Current issues such as global warming and energy conservation are being discussed more than ever worldwide. Today's pavement sustainability evaluation methods recognize the complicated nature of pavement thermophysical characteristics but do not address albedo-related indicators or outcomes. Pavement infrastructure sustainability assessment systems that objectively prescribe certain thermophysical qualities and albedo criteria relating to "cool pavement," "urban heat island," and other cleaner production effects targets are required. The aim of this study was to quantitatively analyze the thermophysical properties and albedo of urban roads to validate the thermal models used in AASHTOWare Pavement ME (PaveME) version 2.3 Design software. Core samples of both portland cement concrete pavement (PCC) and asphalt pavement (AC) were drilled at 10 locations in a number of sites. In the central and eastern United States, seven field sample locations in different cities were chosen to represent a diversity of local aggregate types, pavement varieties and years of age, and environments. New test methods were then developed and used to quantify the thermal properties of pavements, including thermal conductivity (k), specific heat capacity (SH), emissivity, and albedo. The pavement thermal properties from the literature were summarized and compared to the experimental data. The pavement thermal performance varies greatly in different regions. Thermal conductivity values of PCC and AC cores from northern PCC and AC pavement samples were lower than those found in southern samples. Further endeavors are needed to enhance the accuracy of measuring thermal conductivity value and heat capacity value by utilizing pavement samples. Doing so would enable state highway agencies to document the thermal properties of their pavements and determine the appropriate thermal input values to reduce the negative impact of pavement sustainability and achieve cleaner production goals for pavement infrastructure.

This paper examines an approximation method to qualitatively assess the air-cleaning performance (i.e., specifically the elimination of aerial nitrogen oxide, NO, released within vehicular exhaust) by full-scale pavements which contain photo-catalytically reactive titanium dioxide under optimal conditions. Two hypothetical road configurations were considered using this method, including both a two-lane, low traffic density (i.e., 4,000 full-day AADT) and a four-lane, moderate traffic density (i.e., 10,000 full-day AADT) design. These options were then comparatively examined on the basis of expected European Union or United States vehicular emission levels day-time-only percentile elimination approximation results were derived using an extrapolation of lab-based specific contaminant elimination rates (i.e., mass NO removed per surface area per time) relative to contaminant release rates which were projected for EU or US vehicular contaminant emission levels. approximation method, and assuming best-case scenario conditions (i.e., original, un-aged, peak catalytic performance under optimal temperature, relative humidity, etc. conditions), day-timeonly percentile removals in the ~mid-60% to ~90% range were predicted for EU two- and fourlane roadways with low to moderate traffic densities. These EU contaminant elimination approximation percentiles were higher than the actual, observed range (e.g., typically ~mid-10% to ~mid-60% day-time removal percentiles) of published contaminant elimination values which had been measured according to gas-phase contaminant changes during a number of full-scale studies completed at various EU locations and with EU-related vehicle types and emissions. In the case of similar US highway options, th approximated day-time-only elimination percentile results were lower than what was predicted for similar EU road options, with a range of ~30% to ~40%. These latter, lower US road approximations were believed to be related to higher expected US versus EU vehicle emission levels (i.e., by a factor of ~two- to ~three-fold for light and heavy duty vehicles).

This paper addresses a soil bio-stabilization technique using bacterial enzyme-induced calcium carbonate precipitation (BEICP) as an alternative to previous conventional methods including microbial-induced carbonate precipitation and plant-derived enzyme-induced carbonate precipitation. The extracted urease enzyme of viable S. pasteurii was used as a biological source along with calcium chloride and urea to solidify sandy soil and silty sand soil. The bio-treated soil columns were subjected to freeze and thaw (F–T) cycling for a durability evaluation. Engineering properties of bio-cemented soil including unconfined compressive strength, calcium carbonate contents, moisture contents, porosity, permeability, and microstructure were examined before and after the F–T durations. It was found that although bio-stabilizer was able to increase a frost duration of soil, the F–T cycling significantly impacted on the compressive strength of bio-treated soil, due to a formation of microcracks. This investigation has revealed that the BEICP method provided a similar capacity in F–T resistance of soil as using the traditional Portland cement stabilizer, whereas the class F fly ash did not improve F–T durability of medium dense soil.

