Verification that Type V Cement is required for CLSM with high sulfate native soils

Project ID: 2840
Principal Investigator: Janet White
Research Topic: Improving Geotechnical Infrastructure Reliability
Funded Fiscal Years: 2013, 2014 and 2015
Keywords: clsm, flow fill, soil slurry, native soils, type v cement, sulfates

Research Question

Is there a benefit to using Type V cement with Controlled Low-Strength Material (CLSM) made with high sulfate native soils? Will the sulfates in the native soils deteriorate the CLSM over time?

Need and Benefit

CLSM, also known as cement slurry or flow fill, is used under hundreds of thousands of miles of Reclamation pipelines and also used as backfill material along structures. Current specifications require that CLSM made with soils high in sulfate use a Type V (sulfate resistant) cement to mitigate against sulfate attack. Sulfate attack is known to deteriorate concrete when the sulfates in the soil react with the hydrated cement. There is a little or no research on whether or not sulfate attack can occur in low strength CLSM type mixtures and if Type V cement is an appropriate means to mitigate this deterioration. Type V cement is more costly than regular Type II cement, because, Type V cement requires a more expensive raw material mix and more energy to create the <5% C3A clinker.

CLSM is used extensively throughout Reclamation and will be again used on over 100 of miles of pipeline for the upcoming Navajo Gallup Water Supply Project. There is an economic and environmental benefit of using native soils in CLSM rather than the traditional ASTM C33 aggregates. Aggregates make up approximately 75% of the volume of CLSM and using the native soils from the excavation instead of manufacturing and transporting aggregates can be not only a tremendous cost savings but a reduction in carbon production in the environment as well. The TSC would like to perform this research project in order to verify that CLSM produced with native soils will not break down overtime due to sulfate content.

Typically, when concrete needs high sulfate resistance Type V cement is specified along with a minimum water/cementitious ratio. Since CLSM is mixed with the high sulfate soils and placed at a much higher water to cementitious ratio there may not be a benefit in using Type V cement and the extra expense of the specialty cement may not be needed.

The results of this study would not only benefit the Navajo- Gallup project but also have a Reclamation wide benefit as well. Navajo-Gallup would be a partner in this project with supplying native soils from different portions of the project.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Verification that Type V Cement is required for CLSM with high sulfate native soils (final, PDF, 3.3MB)
By Janet White
Publication completed on September 30, 2015

The study described in this report was authorized by the Bureau of Reclamation Research and Development Office, Science and Technology Program. The approved scope of work consisted of materials selection and mixture proportioning study for a CLSM mixture, performing short and long term compressive strength testing, data analysis, and preparation of a final report. The investigation was performed by personnel in the Concrete, Geotechnical and Structural Laboratory at Bureau of Reclamation's (Reclamation) Technical Service Center (TSC).

The following documents were not reviewed. Statements made in these documents are those of the authors. The findings have not been verified.

Is Type V Cement Needed for Controlled Low Strength Material in High Sulfate Soils? (final, PDF, 1.3MB)
By Janet White
Publication completed on September 30, 2016

This bulletin summarizes the research results and potential application to Reclamation's mission.

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Last Updated: 6/22/20