TITLE: Novel Pyrrhotite
Detection Method in Concrete Aggregate
ACQUISITION PROGRAM: NAVFAC
Secondary Program of Record: Facilities Sustainment, Restoration and
Modernization, and NAVFAC Criteria, Non-ACAT
OBJECTIVE: The objective of
this SBIR topic is to develop a portable device or test kit for analyzing the
presence of “pyrrhotite” in damaged concrete structures, as well as loose
aggregate before it is mixed into fresh concrete. The ultimate goal of this
technology is the prevention of costly repairs and replacement of concrete
structures still in their early life cycle.
DESCRIPTION: The concrete
industry is increasingly recognizing the extent of structural damage caused by
a deleterious presence of “pyrrhotite” mineral in concrete aggregate. Current
diagnostics to detect pyrrhotite require petrographic analysis of samples in a
laboratory, a costly and time consuming process. There is a need for
development of a novel and portable method for detecting and quantifying the
presence of pyrrhotite in aggregate and concrete while in the field.
The Navy is a large consumer of cement and aggregate for its many construction
and repair projects of piers, pilings, wharves, runways, and buildings. NAVFAC
is responsible for new construction and sustainment of these facilities. This
responsibility includes design, construction, maintenance and repair services
for all concrete facilities. Additionally, the NAVFAC Criteria Office is
responsible for technical adequacy of all Navy shore facilities design,
construction and maintenance criteria. Pyrrhotite-related concrete corrosion
may be a significant cost factor in Navy facilities sustainment, restoration,
and new construction.
The Navy has issued numerous reports and guidance on Alkaline Aggregate
Reaction, or AAR, and specifically ASR – Alkaline Silica Reaction in concrete,
where “reactive” aggregate containing certain forms of silica combines with
alkali hydroxide in the hydrated cement to form an expanding gel that breaks
the concrete. NAVFAC’s guidance on pavements and marine concrete also mention
the importance of limiting sulfate content in concrete. Although the effects of
sulfate attacks in concrete have been appreciated for decades, the connection
to pyrite and pyrrhotite minerals has only recently (late 1990s onward) been
reported and researched in-depth. This may be due to current concrete
technologies greatly advancing over the past decades. Today’s formulations
include a number of ingredients (admixtures) to enhance both the fresh and the
hardened concrete’s properties. These advanced formulations may contribute to
the recent increase in pyrrhotite-related concrete failures.
Pyrrhotite is a naturally occurring iron sulfide mineral in the particular
chemical form Fe(1-x)S , where x = 0 to 0.125. If pyrrhotite is present in the
concrete, then water and oxygen, already present in the hydrated cement, will
foster a chemical reaction that produces expansive by-products. Numerous recent
news reports of pyrrhotite-caused structural damage are emerging from the U.S.,
Canada, Europe, and other locations around the world, indicating the problem
may be much more widespread than previously thought by the construction
industry. As a timely example, the mineral has been blamed for widespread
foundation cracking in thousands of homes in Quebec, Canada. Officials estimate
that 4000+ homes are affected. The Prime Minister has indicated the Quebec
Province is spending over $30 Million to mitigate the problem, according to the
Various remedial measures for pyrrhotite related concrete corrosion have been
proposed, but the long term effectiveness of such in-place remediation has not
been established. For housing foundations, as an example, the only method of
remediation which can guarantee a permanent solution is removal of the
A portable device or test kit would be of great benefit for analyzing the
presence of pyrrhotite in existing concrete structures suspected of having
pyrrhotite-related damage, as well as in aggregate received at the job-site
prior to mixing. If successful, this technology would prevent concrete
formulations that are “doomed to failure” from being utilized in the DoD’s, and
ultimately commercial, myriad of concrete facilities.
GUIDELINES FOR NEW TECHNOLOGY:
1. Capable of operating in an outdoor field environment.
2. Capable of holding calibration for 8+ hours of continuous operation.
3. Device accuracy should provide at least one order of magnitude linearity,
and be within ±5% of known values, in a range of 0.1 to 10% by weight
4. Capable of consistent, repeatable measurement even with concentration
variation over the desired range.
5. Capable of directly reading and/or “swabbing” the aggregate or solid
6. Capable of operation in an expeditionary environment. Such an environment
for the military would include a lack of sheltering infrastructure with limited
access to a reliable source of electricity and possible intemperate weather.
Marine waterfront locations would further suffer from the presence of salt
spray. Therefore, minimum environmental goals include operability in:
• Temperatures of -10 to +35-degree Celsius
• Humidity levels of 5 to 95% RH
• Water–proof electronics housing.
7. Sized for portability by one person, i.e. a maximum of 22-lbs for all
8. Results provided real-time or near-real-time, with a total cycle time
(sampling input to result output) goal of 5-minutes per sample.
9. System availability and reliability of 1000-hours of operation.
10. Minimal external requirements, i.e. kit should include any needed
chemicals, compressed air or vacuum source, and include battery operation, in
addition to 110-VAC power, if electricity is needed.
PHASE I: Determine
feasibility for the development of a novel pyrrhotite detection method for
efficacy in a laboratory environment, utilizing known standardized levels of
the mineral in both loose aggregate and in formed concrete to assess accuracy.
Development of the pyrrhotite detection method must show feasibility for
eventual portability and field use.
PHASE II: Based on the
results of Phase I, develop and demonstrate a bread-board pyrrhotite detection
device with natural aggregate and concrete samples, and compare to independent
laboratory analyses provide by the government. Assemble a full scale demo
system to validate operation. Demo will be tested at a Navy facility with
suspected pyrrhotite-related concrete degradation in order to prove
Phase II Option, if awarded,
will be used to advance the design to improve accuracy, reliability, and/or
reduced system size.
PHASE III DUAL USE
APPLICATIONS: Based on the results of Phase II, the small business will
commercialize the device in combination with Navy-relevant concrete
construction and repair projects. Private Sector Commercial Potential: The
device would have wide application across both military and commercial sectors
for checking aggregate lots prior to concrete mixing and for on-site failure /
forensic analysis during repair projects.
1. Hawkins, Brian A.,
Implications of Pyrite Oxidation for Engineering Works, Springer International
Publishing, Switzerland, 2014.
2. “Mineral to Blame in
Cracking Foundations”, Durability & Design Magazine, May 11, 2016.
3. Tulis, Ralph H., “Cracked
Foundations Need Study by a State Task Force http://ctviewpoints.org/2015/10/08/cracked-foundations-need-study-by-a-state-task-force/ October 8, 2015.
4. “Feds to Spend $30 Million
in Quebec on Mineral Problem”, Canadian Press Release, April 2016. http://globalnews.ca/news/2622979/ottawa-to-spend-30-million-on-helping-quebec-homeowners-who-have-pyrrhotite/
5. “Pyrite Problem –
Exploring the Implications of Sulfur in Geological Materials for Civil
KEYWORDS: pyrrhotite, pyrite,
framboid, microcrystal, concrete, sulfate, aggregate, oxidation, sulfide
** TOPIC AUTHOR (TPOC) **DoD Notice: Between August 26, 2016 and September 25, 2016 you may talk directly with the Topic Authors (TPOC) to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting September 26, 2016 , when DoD begins accepting proposals for this BAA.
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