Peracetic acid (PAA) was used as an inhibitor to prevent urea hydrolysis in the recovery and concentration of nitrogen in a synthetic urine. Twenty mg/L of PAA was found to be effective in inhibiting urea hydrolysis for seven days before it was concentrated by the progressive freeze concentration (PFC) process. Ammonia concentration, total nitrogen (TN), pH, and electrical conductivity (EC) were monitored. The PFC process, operating with a coolant temperature of -12 ?degrees C and a stabilized synthetic urine temperature of 23 degrees C, reduced the volume of the stabilized synthetic urine by approximately 80% (concentration factor of 5.1) and concentrated the TN approximately 21,000 mg/L with ammonia concentration of approximately 50 mg/L-N. Seven days after the PFC treatment, the urea in the concentrated synthetic urine continued to be fairly stable although addition of PAA may be needed to stabilize the concentrated solution further. The experimental results showed that a combination of using PAA as an oxidizing agent and the PFC process can be an effective and suitable process for source separation systems to concentrate urine to recover nitrogen and produce liquid fertilizer.

A progressive freeze concentration (PFC) process was applied to treat several waters where clean ice was generated one-dimensionally, and salt and impurities concentrate into the liquid phase. The impact of eight process parameters on salt percent removal and ice percent recovery were investigated. They were coolant temperature, stirring rate, advance speed of crystallizer, feed solution concentration, feed solution temperature, ice seeding, crystallizer material, and mixing flow pattern. The significant process parameters found were stirring rate, coolant temperature, and feed solution concentration. Temperature difference between feed solution temperature and coolant temperature is important in minimizing supercooling which has a negative effect on treatment. For example, our results showed a temperature difference of 10 degrees C for a feed solution temperature of 2.5 degrees C were needed to minimize supercooling. Salt percent removal was found to be directly related to while ice percent recovery was inversely related to the stirring rate. Treatment of an artificial seawater (salinity 35.67 g/L) and a RO brine concentrate (salinity 2600 mg/L) resulted in 51% and 70% ice percent recovery and 74% and 97.7% salt percent removal, respectively. An application of the PFC process includes brine concentrate treatment for inland desalination plants.

This paper presents a thermophysical assessment of the extraordinary 'snow white' dolomitic marble material being used for pavement, wall, and even roofing surfaces within the Al Masjid Al-Haram (i.e., Great Mosque) in Makkah City, Saudi Arabia. Extensive use of this extremely white marble with exterior pavements helps maintain a cool surface which is conducive to the site's religiously obligatory barefoot pedestrian contact. Modelled analysis of this site's expected diurnal marble pavement surface temperature during both summer and winter periods was derived using local seasonal weather data. These results conceptually confirmed this marble's remarkable ability to maintain desirable cool-surface conditions even during peak summertime solar insolation periods. Comparative analyses of surface temperatures and energy transfer were also derived for the same site and weather conditions based on the possible alternative use of conventional paving options (e.g., concrete and asphalt). In this case, modelling results indicated that either of the concrete or asphalt options would have generated far hotter surfaces which would be unacceptable, and perhaps even dangerous for bare skin contact, during summer months. (C) 2021 Published by Elsevier Ltd.

Thermophilic aerobic biological treatment systems have many advantages compared to conventional techniques for high-strength wastewaters, including faster biodegradation rates, greater overall process efficiencies, and low rates of residual biosolids production. High reactor temperatures, however, alter the physical, chemical, and biological characteristics of the treatment process, so that the enormous knowledge-base for conventional activated sludge operations no longer directly applies. Several of these unique operating conditions are discussed. Process kinetics are also examined, with a particular focus on the high rate of endogenous decay typically observed with thermophilic systems.

