Long-term evaluation of geotechnical and environmental properties of ash-stabilised road
2022 (English)In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 318, article id 115504Article in journal (Refereed) Published
Abstract [en]
In 2009, a low-volume gravel road in Sweden was stabilised using fly ash from a local paper mill. The objective was to examine whether fly ash could be used to enhance the stability of the road and how the nearby environment would be affected. The technical and environmental properties of the road have been monitored for two, six, and eleven years. Because the construction costs are higher for ash upgrading than for conventional upgrading, knowing for how long the improved properties will remain is relevant. Strength development was studied using a falling weight deflectometer and compressive strength tests. Environmental properties were studied by chemical analysis of road samples, soil, soil pore water, and vegetation. The results showed that the ash sections had higher stiffness than the reference sections. Leaching tests of road samples showed that the mobility of potassium, sodium, chloride, and sulfate decreased with time. Trace element concentrations in soil samples, except barium, were below the Swedish guideline values for sensitive land use. Chromium, lead, and copper were as high or even higher along the reference section than along the ash section. After 11 years, the pH closest to the ash section was slightly enhanced. Concentrations of zinc and cadmium in the soil pore water were the lowest closest to the ash road, although the total concentrations in the soil were at their highest at the same distance. No toxic levels of trace elements were found in the vegetation close to the road, although a clear difference was observed between plants from the ash section and the reference section, using multivariate data analysis. The positive effects on the geotechnical road properties from ash stabilisation remained after 11 years. The environmental impacts on nearby soil and vegetation can be considered low and acceptable. This study demonstrates that the use of biofuel fly ash in infrastructure projects can contribute to the circular economy and effective use of resources because the demand for pristine materials will be reduced.
Place, publisher, year, edition, pages
Elsevier, 2022. Vol. 318, article id 115504
Keywords [en]
Biofuel fly ash, Gravel road stabilisation, Bearing capacity, Leaching, Soil pore water, Vegetation
National Category
Energy Engineering Other Environmental Engineering
Research subject
Waste Science and Technology
Identifiers
URN: urn:nbn:se:ltu:diva-91540DOI: 10.1016/j.jenvman.2022.115504ISI: 000862249600002PubMedID: 35717696Scopus ID: 2-s2.0-85132354004OAI: oai:DiVA.org:ltu-91540DiVA, id: diva2:1671531
Funder
Luleå University of TechnologySwedish Geotechnical Institute
Note
Validerad;2022;Nivå 2;2022-06-17 (joosat);
Funder: Energiforsk; Skogforsk
2022-06-172022-06-172022-11-09Bibliographically approved