CEN Projects

Transportation Engineering: 

1. Laboratory and Field Evaluation of Warm Mix Asphalt Technology to Determine its Applicability for Massachusetts


Warm Mix Asphalt (WMA) is a technology that allows for placement of Hot Mix Asphalt (HMA) mixes at lower temperatures than conventional mixes.  This technology has been used in Europe and currently is being evaluated in the United States.  WMA has several advantages over conventional Hot Mix Asphalt (HMA) including reduction in fuel consumption and savings in fuel costs typically required to heat aggregates to higher production temperatures, and a reduction in visible emissions.  Moreover, since WMA technology can be placed at lower temperatures, the construction seasons can be prolonged.   

Research and Results

The overall goal of this research project was to conduct a laboratory and field evaluation of WMA technology.  This evaluation was facilitated by comparing the properties of HMA mix with and without WMA technology.  Specimens of the control mix and that containing WMA were prepared at the contractors’ plant.  The resultant volumetric properties of the two mixes were compared and differences in production and placement were documented in the field.  The rutting performance of the mixes was evaluated in the laboratory using the Model Mobile Load Simulator (MMLS) and Asphalt Pavement Analyzer (APA). The Dynamic Modulus (E*) of each mix was determined at varying frequencies and temperatures and corresponding Master Curves developed.

Overall, based on the work conducted during this research project, the addition of WMA technology into a conventional mix has yielded a mix with similar volumetric and performance characteristics with the added benefits of increased compaction at lower temperatures and lower visible emissions.


WMA technology has the potential to make an enormous impact on MassDOT highway operations in terms of pavement construction.  Compaction at lower temperatures can elongate the construction season and reduce the time necessary for lane closures during construction. These benefits contribute to the environmentally sound production and placement of HMA mixtures.  


2. Validation and Correlation of Pavement Profiling Devices for QA Implementation


In 1995, the Massachusetts Department of Transportation (MassDOT) increased its efforts to implement a Quality Assurance (QA) specification for its paving projects.  Under a QA specification, both the contractor and MassDOT are required to obtain ride quality measurements with a profiling device for each QA project.  Based on these measurements, the Contractor can be awarded an incentive based on the calculated ride quality values or International Roughness Index (IRI).  The measurements performed by each party are evaluated against the MassDOT specification values.

Research and Results

The purpose of this research project was to set up certification procedures for all profiling devices used on state QA projects.

Based on the results of this study, many conclusions were made.  First, the pre-certification test procedures developed were necessary and provided relevant system checks prior to certification testing.  Second, a full-size bumper mounted profiler was able to be utilized as the reference device, unlike previous research which had utilized rod and level survey measurements or walking profiler data for reference measurements.  Third, cross correlation was able to be utilized to analyze and compare the repeatability and accuracy of each inertial profiler tested to the MassDOT reference device.  Fourth, the utilization of each profiler’s individual IRI generation software in conjunction with the required filtering parameters did not have a noticeable impact on the calculated IRI values obtained from each device. 


An inertial profiler certification/correlation procedure was developed by incorporating elements from different sources resulting in a composite protocol.  The Pavement Management Section at MassDOT found the procedure suitable for implementing the ride quality specifications for QA projects.


3. Evaluation of Specialized Hot Mix Asphalt Mixes for Massachusetts


Throughout the nation many Departments of Transportation have been exploring and implementing the use of specialized types of Hot Mix Asphalt (HMA) such as Stone Matrix Asphalt (SMA), New Generation Open Graded Friction Course (OGFC), Polymer Modified Asphalt (PMA) HMA, Superpave, and Reflective Crack Relief Interlayer (RCRL).  Each of these mixes contains unique qualities.

Based on issues that have arisen during development of trial projects, it is critical to develop new mix designs using the latest technologies.  Many of the mixes used on these trial projects were likely developed under previous specifications that have since been altered.  Most current specifications have been updated to incorporate the use of the equipment for Superpave mix design as opposed to older methods that were based on the Marshall test.

