Civil and Environmental Engineering Commons^™

Global Opportunities To Increase Agricultural Independence Through Phosphorus Recycling, Stephen M. Powers, R. B. Chowdhury, G. K. Macdonald, A, H.W. Beusen, A. F. Bouwman, S. E. Hampton, Brooke K. Mayer, M. L. Mccracklin, D. A. Vaccari

Civil and Environmental Engineering Faculty Research and Publications

Food production hinges largely upon access to phosphorus (P) fertilizer. Most fertilizer P used in the global agricultural system comes from mining of nonrenewable phosphate rock deposits located within few countries. However, P contained in livestock manure or urban wastes represents a recyclable source of P. To inform development of P recycling technologies and policies, we examined subnational, national, and global spatial patterns for two intersections of land use affording high P recycling potential: (a) manure‐rich cultivated areas and (b) populous cultivated areas. In turn, we examined overlap between P recycling potential and nation‐level P fertilizer import dependency. Populous cultivated …

Comment On “Patented Blunderings, Efficiency Awareness, And Self-Sustainability Claims In The Pyrolysis Energy From Waste Sector”, Patrick J. Mcnamara, Daniel Zitomer, Zhongzhe Liu

Civil and Environmental Engineering Faculty Research and Publications

No abstract provided.

Initial Development Of Advanced, High-Rate Treatment Process For Wet Weather Flows, Paige Elyse Peters

Master's Theses (2009 -)

Billions of gallons of untreated water are discharged into lakes and rivers every year due to combined and sanitary sewer overflows during high-intensity precipitation events. Combined sewer overflows (CSOs) and sanitary sewer overflows (SSOs) pose both environmental and public health risks due to potential human contact with contaminated water. To address the overflow issue, a novel, advanced, high-rate wet weather treatment process was investigated. The high-rate treatment process combined chemically enhanced primary treatment (CEPT) with an advanced oxidation process (AOP) using ozone to rapidly remove total suspended solids (TSS) and chemical oxygen demand (COD), inactive E. coli, and oxidize the …

Improved Reliability Of Stormwater Detention Basin Performance Through Water Quality Data-Informed Real-Time Control, Sazzad Sharior

Master's Theses (2009 -)

The objective of stormwater detention basins is to capture stormwater runoff to reduce and delay peak flow and to improve the water quality. These objectives can be improved upon by actively controlling the outflow of the basins rather than traditional passive outflow structures. There are studies demonstrating the performance of the active controls that respond in real-time to basin hydraulics, detention time, and rainfall forecasts. We hypothesize that the performance of these active controls can be improved upon by incorporating real-time water quality data streams into the control algorithm. Furthermore, we hypothesize that performance of these active controls also depends …

Impact Of Electrocoagulation Pretreatment On E. Coli Mitigation Using Electrooxidation, William Mcgregor Lynn

Master's Theses (2009 -)

Small drinking water systems serve approximately 20% of the US population, but they can struggle to comply with the Total Coliform Rule and the Disinfectant and Disinfection Byproduct Rule. Issues with insufficient funds to effectively treat the water and difficulties with the transportation of required chemicals can affect compliance. Electrochemical processes may offer an alternative approach for small water systems as they have demonstrated some advantages over traditional treatments, such as reduced handling and storage of chemicals and cost effectiveness. Sequential electrochemical processes have yet to be tested for the treatment of E. coli in drinking waters. In this study, …

Analysis Of Operational Parameters, Reactor Kinetics, And Floc Characterization For The Removal Of Estrogens Via Electrocoagulation, Emily K. Maher, Kassidy N. O'Malley, Joe Heffron, Jingwan Huo, Brooke K. Mayer, Yin Wang, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Estrogenic compounds can cause human and ecological health issues and have been detected in surface and drinking water. In this research a reactor analysis determined the impact of operational parameters, the best fit kinetic model for the removal of estrone (E1), 17β-estradiol (E2), estriol (E3), and 17α-ethynylestradiol (EE2) using a bench-top iron electrocoagulation reactor, and characterized the floc generated in-situ. The parameters investigated were current density, conductivity, stir rate, and polarity reversal. Estrogen removal correlated well with an increase in current density, while conductivity did not impact removal but did reduce potentials. High stir rates and frequent polarity reversal …

