement and concrete; a summary of the most important facts and conclusions, with references to the pages discuss¬ ing them; data on concrete labor, and conversion ratios. The Elementary Outline of the Process of Concreting, Chapter II, is de¬ signed, not for the civil engineer, but for those seeking simple directions as to the exact procedure in laying a small quantity of concrete. Most of the subjects there treated are discussed at length in subsequent chapters. The Specifications for Cement in Chapter III include the latest recom¬ mendations of committees of our national societies, with incidental changes to adapt them for direct use in purchase specifications. The Concrete Specifications have been prepared by the authors to represent standard practice. Specifications for First-class or High Steel, drawn up by Mr. Taylor, are, we believe, the first recommendations which have been made to safely adapt this important material to reinforced concrete construction. In Chapter IV the Choice of Cement is considered in an elementary fashion, which will serve as a guide to the constructor. Classification oi Cements, Chapter V, distinguishes the various cements and limes manu¬ factured in the United States and Europe. ni IV PREFACE Mr. Spencer B. Newberry, an international authority on the subject treated, has very kindly written for us Chapter VI on the Chemistry of Hydraulic Cement, discussing this complex subject in such a clear and prac¬ tical manner that it will be of interest not only to the scientist, but also to the general reader and to the cement manufacturer. Mr. Newberry has also criticised Chapter V. Chapters VII and VIII give the latest information on the testing of ce¬ ment. Chapter IX presents practical rules for selecting sand for mortar, and the effect of different sands and of foreign ingredients upon its quality. Characteristics of the Aggregate are further treated, and practical data in regard to it are given in Chapter X. The subject of Proportioning Concrete has been treated, at our request, by Mr. William B. Fuller, the concrete expert, and his practical use of mechanical analysis is fully discussed. The tables of Quantities of Materials for Concrete and Mortar, in Chapter XII, and the diagram of curves, will be found useful in estimating materials. The Strength of Concrete, Chapter XX, is taken up from a practical standpoint so that the data may be directly employed in design. The theory and design of reinforced concrete are as yet in an elementary stage, but the rules and tables in Chapter XXI represent the most ad¬ vanced knowledge on the subject. Practical methods of Mixing and Laying Concrete are treated in Chap¬ ters XIII, XIV and XV. Mr. Rene Feret, of Boulogne-sur-Mer, France, whose extended researches enable him to speak with authority, has kindly written for us Chapter XVI, entitled The Effect of Sea Water. Chapters XVII, XVIII and XIX, on Freezing, Fire and Rust Protection, and Water-Tightness are of practical interest to the contracting engineer. Plain and Reinforced Concrete Structures are treated in as much detail as space permits in Chapters XXIII to XXVIII inclusive. The designs are taken mostly from original drawings redrawn by the authors. They have been selected, not as extraordinary productions, but because the data in regard to them may be of use in designing similar structures. Methods of Cement Manufacture in its modern types are described in detail in Chapter XXX. The References in Chapter XXXI will be found especially valuable to one pursuing more extended investigations than can be presented in a volume of this size. They have been selected from the large number contained in the authors’ index, as those which it may be to the advantage of the reader to consult. Note: The chapter numbers have been changed to agree with the Second Edition. PREFACE \ The articles are usually described by their subject-matter rather than by their titles verbatim. Appendix I gives the method of chemically analyzing cement and cement materials according to the recommendations of the American Chemical Society. Additional formulas for reinforced concrete beams, too complicated for insertion in the body of the book, are given in Appendix II, these having been kindly compiled by Prof. Frank P. McKibben for this treatise. The authors desire to express their sincere appreciation of the various kindnesses extended to them while compiling the work. It has been neces¬ sary, because of the lack of authoritative information on many fundamental questions, not only to conduct numerous original investigations, but also to correspond with the most prominient engineers in this country, and with experts in England, France, and Austria. Mr. Feret, besides writing the chapter on The Effect of Sea Water, has kindly criticised Chapter IX, and made numerous suggestions which have been incorporated. Mr. Fuller has examined and criticised all the chapters on practical con¬ struction, and Prof. McKibben has rendered material assistance in the line of investigations and criticisms relating to the theories of reinforced con¬ crete. The authors are indebted to many gentlemen for careful criticism of chapters or portions of chapters, for drawings, or for replies to questions, and take this opportunity to express their sincere appreciation of all such assistance. Among those to