Research and Results

The objectives of this research are to identify the HMA needs of Massachusetts, identify and select the specialized HMA mixes that have applications relevant to the needs of Massachusetts, determine the appropriate Performance Grade (PG) asphalt binder for each specialized mix, develop gradation and mixture designs for each specialized mix according to the most recently available specification and verify the rutting and/or fatigue performance of each mixture using Model Mobile Load Simulator (MMLS).

Anticipated Benefits

Successful design development of these specialized mixes has great benefit potential for Massachusetts.  SMA has been used extensively throughout Europe and has shown significant resistance to rutting and cracking.  Likewise, the new generation of OGFC have been widely used in the US and Europe alike and has shown benefits such as improved safety through enhanced frictional properties, reduced splash and spray, reduced noise, reduced potential for hydroplaning, enhanced driver comfort in the winter, and improved rutting resistance. 


Environmental Engineering: 

1. Autotrophic Biological Denitrification with Hydrogen or Thiosulfate for Complete Removal of Nitrogen from a Septic System Wastewater

Funding agency: The Cooperative Institute for Coastal and Estuarine Environmental Technologies - NOAA

Duration: September 2003 - August 2006


Influx of nitrogen from anthropogenic sources is primarily responsible for coastal eutrophication globally and in the Waquoit Bay NERR – the latter being the area of study of this project.   The predominant source of anthropogenic nitrogen in the WBNERR bay is the effluent from septic tank systems, which serve more than 85% of the homes in this region.   Conventional septic systems remove at best about 23% of the nitrogen in the influent wastewater; thus, there is a great need to introduce technologies that can be applied to onsite wastewater treatment that can achieve higher percentage of nitrogen removal.   Some Innovative/Alternative (I/A) technologies have recently been evaluated that can remove almost 66% of the influent nitrogen.   Conventional heterotrophic denitrification using an external electron donor can produce better results but suffers from the limitations of (i) using a toxic/inhibitory chemical such as methanol, and (ii) producing large amounts of biological sludge that has to handled/disposed of.   We propose a technology - Autotrophic Biological Denitrification  - that has the potential to achieve almost complete nitrogen removal and yet does not suffer from the limitations of heterotrophic denitrification enumerated above.   We propose using elemental sulfur or hydrogen as the electron donor.   The main objectives of this project included, (i) investigate autotrophic biological denitrification of wastewater using H2 and S0 as electron donors, (ii) evaluate the use of various sources of alkalinity to improve stability of S0 oxidizing systems, (iii) gain experience with operation of field-scale S0 oxidizing systems, (iv) evaluate the effects of supplemental organic carbon addition and dissolved oxygen in the wastewater on process efficiency, and (v) evaluate the effect of Empty Bed Contact Time (EBCT) and initial nitrate-nitrogen concentration on process performance. We conducted enrichment studies and lab-scale bioreactor tests at UMass Dartmouth and Amherst campuses.  We also conducted field-scale tests at the Massachusetts Alternative Septic System Test Center in Sandwich, MA to achieve the objectives referred above.  A summary of the major research findings can be listed as: (a) high denitrification rates could be achieved in a sulfur oxidizing bioreactor system treating nitrified wastewater with a hydraulic residence time of eight hours and sufficient pH buffering, (b) crushed oyster shell is the most suitable solid-phase buffer in sulfur-oxidizing denitrification systems, (c) periodic backwashing is needed in sulfur-oxidizing systems to dislodge excess microorganisms from the packed-bed (sulfur and buffer) bioreactor, (d) pH and alkalinity can act as process-control variables, (e) mixotrophic conditions did not enhance the denitrification efficiency for the bioreactor system, and (f) the presence of dissolved oxygen in the influent did not inhibit denitrification performance.   The proposed technology has the potential for immediate commercial application and can be a potent tool for federal, state, and local water quality administrators.


