Effects of curing time and fly ash content on properties of stabilized dredged material

摘要

Properties of raw dredged material (RDM) stabilized with self-cementing Class C fly ash (FA) were evaluated for beneficial use in geotechnical construction applications. Emphasis was placed on evaluating effects of curing time and fly ash content on index and engineering properties relevant to pavement construction. RDM samples were blended with 10, 20, and 30% FA and cured for 2 h, 7 days, and 28 days. Fly ash stabilization reduced plasticity and improved the engineering properties of the stabilized dredged material (SDM). Increasing FA content increased maximum dry unit weight and reduced optimum water content for compaction. Unconfined compressive strength (q_u) increased with FA content and curing time. The effect of curing time on q_u was more significant at higher FA content. Freeze-thaw cycles only reduced the strength of SDM specimens by 5% on average, indicating that SDM was durable to freeze-thaw. Analytical relationships were developed to predict Atterberg limits and qu of SDM at different fly ash contents and curing times. The California bearing ratio (CBR) for the SDMranged from 10 to 20, which is comparable to compacted silty sand or sand and rates as fair to good for pavement subgrade. The resilient modulus (M_R) increased significantly with FA content and varied between 35 and 83 MPa, which is comparable to gravel or crushed stone and rates as good to excellent for subgrade. Results indicate that low-strength dredged materials stabilized with Class C fly ash are viable for beneficial use as pavement subgrade material.