MATTU UNIVERSITY

COLLEGE OF ENGINEERING AND TECHNOLOGY

DEPARTMENT OF CIVIL ENGINEERING
ASSIGNMENT OF CONSTRUCTION EQUIPMENT

NAME ID NUMBER
1: ABDILJEMIL MUHADIN…………………….……….. RU 4567/12
2: Tolessa Kebede…………………………………………RU
3: Zuber edris………………………………………………RU

Submitted to: Mr.

Submission date:

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Q2) Asphalt mixing plant

Definition (i.e. what is asphalt mixing plant)
Types of mixing plant and how they operate
Processes in different types of mixing plants
Add if any
 Before starting about specific Construction plants let’s see what it mean construction plant?
In construction, plant typically refers to heavy machinery and large equipment used on
construction sites – think concrete batching plant, asphalt mixing plant, aggregate crushing plant.
Construction plant is used in many types of construction projects, from rail and road works to
house building.
An essential part of large and complex construction projects is getting sites ready for building and
moving materials from A to B. This is the primary function of construction plant and why it is so
important; without it, work would rarely be able to get off the ground. Plant often represents one
of the largest costs during construction projects. Some commonly used types of construction plant
include excavators, cranes, forklift trucks, breakers, concreting plant, and earth moving plant.
Overall, construction plant plays a crucial role in the construction industry by enabling
construction projects to be carried out efficiently, safely, and effectively.

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Definition of asphalt mixing plant

What is an Asphalt mix plant?
An asphalt mixing plant is a machine used in the construction industry to produce hot mix asphalt
(HMA) for road construction. It is a complex system that combines different materials such as
aggregates, sand, and bitumen to create a high-quality asphalt mix that can be used for various
types of road surfaces. The process involves heating and drying the aggregates, adding the
bitumen, and mixing everything together to create a homogeneous mixture. Asphalt mixing plants
can be stationary or portable, and they come in various sizes and capacities depending on the
specific needs of the project.
There are some basics that are common to all the asphalt mixing plants. They are as below:
Drying and heating of aggregates.
Weighing of aggregates, bitumen and filler material.
Mixing aggregates with bitumen and filler material.
Release of hot mix asphalt.

It is mainly suitable for the construction of highways, graded roads, airports, ports, etc. It has the
advantages of wide application range, high efficiency, large output, stable operation, and good
quality of finished asphalt.

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Advantages of Asphalt Mix Plant

 Accuracy- easier to know the amount of mixed asphalt

 Costing- It reduces the cost of the project and can be used for the next as well
 Time saving-mix is done timely and efficiently
 Fewer wastages
 Material quality is maintained
 Durable

Different Types of Asphalt Mix Plants

Asphalt mixing plants are used to produce different types of asphalt mixtures, such as modified
asphalt mixtures, colored asphalt mixtures, etc. They use sand and gravel aggregates, bitumen,
water, mineral powder, etc. as raw materials. According to different classification standards,
asphalt mixing plants can be divided into different types.

For example, according to mobility, it can be divided into stationary type and mobile type;
according to different mixing methods, it can be divided into continuous drum mixing type and

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intermittent forced mixing type. According to different production capacity, it can be divided
into small, medium and large asphalt plants.

In fact, there are some common types of asphalt mixing plants:

Forced mix asphalt plant

Drum mix plant,
Mobile asphalt plant
Stationary asphalt mix plant

Forced mix asphalt plant is a kind of equipment that uses a forced mixer to mix asphalt mixture.
It is mainly suitable for projects with high requirements on project quality and output, such as
municipal roads, graded roads, airport roads. Drum mix asphalt plants use drying drums to
complete the mixing of asphalt mixture. They are mainly suitable for projects with limited
budget and low quality requirements for finished products, such as township roads and country
roads. Mobile asphalt plants offer lower initial investment costs compared to stationary plants
and are suitable for projects that require frequent relocation

1) Mobile Asphalt Mix Plant

A mobile asphalt mixing plant is compact and portable asphalt equipment designed to produce
asphalt mixture on-site it mixes stone, asphalt and mineral powder according to a certain proportion
to produce asphalt mixture. The unique walking system makes the transition more convenient. The
biggest advantage of mobile asphalt mixing plants is that they can be assembled and disassembled
freely, and once disassembled, they can be reused.
 How it operates
The plant consists of several components that work together to produce the desired asphalt mix.
The first component of the Mobile Asphalt Mix Plant is the cold aggregate supply system. The
aggregates are stored in separate bins and are fed into the plant through a conveyor belt. The
aggregates can include materials such as gravel, sand, and crushed stone.
The second component of the plant is the drying and heating system. The aggregates are dried and
heated in a drum dryer using hot air generated by a burner. This process removes any moisture from
the aggregates and heats them to the desired temperature.

