Review of Design and Construction of Rigid Pavement in Hot Weather Area: The Case of Ditchoto Galafi Junction-Ellidar-Belho Road Project, In Ethiopia.
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Date
2022-06
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Addis Ababa University
Abstract
Most major road networks in Ethiopia are constructed with flexible pavement, this type of
pavement used as the only option considered during the pavement type selection process for
many years. Rigid pavement structure which distributes loads to the subgrade having, as the
main load bearing course, a Portland cement concrete slab of relatively high-bending resistance,
is considered as an alternative option for the first time in Ethiopia with a total length of about
80Kms and a thickness of 40cms in hot weather area, Afar Region. The purpose of this thesis
was to review the Design and construction of rigid pavement in hot weather area: The case of
Ditchoto-Galafi Junction –Ellidar-Belho Road Project. Ditchoto Galafi Junction- Ellidar- Belho
Road project 80kms long located in Afar Region is the first of its kind to be built with Rigid
Pavement in Ethiopia, the maximum temperature will vary from 27oc to 52oc and the annual
rainfall is about 500mm.The design of this Rigid pavement has been reviewed briefly against
the standard of Ethiopian Roads Authority (ERA) Pavement Design Manual.
The findings of construction of Rigid Pavement Road in hot climate area are: water is scarce and
full of salt, long hauling distance of concrete from batching plant, how to minimize thermal
crack and shrinkage in this hot climate, long hauling distance of concrete which affects setting
time of concrete, the manpower is new for construction of rigid pavement having long distance.
The recommendation includes provision of Special Equipment like water treatment plant,
Chiller machine for cooling, Deep water well (>500m) drilling machines, large Concrete
batching plants, 40cm thick Paver and Bulk Cement trucks. Modified cement and different
admixtures including curing compound has been used in the mix design to withstand the hot
weather and heat of hydration. Special construction methodology has been used like night time
concrete paving. The design can be reviewed comparing the results obtained by ERA manual
and AASHTO procedures, mix design optimization has to be made to incorporate the
challenges, water treatment plant should be used to de-saline the water, and Chiller machines
are required to reduce the temperature of water drilled out from wells of 500m depth in order to
use for concrete. The study can be used for similar projects to be built in our country since it
will be better to use local cement than importation of bitumen with foreign currency and also it
has less maintenance cost with longer design life.
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Keywords
Pavement, Rigid, Temperature, Concrete, Cement, Water, Aggregates, Mix Design, Curing, Admixtures