Modelling of waste rubber and glass fibber with response surface method in hot mix asphalt

This paper presents the effect of Temperature (100-180 degrees C), Waste Rubber (WR) content (5-25%), Glass Fibber (GF) content (1-4%) and Bitumen content (3-7%) on performance characteristics of hot mix asphalt (HMA). For this purpose, experimental design matrix was generated depending the central composite design (CCD) for four independent variables. Simultaneous optimisation of dependent variables such as practical specific gravity (PSG), voids, voids of filled with asphalt cement (VFA) and Marshall stability (MS) were analysed. Mathematical models were proposed to fit the experimental results, and all models were found to be statistically significant. It was shown that the optimum conditions with desirable levels was achieved at temperature of 160 degrees C, 12.181% WR content, 4% GF content and 4.917% bitumen content. Following the optimum conditions proposed by the model, PSG is estimated to be 2.401 g/cm(3) with voids of 4.60%, VFA of 70%, MS of 1374.43 kgf. Additionally, the adequacy and validity of the predicted models were determined by conducting validation experiments under optimum ambient conditions proposed by the model. (C) 2019 Elsevier Ltd. All rights reserved.