Rockster impactor contributes to sustainability in Hawaii through processing RAP, crushing coral

Rockster's mobile impact crusher R700S has reached Hawaii - more precisely the island of Oahu. Arist de Wolff and his team of 25 employees were excited about the arrival of their brandnew Austrian crushing plant. Alakona Corp, founded in 1982 by Arist's father Mervyn de Wolff, is an asphalt paving and paving maintenance contracting firm, situated in the Hawaiian capital of Honolulu. Alakona Corp serves Oahu and the neighbouring islands, with a wide list of clients that includes commercial enterprises, developers, property managers, condominium associations and individual owners.

At the very beginning, Alakona Corp focused on pavement maintenance with emphasis on slurry seal, seal coating and minor asphalt repairs. During recent years, the company has moved toward its present service and product mix, deriving its income from asphalt repair, asphalt overlay, new asphalt lay, pavement maintenance, as well as slurry seal, seal coat and crack fill.

Alakona's ideal crusher is designed & produced in Austria

Alakona owns several machines they need for their core business like pavers, rollers, loaders, excavators, slurry and seal coat applicators. When they searched for a crusher to expand their business, they put their focus on compact machinery below 25 tons, which fits their fleet perfectly. 

"We feel that Austrian engineers are really honest. Wolfgang Kormann explained in detail how the machine could be beneficial to us and it is true. We are so flexible in terms of processing different aggregates and the material we produce with our crusher is of high value. We do also like the fact that the return belt can be turned aside, and we can make another fraction, as well as the fine side belt that can be pulled off. The screen box is also very beneficial as it allows us to produce different material sizes by just switching some screens. There are some options that others don't have, and we are very enthusiastic about the hydrostatic drive," says Arist de Wolff. 

Thanks to this drive system, the performance of the R700S is constantly high, as the hydrostatic pressure always adjusts to the power requirements of the crusher. This leads to a lower diesel consumption per tonne of production because the diesel engine always stays within the optimum speed range.

The new line of business: processing RAP

 It was a logical step for Alakona to put emphasis on a recycling business. "Obviously, natural rock isn't gonna be there forever, in future we would have to ship it in from the mainland. Sustainability is the key factor. We need a lot of material for subbases, base coarse or backfills. Using Reclaimed Asphalt Pavement instead of natural aggregate saves resources and money. Moreover, RAP contains a bit of bitumen, it is like a glue, holding everything together and giving more compaction," says Arist de Wolff. Using the attached screening system, Alakona crushes asphalt from 1 1/2 ‘ - 2 ‘ to 1 1/2" minus of a final size material. 

"We're doing a bunch of tests like the CBR, to make sure the final material is suitable for reuse in our construction projects," he adds. The Californian Bearing Ratio (CBR) test is a penetration test used to evaluate the subgrade strength of roads and pavements.

What is coral crushing?

Another material that Alakona processes with the new Rockster crusher is coral. In Hawaii, you find a lot of coral shells underneath the soil. So, when Alakona works on street construction sites close to the ocean, they usually excavate coral. Without a screening system, they run a 3" minus final product, used mostly for landscaping. 

"We like the possibility to use the stockpile belt to get another fraction. Especially for processing coral, we run a 2-3" coarse aggregate from the side belt and 1 1/2 " minus from the screen. Coral is quite a hard rock with high density. The crushed material contains less fines than the crushed asphalt. We can use it as base coarse for house or concrete paths," Arist explains.

Easy transport facilitates entry in contracting business

 With a screen box and return belt, the Rockster R700S weighs only 50,300 lbs (22.8 tons) and can be easily transported with Alakona's own flatbed truck without the need of transport permits. This gives them great flexibility in terms of their future plans, to get a foot in the door of contracting business. It also saves them a lot of time and money. 

"We are able to crush so many kinds of material. Within four days of training this summer, we crushed RAP, coral, concrete and basalt. There are so many possibilities for a lot of different customers like construction companies, privates and of course municipalities. You would think that people on an island would be more aggressive into researching, testing and using recycled material, but they are hesitant in trying new things. It needs to be pushed more and people need to understand that this is the future. There needs to be recycled material especially in construction fields where we could save so much natural resources," Arist said.