When the first Astec Portable Double Barrel® plant was commissioned in the South of Kazakhstan, City of Shymkent, in 2014, there were quite a few doubts within the Kazakhstan hot-mix asphalt (HMA) industry on how relevant continuous technology was for the local market represented by Chinese-, Ukrainian-, and German-manufactured batch plants. The contractor that took the challenge, TOO Bereke, is now harvesting the benefits of its decision.

Technology Changes Outcome

Before bringing the 300 TPH (272 MTPH) Astec plant to its production site at Kazygurt village, Bereke had to operate with three Chinese batch hot-mix plants in order to keep up with the growing production volume. Head of the company laboratory, Akzharkyn Isabayeva, had to spend a lot of time at her plants coping with issues like variations of components metering and constantly changing volumes of injected bitumen. The mix was not stable enough to comply with RK standards and was frequently hard to compact. Bereke had several cases with quality control authorities with regard to its mixes and had to redo the work a few times.

Since the 2015 season (after the Astec plant was commissioned at the end of 2014), the company started to feel more confident about its mixes. Bereke’s confidence came after experiencing what may be the best drying and mixing solution in the industry—the Astec Double Barrel® technology. Good, quality mix brought more jobs to the contractor. In 2016, despite an economic downturn, Bereke is facing one of the most intensive seasons in company history with the overall HMA amount expected to be produced at around 330,000 to 350,000 tonnes (363,762 to 385,808 tons), of which base course mixes represent 90,000 tonnes (99,208 tons), binder course mixes—some 150,000 tonnes (165,346 tons), top layer mixes—90,000 tonnes (99,208 tons), including 30,000 tonnes (33,070 tons) of SMA.

The high capacity and unprecedented reliability of the Astec Double Barrel® plant allowed the contractor to meet all demands for HMA with just the Astec plant. Two of the existing Chinese batch plants were sold to the smaller contractors and removed from the site. The third plant is used for small-scale production of cold mixes for patching over the winter period. About 20 percent of the overall production volume is sold to external customers.

Bereke’s confidence came after experiencing what it describes as the best drying and mixing solution in the industry—the Astec Double Barrel® technology.

Astec Double Barrel®

Bereke’s Astec Portable Double Barrel® plant includes four cold feed bins with variable frequency drives ensuring a high level of aggregates’ fractions mixture precision, and one bin for introduction of reclaimed asphalt pavement (RAP). The plant is equipped with scales and feeders for adding limestone, or any other imported filler, as well as for adding SMA additives (e.g., cellulose fiber). Dust that is recovered by the plant’s baghouse can also be introduced back into the mix wherever mix design allows. A portable, 120-tonne (133 ton) bitumen tank is equipped with a built-in hot oil heater, liquid additives line, a high-precision bitumen metering system, and unloading pumps. The tank, which automatically regulates hot oil and bitumen temperature, has solved the issue of unstable deliveries of bitumen and low temperature of the material that comes in with railroad tanks. The 300 TPH (272 MTPH) Double Barrel® drum drying and mixing unit has been manufactured to introduce up to 50 percent RAP into both HMA and WMA (warm-mix asphalt) mixes. WMA can be produced with the plant due to Astec’s patented warm mix system that ensures foaming of virgin bitumen and proper mixing of the foamed binder with the other mix components.

Exceeding Expectations

The plant’s foreman, Abdurassul AlmaTov, reflects on the plant capacity: “We have been able to produce up to 330 tonnes (363 tons) of mix per hour at 40 percent RAP without any issues. With this Astec plant, our daily output has more than doubled by comparison with our earlier experience of production with three batch plants. In 2016, 3,000 tonnes (3,306 tons) a day (produced) stopped being regarded as something unusually high by the plant operators.”

Roza Myltykbayeva, deputy head of laboratory for TOO Bereke.
Roza Myltykbayeva, deputy head of laboratory for TOO Bereke, checks the compression strength of HMA and WMA core samples.

Unmatched Double Barrel® drying and mixing drum design minimizes both waste of energy generated by the burnt fuel and variations with mix homogeneity. The outer chamber of the drum extends oxygen-free mixing time up to 90 seconds without capacity loss. The long mixing cycles result in high consistency and homogeneity of mixed asphalt along with lower levels of bitumen oxidation. The plant seems to cope very well with mixes that would cause a capacity drop at most of the competition plants (e.g., SMA mixture). Another advantage of the Double Barrel®’s long cycle is that there’s ample time for additives to be introduced and spread among aggregate particles in the mix that allows for much higher consistency. RAP use at an average level of 20 percent across mix designs has made Bereke mixes stronger and less prone to rutting, while use of the Astec’s warm mix system has allowed for transport of mixes to distances up to 300 km (186 mi) without any compaction or quality issues.

Strengthening Position

The company has become a pioneer in the Republic of Kazakhstan in terms of warm mix and RAP use and is strengthening both its economic position and edge-of-technology reputation in cooperation with U.S. engineers and reliable Kazakhstani servicemen (TOO OptimusVia, located in Almaty). Nurlan Abdiev, plant operator, pointed out that service teams, both from the U.S. and Almaty, have already visited the plant twice in the beginning of the year as part of Astec’s courtesy visit program to check the equipment status at the eve of a challenging year. He has also pointed out that it’s been one and a half seasons that the plant has worked with minor spare parts/wear parts issues. He estimated that the company has spent less than $2,000 USD overall for the parts throughout the time since commissioning. Between 2014 and August 2016, Bereke has produced more than 1 million metric tons of HMA and WMA for the South Kazakhstan region with its Astec plant. The contractor is looking forward to growing its presence in the regional market due to the plant cost and technology advantages it has learned and successfully used throughout the year.