Adsorption Of Organic Micropollutants Onto Biochar: A Review Of Relevant Kinetics, Mechanisms And Equilibrium, Yiran Tong, Patrick J. Mcnamara, Brooke K. Mayer

Civil and Environmental Engineering Faculty Research and Publications

As an alternative to activated carbon, biochar has been considered for removal of organic micropollutants from water and wastewater via adsorption. This review elaborates on the fundamental basis of adsorption kinetics, mechanisms, and equilibrium with respect to biochar-based adsorption of micropollutants. The objectives include: 1) linking biochar surface properties with adsorption abilities, 2) categorizing the kinetics of adsorption of aqueous-phase organic compounds onto biochar, 3) categorizing the molecular-scale interactions between organic micropollutants and biochar, and 4) reviewing existing quantitative methods for characterizing adsorption equilibrium of organic micropollutants from water onto an adsorbent surface. To fulfill these goals, the relationships among …

Inactivation Of The Bacterial Pathogens Staphylococcus Pseudintermedius And Acinetobacter Baumannii By Butanoic Acid, G. M. Kennedy, M. Y. Min, J. F. Fitzgerald, M. T. Nguyen, S. L. Schultz, M. T. Crum, Jeffrey A. Starke, M. A. Butkus, D. D. Bowman, M. P. Labare

Civil and Environmental Engineering Faculty Research and Publications

Aims

This study was performed to evaluate the efficacy of butanoic acid against bacterial pathogens including Acinetobacter baumannii and Staphylococcus pseudintermedius.

Methods and Results

Vegetative bacteria were exposed to butanoic acid in vitro and log reduction was quantified using viable count assays. The maximum (8 and 9) log inactivation was determined by qualitatively assaying for growth/no-growth after a 48-h incubation (37°C). Membrane integrity after exposure to butanoic acid was determined by propidium iodide staining, scanning electron microscopy, membrane depolarization and inductively coupled plasma analysis. Cytosolic pH was measured by 5-(6-)carboxyfluorescein succinimidyl ester.

Conclusions

Inhibitory concentrations of butanoic acid ranged …

Closed-Form Solution For Curling Responses In Rigid Pavements, Jaime Hernandez, Imad L. Al-Qadi

Civil and Environmental Engineering Faculty Research and Publications

Closed-form expressions for calculating stresses and displacements of partially restrained concrete pavement caused by a linear temperature gradient are presented. Translational and rotational linear elastic springs along the slab edges defined the partial restraint. In addition to plate theory behavior, the model assumes linear elastic concrete and an infinitely long slab resting on a Winkler foundation. The solutions of curling stresses and displacements were validated using the finite-element (FE) method and quantified the effect of semirigid connections, slab and foundation material properties, and slab thickness and width on them. Rotational and translational restraints, which can be related to joint condition …

From Micro To Macro-Contaminants: The Impact Of Low-Energy Titanium Dioxide Photocatalysis Followed By Filtration On The Mitigation Of Drinking Water Organics, Brooke K. Mayer, Carlan Johnson, Yu Yang, Nicole Wellenstein, Emily K. Maher, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

This study evaluated strategies targeting macro- and micro-organic contaminant mitigation using low-energy titanium dioxide photocatalysis. Energy inputs of 1, 2, and 5 kWh m⁻³ resulted in incomplete oxidation of macro-organic natural organic matter, signified by greater reductions of UV₂₅₄ and specific ultraviolet UV absorbance (SUVA) in comparison to dissolved organic carbon (DOC). The rate of UV₂₅₄ removal was 3 orders of magnitude greater than the rate of DOC degradation. Incomplete oxidation improved operation of downstream filtration processes. Photocatalysis at 2 kWh m⁻³ increased the bed life of downstream granular activated carbon (GAC) filtration by 340% relative …

Toxicity Of Various Pyrolysis Liquids From Biosolids On Methane Production Yield, Seyedfatemeh Seyedi, Kaushik Venkiteshwaran, Daniel Zitomer

Civil and Environmental Engineering Faculty Research and Publications

Aqueous pyrolysis liquid (APL) is a high-COD byproduct of wastewater biosolids pyrolysis that is comprised of numerous complex organic compounds and ammonia nitrogen (NH₃-N). One potential beneficial use of APL is as a co-digestate to produce more biogas in anaerobic digesters. However, some APL organics and NH₃-N are known to inhibit methane-producing microbes. Autocatalytic pyrolysis which uses previously-produced biochar as a catalyst during biosolids pyrolysis, increases energy-rich py-gas while eliminating bio-oil production and reducing COD concentration in the APL (catalyzed APL). However, the catalyzed APL still has a high organic strength and no suitable treatment strategies …