Thermal conductivity, k, is one of the key factors that control heat transfer in concrete. This paper presents the results of an experimental study conducted to analyze the effects of modern concrete materials, such as supplementary cementitious materials (SCMs), normal-weight, lightweight, and recycled aggregates, and steel and polypropylene (PP) fibers, on the thermal conductivity of concrete. The thermal conductivity tests were performed on cylindrical specimens of concrete mixes containing various amounts of these materials. The results indicate that k values of concrete reduced with the amount of SCM (slag and fly ash) replacement for cement. The mineralogy and absorption of normal weight aggregate considerably affect k value of concrete. Replacing normal weight coarse aggregate by lightweight or recycled aggregate reduced the k value of concrete. Addition of steel fiber at a dosage higher than 0.25% (by volume) increased k value of concrete noticeably, whereas the addition of up to 2% PP fiber showed little effect.

Biological induced calcite precipitation is a potential method being investigated for improved soil stabilization. In terms of the associated urea hydrolysis concept, three main strategies have been developed over the last 2 decades: (1) using live urease-producing bacteria, (2) using plant-extracted urease, and (3) using bacterial-extracted urease. This paper focused on evaluating the comparative benefits of two of these methods (i.e., live bacterial cell or extracted bacterial urease methods for induced calcium precipitation) in terms of their biocementation performance. Cell-based induced carbonate precipitation (ICP) (i.e., MICP) testing was completed on standard Ottawa coarse-grained sand (#20/30), and bacterial-enzyme-based (i.e., BEICP) testing was conducted individually on both coarse-grained and fine-grained (#50/70) sands. Distinctly higher unconfined compressive strength (UCS) was achieved with the BEICP method when evaluated at similar levels of calcium precipitation. Residual permeability levels remained markedly higher after BEICP testing versus MICP. The UCS of BEICP coarse-grained treated sand was approximately 450-1,500 kPa, whereas that of fine-grained treated sand had a notably lower range (i.e., 250-900 kPa) when evaluated at similar levels of CaCO3 production. These results indicate that calcium carbonate content is not the sole factor which impacts the strength of biocemented sand. Additional test-tube investigation of ICP-derived CaCO3 precipitation was used to evaluate the chemical conversion efficiency for each method, i.e., live cells (i.e., Sporosarcina pasteurii) or bacterial-extracted urease. The calcite precipitation ratio declined at higher substrate chemical concentrations. However, this ratio increased with higher rates of enzymatic activity.

AbstractThis paper provides an analytical assessment of the feasibility of wind energy for Saudi Arabia's envisioned NEOM city, which plans to use only renewable energy. A probability density function was fit to winds simulated for the NEOM region during 2014‐2018. Using this distribution, the optimal wind turbine was selected as the one with the largest capacity factor and smallest levelized cost of energy (LCOE). Financial, environmental, and risk analysis of a wind farm consisting of 100 of these units was also performed. A Weibull distribution determined by changing the shape and scale parameters to minimize the mean squared error offered the best fit to the measured wind speeds at this location. The estimated power density showed that the NEOM site warrants a Class 3 classification, which means wind energy systems would be suitable for commercial operation. A 3.2‐MW wind turbine, which is optimal for this location, has a capacity factor varying from 31.9% to 41.4% and LCOE that ranges from 6.99¢ to 8.32¢ per kWh. The 320‐MW wind farm has a positive net present value, a simple payback period of 13.8 years, and a LCOE of 6.6¢ per kWh. By installing this farm, potential annual savings of CO2 are around 106 metric tons.

