There is much interest in the industry in finding safe, reliable, and economic ways to detoxify and dispose of production wastes. A laboratory test program was designed to study the feasibility of reuse of solidified steel industry waste sludges as a construction material. The particular application reported is the use of the material as a capping barrier system over an existing lagoon. Random cracking of the solidified slabs is investigated. Various strength tests on cured specimens of wet mixed and solidified samples were conducted. The specimens were cured in seven different environments of temperature and humidity. The laboratory tests included unconfined compression, unconfined tension, and fracture toughness tests. The strength parameters were correlated with curing time, curing temperature, mix water content, and proportion of surface active reagents added. It was observed that the curing conditions that brought about higher compressive strengths were not favorable for the development of fracture resistance of the material. The unconfined compressive and tensile strengths of the material appeared to gain high values when the material was cured in high humidity-moderate temperature environments, whereas its fracture resistance improved at low moisture gradients. The high and low humidity conditions resulted in poor fracture resistance. The results obtained with varying contents of the surface active reagents indicated that there may be optimum proportions of these additives for which the highest strength and fracture resistance values are developed. Increasing the mix water content appeared to reduce both the strength and fracture resistance of the material.

The subject of resource recovery and reuse of waste materials has gained much attention within the past decade, principally because of the increased number of environmental statutes and regulations that necessitate minimizing waste disposal (1, 2). The benefits of reusing stabilized or solidified waste materials should be twofold:(a) compliance with regulations, thus helping to reduce environmental hazard, and (b) added economy. These materials can be an inexpensive alternative for conventional materials provided that (a) there are no adverse effects to the environment, and (b) the performance of the created material is similar or equal to the one it replaces. With the landbans of the Environmental Protection Agency (EPA)(3), the chemical fixation and solidification (CFS) of liquid and sludge wastes vastly increased. The use of CFS for waste materials dates back to the 1970s (4). However, the development and use of the technology in ground improvement methods (eg, soil stabilization, rock and soil grouting) and in construction of base courses for paved surfaces have