Using Online Discussions To Develop The Entrepreneurial Mindset In Environmental Engineering Undergraduates: A Case Study, Lisa B. Bosman, Nathalie Duval-Couetil, Brooke K. Mayer, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Entrepreneurship is an important aspect of the U.S. and global economy. As such, developing an entrepreneurial mindset is crucial for both engineering students and practicing engineers. The purpose of this paper is investigate the role of online discussions, as a pedagogical approach, in the development of the entrepreneurial mindset, and explore a variety of approaches to assess student learning outcomes. Online discussions prompts were created for environmental engineering courses using the Kern Engineering Entrepreneurial Network (KEEN) framework. The framework proposes that an entrepreneurial mindset can be fostered in students by promoting curiosity, encouraging connections, and creating value. This paper describes …

Long-Term Impact On Environmental Attitudes And Knowledge Assessed Over Three Semesters Of An Environmental Engineering Sequence, Benjamin Michael Wallen, Nathaniel Sheehan, Luke Plante, Erick Martinez, Jeffrey A. Starke

Civil and Environmental Engineering Faculty Research and Publications

The pedagogy employed in a three-course environmental engineering sequence is investigated to determine the efficacy of enabling long-term improvement of knowledge and attitudes toward the environment. These three courses incorporate concepts of the five grand challenges released by the National Academy of Engineering and National Academy of Sciences and increase the breadth of knowledge for T-professionals. Previous studies of lengths from a few weeks to semester long courses evaluated the potential causality among various demographics and environmental knowledge and attitudes. The research presented herein contrasts and compares changes in environmental knowledge based upon a 12-question survey and changes in environmental …

Meta-Analysis Of Non-Reactive Phosphorus In Water, Wastewater, And Sludge, And Strategies To Convert It For Enhanced Phosphorus Removal And Recovery, Kaushik Venkiteshwaran, Patrick J. Mcnamara, Brooke K. Mayer

Civil and Environmental Engineering Faculty Research and Publications

Current and future trends indicate that mining of natural phosphorus (P) reserves is occurring faster than natural geologic replenishment. This mobilization has not only led to P supply concerns, but has also polluted many of the world's freshwater bodies and oceans. Recovery and reuse of this nuisance P offers a long-term solution simultaneously addressing mineral P accessibility and P-based pollution. Available physical, chemical, and biological P removal/recovery processes can achieve low total P (TP) concentrations (≤100 μg/L) and some processes can also recover P for direct reuse as fertilizers (e.g., struvite). However, as shown by our meta-analysis of over 20,000 …

Stochastic Water Balance Dynamics Of Passive And Controlled Stormwater Basins, Anthony J. Parolari, Steven Pelrine, Mark S. Bartlett

Civil and Environmental Engineering Faculty Research and Publications

Urbanization and changing rainfall intensities affect the performance of urban stormwater infrastructure, creating the necessity to design resilient stormwater systems. One proposed method to increase the resilience of stormwater infrastructure is the active control of system flows. To improve the understanding of actively-controlled urban water infrastructure function under variable hydro-climate, we develop a stochastic water balance model for stormwater retention and detention basins with both passive and actively-controlled outflow structures. Under active outflow control, the outflow valve is closed until the water level in the basin reaches a specified maximum at which point the valve opens and the basin empties. …

Epoxy Interlocking: A Novel Approach To Enhance Frp-To-Concrete Bond Behavior, Cheng Jiang, Baolin Wan, Yu-Fei Wu, John Omboko

Civil and Environmental Engineering Faculty Research and Publications

This paper presents a novel approach which can enhance the interfacial bond behavior between fiber reinforced polymer (FRP) composite material and concrete. Epoxy ribs are formed by grooving on the concrete surface before epoxy is applied. The dowel action from the epoxy ribs leads to an “epoxy interlocking” effect. The mechanism of the proposed epoxy interlocking approach was analyzed in this paper from both adhesion and interlocking aspects. Furthermore, the partial interaction of the epoxy interlocking was quantified and calibrated by experimental results. The epoxy interlocking in the tested specimens led to an 88.8% increase in bond strength on average. …

