PAVING UNDER STOCKPILES PAYS OFF ENVIRONMENTALLY AND ECONOMICALLY Operational Tips: The Road Forward to Lower Emissions and Higher Profits By NAPA Contractors are continuously searching for the latest technical innovations that will make their plants more efficient and cost-effective to operate. Governments and citizens, especially young people, want transparency and are calling for companies to be greener and develop sustainability goals. With new industry goals centered around carbon neutrality in 2050, it is fortunate that increasing profitability and reducing emissions often go together. One of the most impactful asphalt plant efforts is reducing aggregate moisture, and one way to do this is to pave the stockpile area. According to Greg Renegar, president of Astec Industries, approximately 50% of the energy required to produce asphalt mixtures is to remove water. Reducing moisture by 1% can reduce fuel consumption by approximately 10%. In addition, a 1% moisture reduction can also increase production — by approximately 12%. Finally, a paved stockpile area will decrease aggregate loss by preventing aggregate contamination caused by stockpiled material being comingled with the underlying material. Unpaved stockpiles can result in a 3% aggregate loss per year. Michigan Paving & Materials, A CRH Co., had leftover mix after conducting trial runs and decided to use it to pave under a portion of their stockpile area at their Grand North asphalt plant in Comstock Park, Michigan. For comparison purposes, the company left unpaved a similar aggregate stockpile at a plant eight miles away in Grand Rapids. Since the plants are geographically close together, both experience the same levels of precipitation annually. The fine aggregate in the stockpile that was paved accounts for about 20% (80,000 tons) of the plant’s annual production. Michigan Paving measured the moisture in the stockpile from April through November 2020 and found that the percentage of moisture in the paved stockpile was 4.6%, while the unpaved stockpile averaged 5.2% moisture. A detailed analysis found that 25
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