This technical note examines the splitting tensile strength properties of natural sand treated with polyvinyl acetate (PVA) fiber in combination with biocementation using the microbially induced calcite precipitation (MICP) process. Ottawa 20-30 sand was mixed with PVA fiber at five different fiber ratios (0.0%, 0.2%, 0.4%, 0.6%, and 0.8% by weight) and then stabilized using urease-producing bacteria plus urea and calcium chloride (CaCl2) solutions. Splitting tensile strength was determined for the treated sand samples. The results showed that the splitting tensile strength and splitting secant elastic modulus increased with increasing in either calcium carbonate content or fiber ratio. The use of PVA fibers together with MICP treatment could also increase the failure strain and the postfailure splitting tensile strength.

This paper examines the bio-derived stabilization of sand-only or sand-plus-silt soils using an extracted bacterial enzyme application to achieve induced calcite precipitation (ICP). As compared to conventional microbial induced calcite precipitation (MICP) methods, which use intact bacterial cells, this strategy that uses free urease catalysts to secure bacterial enzyme–induced calcite precipitation (BEICP) appears to offer an improved means of bio-stabilizing silty-sand soils as compared to that of MICP processing. Several benefits may possibly be achieved with this BEICP approach, including bio-safety, environmental, and geotechnical improvements. Notably, the BEICP bio-stabilization results presented in this paper demonstrate (i) higher rates of catalytic urease activity, (ii) a wider range of application with sand-plus-silt soil applications bearing low-plasticity properties, and (iii) the ability to retain higher levels of soil permeability after BEICP processing. Comparative BEICP versus MICP results for sand-only systems are presented, along with BEICP-based results for stabilized soil mixtures at 90:10 and 80:20 percentile sand:silt ratios. This BEICP method’s ability to obtain unconfined compressive strength results in excess of 1000 kPa with sand-plus-silt soil mixtures is particularly noteworthy.

Concrete pavements containing TiO2 can be used for air pollution control by oxidizing NOx under UV-bearing sunlight. This study employed a bench-scale photoreactor to estimate NO oxidation rates for varied environmental conditions. Rates correlated positively with NO inlet concentration and irradiance and negatively with relative humidity. No correlation occurred with flow rate. A decrease in slab moisture (previously unstudied) positively correlated with NO oxidation rate at 0-2% loss of saturated mass, but negatively correlated at losses greater that 2%. Although prior researchers deemed temperature insignificant, data indicated a positive correlation. Overall, rates ranged from 9.8 to 64 nmol.m(-2).s(-1). (C) 2015 Elsevier Ltd. All rights reserved.

This paper summarizes the efforts and the outcomes of a pilot student internship program developed jointly in 2012 by the Iowa Department of Transportation (DOT) and the Institute for Transportation at Iowa State University. In 2012, Iowa was the only state DOT to use federal funds for the internship program, which was initiated as a summer program with 56 interns assigned to DOT offices and projects across the state. The paid internship program was extended into the fall semester with 22 students assigned to offices in Ames, Iowa. The program had engineering and nonengineering positions and was developed to provide experiential learning opportunities, to address Iowa DOT's workforce needs, and to attract undergraduate students to transportation careers. More than 80% of the interns and more than 90% of the supervisors, choosing from multiple choice responses, rated the program outcomes as great or okay. The interns valued opportunities to work in professional settings where they had responsibilities entrusted to them, interactions with other professionals and practitioners, an opportunity to understand real-world application of their course work, and the chance to gain first-hand experience working on transportation projects, as well as to learn about expectations in a professional setting. Supervisors noted the importance of establishing a continuation of the internship and cooperative education programs for future students. Nearly 100% of the interns and fully 100% of the supervisors said that they would recommend the program to students. Because of the student contributions during the internship, Iowa DOT was able to complete many activities that would not have been completed.

