Experimental Study on Particulate Matter Generation and Mitigation Technologies during the Crushing of Waste Concrete Sleepers for Recycling Purpose

This study investigated the concentration of particulate matter (PMs) generated during the crushing process of waste concrete sleepers at railway sites. Using a light scattering-based device, concentrations of particulate matter (PM₁₀, PM₄, PM_2.5, and PM₁) were measured within a 2.5-meter radius of the crushing site during the concrete sleeper crushing. The results revealed that the crushing process led to average increases in PM10 and PM2.5 concentrations by 23,881 ㎍/㎥ and 3,880 ㎍/㎥, respectively, with maximum levels reaching 77,630 ㎍/㎥ and 14,862 ㎍/㎥. Furthermore, particle size distribution analysis indicated that approximately 50% of the particulate matter ranged between 4-11 ㎛, capable of penetrating the respiratory tract, while approximately 37% were smaller than 4 ㎛, posing a risk of deep lung infiltration. To reduce the particulate matter generation when crushing waste concrete sleepers, cyclone and water spray technologies were applied both individually and in combination during the crushing process. The combined application of both technologies achieved significant reductions of 70% in PM₁₀ and 65% in PM_2.5 concentrations compared to the case without mitigation measures.