Optimisation of composite asphalt mixture involving glass fibre and nano clay based on central composite design

ABSTRACT

Different types of additives are used in asphalt modification to enhance several properties within the asphalt pavement. In various cases, modification is needed by using multiple additives, which is called composite modification. In this study, glass fibre and nano clay were used to modify the asphalt pavement. The amount of these two additives, together with the optimum bitumen content, was determined by the response surface methodology (RSM). Central composite method (CCD) was used for determining the optimum amount of independent variables (nano clay, glass fibre, bitumen content), by evaluating the dependent variables. Marshall mixture design criteria and minimum bitumen content, were the optimal conditions. As a result, the mixture containing 0.2% glass fibre, 3.693% nano clay and 4.096% bitumen content, was predicted to give the most desirable characteristics. Additionally, verification tests were conducted to evaluate the adequacy of the predicted model. The results were within the 95% confidence intervals for all response variables, which demonstrates the validity of the model obtained in the study. Consequently, CCD can be used to obtain design optimisation of asphalt modification with less mixture production for experimental stages. This is a substantial advantage, which supports human safety and environment- friendly practices.

KEYWORDS:

• Asphalt modification
• central composite design
• response surface methodology
• nano clay
• glass fibre
• Marshall mix design
• hot mix asphalt

Acknowledgement

The author would like to thank Zeynel Baran Yıldırım for technical assistance during the experimental stage of the study.

Disclosure statement

No potential conflict of interest was reported by the author(s).