xxii TABLE OF CONTENTS. 



PAGE: 



Available methods of investigation 566 



Synthetic investigations 567 



Microscopic investigations 568 



Theories of constitution 569 



Setting properties of Portland cement 572 



Replacement of silica by other acids 573 



Replacement of alumina by iron oxide 573 



Replacement of lime by magnesia 574 



Replacement of lime by other bases 574 



References on the constitution of Portland cement 575 



Composition of Portland cement 575 



Gradual change in composition since 1850 575 



Analyses of American Portland cements 576 



Standard methods for analysis 576 



CHAPTER XXXIX. 



PHYSICAL PROPERTIES. TESTING METHODS. 



Physical properties of Portland cement 583 



Value of tests for fineness 584 



Specific gravity = 585 



Setting properties 586 



Tensile strength 586 



Compressive strength 588 



T^atio of compressive to tensile strength 589 



Modulus of elasticity 591 



Sand cement or silica cement 592 



List of references on sand cement 596 



Effect of heating on Portland cement 597 



Effects of salt and freezing 598 



Effects of exposure to sea-water 602 



Standard methods of testing, Am. Soc. C. E 603 



CHAPTER XL. 



SPECIFICATIONS FOR PORTLAND CEMENT. 



New York State Canals, 1896 614 



Rapid Transit Subway, N. Y. City, 1900-1901 615 



Department of Bridges, N. Y. City, 1901 616 



Engineer Corps, U. S. Army, 1902 617 



U. S. Reclamation Service, 1904 620 



Canadian Society of Civil Engineers 622 



Concrete Steel Engineering Company 624 



British Standard Specifications 625 



American Society for Testing Materials, 1904 629 



