Stages of the establishment of the roadFirst phase of engineering design :1 . Selects the route on the basis of the following:A - economic terms (less amounts of drilling and filling - less obstacles and properties ) .B - on the national ( services to cities and villages ... ) .1 . After selecting the track is lifted surveyors elementary track and surrounding facilities ....2 . Be
attributed to the work of the design in order to achieve lower amounts
of drilling and filling and fits with facilities located in the path of
the road.Second phase of structural design :Is
determined by the thickness of the layers and the quality of the
materials used depending on the expected loads on the road and the
nature of the material available .Third, the implementation phase :2 . Layers of backfill Fill embankment:- Consist of a mixture of gravel and silt materials and Alsellt and bridge layers thickness of no more than 30 cm .-
Backfill materials can be rocky layer thickness (40 cm) or (50 cm) or
(100 ) cm depending on the force of the bullets used and the size of
the largest stones no more than two-thirds of the thickness of the
layer .-
Can backfill material ( sand ) , provided the work (plating) any
business end of the barrier side of the clay material to prevent the
sand from collapsing .-
Test layers are filling Messahaa and laboratory work experience Cone
sand (sand cane test) are required to have the relative density of not
less than 90 % of the density Albrooctor ( maximum dry density ) in
layers that will be far from the road surface > 60 cm .- Are required to have the relative density of not less than ( 95 %) of the top layers .-
Is determined by the maximum dry density test proctor work by taking
samples of the materials used in the filling and put it in your
Albrooctor and pounded on three layers every time you hit the (25) blow
. The
dry density is determined in each case and is plotted curve of which is
determined by the maximum dry density and the optimum ratio of water
(OMC).3 . Base layer : Sub grade:And
placed over another layer of rubble and consists of top material
quality of the layers of rubble and be classified (A2-4 & A-1-a
& A-1-6) A three classifications and have a thickness in the range
of (20 cm) or by design, and is mixed with water and
compacted to the density ratio of not less than 98 %, according to the
density of Albrooctor that works the same way as layers of backfill . And is tested as well Messahaa .4 . Pebble base layer : Agg. Base Caurse:It
consists of materials , crushed stone crushers and graded and solid and
is mixed with water and returned that using the uniqueness Finisher and
mechanical compaction of bullets .The ratio of its dry density of not less than 100 % of the test proctor .There
Hzhaltqh in highways and airports, only the agricultural roads is
placed above the asphalt base layer directly below the work of gravel
layer basis .5 . Impregnation layer : Prime coat:It
is a (MC) Asphalt mixture is sprayed by kerosene over the base layer
before placing asphalt b (48) at least an hour and have an average of
0.65 l / m 2 to 1.75 l / m 2 .6 . The base layer of asphalt : BBC:A
layer of asphalt first placed over the MC is composed of materials of
stone , crushed and graded blended bitumen and maximum size of 1.5
inches and the thickness of 6 cm to 10 cm by design and is
characterized by a layer of asphalt second (surface ) as the most
roughness and are produced from mixer at a temperature of 160 m + 17:00 and uniqueness Boisthlafradh (Finisher) is compacted stages of iron and rubber rollers .7 . Adhesive layer (R.C) Tack Coat:It consists of adding gasoline to the bitumen .And
is sprayed onto the first layer of asphalt in preparation for the work
of the second layer in order to paste layers and sprinkle each other at
a temperature of 80-95 m and spraying rate of 0.1 to 0.2 l / m 2 .- Increase the rate of spraying lead to the appearance of spots bitumen (bleeding) on the final asphalt surface .- Lack rate of spraying lead to creep the second layer and the crescent cracks in the asphalt .How to determine the rate of spraying each of the MC & RC:Is
equipped with a sheet of tin measured 1 × 1 meter and is measured and
weighed accurately placed on the road and moving car spray to reflect
from it, and then be weighed again , where the weight difference is the
rate of spraying. Is
a lack of , or increase the speed of the car until they are getting the
speed at which lead to the required rate is spraying so quickly .8 . Asphalt surface layer : Wearing course:Is
a layer of asphalt final and have a thickness of 3-5 cm by loads show
her the way and are returned that after spraying layer RC directly and
are returned that at a temperature of 160 +5 m and consists of bitumen
mixture with stones caused by cracking crushers and have a maximum size
has three quarters of an inch . It is smooth on the first layer .And
is compacted in the same way your blood layer of asphalt first and is
tested then take Oquar to identify fish and compaction are also Test
surface smoothness using the device (RD) , where he 's specifications
and the Ministry of Transport Arabia should check less than 1.2 mm in
the case of 02/01 to 06/01 be accepted by discount In the case of > 1.6 mm asphalt is removed and a new asphalt work at the expense of the contractor
ليست هناك تعليقات:
إرسال تعليق