Underground Construction - December 2017 - 64

CIGMAT Report
Center for Innovative Grouting Materials and Technology

CIGMAT Report 2017
by C. Vipulanadan, Ph.D., P.E., professor and director of Center for Innovative Grouting Materials and Technology (CIGMAT) and
Texas Hurricane Center for Innovative Technology (THC-IT), Department of Civil and Environmental Engineering, University of Houston

CIGMAT Strives To Transfer Research
To Actual Applications

Research studies performed at the University of Houston's Center for
Innovative Growing Materials and Technology (CIGMAT) are focused on
maintaining energy, water and wastewater infrastructure and pipelines;
developing new, smart materials for construction, maintenance and repairs;
and detecting and quantifying corrosion and environmental issues. The
Director of CIGMAT is Dr. C. Vipulanandan (Vipu), Ph.D. P.E., professor of
Civil Engineering, University of Houston, Houston, TX. Ongoing research at
CIGMAT is funded by federal, state and local agencies and industries.
Over the past two decades, over five dozen commercial products - including rapid repair materials, coatings, grouts, liners, cementitious and
polymer composites and pipes - have been researched and tested for a
number of applications. Microbial fuel cell technology is being further
developed to treat and recycle highly salty fracturing fluids. Also, the observed trends are analytically and numerically modeled to better understand the influence of various testing and environmental parameters.
CIGMAT's commitment to transfer technology from control studies
to actual applications, led to development of unique testing facilities in
recent years, such as high-pressure and high-temperature (HPHT) testing
of materials for oil and gas infrastructure applications, and EPA-approved
protocols to test grouts and coatings for infrastructure rehabilitations. As
another example, the Life Cycle Cost model (CIGMAT-LCC) for wastewater systems, available on the CIGMAT website, is being used by cities,
counties and the public.
Current projects involve basic research, as well as applied field research
related to both onshore and offshore applications. Examples include:
* Developing "smart" materials including cement (being patterned in
over 135 countries), drilling fluids, spacer fluids and grouts for various
applications.
* Evaluating long-term performance of micro-silica based cement liners.
* Characterizing polypropylene composite coatings for deepwater oil
pipelines.
* Developing methods to treat contaminated soils and expansive clays.
* New non- destructive technology for detecting and quantifying corrosion (being patterned in over 135 countries), and multifunctional
microbial fuel cells.

Micro-silica Based Cement Liners for Manholes
Since cementitious materials are used in various onshore and offshore infrastructures, there are rising concerns about changes in their mechanical
and physical properties under long-term exposure to adverse environments. Hence, cement concrete response to chemical environments must
be investigated.
The cement material deterioration may be caused by many factors,
including temperature cycles, carbonation, alkali-aggregate reaction, and
attacks by sulfates, acids and other chemicals; and is seldom caused solely

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by one of these processes. Usually, deterioration is due to the combined
effect of several factors at the same time or successively.
The mechanism of attack is also different, depending on the condition
and type of concrete. In the case of a dry environment, the formation of
reaction products may cause expansion in the pores and capillaries due
to the salt crystallization. Micro-cracks may develop, which will allow
deeper penetration of the ions and accelerate the rate of corrosion. In a
wet environment, acid droplets interact and make soluble salts, which are
subsequently formed and leached out. Due to leaching of the soluble salts,
the cement binder is affected and concrete loses its strength. Due to acid
attack, the concrete surface becomes more porous and permeable, making
it easier for further chemical attack.
Concrete can be used without secondary protection in a sulfate environment provided the sulfate concentrations are less than 6000 mg/L. If
the sulfate concentration is more than about 6000 mg/L, surface coatings
are usually applied on concrete to protect it from corrosion. Degradation
takes place in the form of cracking, pop-outs from loss of coarse aggregate, and disintegration of hydrated cements. Sulfate ions present in soil,
groundwater, seawater, decaying organic matter and industrial eﬄuents
are known to have an adverse effect on the long-term durability of concrete.
Manholes are a very critical component of the wastewater collection
system. They are designed as access points to wastewater system pipelines, allowing for inspection, maintenance and rehabilitation. The manhole has long been overlooked as a major source of inflow and infiltration,
and this has proven to be a costly mistake. While it is becoming important
for designers and material developers to understand the environmental
effects on cement liners, effects due to long-term exposure to the wastewater environment have not been fully examined.
This study was focused on quantifying the performance of a micro-silica based cement liner in service for 5, 10, 15 and 25 years. The overall
objective was to investigate the effect of aging on a microsilica-based
cement liner material (Reliner MSP) in a wastewater environment, using
field samples obtained from various active manholes in Houston and San
Antonio, TX. Specific objectives were to:
* Visually inspect the quality of the core samples.
* Quantify the water uptake by the core samples.
* Determine the constituents of the core samples using XRD and other
methods.
* Relate the age of samples to qualified properties of the samples.
Houston is the fourth-largest city in the U.S., with a population of over
2 million. Its wastewater system has more than 6,250 miles of pipelines,
425 lift stations and 100,000-plus manholes. The city is currently spending over $100 million per year to clean and rehabilitate its wastewater
systems, with a strong emphasis on relining the manholes.
Underground Construction December 2017

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Underground Construction - December 2017

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