Effect of Confining Stresses on the Mechanical Properties of Soil-Cement Mixed Samples
Effect of Confining Stresses on the Mechanical Properties
of Soil-Cement Mixed Samples
George Onorato (GEI Consultants, Inc.)
Mr. Onorato has over 24 years of consulting, project management, and specialty remedial design experience performing geo-environmental projects across US and Canada. His experience encompasses a broad-range of geotechnical and environmental consulting, detail engineering designs, and specialty construction related project work. Mr. Onorato experiences also include serving as lead geotechnical/remedial designer for several US EPA Superfund and former MGP utility sites. Over the past 15 years, Mr. Onorato has gained extensive experience with the evaluation of site geo-chemistry and barrier wall mix design studies for the design and construction of many types of seepage groundwater barrier walls systems and contaminate stabilization/solidification applications. This work has included specific geotechnical/geochemical laboratory studies, material design, chemical compatibility evaluations, strength and modulus design, and development of site specific CQA testing programs.
Deep soil mixing (DSM) and in-situ solidification (ISS) techniques are both common technologies for producing soil-cementous materials for many types of MGP related remedial applications including treatment of impacted soils or construction of groundwater containment systems (barrier walls). Given the importance of all these applications to meet their performance criteria and the high cost associated failure at meeting these requirements, it’s important to have confidence in the final properties of the soil-mixed materials. Although there have been many studies on cement-mixed soils using different types of soils, there is little common practice for evaluating the stress-strain curing behaviors of this types of material. In the field, especially at depth, the cementation bonds of soil-cement materials are formed under effective stress loading conditions; however, in most cases these conditions are typically not considered as most specimens are cured and tested under ambient atmospheric conditions. This has led to an underestimation of the mechanical properties of the soil-cement mixed material. This discussion presents the effect of curing stress on the strength, permeability, density, and deformation characteristics of soil-cement-mixed material. This presentation discussed field and laboratory techniques necessary for evaluating the effect of effective confining stresses on the materials mechanical properties and a comparison of typical results when not considered. The presentation provides real bench study and field testing results and how these results can affect the overall quality control testing program and quality assurance evaluation for a project.