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The third component of the plant is the hot aggregate elevator. The dried and heated aggregates are
lifted to the top of the mixing tower using a hot aggregate elevator. This is where the actual mixing
process takes place.
The fourth component of the plant is the vibrating screen. The aggregates are screened to remove any
oversized particles or debris. This ensures that only properly sized aggregates are used in the mix.
The fifth component of the plant is the weighing system. The aggregates, filler, and bitumen are
weighed separately and accurately before being mixed. This ensures that the correct proportions of
each material are used in the mix.
The sixth component of the plant is the mixing tower. The aggregates, filler, and bitumen are mixed
together in the mixing tower to produce the asphalt mix. This process involves thorough mixing to
ensure that all materials are evenly distributed.
The seventh component of the plant is the filler supply system. The filler is added to the mix to
improve its stability and durability. Fillers can include materials such as limestone dust or hydrated
lime.
The eighth component of the plant is the bitumen supply system. The bitumen is added to the mix to
provide the necessary binding properties. Bitumen is a viscous, black material that is derived from
crude oil.
The final component of the plant is the control system. The entire process is controlled by a
computerized control system that ensures the accurate production of the asphalt mix. The control
system monitors and adjusts the various components of the plant to ensure that the mix is produced to
the desired specifications.
Once the asphalt mix is produced, it can be loaded onto trucks and transported to the construction site
for use in road construction projects. The Mobile Asphalt Mix Plant is a versatile and efficient tool
for producing high-quality asphalt mixes on-site.

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2) Stationary Asphalt Mix Plant

A Stationary Asphalt Mix Plant is a type of asphalt plant that is designed to be installed in a fixed
location and is not meant to be moved. This type of plant is commonly used for larger road
construction projects where a large quantity of asphalt mix needs to be produced.It produces all types
of mixtures suitable for construction projects.

A stationary asphalt mix plant is a type of mixing equipment that is used to produce a black mixture
suitable for laying asphalt pavement. It heats aggregate and bitumen to a certain temperature
according to a certain ratio

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 How the operate

The plant consists of several components that work together to produce the desired asphalt mix.
Firstly the cold aggregate supply system stores the aggregates in separate bins and feeds them into
the plant through a conveyor belt. Secondly the drying and heating system dries and heats the
aggregates in a drum dryer using hot air generated by a burner, removing any moisture from the
aggregates and heating them to the desired temperature.

Thirdly the hot aggregate elevator lifts the dried and heated aggregates to the top of the mixing
tower, where the actual mixing process takes place. The vibrating screen screens the aggregates to
remove any oversized particles or debris. The weighing system accurately weighs the aggregates,
filler, and bitumen before they are mixed, ensuring that the correct proportions of each material are
used in the mix.

Fourthly the mixing tower is where the aggregates, filler, and bitumen are mixed together to produce
the asphalt mix. The filler supply system adds filler to the mix to improve its stability and durability,
while the bitumen supply system adds bitumen to provide the necessary binding properties.

Finally the control system monitors and adjusts the various components of the plant to ensure that the
mix is produced to the desired specifications. Once the asphalt mix is produced, it can be loaded onto
trucks and transported to the construction site for use in road construction projects.

In summary, the Stationary Asphalt Mix Plant is an essential tool for producing high-quality asphalt
mixes for large-scale road construction projects. Its reliable and efficient design ensures that asphalt
mixes are produced consistently and to the desired specifications.

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3) Drum Mix Asphalt Plant:

A drum mix asphalt plant is a type of plant used for producing asphalt mixtures for road construction
projects. This plant uses a drum dryer to dry and heat the aggregates before they are mixed with the
bitumen and filler. The drum dryer rotates continuously, allowing the aggregates to be heated evenly
and thoroughly. This process ensures that the asphalt mix produced is of high quality and suitable for
use in road construction projects. Once the aggregates are dried, they are then mixed with the
bitumen and filler in the drum mixer. The resulting asphalt mix is then discharged from the drum and
transported to the storage silos. Drum mix asphalt plants are preferred by contractors and
construction companies because they are efficient, reliable, and produce high-quality asphalt
mixtures.

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 How it operates

A drum mix asphalt plant operates by first feeding cold aggregates such as gravel, sand, and crushed
stones into the drum dryer. The dryer is heated by a burner that runs on fuel oil or natural gas, and the
aggregates are dried and heated as they move through the drum. The temperature inside the drum can

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reach up to 300 degrees Celsius, ensuring that the moisture content of the aggregates is reduced to a
minimum.

As the aggregates move through the drum, they are lifted and dropped by flights attached to the interior of
the drum. This action ensures that the aggregates are heated evenly and thoroughly. At the end of the
drum dryer, the hot aggregates are discharged into a hot elevator that lifts them to the top of the drum
mixer.
In the drum mixer, the hot aggregates are mixed with bitumen and filler materials such as limestone dust
or hydrated lime. The bitumen is added in a controlled manner to ensure that it coats the aggregates
evenly. The mixing process takes place for a specific duration, depending on the type of asphalt mix
being produced.

