Transverse Strength of Mortars Compared to Tensile and Com- pressive Strength. - Richness of Mortar; Consistency. - Transverse Tests of Concrete Bars: Variations in Mortar Used; Consistency; Change in Volume during Setting. — Coefficient of Expansion of Mortar and Concrete. Fire-Resisting Qualities of Concrete. ART. 60. PRESERVATION OF IRON AND STEEL BY MORTAR AND CONCRETE 350 ART. 69. BEAMS WITH SINGLE REINFORCEMENT Formulas for Constant Modulus Elasticity; for Varying Modulus. Excessive Reinforcement. Tables of Strength. Foundation; Base; Wearing Surface; Construction; Cost. CHAPTER XXII. SPECIAL USES OF CONCRETE (CONTINUED): BRIDGES, DAMS, LOCKS, AND BREAKWATERS ART. 81. BRIDGE PIERS AND ABUTMENTS AND RETAINING WALLS Bridge Piers; Steel Shells. - Repair of Stone Piers. Retaining PART I CEMENT CLASSIFICATION AND MANUFACTURE CHAPTER I DEFINITIONS AND CONSTITUENTS ART. 1. GENERAL CLASSIFICATION OF HYDRAULIC PRODUCTS 1. The use of a cementitious substance for binding together fragments of stone is older than history, and it is known that the ancient Romans prepared a mortar which would set under So far as our present knowledge of cement manufacture is concerned, however, the credit of demonstrating that a limestone containing clay possessed, when burned and ground, the property of hardening under water, is due to Mr. John Smeaton, who announced this as the result of his experiments made in 1756 in seeking a material with which to build the Eddystone Lighthouse. After this discovery by Smeaton nearly sixty years elapsed before M. Vicat gave the true explanation. of this action, namely, that the lime during burning combined with the silica to form silicate of lime, the essential ingredient of hydraulic limes and cements. In 1796, Parker, of London, obtained a patent for the manufacture of a cement from septaria nodules, and aptly named his product "Roman Cement." In 1824, Joseph Aspdin of Leeds, England, patented a process of manufacture of "Portland Cement." 2. The cements in general use in the United States to-day are of two kinds, Portland cements and natural cements, and in what follows our attention will be directed almost entirely to these two products. Common limes were formerly used largely in engineering construction, but have of late been almost entirely superseded, |