Statistical analysis of component content deviation from job-mix formula in hot mix asphalt

Abstract

Dose masses of bitumen and finite dosing mineral materials (imported fillers, reclaimed dust and hot fractions) weighed by the dosing systems (batchers) of batch type asphalt mixing plant (AMP) shall guarantee that the percentage component ((bitumen (B), mineral fillers (MF), fine aggregate (FA) and coarse aggregate (CA)) content in all mixes of the hot mix asphalt (HMA) mixture batch meets the design content established in the job mix formula (JMF). Batchers do not always weigh the doses of HMA mixture materials accurately and succinctly. Factual deviations of component content from JMF and variation worsen HMA composition and properties. Statistical characteristics suitable to evaluate the quality of HMA mixture are presented. Parameters showing the quality of HMA mixtures produced in AMP in Lithuania are analyzed. The results of laboratory testing obtained from taking and analyzing representative HMA mixture subsamples during the whole production period are presented. The analysis of column diagrams and histograms showed that deviations of component content from JMF in hot mix asphalt produced in modern AMP are frequently smaller than statistical deviations. It shows that broad intervals established in the standards do not encourage to explore all structural and technological capabilities of AMP.