whom especial acknowledgment is due are the following: Messrs. Earle C. Bacon, David B. Butler (England), Harry T. Buttolph, Howard A. Carson, Edwin C. Eckel, William E. Foss, George B. Francis, fohn R. Freeman, Charles S. Gowen, Allen Hazen, Rudolph Hering, James E. Howard, Richard L. Humphrey, A. L. Johnson, George A. Kim¬ ball, Robert W. Lesley, Alfred Noble, William Barclay Parsons, Henry H. Quimby, George W. Rafter, Ernest L. Ransome, Clifford Richard¬ son, Thomas F. Richardson, A. E. Schutte, W. Purves Taylor, Edwin Thacher, Leonard C. Wason, George S. Webster, Robert Spurr Weston, Joseph R. Worcester; and Professors Ira O. Baker, Lewis J. Johnson, Edgar B. Kay, Gaetano Lanza, Charles L. Norton, Charles M. Spofford, George F. Swain, Arthur N. Talbot. Cuts have kindly been furnished by Allis-Chalmers Co., Austin Manu¬ facturing Co., Automatic Weighing Machine Co., Bonnot Co., Bradley Pulverizer Co., Clyde Iron Works, Contractors Plant Co., Drake Standard VI PREFA CE Machine Works, Fairbanks Co., Falkenau-Sinclair Machine Co., Farre] Foundry and Machine Co., Iroquois Iron Works, Kent Mill Co., Link-Belt Engineering Co., McKelvey Concrete Machinery Co., W. F. Mosher & Son, Tinius Olsen and Co., Philadelphia Pneumatic Tool Co , Thos. Prosser and Son, Ransome Concrete Machinery Co., Riehle Bros. Testing Machine Co., Robins Conveying Belt Co., Sherburne and Co., T. L. Smith, Henry Troemner, Tucker and Vinton. FREDERICK W. TAYLOR. SANFORD E. THOMPSON. February, 1905. The writer wishes to state that the investigation and study necessary for the writing of this book were done bv his colleague, Mr. Thompson, and desires that full credit for this should be given to him. Frederick W. Taylor. PREFACE TO SECOND EDITION The second edition aims to cover the developments in the design and con¬ struction of reinforced concrete since the issue of the first edition. To accomplish this, more than 200 pages of entirely new and original text and tables have been added, giving to the constructing engineer, the architect, and the contractor data for design and for building, and to the student a comprehensive and practical text and reference book. One of the principal objects also in writing and in revising the book has been to make it useful to those men who are practically engaged in this class of work and yet who are unable to devote enough of their time to make either a profound or an original study of it. Attention is directed to the new Chapter I, in which many of the essentials of concrete construction are pointed out and the reader is warned against the serious errors that have frequently been made in this field. The chapter on Reinforced Concrete Design, which is increased from 51 to 13 1 pages, includes a comprehensive statement of the details of design. Features of special interest in this chapter are the treatment of column design; the discussion of shear and diagonal tension; the design of the supports of beams and girders; the treatment of bending moments; the design of flat plates; the most recent tests on hooked bars; the analysis of shrinkage and temperature reinforcement; and careful notes relating to many smaller though not less important details. Tables and diagrams for design cover¬ ing over 20 pages are prepared for office use. A complete example of floor design gives the mathematical computations in detail for all the parts of the several members. In subsequent chapters are treated the designs of retaining walls, footings, culverts, and chimneys. Prof. Frank P. McKibben has kindly prepared the chapter on Arches, which presents the design of the arch by the elastic theory and gives a com¬ plete example with all the steps to be followed. In Chapter XXIX brief reference is made to a variety of structures in which concrete is employed as the building material. Prominent among the changes in the first part of the book, which is devoted to plain concrete, are the revised Specifications for Cement and Con- vii Vlll PREFACE crete in Chapter III; Chapter IX on Proportioning; the enlargement of Chapters XIV and XV on Mixing and Depositing; the addition on pages 236 and 237 of tables for quantities of materials for rubble concrete; and the insertion of the most recent tests and conclusions on the strength and permeability of concrete. The list of references in Chapter XXXI has been increased over fifty per cent, new references having been carefully selected from the immense quantity of current literature published since the first issue of our book. The large increase in the quantity of material has necessitated a rearrange¬ ment of the matter and beyond page 235 the pages have been renumbered. To simplify the formulas, the demonstrations have been placed as far as possible in footnotes or appendices. By the use of a thinner but higher quality of paper the book is increased but slightly in size. The authors desire to express their appreciation of assistance rendered in the work of revision. Special acknowledgment is due to Messrs. E. D. Boyer, R. D. Bradbury, William B. Fuller, Frank P. McKibben, Spencer B. Newberry, George F. Swain, Arthur N. Talbot, and Joseph R. Worces¬ ter; also to Mr. Edward Smulski for his original studies for the matter on Reinforced Concrete Design. September , 1909 FREDERICK W. TAYLOR. SANFORD E. THOMPSON. CONTENTS CHAPTER I PAGE Essential Elements in Concrete Construction i CHAPTER la Concrete Data Definitions. 