2. Environmentally Benign Synthesis of Sodium Hydroxide Without Chlorine Using Ion Exchange Fibers

Funding agency: United States Environmental Protection Agency (EPA)

Duration: December 2003 - December 2006


Although chlorine has many beneficial applications, its bulk usage  to produce chlorinated solvents, vinyl chloride, chlorofluorocarbons etc. continues to have long-term adverse impacts on the environment.  In the recent past, use of chlorine as "bleach" in the pulp and paper industry has also come under severe scrutiny due to the generation of toxic chlorinated organics including dioxins.  Currently, the production of sodium hydroxide (NaOH) and chlorine (Cl2) are closely linked and they are produced universally as co-products of electrolysis processes.  Thus, the chlorine availability and surplus in the market place is governed by NaOH demands.  As long as chlorine production remains coupled with the production of NaOH, it will be nearly impossible to promulgate regulations banning or reducing productions  of various chlorinated compounds and enforcing  them  globally.  Only an economic and ecologically clean route  to independently synthesize sodium hydroxide without co-production of excess chlorine may help achieve such environmental goals.

The proposed study involves innovative use of  Ion Exchange  (IX)  fibers to synthesize highly pure NaOH without co-production of chlorine.  The operationally simple fixed-bed process essentially converts inexpensive lime and sea water into sodium hydroxide without requiring or producing any regulated chemicals. In addition, the process offers a unique opportunity to reuse/sequester carbon dioxide, a greenhouse gas. The unique properties of IX fibers that make the proposed process both environmentally and economically attractive are: i) its amenability to efficient regeneration with carbon dioxide and harvested snowmelt/rainwater; ii) its suitability to handle dilute suspensions in  fixed-bed configurations; iii) its  superior sorption/desorption kinetics compared  to  commercial zeolites or ion exchange  resins. Laboratory investigations confirm that the sodium hydroxide produced is free of any impurity and significantly purer than that produced by the most widely used diaphragm cell process. 


3. Processing and Reuse of Street Sweepings and Catchbasin Cleanings

Funding agency: Massachusetts Department of Transportation

Duration: July 2005 - December 2007


MassHighway generates approximately 30,000 cubic yards of street sweepings and catch basin cleanings every year.   A major thrust of existing policy is to dispose this material in a landfill or use it as daily landfill cover.   However, with rapidly shrinking landfill space and high tipping fee, it is critical to consider reuse and recycle alternatives for this material.  We conducted an extensive study of the physical, chemical, and geotechnical properties of fresh, virgin sand, street sweepings and catch basin cleanings.    The physical properties examined include grain size, density, organic content, moisture content, uncompacted void content, and specific surface area.  Broad classes of chemical contaminants analyzed include RCRA-8 metals, volatile organics, polynuclear aromatic hydrocarbons, benzene, toluene, ethyl benzene and xylene, gasoline-range petroleum hydrocarbons and diesel-range petroleum hydrocarbons.  Geotechnical characterization included image analysis for angularity, form and texture, uncompacted void content, and British Pendulum Number (BPN) test.  The primary reuse options evaluated for street sweepings and catch basin cleanings include (a) reuse on pavements to provide traction and anti-skidding, (b) reuse as fine aggregates in bituminous concrete pavement, and (c) as a compost additive.

4. Use of Sulfur Oxidizing Denitrifying Bioretentin Systems for Control of Nonpoint Sources of Nitrogen

Funding agency: The Cooperative Institute for Coastal and Estuarine Environmental Technologies - NOAA