Once the mixing process is complete, the asphalt mix is discharged from the drum mixer into trucks or
transporters that take it to storage silos. The mix is kept in the silos until it is ready to be transported to the
construction site.
Drum mix asphalt plants are efficient because they can produce large quantities of asphalt mix quickly.
They are also reliable because they have fewer moving parts than other types of asphalt plants, reducing
the risk of breakdowns. Additionally, drum mix asphalt plants produce high-quality asphalt mixes that
meet industry standards and are suitable for use in road construction projects.

4) Batch Asphalt Mix Plant (forced mixing asphalt)

As the name implies, the forced mixing asphalt plant is a kind of equipment that uses a forced
mixer to mix asphalt mixture. It is also called asphalt batch mix plant. It is mainly suitable for
projects with high requirements on project quality and output, such as municipal roads, graded
roads, airport roads, etc.

This type of plant is suitable for small to medium-sized projects that require frequent changes in
the mix design. The batch plant consists of several components, including cold feed bins, a dryer
drum, a mixer, and storage silos. Regular maintenance and cleaning of the equipment is
necessary to ensure that the plant operates efficiently and produces high-quality asphalt mix. The
plant must also comply with environmental regulations to minimize emissions and protect air
and water quality.

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Its advantages

 Modular design, reasonable layout, quicker and more convenient disassembly-transportation-

installation.
 Mass production and large output range can meet the needs of projects of different scales.
 It is equipped with a two-stage dust collector. The dust removal effect is good, and it is
suitable for areas with higher environmental protection requirements.
 How it operates

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1. Check that all equipment is in good working condition: Before starting the plant, it is important to
check that all equipment is in good working condition. This includes checking the cold feed bins,
dryer drum, mixer, and computerized system for any signs of wear and tear or damage.
2. Load the aggregates into the cold feed bins: The first step in the mixing process is to load the
aggregates into the cold feed bins. These bins are typically located at the top of the plant and are
used to store different sizes of aggregates.
3. Start the dryer drum and heat the aggregates to the desired temperature: Once the aggregates are
loaded into the cold feed bins, they are transported to the dryer drum. The dryer drum heats up the
aggregates to the desired temperature, which is typically between 150-180°C.
4. Transport the heated aggregates to the mixer: Once the aggregates are heated to the desired
temperature, they are transported to the mixer. The mixer is where the aggregates are mixed with
bitumen and filler materials to create the asphalt mix.
5. Add the bitumen and filler materials to the mixer according to the desired mix: The bitumen and
filler materials are added to the mixer according to the desired mix. The amount of bitumen and
filler materials added depends on factors such as the type of asphalt mix being produced and the
temperature at which it will be applied.
6. Use the computerized system to control the mixing process: The mixing process is controlled by a
computerized system that monitors and adjusts the temperature, speed, and other variables to
ensure that the mix is consistent and of high quality.
7. Once the mix is complete, discharge it into trucks or storage silos: Once the mix is complete, it is
discharged into trucks or storage silos. The mix is typically transported to construction sites where
it will be used for paving roads, parking lots, and other surfaces.
8. Regularly maintain and clean the equipment to ensure efficient operation and high-quality mix:
To ensure that the batch asphalt mix plant operates efficiently and produces high-quality mix, it is
important to regularly maintain and clean the equipment. This includes cleaning the dryer drum,
mixer, and other components, as well as checking for any signs of wear and tear.
9. Follow all environmental regulations, which may involve installing pollution control equipment:
Batch asphalt mix plants can produce emissions that are harmful to the environment. To mitigate
these emissions, it is important to follow all environmental regulations, which may involve
installing pollution control equipment such as bag houses or scrubbers. These devices help to
capture and remove pollutants from the air before they are released into the environment.
Main Components of Batch Asphalt Plant

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1. Charging conveyor
2. Drying drum with burner
3. Cold fed bins
4. Pre-separator
5. Mixing units
6. Weighing hoppers
7. Control cabin
8. Panel
9. Bitumen storage tanks.

Processes in different types of mixing plants

The processes are the same with the how they operate and we cited with their types above.

There are different types of mixing plants used for producing asphalt mix, including batch plants, drum
plants, and continuous mix plants. Here are the processes involved in each type of plant:

1. Batch Plants: Batch plants produce asphalt mix in batches, which means that a specific amount of
materials is mixed at a time. The process involves loading the aggregates into cold feed bins, heating
them in a dryer drum, transporting them to a mixer where they are mixed with bitumen and filler
materials, and then discharging the mix into trucks or storage silos.

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2. Drum Plants: Drum plants use a continuous process to produce asphalt mix. The process involves
heating the aggregates in a dryer drum, adding bitumen and filler materials to the mix as it moves through
the drum, and then discharging the mix into trucks or storage silos.

3. Continuous Mix Plants: Continuous mix plants also use a continuous process to produce asphalt mix.
The process involves mixing the aggregates with bitumen and filler materials in a pugmill or similar
mixing device, and then discharging the mix into trucks or storage silos. Continuous mix plants are
typically used for producing large quantities of asphalt mix.

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