2C Weights and Volumes. 2Cj Cement Testing for the Small Purchaser. ^ Summary of Important Facts and Conclusions. 5 Data on Handling Concrete. 9 Conversion of Foreign to American Measures. 9 CHAPTER II Elementary Outline of the Process of Concreting Where Concrete may be Used. xx Selection of Materials. I2 Proportions... x ^ Quantities of Material. I4 Tools and Apparatus required for Concrete Work. 17 Construction of Forms. Xg Directions for Mixing and Placing Concrete. 20 Approximate Cost of Concrete Materials and Labor. 24 The Strength of Concrete. 26 CHAPTER III Specifications Brief Specifications for Purchase of Cement. 29 Full Specifications for Purchase of Portland Cement. 29 Full Specifications for Purchase of Natural Cement. 31 Contract and Specifications for Portland Cement Concrete. 32 , Specifications for First-Class Steel for Reinforced Concrete. 38 CHAPTER IV The Choice of Cement The Class of Cement. 41 The Selection of the Brand. 45 ix X CONTENTS CHAPTER V Classification of Cements PAGE Portland Cement. 48 Natural Cement; Le Chatelier’s Classification of Natural Cements. .... 49 Puzzolan Cement. 50 Hydraulic Lime; Common Lime. 52 Sub-Classification of Portland Cements. 53 CHAPTER VI Chemistry of Hydraulic Cements. — By Spencer B. Newberry Introduction. 54 Materials. 55 Proportion of Ingredients. 57 Effect of Composition on Quality. 62 CHAPTER VII Standard Cement Tests Standard Methods of Cement Testing. 6 3 Elementary Directions for Testing Soundness. 79 Apparatus for a Cement Testing Laboratory. 80 Specific Gravity of Different Cements. 81 Advantages of Fine Grinding. 82 American vs. European Sieves. 84 Separating Material passing No. 200 Mesh Sieve. 8^ Quantity of Water for Neat Paste and Mortar. 8^ Arbitrary Periods of Setting. 88 European Methods for Determining Set. 89 Rate of Setting. 90 American and European .Standard Sands Compared. 90 Form of Briquette for Tensile Tests. 92 Conversion of Metric Units of Strength to English Units. 9^ Machines for Testing Tensile Strength. 9 3 Effect of Eccentricity in placing Briquettes. 93 Rate of Applying Strain. 94 Tensile Tests of Neat Cement and Mortar. 97 Soundness or Constancy of Volume. 101 CHAPTER VIII Special Tests of Cement and Mortar Color of Cement. in O Weight of Cement. 114 Microscopical Examination of Portland Cement Clinker. nc; Compressive Tests of Cement. 116 Transverse Tests of Cement. I2o Adhesion Tests of Cement. 12I CONTENTS xi PAGE Shearing Tests of Cement and Mortar. 125 Abrasion and Porosity Tests. 125 Permeability or Percolation Tests. 128 Yield Tests of Paste and Mortar. 129 Tests of Rise in Temperature while Setting. 130 Tests of Sand for Mortar. 131 CHAPTER IX Strength and Composition of Cement Mortars Laws of Strength. 133 Strength of Similar Mortars Subjected to Different Tests. 134 Relation of Density to Strength. 134 Granulometric Composition of Sand — Feret’s Three-Screen Method of Analysis.... 142 Effect of Size of Sand upon the Strength of Mortar. 147 Tests of Density and Strength of Mortars of Coarse vs. Fine Sand. 149 Practical Applications of the Laws of Density. 149 Conversion of Mechanical Analysis to Granulometric Composition. ..... 15 1 Effect of Quantity of Water upon Strength of Mortars. 152 Sand vs. Broken Stone Screenings. 153 Sharpness of Sand. ;. 154a Effect of Natural Impurities in Sand upon Strength of Mortar. 154a Effect of Mica in Sand upon Strength of Mortar. 154c Effect of Lime upon Strength of Mortar. i54d Ground Terra-Cotta or Brick as a Substitute for Sand. 156 Effect of Regaging Mortar and Concrete. 157 Tests of Sand for Mortar and Concrete. / 159 Effect of Gaging with Sea Water. 159b CHAPTER X Voids and Other Characteristics of Concrete Aggregates Laws of Volumes and Voids. 160 Classification of Broken Stone. 161 Average Specific Gravity of Sand and Stone. 163 Method of Determining Specific Gravity. 164 Method of Determining Voids. 165 Voids and Density of Mixtures of Different Sized Materials. 168 Photographs of Sand. 175 Effect of Moisture on Sand and Screenings. 176 Compacting of Broken Stone, Gravel, and Sand. 179 Defining Coarseness of Sand by its Uniformity Coefficient. 18 1 CHAPTER XI Proportioning Concrete, — By William B. Fuller Importance of Proper Proportioning. 183 Methods of Proportioning. 184 Xll CONTENTS PAGE Principles of Proper Proportioning. 185 Determination of the Proportion of Cement. 186 Proportioning by Arbitrary Selection of Volumes. 187 Screened vs. Unscreened Gravel or Broken Stone. 188 Proportioning by Void Determination. 189 Rafter’s Method of Proportioning. 192 French Method of Proportioning. 192 Mechanical Analysis. 193 Studies of the Density of Concrete. 200 Relation of Density to Strength. 204 Laws of Proportioning. 204 Application of Mechanical Analysis Diagrams to Proportioning. 206 Curve of Mix to Best Fit the Maximum Density Curve. 208 Volumetric Synthesis or Proportioning by Trial Mixtures. 210 Proportions of Concrete in Practice. 213 CHAPTER XII Tables of Quantities of Materials for Concrete and Mortar Expressing the Proportions. 217 Theory of a Concrete Mixture. 220 Formulas for Quantities of Materials and Volumes. ./. 221 Tables and Curves of Quantities of Materials and Volumes. 225 Tables of Rubble Concrete. 238 CHAPTER XIII Preparations of Materials for Concrete Storing Cement. 