"The concrete industry in the United States represents one of the fastest growing segments of the national economy. Many reasons for this may be given, among which are, the durability of concrete structures, the local availability of a large portion of the materials used in concrete, and its wide range of adaptability to the designs of engineers and architects.
One of the most recent changes in concrete usage is the change from reinforced concrete to prestressed concrete. The term prestressed as used herein refers to any type of reinforced concrete in which the reinforcing material has a stress prior to the application of loads on the structure. Prestressed concrete is not new. It has been used successfully in Europe for several years and recently in the United States, particularly in buildings and bridges, to some extent. Many of the prestressed concrete projects in the United States are of a more or less experimental nature, trying different methods of stressing in order to perfect better anchorage and improve construction procedures.
Recently the use of prestressed concrete has been proposed as a surface for highways. Concrete as a surface for highways has many advantages over other forms of paving, the main one being its relatively long usable life. This feature by itself makes concrete a widely used paving material. The disadvantages of concrete are many among which are, high initial cost, longer period of construction, and many construction joints which cause rough riding characteristics. Another disadvantage is a maintenance problem occurring when older concrete pavements fail due to transverse cracks. These cracks often occur during the first year or two of the pavement's life, but do not cause serious problems until they become quite large and cause rough areas in the surface of the pavement. Transverse cracks are of two types. First, construction joints to allow for length changes caused by the expansion or contraction due to temperature changes in the pavement, and second, failures caused by deflection of the slab and subgrade due to heavy loads applied to the pavement. Cracks occurring in pavements poured on certain types of subgrade soil often develop a condition called pumping. This action consists of the deflection of the slab under moving loads which results in the ejection of water carrying soil particles in suspension.
Conventional steel reinforcement has been used with varying degrees of success to correct the above mentioned disadvantages of concrete pavements. Cracks still occurred and construction joints were left at varying intervals. These cracks cause trouble on a somewhat reduced scale but the cost of a reinforced pavement is much higher in both material costs and labor costs.
Prestressing concrete pavements may be a means of eliminating most of the cracks and many of the construction joints which are the major source of difficulty.
This research project has as a goal a prestressed highway pavement which will have as many as possible of concrete's inherent good advantages, and the fewest possible disadvantages"--Introduction, pages 1-2.
Carlton, E. W.
Civil, Architectural and Environmental Engineering
M.S. in Civil Engineering
Missouri School of Mines and Metallurgy
iv, 138 pages
© 1957 William M. Baldwin, All rights reserved.
Thesis - Open Access
Library of Congress Subject Headings
Concrete slabs -- Testing
Strains and stresses
Prestressed concrete -- Testing
Pavements -- Cracking
Print OCLC #
Electronic OCLC #
Link to Catalog Recordhttp://laurel.lso.missouri.edu/record=b2614165~S5
Baldwin, William M., "The magnitude and directions of strains and stresses in edge loaded concrete slabs" (1957). Masters Theses. 2194.