Batch Plant & Mix Design

Batch Plant

The asphalt originated from Lakeside Industries’ drum plant (see Figure 1) in Issaquah, WA which is approximately 20 miles from the project site.
This counter flow drum plant uses natural gas or diesel fuel to dry/heat the aggregate. The fuel source can be changed as necessary to use the least expensive fuel available. The output of this plant is 500 tons/hour, but can be increased slightly to full capacity, as operations require. The HMA is stored in one of four storage silos (see Figure 2) until it is placed in trucks and transported to the site. The system is fully automated to produce the exact mix design required in the project specifications.

Lakeside owns the entire aggregate pit where the drum plant resides, but it shares the site with Cadman Heidelburg Cement Group who operates a concrete batch plant on the site. The site houses a pit, aggregate crushers, sorting equipment, aggregate stockpiles, a concrete batch plant, a HMA drum plant, equipment maintenance space, QC testing facilities, and all the support equipment one might expect for this operation. Both Lakeside and Cadman have large stockpiles (see Figure 3) of aggregate and Recycled Hot Mix on the site for their daily plant operations.

Figure 1. Lakeside Industries HMA Drum Plant, Issaquah WA

Figure 2. HMA storage silos at Lakeside Industries drum plant

Figure 3. Stockpiles and pit at Lakeside Industries drum plant

Mix Design

The contractor submitted a mix design and samples to SDOT, which in turn used WSDOT testing laboratories for validation of the contractor’s test results. The validation process approved the mix design for use on this project (see Lakeside Verification Report).

A higher grade HMA, PG 70-22, was used on this job because traffic consists of both very slow-moving vehicles and a high proportion of buses. This higher grade HMA mix should better resist rutting and shoving. Of interesting note, the project specification disallows the use of Recycled Asphalt Pavement (RAP) with PG 70-22.