239 Screening Sand and Gravel. Methods and Costs. 239 Stone Crushing. Methods and Costs. 241 Washing Sand and Stone. 250 CHAPTER XIV Mixing Concrete Mixing Concrete by Hand. 2 si Mixing by Machinery. 255 Concrete Plants. 266 CHAPTER XV Depositing Concrete Handling and Transporting Concrete. 276 Depositing Concrete on Land. 277 Consistency of Concrete. 279 Ramming or Puddling. 281 Bonding Old and New Concrete. 284 Contraction Joints. 28s CONTENTS PAGE Facing Concrete Walls. 288 Forms for Mass Concrete. 293 Rubble Concrete. 296 Depositing Concrete under Water. 301 CHAPTER XVI Effect of Sea Water upon Concrete and Mortar. — By R. Feret External Phenomena. 309 Action of Sulphate W aters. 310 Chemical Processes of Decomposition. 311 Search for Binding Materials Capable of Resisting the Action of Sea Water 312 Methods of Determining the Ability to Resist Action of Sulphate Waters 314 Mechanical Processes of Disintegration. 315 Proportions for Mortars and Concretes. 316 Mixtures of Puzzolan and Slag with Cements. 317 Various Plasters and Coatings. 318 CHAPTER XVII Laying Concrete and Mortar in Freezing Weather Effect of Freezing. 319 Methods of Construction in Freezing Weather. 323 CHAPTER XVIII Fire and Rust Protection Protection of Steel by Concrete. 327 Chemical Union of Steel and Cement. 330 Fire Protection. 331 Concrete vs. Terra-Cotta; Cinder vs. Stone Concrete. 333 Thickness of Concrete required to Protect Metal from Fire. 333 Theory of Fire Protection. 334 Tests of Fire Resistance; Conductivity of Concrete and Imbedded Steel. 335 Influence of Cracks in Reinforced Concrete upon the Corrosion of Steel. 336 Protecting Structural Steel. 337 CHAPTER XIX Water-Tightness Laying Concrete for Water-Tight Work. 338 Proportioning Water-Tight Concrete. 339 Thickness of Concrete for Water-Tight Work. 340 Special Treatment of Surface. 341 Introduction of Foreign Ingredients. 342 Layers of Waterproof Material. 344 Construction without Waterproofing. 347 Methods of Testing Permeability. 347 Results of Tests of Permeability. ■. 35 1 XIV CONTENTS CHAPTER XX Strength of Plain Concrete PAGE Compressive Strength of Concrete. 355 Table of Compressive Strength. 359 Weight of Concrete of Different Proportions. 362 Compressive Tests of Plain Concrete. 362 Effect of Concentrated Loading. 367 Strength of Short Prisms. 369 Plain Concrete Columns. 371 Strength of Machine vs. Hand Mixed Concrete. 372 Eccentric Loading. 372 Concrete vs. Brick Columns. /..... 373 Safe Strength of Concrete. 373 Growth in Strength of Concrete. 374 Transverse Strength of Concrete. 378 Formula for Transverse or Bending Stress in Plain Concrete. 379 The Fatigue of Cement. 381 Strength of Concrete in Shear. 382 Effect of Consistency upon the Strength. 383 Gravel vs. Broken Stone Concrete. 385 Effect of Size and Quality of Stone or Gravel upon Strength of Concrete. 389 Effect of Percentage of Cement upon the Strength of Concrete. 392 Destructive Agencies. 392 Strength and Elasticity of Cinder Concrete. 394 Making Concrete Specimens for Testing. 395 CHAPTER XXI Reinforced Concrete Design General Principles of Reinforced Beams. 400 Modulus of Elasticity of Steel. 402 Modulus of Elasticity of Concrete. 403 Value to Use for the Ratio of Elasticity in Compression. 408 Elongation or Stretch in Concrete. 408 Quality of Reinforcing Steel. 413 Straight Line Theory. 41^ Location of Neutral Axis. 416 Design of a Rectangular Beam. 416 Depths and Loads for Different Bending Moments. 419 Formulas to Review a Beam already Designed. 419 Design of Slabs. 421 Square and Oblong Slabs. 422 Design of T-Beam. 423 Beams with Steel in Top and Bottom. >. 427 Design of a Continuous Beam at the Supports. 428 Effect of Varying Moment of Inertia upon the Bending Moment. 430 Span of a Continuous Beam or Slab. , >. ; ^ r Distribution of Slab Load to the Supporting Beams. 4^1 CONTENTS xv PAGE Distribution of Beam and Slab Loads to Girders. 432 Bending Moments and Shears. 4^0 Shear and Bending Moment Diagrams. 43- Bending Moments to Use in Design of Reinforced Beams. 439 Shearing Forces in a Beam or Slab. 44 x Diagonal Tension. 443 Reinforcement to Prevent Diagonal Cracks in Beams. 445 Computation of Shear and Diagonal Tension. 446 Vertical and Inclined Reinforcement. 448 Graphical Method for Spacing Stirrups. 452 Diameter of Stirrups. 433 Ratio of Span to Depth which Renders Stirrups Unnecessary. 435 Bond of Steel to Concrete in a Beam. 436 Points to Bend Horizontal Reinforcement. 438 Spacing of Tension Bars in a Beam. 439 Depth of Concrete below Rods. 460 Bond of Concrete to Steel to Resist Direct Pull. 461 Length of Bar to Prevent Slipping. 464 Value of Hooked Bars in Bond. Classification of Arches. Arrangement of Spandrels and Rings .. Hinges. Shape of the Arch Ring. Thickness of Ring at Crown .. Live Loads for Highway Bridges .. Live Loads for Railroad Bridges .. Dead Loads and Earth Pressure. Outline of Discussion on Arch Design .. Relation between Outer Loads and Reactions at Supports. Notation .. Three-Hinged Arch. Two- Hinged Arch. “Fixed” or “Continuous” Arches. Relation between Outer Forces and the Thrust, Shear and Bending Moment for the Fixed Arch. Thrust, Shear and Moment at the Crown. Graphical Method for Finding Constant j .. Line of Pressure. Effect of Temperature and Thrust. Effect of Rib Shortening Due to Thrust. Distribution of Stress over Cross Section. Distribution of Stresses in Plain Concrete or Masonry Arch. Sections. .. Distribution of Stresses in Reinforced Concrete Sections. Method of Procedure for the Design of an Arch. Loadings to Use in Computations . .. Allowable Unit Stresses. Design of Abutment. Erection .. Examples of Arch Bridges. PAfiK 536 536 538 539 540 540 541 543 544 544 545 545 546 547 548 549 55i 554 555 555 558 558 560 563 574 580 583 583 586 590 CHAPTER XXIII Sidewalks, Basement Floors and Pavements Materials for Concrete Sidewalks . . 