P R OJ E C T M A N AG E M E N T
Larsen Shares RAP Crushing Tips FROM EVOQUIP
L
arsen Dirtworks LLC, Foreston, Minnesota, prides itself on helping customers run smooth and lucrative operations. A recent project making 1-inch minus reclaimed asphalt pavement (RAP) for shouldering in Magregor for County Route 3 helped showcase how that work comes together.
PROJECT MANAGEMENT
Larsen Dirtworks has been running an EvoQuip Cobra 230R impact crusher with an integrated afterscreen system. President Mark Larsen identified some of the advantages this machine offers the company’s operations for a range of applications. Those applications? The company crushes for contractors and utilities companies in Iowa, Minnesota, North Dakota, South Dakota, and Wisconsin. They see the benefit in reusing the material on job sites and eliminating trucking. For RAP jobs, Larsen crews typically make 5/8-inch minus product on the Cobra 230R, with production of up to 215 TPH. On concrete crushing jobs, they typically make 18-inch minus infeed resulting in a product of 1 ½-inch minus with production of up to 200 TPH.
APRON SETTINGS
Larsen said that the ability to adjust apron settings, depending on the application, makes a huge difference to them as settings for concrete and asphalt crushing are different. For the shouldering project on CR 3, they had the aprons set at 1 inch and 2 inches with two up and two down. He also spoke of the ease of adjusting the aprons. “It takes longer to wait for the rotor to stop than it does to adjust them, and it’s so quick and easy.” Aprons can be controlled by remote control from the excavator. He stated that this significantly increases uptime and reduces blockages. They pre-screened the material for the CR 3 project and were able to reduce the wear cost and increase the production numbers—they went from 200-225 TPH without pre-screening to close to 400 TPH with pre-screening, Larsen shared. Changing screen media is “quick” as well. “It is super easy to change screens in the machine and they can be changed in under an hour,” Larsen said. “In jobs where no screen is required, we can remove the closed-circuit system in five to six minutes. We also have the ability to unload and be crushing in 45 minutes.”
TEMPERATURE CONSIDERATIONS
Tonnage and temperature play a role in a job’s efficiency. Larsen has found that on job sites where there is less than 10,000 tonnes, the Cobra 230R can bring savings with its mobility. Jobs can cost over $10,000 in mobilization for portable setups. He shared: “We find we can save up to 70% on mobilization for our contractors 14 | AUGUST 2022
Larsen Dirtworks LLC has been running an EvoQuip Cobra 230R impact crusher for applications such as reinforced concrete, recycled asphalt, construction and demolition waste, and natural rock. The integrated afterscreen system on the Cobra 230R is designed to achieve the required product spec while oversize material is either recirculated for crushing or stockpiled.
and it is a fast setup to begin work quickly. The Cobra 230R can be tracked between multiple piles in minimal time and the machine can be adjusted to make a variety of products depending on the contractor’s needs.” QUICK TIP: Larsen suggested: If your material has a lot of fines in it, try cleaning twice a day—once at lunchtime and once at the end of the shift.
He also commented on timing, as it relates to weather conditions, to get optimum production. “RAP is easier to process below 70 degrees [ambient] because it gets gummy at higher temperatures.” Larsen shared that in higher ambient temperatures, the team will see better production and fracturing early in the day. He also shared that it’s very important for crushing contractors to remember to clean out the chamber at the end of the day as well as cleaning the radiator. He shared that with the Terex chamber, this cleaning is fairly simple, but is essential. If your material has a lot of fines in it, Larsen recommended cleaning it twice a day—typically at lunch and end of day. For the CR 3 project, the material was dry and there was notably less buildup on the inside of the chamber. The pre-screening helped remove build-up as well. For more information, contact EvoQuip, a Terex brand, via gemma. mckelvey@terex.com.
