Evaluation of Non-nuclear Moisture Meters and Moisture-Density Gages for Reclamation Construction QC/QA
Project ID: 8920
Principal Investigator: Robert Rinehart
Research Topic: Improving Geotechnical Infrastructure Reliability
Funded Fiscal Years: 2013
Keywords: non-nuclear electronic moisture density gage, nuclear gage, roller compacted concrete, soil, soil cement, controlled low strength material, construction control
Reclamation commonly incorporates materials such soil cement, controlled low strength material (CLSM, flowable fill), and roller compacted concrete (RCC) into its projects. Regardless of the mix design and project specifications, ensuring proper construction of these materials is critical to their long-term success. Traditional quality control/quality assurance (QC/QA) methods for these materials are often slow (providing results several days after the material has been placed), expensive and labor intensive, or rely on nuclear technology.
Several new, non-nuclear technologies exist which claim to enable the rapid measurement of moisture, or the combination of moisture and density of these materials (soil, soil cement, CLSM, and RCC). Being new, these technologies have not been rigorously tested and approved for use by Reclamation. The scoping study proposed herein will consist of a literature and industry review of the use of these devices, and is designed to precede a conducting research study. As guided by the scoping study, the conducting study will systematically investigate the efficacy of several commercially available non-nuclear rapid moisture meters and non-nuclear moisture-density gages for performing rapid quality control/quality assurance (QC/QA) testing on soil, soil cement, CLSM, and RCC. Efforts will also be made during the scoping study to develop partnerships with regional offices as well as the manufacturers and vendors of the most promising devices to make the subsequent conducting research more cost effective.
If proven effective and reliable, these technologies will produce significant cost saving by (1) reducing QC/QA field testing time, and (2) eliminating the need for costly nuclear-density gages. Further, given that the feedback from QC/QA testing would be available immediately (rather than days to weeks later such as in the case of soil cement and CLSM) a higher quality product would result from the use of these new technologies.
Need and Benefit
Reclamation is currently undertaking the design and construction of several large pipeline projects (e.g., Navajo-Gallup Water Supply Project, Arkansas Valley Conduit). It is anticipated that these jobs involve placement of large quantities of soil cement and CLSM. Further, Reclamation is seeing an increase in the use of RCC at a variety of structures. Traditional methods of construction control for these materials are time consuming and labor intensive, and often don't provide feedback for several days. Regional personnel in charge of construction inspection are already stretched thin, and there is a clear need to develop and implement more efficient and effective construction control methodologies for soil cement, CLSM, and RCC. New technologies exist which have potential to greatly decrease the labor and cost associated with construction control while at the same time providing much faster feedback. These technologies will be investigated here and recommendations for their use will be developed.
Further, the cost and administrative workload associated with nuclear moisture-density gages is high and increasing rapidly. Nuclear material permitting and licensing costs (which are in addition to the cost of buying the gage itself) are currently $1,500 per gage per year and set to more than triple in the coming year. Personnel exposure monitoring is $120 per person per year and increasing. Gage operators are required to take annual exposure and use training. Labs that use the gages are required to provide secure containment and transport, and transportation across state lines requires additional permitting. Clearly, the use of the nuclear-density gage includes many costs in addition to the purchase of the gage, and poses a significant hardship for regional offices tasked with construction control. However, given the need to perform thorough and rapid QC/QA of construction involving soil cement, CLSM, and RCC, Reclamation is witnessing an increase in the use of the nuclear gage, even in the face of this hardship. The new non-nuclear technologies provide one potential solution to the nuclear gage dilemma, and for this reason need to be systematically investigated.
The following documents were not reviewed. Statements made in these documents are those of the authors. The findings have not been verified.
Project Synopsis (final, PDF,
By Robert Rinehart
Report completed on May 27, 2014