593 Tools . • *; . . • • 597 Method of Laying Sidewalks . 598 Cost and Time of Sidewalk Construction. . . 604 Driveways . 606 Concrete Street Pavements . 606 CHAPTER XXIV Concrete Building  619 Wall Forms . • . 621 Concrete Columns . 623 Cost of Concrete Building Construction. . . 624 Domes . 626 Walls of Mortar Plastered upon Metal Lath . 627 Ornamental Construction. . . 628 Concrete Building Blocks ; Concrete Tile . . 629 Reinforced Concrete Chimneys . 630 Design of Reinforced Concrete Chimneys . 632 Summary of Essentials in Design and Construction . 634 Example of Chimney Design. . . 636 CHAPTER XXV Foundations and Piers Bearing Power of Soils and Rock . 639 Concrete Capping for Piles . 641 Design of Concrete Foundations and Footings . 641 Reinforced Concrete Footings . 644 Combined Footings . 647 Spread Footings. . . . 649 Foundation Bolts . 650 Concrete Piles . 650 Sheet Piling . 653 Bridge Piers . 654 Foundations Under Water . . 656 CHAPTER XXVI Dams and Retaining Walls Retaining Walls . 659 Foundations . 660 Design of Retaining Walls of Gravity Section . . . 661 Angle of Internal Friction . 662 Weight of Earth ; Backing . . 662 Earth Pressure. . . 663 Design of Reinforced Retaining Walls . . 666 Example of Retaining Wall of T-Type . . 668 Example of Retaining Wall with Counterforts. . . . 671 Copings . * . . . 674 Dams . 674 Core Walls . . . ^7 6 xviii CONTENTS CHAPTER XXVII Conduits and Tunnels Conduits. Design and Construction. Tunnels. Design and Construction. Subway Design. Design of Conduits. PAGE 670 689 692 69 3 CHAPTER XXVIII Reservoirs and Tanks Open and Covered Reservoirs . 695 Tanks. Method of Construction . 698 Storage Reservoirs . 701 CHAPTER XXIX Cement Manufacture Historical . 705 Production of Cement . 706 Portland Cement Manufacture . 707 Natural Cement Manufacture . 722 Puzzolan Cement Manufacture . 723 CHAPTER XXX Miscellaneous Structures CHAPTER XXXI References to Concrete Literature APPENDIX I Method for Analysis of Limestone, Raw Materials and Portland Cements of the American Chemical Society, with the advice of W. F. Hillebrand. APPENDIX II Deduction of Formulas for Rectangular Beams; T-Beams ; Beams with Steel in Top and Bottom; Rectangular Beams, Concrete Bearing Tension; and Rectangular Beams, Compression Stress as a Parabola. APPENDIX III Deduction of Formulas for Chimney and Hollow Circular Beam Design. APPENDIX IV Method of Combining Mechanical Analysis Curves. A Treatise on Concrete CHAPTER I.. ESSENTIAL ELEMENTS IN CONCRETE CONSTRUCTION The forming of concrete structures is essentially a manufacturing opera¬ tion, and requires more close attention to detail both in the design and the building than most other classes of construction. For the benefit of those who are not thoroughly experienced, a number of the most essential elements are recorded below with references to pages upon which more detailed information may be obtained. General properties of materials and of concrete are outlined in Chapter la on Concrete Data, and Chapter II, page n, gives in elementary form an outl ne of the process of concreting. CEMENT PAGE Except for unimportant structures, the cement should be sampled and tested in a laboratory . . . 63 Even if not tested, cement should be purchased with the requirement that it must pass the specifications of the American Society for Testing Materials . 29 Portland cement is the only cement that can be used for all kinds of concrete work . 12 SAND Tests of the sand, unless it comes from a bank which has been pre¬ viously tested, are as necessary as tests of the cement . 159 Even a small amount of vegetable matter in sand prohibits its use 154b Fine sand, even if free from vegetable matter, makes a much weaker concrete than coarse sand. If it is necessary to use fine sand, therefore, the proportion of cement should be increased. ... 136, 159a If the grains are mostly less than 3^ inch diameter, nearly double the amount of cement should be used than with an equally clean sand having mixed grains running up to \ inch, in order to obtain equal strength . 159a For unimportant work, fine sand, if clean, may sometimes be used, but it is usually cheaper to import a coarse sand and use leaner proportions . . — 149, 159a 2 A TREATISE ON CONCRETE COARSE AGGREGATE pARF The maximum size of the stones should be such that the concrete is » readily placed around the steel reinforcement and into the cor¬ ners of the forms. For reinforced concrete a maximum size of one inch is frequently specified . . 34 If the stone contains dust, it must be uniformly distributed through-. out the stone, and the proportion smaller than J inch should be determined by test and considered as sand when proportioning. 34 Soft stone should be avoided in important structures. 