Duration: September 2006 - August 2008


Two-thirds of estuaries and bays in the U.S. are either moderately or severely degraded by eutrophication (increase in phytoplankton production) due largely to excessive nitrogen (N) inputs (Pew Oceans Commission, 2003).  Eutrophication is a key driver in a number of environmental problems including reduced light penetration resulting in seagrass mortality, increases in harmful algal blooms and hypoxic and anoxic conditions.  Control of point-sources of N has been a major focus of environmental regulatory agencies, and has resulted in stricter regulations for wastewater treatment.  Control of non-point sources of N, such as atmospheric deposition, fertilizer use, combined sewer overflows (CSOs) and agricultural runoff has lagged, however, but must be addressed in order to control eutrophication.  A number of best management practices (BMPs) are used for non-point source control, including sedimentation basins, lagoons, grassed swales, infiltration basins, constructed wetlands and bioretention systems.  This project evaluated a bioretention system that has the potential for removal of N present in the nonpoint source influent as either organic-N, ammonia-N, or Nitrate-N.  In this system, runoff was first conveyed through an aerobic nitrifying sand layer and then through a submerged denitrifying layer supplied with an electron donor.  Side-by-side pilot-scale experiments were conducted with bioretention systems utilizing both elemental sulfur and wood chips as substrates for denitrification at varying hydraulic loading rates (HLR), influent concentrations and wetting and drying periods.  Total N removal efficiencies greater than 88% were observed in both units with synthetic stormwater.  In field tests with dairy farm runoff and high a HLR, moderate removal efficiencies were observed for COD (46%), suspended solids (69%), total P (66%), and total N (65%).  During the second season, operational changes on the farm resulted in lower organic, solids and nutrient loadings resulting in improved bioretention system effluent quality, especially with regard to suspended solids (81% removal) and total N (82% removal).  The systems were not hydraulically overloaded even at 20 times the normal HLR. Somewhat better overall performance and cold temperature tolerance was observed in the wood-based unit than the sulfur based unit.  This passive bioretention system can be easily constructed and needs little maintenance.  The only long-term (once in a couple of years) maintenance issue is the replenishment of the denitrification media and changing of the top soil as it may be clogged due to Total Suspended Solids (TSS) in the influent. 


5. Development of Fiber-based Technology for Creating New Opportunities in Economically-depressed Northeastern US

Funding Agency: NSF Partnerships for Innovation Program

Duration:       February 2008 - January 2011


Southeastern Massachusetts was once an economic magnet of New England and beyond, primarily for its whaling, textile, and fishing industries.   But with the disappearance or relocation of these industries, it is facing severe economic challenges today.   With the textile industry, however, a strong infrastructure exists even today and a thrust toward knowledge-based, high-end manufacturing can be a significant component of economic revival of this region.   In this regard, recent breakthroughs in research conducted at University of Massachusetts Dartmouth (UMD) and Lehigh University have aroused significant interest of the private sector in the following areas:

  1. Synthesis of ion-exchange fibers (IXF) with diameter as low as 100 nanometers
  2. Capability of inserting nanoparticles of metal oxides as low as 5 nanometers in the core of the IXF, resulting in unique properties of the resulting fiber that can be harnessed in environmental treatment applications
  3. Capability of producing woven or non-woven sheets or fibers of the IXF.

Besides UMD and Lehigh University, the proposed project includes seven private partners with strong business commitment to bring the research innovations to the marketplace.   Based on their technical expertise and business interest, these private companies can be grouped as,

(i)    companies committed to scale-up and manufacture of IXF,

(ii)  specialty engineering companies that deliver packaged systems (containing IXF) for target applications.

In addition, this collaboration will continue to serve as a nucleus for new research ideas leading to marketable innovations in related areas.   Moreover, UMD has a disproportionately higher percentage of first-generation university students from a non-English speaking background.   This project, therefore, will provide education and employment opportunities for a diverse group of underrepresented groups in the region.   This Partnership for Innovation (PFI) proposal embodies a plan to catalyze the ongoing activities among all constituents and attract new technology-oriented small companies as active partners.


6. The Role of Scale in the Development and Evolution of Stratified Shear Turbulence, Entrainment and Mixing 

Funding Agency: Office of Naval Research

Duration:       May 2015 - May 2018


The goal of this research effort is to use existing field and laboratory data, along with direct numerical simulation (DNS) models to explore the variation of turbulence parameters across significant spatial scales.  This work will allow better communication between laboratory studies and observations of stratified-shear turbulence in the oceans, and will lead to better parameterizations of turbulence in ocean models, and more effective predictions of ocean processes.  Most studies to date have assumed that stratified-shear turbulence is essentially independent of Reynolds number, Re, once a specific critical value of Re is exceeded.  Recent comparisons of field and laboratory data suggest otherwise.  This is a potentially significant realization that could have profound implications for our understanding of stratified-shear turbulence and the development of robust turbulence closure models.  This project will utilize a combination of field data, laboratory data, and DNS simulations to provide a robust view of various turbulence parameters across at least 4 to 5 orders of magnitude in Re.  These data will first be used to validate proposed equations relating entrainment (e.g. Ellison and Turner 1959; Christodoulo 1986; Yuan and Horner-Devine 2013) and buoyancy flux (e.g., Smyth et al 2001; MacDonald and Chen 2012) across Reynolds number space, then to assess the behavior of u*/∆u as a function of Re.  A significant challenge in compiling the necessary data will be in developing enough high quality, reliable estimates of turbulence quantities across the desired range of Re.  Field data will generally support the high end of the range, while existing laboratory datasets will be supplemented with new DNS simulations to fill in the low end of the range. 


