chapter 3 rigid pavement - DOT On-Line Publications - Department ...

serve as a leveling course, to correct superelevation, and to serve as a
bondbreaker to the 6-inch CRCP overlay. The 6-inch CRCP overlay uses
15 deformed bars spaced at 8.5 inches (0.6 percent steel of the cross
sectional area). Transverse steel (#4 bars) was spaced at 34 inches and
tied underneath the longitudinal steel. The steel reinforcement was
supported on metal chairs and the plans specified a cover tolerance of
2 l/2 - 2 11/16 inches.
The added 12-foot wide CRCP lane was placed on the outside of the overlay
portion. The new lane is a g-inch CRCP on a &inch crushed granular base.
It uses #5 deformed bars spaced at 5.5 inches (0.6 percent of the cross
sectional area). Transverse steel (#4 bars) was spaced at 30 inches and
tied underneath the longitudinal steel. The steel reinforcement was
supported by metal chairs and the plans specified a cover tolerance of
3 3/8 - 3 7/8 inches.
The plans provided the option of constructing the added right lane with the
overlay or separately with a keyway. State highway personnel, however,
report the keyway construction joint was likely used. The plans indicate
there are tie bars in the keyway but we are unable to determine their
length or spacing.
Traffic survey data gathered during the overlay design stage (1970)
indicate ADT of 10,600-14,050; 12-13 percent trucks; projected 1991 ADT
of 40,650-42,450; 12-13 percent trucks.
An extensive soils investigation was conducted during the overlay design
stage. A brief review of the soil boring tabulation indicated the presence
of silt, and rock fragments occurring within the top 5 feet of roadbed in
the location of the widened outer lane. Little information is available
for the roadbed beneath the original pavement. Also, there is little
information available concerning the condition of the original pavement
during design Cf the overlay.
Three cores of the existing CRCP pavement were recently taken and a
petrographic examination was conducted. An analysis of the cores is found
in Section VI.
A French drain was installed where the original roadway was in sag
alignment and then daylighted to the reconstructed 6:l side slopes. State
personnel have stated these are not presently functioning.
The inside shoulder width is 4.0 feet. The outside shoulder is 10.0 feet.
Each is a 3-inch thick bituminous ccncrete shd'ulder on a 7-inch dense-
graded stabilized aggregate subbase. The shoulder joint was designed to be
sealed with hot-poured, rubber-asphalt joint sealing compound.
Personnel kho were present during the overlay construction projects
reported that the -reject was shut dowh several times because of fines and
clay balls in the 'ggregate. Also, th:-:-e were difficu;;ies in finishing
the slab. The w .bound overlay (middie and high speed) lanes were placed
in May-July perioa. The eastbound overlay lanes were placed in October and
3.7.4