A Performance Evaluation of Fly Ash-Plastic Aggregate in Hydraulic Backfilling: A Comparative Study

Area of Science:

• Materials Science
• Geotechnical Engineering
• Environmental Science

Background:

• Underground mining necessitates void filling to prevent subsidence and mitigate post-mining issues.
• Sand is the traditional backfill material, but its demand and slow replenishment drive the need for alternatives.
• Fly ash (FA) is a potential substitute, but its slow settling and hydrostatic pressure issues limit its application.

Purpose of the Study:

• To investigate fly ash-plastic aggregate (FPA) as a viable hydraulic backfill material.
• To address the limitations of using fly ash alone in mine backfilling.
• To develop an improved backfill material using a blend of fly ash and recycled plastic.

Main Methods:

• Developed fly ash-plastic aggregate (FPA) by mixing fly ash with high-density polyethylene (HDPE) plastic in an 80:20 ratio.
• Evaluated the physical, mechanical, and morphological properties of the developed FPA.
• Assessed FPA against standard requirements for hydraulic backfilling.

Main Results:

• The addition of plastic as a binder significantly enhanced the physical, mechanical, and morphological properties of fly ash.
• FPA demonstrated improved settling rates and reduced hydrostatic pressure compared to pure fly ash.
• The developed FPA material met and exceeded established standards for hydraulic backfilling.

Conclusions:

• Fly ash-plastic aggregate (FPA) is a promising alternative material for hydraulic backfilling in underground mines.
• FPA offers a sustainable solution by utilizing waste plastic and fly ash.
• This material effectively addresses the limitations of traditional sand and pure fly ash backfills.