Aging Effects in Field-Compacted Dredged Material: Steel Slag Fines Blends

AbstractThis paper contains the results of aging study performed on 365-day-old trial highway embankments constructed of field-compacted dredged material (DM), steel slag fines (SSF), and three DM-SSF blends. Key findings include that moisture content of the internal core at 365 days was essentially unchanged from the as-built conditions, and the bulk (major oxide) chemistry of the DM-SSF blends matched what was predicted by the field blending ratios. The addition of SSF to the 100% DM resulted in significant pH buffering and in strength increases up to a factor of 2, as measured by the average cone penetrometer test (CPT) tip resistance. Refusal (>115 MPa or >1,200 t/ft2) was encountered in the 100% SSF embankment at a depth of approximately 1.5 m. The 365-day aged 100% DM and 80/20 DM-SSF blend had effective friction angles on the order of 34 and 52°, respectively, where the dry DM content is reported first. Quantitative X-ray diffraction analyses indicated that no new crystalline phases were observed in the DM-SSF blends, such as those commonly associated with typical cementation reactions. For 365-day-old DM-SSF blends containing between approximately 1 mg/kg (100% SSF) and 26 mg/kg (100% DM) total arsenic, the 95% upper confidence limit on the average. As concentration from the combined toxicity characteristic leaching procedure/synthetic precipitation leaching procedure (TCLP/SPLP) leaching results was less than the SPLP detection limit (0.028 mg/L), suggesting that the environmental risk associated with beneficially using the DM-SSF blends may be negligible.