390 Gravel, if used, must be clean; that is, the particles must be free from coating of vegetable matter or clay which will retard the setting or prevent the cement from sticking to the pebbles — 34, 386 Gravel can be washed satisfactorily only with special apparatus. 250 REINFORCEMENT All steel should be subject to the bending test. 415 Steel must be placed in exact position called for on plans. 37 Steel must be fixed in place so that it cannot be moved during the process of concreting. 37 Round steel can be safely used in reinforced concrete since with proper imbedment the concrete adheres to it with sufficient bond to develop the full strength of the steel at its elastic limit. 461 Square and flat bars do not bond as well as round. 463 Deformed bars, that is, bars with irregular surfaces, are especially useful where the stress falls off rapidly, as in footings. 463, 645, 670 Deformed bars are also advantageous for temperature reinforcement 500 Structural steel, like T-bars and I-beams, are not so good for rein¬ forcement as plain round or deformed steel bars. 465 Structural steel may be used in columns either to take the entire load with concrete around it for protection, or else to act with the concrete. Although generally less economical than plain bars, it may permit smaller sized columns. 497 High carbon steel, if of satisfactory quality and thoroughly tested, may be used with a higher working stress than mild steel. 38, 414 High carbon steel, unless of special quality, is apt to be brittle, and should not receive higher working stress than mild steel. 413 Steel will not rust if completely surrounded with concrete of a wet consistency. 327 Changes in temperature will not cause separation of steel from the concrete. 287 ESSENTIAL ELEMENTS 20- PAGE PROPORTIONING, MIXING AND PLACING Proportions must be accurately measured. 251 Mixing must be thorough; concrete is improved by long mixing. .. 251 Machine mixing is better than hand mixing. 255, 372 Enough water must be used in reinforced concrete so that the mass will just flow sluggishly around the steel to thoroughly imbed it. If cement with a flash set has been used inadvertently the concrete must be soaked with water until it hardens. Old and new concrete must be bonded for tight work . 37, 284, 338 Joints in floor construction should be made in center of span . 37a, 284 Surface treatment must be skillful, roughening is usually best . 288 Plastering on external surfaces should be avoided . 288 FORMS % Forms must be braced securely to avoid being thrown out of line by the concrete or by the workmen . 19, 37, 294 Struts and braces supporting the forms must be strong enough to withstand the weight of the concrete above it and also a construc¬ tion load of 50 to 75 pounds per square foot . 294, 617 Boards and planks need but few nails unless the forms are built so that the pressure tends to separate them from the cleats . 620 Forms should be tight enough to prevent mortar flowing away and leaving unsightly stone pockets . 37, 623 Forms should be thoroughly cleaned of all dirt and chips before laying concrete. A steam hose is effective for this purpose _ 36 Column forms should be made with cleanout opening in lower end. Forms cannot be straightened or lined up after concrete is placed 295 Wall forms usually may be removed in 24 to 48 hours . 296/ Forms supporting reinforced members should be left in place until the concrete rings sound and is not readily chipped by a blow from a pick. In mild weather 1 to 4 wreeks is usually sufficient, according to the character of the member . 296 Great caution must be used in cold weather, as the concrete sets slowly; sometimes the forms must remain until warm weather.. 296 If dead load, that is, weight of the concrete itself, is large, the forms must be left longer for concrete to attain sufficient strength . 296 A TREATISE ON CONCRETE 2 b -PAGE Earth must not be backfilled against a wall until it is 3 to 4 weeks old unless forms are left in place and braced . 620 DESIGN Reinforced concrete should be designed by experienced engineers. . . 702 Bending moments must be selected for individual conditions. .. .433, 439 Neither steel nor concrete must be overstressed in any part.... 418,420 A T-beam must be deep enough to prevent overstressing concrete in the flange . . 424 Width of flange of T-beam is limited by span and thickness of slab.. 423 Steel must be placed across the top of a girder . 422, 443 A continuous beam or slab must be designed at its support to resist negative bending moment. This requires as much steel at the top over the support as at center of member in the bottom _ 428 Provision must be made for compression in the bottom of a continu¬ ous beam or slab at the support . . 428 Shear in a T-beam must be studied to see that the stem is large enough 424 Vertical or inclined steel is usually necessary to resist diagonal tension. 445 Bars must be small enough to resist the bond stress . . 457 Ends of bars must be imbedded far enough to provide bond sufficient to prevent danger of pulling out . . 464 Columns may be reduced in size by using rich proportions, vertical reinforcement, hooping, or a combination of these . 489 Hooping serves to increase the toughness of the column . 492 The working strength of a hooped column, however, must not be based on its ultimate crushing strength . 