# New Explosive-Circulation Technology of Tire Recycling for the Production of Crumb Rubber with Modified Surface

## TL;DR

A new industrial method for recycling tires using explosions produces crumb rubber with a modified surface that improves road bitumen properties.

## Contribution

A novel explosive-circulation tire recycling technology is introduced, enabling crumb rubber with enhanced surface properties for road construction.

## Key findings

- The explosive process creates crumb rubber with good wettability, eliminating the need for surface activation.
- The rubber crumb improves bitumen hardness at low temperatures, reducing it from 217 to 161 MPa at −16 °C.
- Surface modification is attributed to polar groups formed during the explosion, confirmed by AFM, GC, MS, GPC, and XPS analyses.

## Abstract

The article reports on the development of a fundamentally new, effective technology for recycling waste tires using the explosive-circulation technology method, which was implemented in industry at a working factory. The construction of an explosion-circulation reactor, in which tires are destroyed under the influence of an explosion, is described. The main technological stages of the reactor operation include the formation of a tire package with a height of about 2.4 m and a mass of up to 1000 kg; cooling the package by air turbo-cooling machine to a temperature of minus 70–80 °C; placing the package into the reactor; initiating the explosive charge; and removing the tire shedding products with a subsequent granulometric classification of the resulting rubber crumb. The resulting rubber crumb has good wettability, which eliminates the need for an additional technological stage of activating the crumb surface. This made it possible to successfully use the obtained rubber crumb to improve the characteristics of road construction bitumen, the hardness of which at −16 °C decreased from 217 to 161 MPa. Using atomic force microscopy (AFM), gas chromatography, mass spectrometry, GPC, and XPS, it was established that the good wettability of the crumbs is explained by the formation of molecules with polar groups (C-O, C=O, C(O)O, C-S, C-SOx, Zn-S, O-Si(O)-O) on the crumb surface as a result of the explosion.