Long-duration surface missions to the Moon or Mars will require life support systems that maximize resource recovery to minimize resupply from Earth. To address this need, NASA previously proposed a Series-Bosch (S-Bosch) oxygen recovery system, based on the Bosch process, which can theoretically recover 100% of the oxygen from metabolic carbon dioxide. Bosch processes have the added benefits of the potential to recover oxygen from atmospheric carbon dioxide and the use of regolith materials as catalysts, thereby eliminating the need for catalyst resupply from Earth. In 2012, NASA completed an initial design for an S-Bosch development test stand that incorporates two catalytic reactors in series including a Reverse Water-Gas Shift (RWGS) Reactor and a Carbon Formation Reactor (CFR). In 2013, fabrication of system components, with the exception of a CFR, and assembly of the test stand was initiated. Stand-alone testing of the RWGS reactor was completed to compare performance with design models. Continued testing of Lunar and Martian regolith simulants provided sufficient data to design a CFR intended to utilize these materials as catalysts. Finally, a study was conducted to explore the possibility of producing bricks from spent regolith catalysts. The results of initial demonstration testing of the RWGS reactor, results of continued catalyst performance testing of regolith simulants, and results of brick material properties testing are reported. Additionally, design considerations for a regolith-based CFR are discussed.

Pavements which have been blended, coated, sprayed, etc., with photocatalytic TiO2 additives have attracted world-wide interest during the past decade-plus period based on their environmentally beneficial abilities to provide reactive (i.e., 'smog-eating pavement' plus 'self-cleaning') and reflective (i.e., 'cool pavement') impacts. The former 'reactive' capabilities notably involve a de-polluting property where TiO2 irradiation with UV-A spectrum light is able to oxidatively convert a variety of problematic organic and inorganic pollutants within both atmospheric and aqueous runoff zones. This suite of transportation-generated amenable contaminants notably includes NOX residuals which otherwise represent a serious environmental and human-health challenge within high traffic density, inner-urban highway locations with high-density adjacent resident populations. Multiple laboratory-level photo-reactor studies published over the past several decades have demonstrated this photocatalytic NOX-removal capability, while at the same time scientifically exploring and elucidating key relationships between NOX abatement and various environmental factors (e.g., light wavelength and intensity, ambient relative humidity and surface moisture, pavement temperature, surface soiling impacts, etc.). Field monitoring, albeit in more limited fashion, has provided similarly supportive findings at a number of locations involving not only TiO2-bearing pavements but also locations paved with blocks, pavers, bricks, etc. which have been sprayed or coated with TiO2-enriched admixtures. This chapter, therefore, provides an overview of the related literature covering academic, industrial, patent, and related perspectives and both experimental and full-scale findings. While this existing body of knowledge is substantial, complementary conclusions are also provided regarding recommendations for additional research which appears warranted to pragmatically strengthen the future understanding of TiO2-related pavement performance.

The USEPA's 2010 mercury rule, which would reduce emissions from non-hazardous waste burning cement manufacturing facilities by an estimated 94%, represents a substantial regulatory challenge for the industry. These regulations, based on the performance of facilities that benefit from low concentrations of mercury in their feedstock and fuel inputs (e.g., limestone concentration was less than 25ppb at each facility), will require non-compliant facilities to develop innovative controls. Control development is difficult because each facility's emissions must be assessed and simple correlation to mercury concentrations in limestone or an assumption of ‘typically observed’ mercury concentrations in inputs are unsupported by available data. Furthermore, atmospheric emissions are highly variable due to an internal control mechanism that captures and loops mercury between the high-temperature kiln and low-temperature raw materials mill. Two models have been reported to predict emissions; however, they have not been benchmarked against data from the internal components that capture mercury and do not distinguish between mercury species, which have different sorption and desorption properties. Control strategies include technologies applied from other industries and technologies developed specifically for cement facilities. Reported technologies, listed from highest to lowest anticipated mercury removal, include purge of collected dust or raw meal, changes in feedstocks and fuels, wet scrubbing, cleaning of mercury enriched dust, dry sorbent injection, and dry and semi-dry scrubbing. The effectiveness of these technologies is limited by an inadequate understanding of sorption, desorption, and mercury species involved in internal loop mercury control. To comply with the mercury rule and to improve current mercury control technologies and practices, research is needed to advance fundamental knowledge regarding mercury species sorption and desorption dynamics on materials within cement facilities.