495 ESTIMATING. Cost of materials is readily estimated from the quantity used.. --24, 231 Cos: of labor of mixing, and placing concrete can be estimated with close approximation . . 24 The cost of forms and incidental expense are the most difficult items to correctly estimate and vary largely with surrounding condi¬ tions. For this reason, estimates for reinforced concrete must be based upon very accurate data and large experience 26 CONCRETE DATA 2C CHAPTER la CONCRETE DATA DEFINITIONS SEE PAGE Aggregate is the inert material, such as sand, broken stone, etc., with which the cement or other adhesive material is mixed to form con¬ crete or mortar. The term is sometimes erroneously applied to the coarse material, such as broken stone, only. Akron Cement is a Natural cement from the vicinity of Akron, N. Y. 49 Beton is the French word for concrete. Beton-Coignet is a mixture of hydraulic lime, cement, and sand _ 42 Concrete* is an artificial stone made by mixing cement, or some simi¬ lar material — which after mixing with water will set or harden so as to adhere to inert material, — and an aggregate com¬ posed of hard, inert particles of varying size, such as a combina¬ tion of sand or broken stone screenings, with gravel, broken stone, cinders, broken brick, or other coarse material. Concrete Rubble is masonry of large stones, usually of derrick size, with joints of concrete instead of mortar . 296 Density represents the ratio of the sum of the volumes or mass of the particles, or absolutely solid substance, of a material contained in a measured unit volume to the total measured unit volume. . 138a Granolithic is concrete consisting of Portland cement and fine broken stone or sand troweled to form a wearing surface . 600 Grappiers Cement ( Ciment de grappiers ) is made in France from particles which have escaped disintegration in the manufacture of hydraulic lime . 50 Hydrated Lime is specially prepared powdered slaked lime . 53 Hydraulic Lime contains lime and clay in such proportions that it hardens under water . 52 James River Cement is a Natural cement from the James River Valley 49 Laitance is decomposed cement formed in the presence of an excess of water . 302 Laitier Cement ( Ciment de laitier ) is the French name for Puzzolan or slag cement . 5° ♦Also applied to mixtures of an aggregate with a material such as asphalt - which liquefies on application of heat. 2(1 A TREATISE ON CONCRETE SEE PAGE Lime of Teil ( Chaux du Teil ) is a celebrated hydraulic lime of France 52 Louisville Cement is a Natural cement from the vicinity of Louisville, Ky . . . 49 Mortar is a mixture of cement or lime and sand or other fine aggregate having water added so as to make it like a paste. Natural Cement is made from natural rock containing the required constituents in approximately uniform proportions . 49 Parker’s Cement is a term sometimes used in England for Natural or Roman cement . . . 49 Paste is a mixture of neat, i.e., pure, cement or lime with water. Portland Cement is made from an artificial mixture of materials con- taming lime and clay . 48 Puzzolan Cement is a mechanical mixture of slaked lime with blast furnace slag, or with natural puzzolanic matter, such as vol¬ canic ash . 50 Reinforced Concrete is concrete in which steel is imbedded to increase its strength. Roman Cement is the English name for Natural cement . 49 Rosendale Cement is a Natural cement from the Rosendale District in eastern New York State . 49 Rubble Concrete is concrete in which large stones are placed . 296 Sand Cement or Silica Cement is a mechanical mixture of Portland cement and fine sand. . . 42 Slag Cement is the name sometimes given to Puzzolan cement.... 50 Vassy Cement ( Ciment de V assy) is a common French Natural cement 49 Voids are the spaces throughout a mass of concrete, mortar, or paste that are filled with air or water. . . . . 135 WEIGHTS AND VOLUMES Portland Cement weighs per barrel, net. /“ “ bag “. Natural Cement weighs per barrel, net. “ “ “ “ bag, net. Cement Barrel weighs from 15 to 30 lb., averaging about Portland Cement is assumed in standard proportioning to weigh per cubic foot. Packed Portland Cement, as in barrels, averages per cubic foot about. Packed Portland Cement based on 3.5 cubic feet barrel contents weighs per cubic foot . . . .. 3 76 lb. 29 94 • • 29 282 a 31 94 u 31 20 u 100 u 217 TI5 11 219 io8£ «( CONCRETE DATA 3 Loose Portland Cement averages per cubic foot about . .. Volume of Cement Barrel, if cement is assumed to weigh ioo lbs. per cubic foot. American Portland Cement Barrel averages between heads about. Foreign Portland Cement Barrel averages between heads about. Natural Cement Barrel averages between heads about .... Weight of Paste of neat Portland cement averages per cubic foot about. Volume of Paste made from ioo lb. of neat Portland ce¬ ment averages about. Volume of Paste made from one barrel of neat Portland cement averages about. Weight of Portland Cement Mortar in proportions i :2\ averages per cubic foot. Weight of Concrete and Mortar varies with the proportions as well as with the materials of which it is composed Weight of Portland Cement Concrete per cubic foot.... Cinder Concrete averages. Conglomerate Concrete averages. Gravel Concrete averages. Limestone Concrete averages. Sandstone Concrete averages. Trap Concrete averages. Loose Unrammed Concrete