Impact Of Wide-Base Tires On Pavements: A National Study, Imad L. Al-Qadi, Jaime Hernandez, Angeli Gamez, Mojtaba Ziyadi, Osman Erman Gungor, Seunggu Kang

Civil and Environmental Engineering Faculty Research and Publications

This paper summarizes a multi-year effort comparing the new-generation wide-base tires (NG-WBT) and dual-tire assembly from a holistic point of view. The tires were compared considering not only pavement damage but also environmental impact. Numerical modeling, prediction methods, experimental measurements, and life-cycle assessment were combined to provide recommendations about the use of NG-WBT. A finite element (FE) approach considering variables that are usually omitted in the conventional analysis of flexible pavement was used for modeling pavement structures combining layer thickness, material properties, tire load, tire-inflation pressure, and pavement type (interstate and low volume). A prediction tool, ICT-Wide, was developed based …

Development Of Domain Analysis To Predict Multi-Axial Flexible Airfield Pavement Responses Due To Gear And Environmental Loadings, Angeli Gamez, Jaime Hernandez, Imad L. Al-Qadi

Civil and Environmental Engineering Faculty Research and Publications

Flexible pavement design procedures use maximum mechanistic strains to predict service life via empirical transfer functions. The conventional method of using predefined point locations for potential damage may not accurately represent realistic pavement scenarios. For instance, flexible airfield pavement analysis mainly considers the critical strain at the bottom of the asphalt concrete (AC), which may not characterize near-surface cracking potential. In lieu of point strains, domain analysis, a new method, accounts for the multi-axial behavior of pavements, as inherently excited by three-dimensional (3-D) and nonuniform aircraft tire–pavement contact stresses. Initially applied on highway pavements considering truck tire loading, this approach …

Ion Exchange For Nutrient Recovery Coupled With Biosolids-Derived Biochar Pretreatment To Remove Micropollutants, Yiran Tong, Lee K. Kimbell, Anna Avila, Patrick J. Mcnamara, Brooke K. Mayer

Civil and Environmental Engineering Faculty Research and Publications

Wastewater, especially anaerobic treatment effluent, contains high ammonia nitrogen (NH₄-N) and inorganic orthophosphate (PO₄-P), which necessitate additional treatment to meet stringent discharge regulations. Ion exchange regeneration is a process that can be adopted for not only removing but also recovering nutrients. However, recovering nutrients by ion exchange from nutrient-rich effluents that also contain micropollutants (which typically pass through anaerobic treatment as well) may result in subsequent problems, since micropollutants could end up in ion exchange effluent, regenerant, or recovered fertilizer products. Micropollutant removal by a nonselective adsorbent, such as biosolids-derived biochar, before nutrient recovery processes would …

Axial Compressive Behavior Of Square Ice Filled Steel Tubular Stub Columns, Yanlei Wang, Guipeng Chen, Baolin Wan, Hao Lin

Civil and Environmental Engineering Faculty Research and Publications

Concrete has many limitations in the building construction in cold areas. However, there is abundant ice in those regions. Therefore, using ice as a substitute for concrete has been explored by researchers. Inspired by the idea of square concrete filled steel tube (CFT), a new column form termed square ice filled steel tubular (IFT) column is proposed in this study. It consists of a square outer steel tube with the inner space filled with ice. A total of eighteen stub columns were made and tested under axial compression, including three circular plain ice specimens, nine square IFT specimens and six …

Sub-Pilot-Scale Autocatalytic Pyrolysis Of Wastewater Biosolids For Enhanced Energy Recovery, Zhongzhe Liu, Simcha L. Singer, Daniel Zitomer, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Improving onsite energy generation and recovering value-added products are common goals for sustainable used water reclamation. A new process called autocatalytic pyrolysis was developed at bench scale in our previous work by using biochar produced from the biosolids pyrolysis process itself as the catalyst to enhance energy recovery from wastewater biosolids. The large-scale investigation of this process was used to increase the technical readiness level. A sub-pilot-scale catalytic pyrolytic system was constructed for this scaled-up study. The effects of configuration changes in both pyrolytic and catalytic reactors were investigated as well as the effect of vapor-catalyst contact types (i.e., downstream, …

