Predicting Marshall stability and flow of bituminous mix containing waste fillers by fuzzy logic

The practice of using different non-biddable wastes in place of conventional filler is successively extended nowadays, leading it hard to predict the properties of modified bituminous mixes. The present work aims to explore the effect of using rice husk ash (RHA) and fly ash (FA) as alternative filler in place of conventional filler like hydrated lime (HL) on Marshall stability and flow of bituminous mix by fuzzy logic. This study involves the preparation of samples having seven different bitumen content varying from 3.5% to 6.5% with 0.5% increment. Mixtures containing 2%, 4%, 6% and 8% of HL, RHA and FA separately as filler were fabricated and compared with the control mix (i.e. mix containing 2% hydrated lime as filler). Further, the Marshall mix design procedure was followed to determine the optimum bitumen content (OBC) of each mix. Experimental results showed that the replacement of conventional filler with RHA and FA improved the Marshall properties and decreases the OBC values of the modified mix when added with 4% filler ratio. Further, for predicting the Marshall stability and flow, a Mamdani-type fuzzy inference system model was devised in Matlab toolbox using percentage bitumen, air voids, percentage of HL, RHA and FA as input and Marshall stability and flow as output. In comparison, it is realized that predicted values are closely relevant to the actual one and the prediction ability of the fuzzy logic model is suitable for getting the said values by avoiding the expensive, time consuming and repetitive laboratory tests.