is 5% to 25% lighter than con¬ crete in place, varying with the consistency. SEE PAGE 9 2 lb. £19 3.8 cu.ft. 217 3.5 “ “ 218 3.25 “ “ 219 3*75 “ “ 137 lb. 376 0.86 cu.ft. 229 3.2 “ “ 229 i35 lb. 112 (< 150 “ 150 “ 148 “ «< *43 155 u 362 61 1 277 CEMENT TESTING FOR SMALL PURCHASERS Soundness. A sound cement will not go to pieces on the work. The test is therefore of greatest importance, and is often the only one necessary. Take about \ pound, or one cupful, of Portland cement and mix by knead¬ ing ij minutes with sufficient water to form a paste of a consistency like putty. Press portions of the paste on to 3 pieces of window glass 4 inches square, so as to make 3 pats each about 3 inches in diameter and J inch thick at center tapering to a thin edge, and place in moist air for 24 hours. Then keep one pat in air at moderate temperature (about 6o° or 70° Fahr.) for 28 days, keep second pat in water for 28 days, and place third pat in loosely closed vessel over boiling water and keep there for five hours. Reject cement if any pats show radial cracks or curl or crumble. The air 4 A TREATISE ON CONCRETE pat should not change color. Portland cements may be accepted on the steam test alone if time is limited. Natural cements should be subjected to water and air but not to steam. (See p. 79.) Fineness. The finer the cement of a certain class the higher is its value. Sift 5 ounces of dry cement containing no lumps through a sieve about 6 to 8 inches diameter with 100 meshes per linear inch. Not more than \ ounce of either Portland or Natural cement should remain on sieve. To compare quality of two brands otherwise similar, sift through a 200-mesh sieve and choose the finer cement. (See p. 67.) Setting. A quick-setting cement is difficult to handle on the work and a too slow setting cement delays removal of forms. If a Vicat needle cannot be obtained for testing, use the Gillmore needles, — two steel rods, one, one-twelfth inch diameter at its end, loaded to weigh £ pound, the other, one-twenty-fourth inch diameter loaded to weigh 1 pound. A pat of pure Portland cement paste made like the soundness pat must not be able to support the weight of the lighter needle until 30 minutes after mixing, and must support the heavier needle in less than 10 hours. A paste or mortar or concrete has reached its final set when it will support a pressure of the thumb without indenting. (See p. 70.) Purity. “Provide a glass-stoppered bottle of muriatic acid, two shallow white bowls or two J-inch by 6-inch test tubes, a glass rod, and a pair of rubber gloves. Put in a bowl or a tube as much cement as can be taken on a nickel 5-cent piece; moisten it with half a teaspoonful of water; cover with clear muriatic acid poured slowly upon the cement while stirring it with the glass rod. Pure Portland cement will effervesce slightly, and will give off some pungent gas and will gradually form a bright yellow jelly without any sediment. Powdered limestone or powdered cement-rock mixed with the pure cement will cause a violent effervescence, the acid boiling and giving off strong fumes until all the carbonate of lime has been consumed, when the bright yellow jelly will form. (See p. 30.) *Judson’s City Roads and Pavements, 1902. CONCRETE DATA 5 Specific Gravity. The test requires delicate apparatus and is seldom nec¬ essary. Specific gravity of Portland cement should exceed 3.1. (See p. 30.) Magnesia must not exceed 4%. (See p. 30.) Sulphuric Anhydride must not exceed 1.75%. (See p. 30.) Color is no indication of quality. (See p. 113.) Weight is no indication of quality. (See p. 114.) PROPERTIES OF SAND AND SCREENINGS SEE PAGE Sharpness of grain is not necessary. 154a Quality of sand is chiefly dependent upon the coarseness and relative coarseness of its grains. 147 Clay or Loam in sand is sometimes injurious to mortars because introducing too much fine material, while in other cases it may be beneficial because the fine material is needed. 154# Specific Gravity of dry sand may be taken at 2.65. 163 Voids in sand cannot be accurately determined by pouring water into it, but can be found by weighing the sand and finding its moisture 165 Comparison of Sands cannot be made by a study of voids because of the effect of varying degrees of moisture. 177 Moist Sand measured loose is lighter in weight than loose dry sand. 176 Coarse Sand requires less water than fine sand, and when mixed with cement makes a denser mortar. 216 Fine Sand with grains of uniform size weighs nearly the same when dry and has nearly the same percentage of voids as screened coarse sand. Fine sand with ordinary moisture is, on the other hand, lighter and more porous than coarse sand. 170 Mixed Sand usually weighs more and contains a smaller volume of voids than coarse or fine sand .... ......... » 171 PROPERTIES OF COARSE OR MIXED AGGREGATE Equal Spheres if symmetrically piled in the theoretically most compact manner would have 26% voids, but by experiment it is found that in practice it is impossible to pile them so as to get below 44% voids. o » —. 169 Voids are approximately equal in the different portions of a dry ma¬ terial which has been screened to uniform sizes. 170 Smallest Percentage of Voids occurs in a mixture of sizes so graded that the voids of each size are filled with the largest particles which will enter them „. - - ° °. -. 