Investigation of reclaimed asphalt pavement batching process in an asphalt mixing plant

Abstract

The practice of incorporating reclaimed asphalt pavement (RAP) into hot-mix asphalt (HMA) is common within the paving industry as a cost-effective source of quality paving binder and aggregate. The environmental and economic benefits of using RAP in HMA applic ations could be pushed up to the limit, by producing totally recycled hot-mix asphalt (RHMA) (100 % RAP), but the performance of this alternative must be satisfactory. In fact, these mixtures could possibly present problems of workability and durability, hi gher binder aging and low fatigue cracking resistance. When RAP is recycled in an asphalt mixing plant (AMP), like in producing virgin HMA mixtures, inevitable systematic and random errors of performed technological operations, inhomogeneity of fillers and RAP influence on the dispersion (variation) of RHMA mixture components‘ quantities and deviations from JMF. In this study during the season of asphalt mixture production in 2014, the statistical parameters were calculated according to the data obtained fr om one of the Lithuanian companies, which collected and systematized RAP batch masses, when before batching it was pre-dried and pre-heated in an additional dryer. These parameters of batch mass and RAP content in RHMA position and dispersion were used whe n evaluating the accuracy and precision of the recycling process in an asphalt mixer. The obtained data showed that when RHMA mixtures are produced in a modern batch-type AMP, RAP is batched accurately, but not precisely enough.