Irradiated polyethylene terephthalate and fly ash based grouts for semi-flexible pavement: design and optimisation using response surface methodology

ABSTRACT

This study explores the effectiveness of using recycled irradiated waste polyethylene terephthalate (PET) as a partial replacement for cement in the formulation of cementitious grouts. This study investigates the impact of regular and irradiated PET and fly ash (FA) on the flowability, drying shrinkage, compressive strength and flexural strength of cementitious grouts. It was observed that partial replacement of cement with normal PET (in the range of 5–10% by mass of cement) resulted in a reduction (between 26% and 46%) in compressive strength of the cured grout. Interestingly, the use of irradiated PET instead of regular PET restores 8–22% of the compressive strength. Additionally, response surface methodology (RSM) is used to design the experiments, analyze the responses, and optimise the independent variables. A high R² and adequate precision of the ANOVA is an indication of a good agreement between the factors and responses. Besides, gamma irradiation makes it possible to use a higher percentage of 2.57–4.75% waste PET as cement replacement while retaining the target flow and strength properties. Therefore, the proposed treatment of PET with gamma radiation could be an effective way for recycling waste PET and a significant step towards achieving the zero-waste challenge.

KEYWORDS:

• Polyethylene terephthalate
• fly ash
• gamma irradiation
• flow
• compressive strength
• flexural strength
• response surface methodology
• ANOVA

Disclosure statement

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

Additional information

Funding

The authors would like to acknowledge the support of Universiti Teknologi PETRONAS for providing financial and laboratory facilities to complete this study.