Utilization of Clumped Clinker Ash from a Woody Biomass Power Plant for Pavement Elements of Secondary Roads in Forested Areas

Abstract

Woody biomass power plants produce significant amounts of ash during operation. Although sandy bottom ash has been used as a fertilizer, clumped clinker ash has seen little utilization. A company operating a woody biomass power plant in the western part of Kochi Prefecture, Japan, has started to distribute clumped clinker ash for use as a paving material for spur roads in forest areas, especially where the soil is prone to being muddy. Considering the relatively high alkalinity of clinker ash, its potential chemical impacts on the surrounding area of paved spur roads must be considered. To obtain approval from a local government for the use of clumped clinker ash as a road paving material, a series of field tests was conducted in 2023 to determine the strength of the road surface and any influence of alkalinity on adjacent soils. The results implied that the amended road surfaces had the same strength as the traditional unpaved, bare soil pavements when there was not much precipitation and sufficient compaction was applied. The pH values of the soils around the paved spur roads, which have intrinsic low acidity typical of forest soils, shifted from slightly acidic to slightly alkaline after paving at some of the points measured.