# Validation of the recycled backfill material for the landslide stabilization at a railway line

## TL;DR

A new composite material made from paper industry residues was tested and successfully used to stabilize landslides along a railway line.

## Contribution

A validated composite material from paper sludge and ash for landslide stabilization is introduced and tested at scale.

## Key findings

- A composite of 70% paper sludge ash and 30% paper sludge achieved sufficient compressive and shear strength when compacted optimally.
- The composite's hydration process required a defined time interval between mixing and installation for optimal performance.
- A 50-meter retaining wall using the composite was successfully constructed, demonstrating its real-world feasibility.

## Abstract

In mountain areas landslides many times endanger safety of transport infrastructures, and these must be stabilized with retaining wall structures. In this paper the validation of a new composite as a backfill material for landslide stabilization with a large scale demo retaining wall is presented. The new composite was made from residues of paper industry, which uses for its production deinking process. New composite was validated with the laboratory tests, construction of small demo sites and at the end with a large demo retaining wall structure with a length of 50 m. It was concluded that the paper sludge ash and the paper sludge are in proportion 70:30, compacted on the optimal water content and maximum dry density, reached sufficient uniaxial compressive and shear strength. However, the composite's hydration processes required the definition of an optimal time between the composite mixing and installation. In 2019, the retaining wall structure from the new composite was successfully built. The large demo structure is an example of the knowledge transfer from the laboratory to the construction site, in which composite and installing technology could be verified.