Road structure – process – or apparatus – Pavement – Including joint means
Reexamination Certificate
2007-05-29
2007-05-29
Hartmann, Gary S. (Department: 3671)
Road structure, process, or apparatus
Pavement
Including joint means
C404S047000, C404S056000
Reexamination Certificate
active
10827613
ABSTRACT:
A device to ensure that when the transverse contraction joint in a pavement and the like cracks, the crack extends through the middle of the dowel bar. A dowel is a smooth continuous bar that is embedded in a concrete pavement. It provides vertical shear resistance across a joint. Shortly after the concrete is place and sets, the concrete pavement starts to dry out. The drying out process produces a strain in the concrete pavement due to shrinkage causing the concrete to crack. In order to control the cracking, a saw cut is made in the pavement. The saw cut is centered in the middle of the embedded dowel bar. The saw cut provides a weaken plane in the pavement, thereby controlling the location of the crack. The saw cut and crack form the transverse contraction joint in the pavement. The crack extends from the bottom of the saw cut through the dowel bar to the bottom of the pavement. The crack does not always extend straight down to the bottom of the pavement. The crack typically extends in a diagonal direction down to the bottom of the pavement. This results in a short and long sections of the dowel bar providing shear resistance across the joint. The difference in dowel bar sections results in higher stresses at the shorter end of the dowel bar, shortening the overall life of the pavement. The Pavement Crack Initiator provides a weaken plane in the pavement and ensures that the crack extends through the middle of the dowel bar, evenly distributing the stresses on either side of the dowel bar. With the stress distributed evenly across the joint in the pavement, the joint operates as designed and thereby ensuring the design life of the pavement is achieved.
REFERENCES:
patent: 2179911 (1939-11-01), Wilmoth
patent: 2269703 (1942-01-01), Bagwill
patent: 2572550 (1951-10-01), White et al.
patent: 2589815 (1952-03-01), Jacobson
Design and Construction of Joinrs for Concrete Street APCA, 1992.
Design and Construction of Joints for Concrete Highway APCA, 1991.
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