There is a high demand from Road Departments throughout Africa and other third world

countries to develop a small mobile Hotmix machine for Bitumen Road repairs to become

independent from traditional stationary bitumen heating-mixing-batching plants, as well as

eliminate the use of firewood for heating the Hotmix. The Rotomix has been designed to cater

for this demand and provide a viable alternative to traditional road repair technology.

 

The first iteration of the Rotomix design was introduced as a prototype in 2007.The first

machine has been extensively tested with the Road Department of the Ministry of Public Works

and Roads in Nairobi/ Kenya. The successful testing resulted in an order of 5 machines with

more orders in progress. The success of the prototype encouraged me to seek out a capable

manufacturing company in South Africa to service the African Market.

 

The Rotomix technology is patented in many countries and is the only mobile Bitumen

heater/mixer with a specially designed vertical mixer Vessel using a gas or oilburner (diesel) at

the bottom of the Vessel. The flame is in direct contact with the Vessel floor and has a heavyduty agitator inside the Vessel to mix the aggregate. This unique combination of functionality has numerous advantages over other conventional horizontal heater vessel designs.

 

The Rotomix is easy to operate and is capable of maintaining and repairing potholes on tarmac

roads, driveways, yards etc… The Rotomix can be manually filled by driving the machine to a

stock pile, truck or trailer. Alternatively it can be filled by a bucket loader with a special

attachment for this purpose.

 

Aggregate mix is transferred into the heating Vessel through the top cover while the agitator in

the heating vessel is constantly rotating. The mixture is heated up to the required temperature of

approx.190ᵒC. Steam visible through the open cover indicates that the aggregate mixture is

losing moisture. As soon as all the steam formation ceases the mixture has reached the

appropriate temperature and is ready for the tar (bitumen) to be added into the mixture. The

correct ratio of aggregate to tar (bitumen) content is specified by the Road Engineer in charge.

 

The aggregate mixture can be viewed through the top cover of the heating vessel in operation

and allows for changes to the aggregate to bitumen ratio to be made at any time during the

heating/mixing process. It takes approx.55 minutes for the first mixture to reach the required

temperature with subsequent mixtures taking approx. 45 minutes. The machine is then driven to

the pothole and the Vessel is tilted to pour the mixture into the pothole. (Correct pothole

preparation should be done prior to pouring the mixture into the hole)

 

At the end of the working day, the Vessel should be cleaned of large deposits of mixture.

Smaller deposits can be left inside and re-heated for 15 minutes the next time the machine is

used. This cleaning process is much faster and simpler than traditional designs where the heating

vessel must be re-heated before the agitator is activated.

 

The Rotomix is also capable of heating tar-bitumen only to fill and seal cracks in roads or to seal

bridges and roofs. Using our unique oil burner technology, the furnace is fully enclosed and

resistant to wind gusts allowing the heater to operate while travelling to the work site. The

Rotomix is capable of heating and mixing any material to temperatures of up to 250ᵒC.

 

When the demand arose for a unit capable of mixing a larger quantity of Hotmix we developed a

new larger trailer mounted 3 Ton Rotomix to complement the existing models. All models are

designed to operate as mobile Bitumen Road mix batching plant to allow the user to be fully

independent from a traditional stationary hot mix plant and are ideal for use in very remote

locations where there are no Stationary batching plants nearby.

 

The 3 T Rotomix has a tare weight of 9.5 Tons and requires a heavy towing truck. To make the

best use of the size of the towing vehicle we developed a hopper with 17 Ton capacity for dry

pre-mixed aggregate to be mounted on the towing vehicle to provide sufficient aggregate for a

full day’s work. The bitumen required is available in various Australian Standard specifications

and can be provided in 10 Kg packages stored in front of the hopper along with tools and heating

fuels.The Rotomix does not require emulsions based on bitumen.

 

The dry aggregate is transferred from the hopper into the Rotomix via conveyor belts powered

by the Rotomix hydraulic system meaning the towing vehicle does not require provisions for

hydraulics. The hydraulic controls are conveniently located to allow the operator to oversee the

transfer process. Four load cells are fitted to the hopper to monitor the exact weight of the

transferred aggregate via easy to read Digital read out located next to the hydraulic activators for

the conveyor belts. The load cells are used to monitor the amount of aggregate transferred to the

Heater Vessel to allow for an exact ratio of aggregate to bitumen to be calculated to achieve a

perfect mixture. Batches of any size are possible, from a wheelbarrow size up to 3 Tons.

 

The Heating Vessel is insulated using a highly efficient material to reduce the heating time of a

3 Ton mixture to approx. 60 minutes using 20-30 L of heating oil or diesel, depending on the

required temperature. The mixing temperature in the tank is constantly monitored by temperature

sensors with Digital readouts located near the discharge gate hydraulic activator valves.

 

The moisture content of the aggregates after heating up to 140ᵒC prior to adding the bitumen is

0% which is signaled once steam is no longer visible. The hot aggregate expands and the

capillaries in the aggregate replace the moisture with the hot liquid bitumen resulting in a very

strong bond between the aggregate and the bitumen.As the high temperatures required can be

maintained at all times at the construction site it is possible to produce an A1 quality mix and

sealing of a pothole can be done to perfection.

 

To easily and fully discharge the mix, the tank can be tilted backwards while simultaneously

lifting the transfer conveyor at the front to rule out mistakes by the machine operator. Cleaning

of the Vessel is easily accomplished through the discharge gate to remove any larger materials

while small deposits can be ignored. When resuming work, the vessel should be reheated to

approximately 100–130ᵒC to melt the previous bitumen mix particles and re-use them again.

 

The Rotomix technology is the ideal solution for time saving and cost effective maintenance and

repair of roads with high quality patching material, particularly in rural and remote areas

currently only serviceable with alternative materials like cold mix or other inferior repair

materials resulting in reoccurrence of the potholes after a very short time.

Please contact us for any additional information you may require and to visit us to view the

Rotomix or to arrange for a demonstration