7. Reducing the cost of wave energy with an innovative tethered ballast system 

Funding Agency: Massachusetts Seaport Economic Council

Duration:       July 2016 - July 2018


Our technological improvements on the point absorber wave energy device are simple, yet may represent a game changer in the wave energy industry, which has been plagued by high costs, driven in large part by device manufacturing and deployment costs.  Our solution to this problem is a tethered ballast system (provisional patent filed by UMass Dartmouth in December 2015), designed to replace the rigid spar that traditionally forms the “foundation” of modern point absorber systems.  These rigid spars are typically constructed of steel and extend tens of meters below the water line, resulting in significant manufacturing, deployment, and maintenance costs.  These costs could be all but eliminated with the use of a tethered ballast system.  Given these potentially huge cost savings, our technology will be disruptive in the wave energy marketplace.  This project will fund the development of the tethered ballast system, which will ultimately be applicable to a wide array of point absorber wave energy converter technologies, from the utility scale, to the local/distributed energy scale, where devices can provide local power solutions for moored sensors, telecommunications base stations, and other coastal ocean devices.  The small-scale market provides a generation of revenue within two to four years, and a springboard for utility scale development, through direct reinvestment of revenue, and by reducing the risk barrier for private investment in wave energy. 


8. A cost-disruptive, low impact, modular form factor low-head hydropower system 

Funding Agency: US Department of Energy (DOE) / Massachusetts Department of Energy Resources (MADOER)

Duration:       February 2016 - March 2018


Assessments sponsored by the U.S. Department of Energy show that new stream reach potential in the USA is about 460 TWh/yr.  Most of the available sites have sustainability challenges that can be partly addressed by run-of-river (ROR) projects, considered environmentally friendly because of their modest impoundments and minimal downstream hydrographic changes.  Cost is one of the major problems with harnessing this potential. According to a prominent Oak Ridge National Laboratory study, initial capital costs make up 51-73% of the levelized cost of energy (LCOE) and are a critical barrier to the development of many low-head sites. The study reports only about a third of the technically feasible capacity in the USA is cost-effective for development based on currently available technologies and energy market values, even factoring in renewable energy credits and feed-in tariffs. Reducing initial costs will lead to additional development of small hydro projects. Another barrier is that most low-head power installations take years to deploy, also inflating costs, and when removed leave behind a lasting environmental impact.  Recognizing this problem and opportunity, local New Bedford startup Littoral Power Systems Inc. (LPS) has conceived a modular low head system, scalable for head from approximately 7 to 50 feet, depending on the type of deployment. The system is conceived principally for small hydro projects, and in particular, ROR applications and dam-toe schemes. It offers the major benefit of very low initial cost due to an innovative form factor: the components of the system are mounted, transported and partially deployed in standard 10- to 40-foot shipping containers with structural and hydraulic modifications.  A modular system allows for low-impact installations that, when removed, leave little if any perceptible trace that it was ever there. The systems can be grid-connected or used to develop nongrid project- or community-specific power. The funded project brings together engineers and researchers from LPS, UMass Dartmouth, GZA GeoEnvironmental, Inc. (Norwood, MA), Alden Research Laboratories (Holden, MA), and the National Renewable Energy Laboratory (Golden, CO) to develop a proof of concept design of integrated dam modules, penstock/turbine modules, spillway modules, leak proof connections, stabilizers, and seepage controls and tests a full size prototype of an integrated dam section for structural integrity, leak resistance, and ease of installation. An intermediate goal of the proof of concept design is to achieve an approximately 20% reduction versus state-of-the-art, based on a 50% reduction in capital costs. The principal componentry will be advanced to technology readiness level (TRL) 6 through analysis, numerical simulation, computational fluid dynamics, and full scale testing at the Alden facility.