Removal Of Antibiotic Resistance Genes In An Anaerobic Membrane Bioreactor Treating Primary Clarifier Effluent At 20 °C, Anthony D. Kappell, Lee K. Kimbell, Matthew Seib, Daniel Elliott Carey, Melinda J. Choi, Tino Kalayil, Masanori Fujimoto, Daniel Zitomer, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Anaerobic membrane bioreactors (AnMBR) play a key role in future plans for sustainable wastewater treatment and resource recovery because they have no energy-intensive oxygen transfer requirements and can produce biomethane for renewable energy. Recent research results show that they can meet relatively stringent discharge limits with respect to BOD₅ and TSS when treating municipal wastewater primary effluent. Sustainable used water recovery plans should also consider removal of unregulated pollutants. Antibiotic resistance genes (ARGs) represent an important emerging contaminant due to public health concerns surrounding the spread of infections resistant to common antibiotics. Conventional activated sludge processes have demonstrated mixed …

Strain Monitoring Of Concrete Components Using Embedded Carbon Nanofibers/Epoxy Sensors, Yanlei Wang, Yongshuai Wang, Baoguo Han, Baolin Wan, Gaochuang Cai, Zhizheng Li

Civil and Environmental Engineering Faculty Research and Publications

In this study, embedded strain sensors based on the principle of piezoresistivity were fabricated by epoxy-based composites filled with different contents of carbon nanofibers (CNFs). The piezoresistive performances and relevant parameters including gauge factor, linearity, repeatability and hysteresis of these sensors were investigated. A compensation circuit was proposed to eliminate the influence of temperature on sensing signals of the sensors. The CNFs/epoxy sensors were embedded into concrete cylinders to monitor their compressive strains under monotonic and cyclic loadings, thereby assessing practical applications of the CNFs/epoxy sensors as strain sensors for monitoring concrete structures. The results indicate that the sensors containing …

A New Thickness-Based Accelerated Aging Test Methodology For Resin Materials: Theory And Preliminary Experimental Study, Yanlei Wang, Xue Zhang, Gaochuang Cai, Baolin Wan, Danièle Waldmann, Yuan Qu

Civil and Environmental Engineering Faculty Research and Publications

This paper proposes a novel accelerated test method based on the thickness of resin materials. This method is to overcome the adverse influence of high temperature on the reliability of experimental results of the accelerated tests widely adopted in the current practice. To verify the proposed thickness-based accelerated method (ThAM), an experimental investigation was conducted focusing on the water absorption and tensile properties of epoxy resin. The results suggest that the existing temperature-based accelerated method (TAM) cannot be applied when the test temperature is high as in this case the degradation mechanism of materials is probably changed. The acceleration factor …

Metagenomics Reveal Triclosan-Induced Changes In The Antibiotic Resistome Of Anaerobic Digesters, M. Fujimoto, Daniel Elliott Carey, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Triclosan (TCS) is a broad-spectrum antimicrobial used in a variety of consumer products. While it was recently banned from hand soaps in the US, it is still a key ingredient in a top-selling toothpaste. TCS is a hydrophobic micropollutant that is recalcitrant under anaerobic digestion thereby resulting in high TCS concentrations in biosolids. The objective of this study was to determine the impact of TCS on the antibiotic resistome and potential cross-protection in lab-scale anaerobic digesters using shotgun metagenomics. It was hypothesized that metagenomics would reveal selection for antibiotic resistance genes (ARGs) not previously found in pure culture studies or …

An Environmental Science And Engineering Framework For Combating Antimicrobial Resistance, Amy Pruden, Reinaldo E. Alcalde, Pedro J.J. Alvarez, Nicholas Ashbolt, Heather Bischel, Natalie L. Capiro, Emily Crossette, Dominic Frigon, Kassandra Grimes, Charles N. Haas, Kaoru Ikuma, Anthony D. Kappell, Timothy M. Lapara, Lee K. Kimbell, Mengyan Li, Xu Li, Patrick J. Mcnamara, Youngwoo Seo, Mark D. Sobsey, Emanuele Sozzi, Tala Navab-Daneshmand, Lutgarde Raskin, Maria Virginia Riquelme, Peter Vikesland, Krista Wigginton, Zhi Zhou

