Project Title: Development of Beneficial Use Alternatives for the Management of Dredged, Contaminated Sediments
Principal Investigator(s): Kevin H. Gardner

Accomplishments
Scheduled Tasks:
The long term goal of this project is to investigate the feasibility of the beneficially use of contaminated dredged sediments as partial feedstock materials to manufacture portland cement.

The scheduled tasks for this research project are almost complete. Jennifer Dalton, one of the two graduate students working on the project, successfully defended her Master’s thesis in August, 2002. The environmental studies on the manufactured materials are continuing presently, and will conclude in December, 2002. The scheduled tasks were

• Continue pH-static leaching investigation;
• Begin study of contaminant phases that control the availability of contaminants from DM-clinker and DM-concrete material.
• Finalize XRPD results to allow for more distinct conclusions on clinkers manufactured in the muffle furnace with varying percentages of DM.
• Manufacture portland cement clinker containing 11.25%DM at pilot-scale using a rotary kiln. This process more closely resembles the full scale manufacture and will be done through a subcontract to Construction Technology Laboratory (CTL) in Skokie, IL (the research arm of the Portland Cement Association).
• Use ASTM tests to evaluate the soundness of the cement produced (including compressive strength and setting time). These tests have not been possible until now due to the small amounts of clinker produced in the muffle furnace.

Progress on Tasks
These tasks are all complete except for the contaminant phase investigations.

Dissemination Activities
Gardner, K.H. "Characterization for Upland Beneficial Use of Contaminated Sediments," Northeast Waste Management Officials Association Conference on Characterization of Contaminated Sediments for Upland Reuse, Westford, MA, May 14, 2002.

Weimer, M., J. Dalton, K.H. Gardner, "Beneficial Use of Contaminated Dredged Sediments in Portland Cement Manufacture," Dredging ’02 ­ 3rd International Specialty Conference on Dredging and Dredged material Disposal, Orlando, FL, May 5-8, 2002.

Difficulties Encountered
None.

Anticipated Success in Meeting Project Objectives in Scheduled Project Period
It is anticipated that the project objectives will be met in the scheduled project period.

Preliminary Results
Figure 1 below shows that the alite content in the clinker samples manufactured in the laboratory with dredged material decreased as the dredged material content increased. Statistical analysis found that the clinker samples with medium and high dredged material replacement had alite contents significantly different than the control clinker with 99.7% and 99.9% confidence respectively. No significant difference was noted between the low dredged material replacement and the control (a 73.8% confidence that there was a difference).

Figure 2 below shows the strength performance of mortar cubes manufactured using dredged material in the pilot scale study compared with mortar cubes made using a control cement that was manufactured under full-scale conditions. Figure 3 compares the average strength values to standard requirements.

The mortar cubes made with pilot scale cement had an average maximum stress less than that specified in ASTM C150 at days 3 and 7 (there is no requirement for day 1, it is just recorded) for Type I and II cements. By day 28 the dredged material mortar cubes had surpassed the optional strength requirement in ASTM C150 for Type I and II cements (same strength value).

Tasks and activities for next reporting period

Tasks for the next reporting period
The final tasks to complete are:

• X-ray photoelectron spectroscopic studies of metal-doped clinkers to provide direct evidence of phase distribution of heavy metals in clinkers and concrete materials.
• pH-dependence leaching tests on concretes produced using clinkers manufactured with dredged materials.
• Geochemical modeling of leaching process to gauge ecological or human health impacts from use of dredged materials.
• Final Report preparation and submission.

Concerns or difficulties
No potential concerns or difficulties are predicted at this time.

Expenditures
Expenditures at this time are in the range anticipated for the work accomplished to date.