A simulation methodology for online process control of hot mix asphalt (HMA) production

The quality of hot mix asphalt (HMA) is directly related to the quality of the input aggregates and the control of the production process. Many factors such as aggregate gradation and moisture level affect the quality of hot mix asphalt. As state agencies dictate certain standards on quality of the product, some quality assurance techniques have been used in HMA plants. In the current practice, a production sample is taken and analyzed in the lab. The lab analysis takes approximately two hours, making it difficult to quickly correct production mix problems. In this paper, a new online process control of asphalt production system designed to overcome this problem is described. In the proposed system, an image processing system continuously analyzes images of the samples and the required corrective action is taken instantly by a computerized optimization system. In this paper, the simulation model of the proposed online process control system is presented and the results are discussed.