Civil and Environmental Engineering Faculty Research and Publications

On June 20, 2017, members of the environmental engineering and science (EES) community convened at the Association of Environmental Engineering and Science Professors (AEESP) Biennial Conference for a workshop on antimicrobial resistance. With over 80 registered participants, discussion groups focused on the following topics: risk assessment, monitoring, wastewater treatment, agricultural systems, and synergies. In this study, we summarize the consensus among the workshop participants regarding the role of the EES community in understanding and mitigating the spread of antibiotic resistance via environmental pathways. Environmental scientists and engineers offer a unique and interdisciplinary perspective and expertise needed for engaging with other …

Accounting For Landscape Heterogeneity Improves Spatial Predictions Of Tree Vulnerability To Drought, Amanda M. Schwantes, Anthony J. Parolari, Jennifer J. Swenson, Daniel M. Johnson, Jean-Christopher Domec, Robert B. Jackson, Norman F. Pelak, Amilcare Porporato

Civil and Environmental Engineering Faculty Research and Publications

As climate change continues, forest vulnerability to droughts and heatwaves is increasing, but vulnerability varies regionally and locally through landscape position. Also, most models used in forecasting forest responses to heat and drought do not incorporate relevant spatial processes.

In order to improve spatial predictions of tree vulnerability, we employed a nonlinear stochastic model of soil moisture dynamics accounting for landscape differences in aspect, topography and soils. Across a watershed in central Texas we modeled dynamic water stress for a dominant tree species, Juniperus ashei, and projected future dynamic water stress through the 21^st century.

Modeled dynamic water …

Strain And Damage Self-Sensing Of Basalt Fiber Reinforced Polymer Laminates Fabricated With Carbon Nanofibers/Epoxy Composites Under Tension, Yanlei Wang, Yongshuai Wang, Baolin Wan, Baoguo Han, Gaochuang Cai, Ruijuan Chang

Civil and Environmental Engineering Faculty Research and Publications

This study investigated the strain and damage self-sensing capabilities of basalt fiber reinforced polymer (BFRP) laminates fabricated with carbon nanofibers (CNFs)/epoxy composites subjected to tensile loadings. The conduction mechanisms based on the tunnel conduction and percolation conduction theories as well as the damage evolution were also explored. A compensation circuit with a half-bridge configuration was proposed. The results indicated the resistivity of the CNFs/BFRP laminates and CNFs/epoxy composites exhibited similar change rule, indicating that the conductive networks of CNFs/BFRP laminates were governed by CNFs/epoxy composites. With the increase of strain under monotonic tensile loading, the electrical resistance response could be …

Managing Diffuse Phosphorus At The Source Versus At The Sink, Katrina A. Macintosh, Brooke K. Mayer, Richard W. Mcdowell, Stephen M. Powers, Lawrence A. Baker, Treavor H. Boyer, Bruce E. Rittmann

Civil and Environmental Engineering Faculty Research and Publications

Judicious phosphorus (P) management is a global grand challenge and critical to achieving and maintaining water quality objectives while maintaining food production. The management of point sources has been successful in lowering P inputs to aquatic environments, but more difficult is reducing P discharges associated with diffuse sources, such as nonpoint runoff from agriculture and urban landscapes, as well as P accumulated in soils and sediments. Strategies for effective diffuse-P management are imperative. Many options are currently available, and the most cost-effective and practical choice depends on the local situation. This critical review describes how the metrics of P quantity …

Properties And Mechanisms Of Self-Sensing Carbon Nanofibers/Epoxy Composites For Structural Health Monitoring, Yanlei Wang, Yongshuai Wang, Baolin Wan, Baoguo Han, Gaochuang Cai, Zhizheng Li

Civil and Environmental Engineering Faculty Research and Publications

In this paper, carbon nanofibers (CNFs) with high aspect ratio were dispersed into epoxy matrix via mechanical stirring and ultrasonic treatment to fabricate self-sensing CNFs/epoxy composites. The mechanical, electrical and piezoresistive properties of the nanocomposites filled with different contents of CNFs were investigated. Based on the tunneling conduction and percolation conduction theories, the mechanisms of piezoresistive property of the nanocomposites were also explored. The experimental results show that adding CNFs can effectively enhance the compressive strengths and elastic moduli of the composites. The percolation threshold of the CNFs/epoxy composites is 0.186 vol% according to the modified General Effective Media Equation. …