"One of the principal types of heavy duty pavements in use in Missouri and in many other states is that known as rigid type portland cement concrete.
There have been two major trends in this type of pavement design. One of these trends is the use of short slabs, i.e., 15 to 25 feet, with no reinforcement. Another trend consists of concrete slabs containing distributed reinforcement such as wire mesh or reinforcing bars with joints occurring at fairly large intervals of 50 to 100 feet. As loads on the highways have increased the designers have increased the slab thicknesses and a consequential reduction in flexibility has reduced the degree of load distribution through the vertical layers of the paving system. In addition to added expense for subgrade stabilization this lack of flexibility has contributed to many cracks being formed in the paving slabs after a very short loading period and in some cases even before the slab has been loaded, i.e., within 72 hours after pouring. It has been proposed that these early cracks may have been caused by temperature and moisture warping a short time after pouring and the aggravation caused by heavy and repeated loads caused them to widen or open to a point that they affect the material useful life of the roadway. Investigations are now being conducted at the Missouri School of Mines and Metallurgy to determine the effect of temperature and moisture variations on strains in a concrete slab.
There exists an additional approach to the design of rigid type concrete pavements. This approach is the use of prestressed concrete slabs. Within the space or the past few years, the use of prestressed concrete tor buildings and bridges in the United States has grown from a completely new idea into an accepted method of concrete construction. In Europe, shortages of materials and enforced economies in construction have given prestressed concrete a substantial impetus in the construction of apartment type dwellings and the rebuilding of bombed out bridges and docks. A considerable amount of work has been done, both in the United States and Europe, in the particular fields of structural design named in the two preceding sentences. However, neither in Europe nor the United States has enough basic research been done to apply the prestressing of concrete slabs to highway construction. Studies have indicated, however, that the above mentioned cracking may be controlled and that greater loads may be carried by prestressed slabs thinner than the slabs now in use if the necessary economical designs and prestressing techniques can be developed.
This investigation will attempt, by tests and analysis to determine some of the inherent properties of plain nonreinforced concrete used by the Missouri State Highway Department. It is hoped, that, by providing a better understanding or the nature of plain concrete the information gathered in this investigation will aid in the design and use of prestressed concrete slabs for highways in the United States "--Introduction, pages 1-2.
Carlton, E. W.
Civil, Architectural and Environmental Engineering
M.S. in Civil Engineering
Missouri School of Mines and Metallurgy
vi, 141 pages
© 1956 Peter G. Hansen, All rights reserved.
Thesis - Open Access
Library of Congress Subject Headings
Concrete -- Testing
Prestressed concrete -- Testing
Concrete slabs -- Testing
Print OCLC #
Electronic OCLC #
Link to Catalog Record
Hansen, Peter G., "Physical properties of concrete at early ages" (1956). Masters Theses. 4090.