Although the use of pervious concrete is expanding, only a limited number of scholarly papers have been published on the resistance of pervious concrete to deterioration under frost action. Based on this need for additional research on the durability of pervious concrete in cold regions, the objective of this research was to evaluate the resistance of pervious concrete to degradation during freeze-thaw cycling under different soil clogging and water saturation conditions. The laboratory research associated with this project involved three primary measures of pervious concrete performance, including freeze-thaw durability, compressive strength, and permeability. Testing associated with freeze-thaw durability involved two levels of soil clogging, two water saturation conditions, and two curing durations in a full-factorial experimental design. Field testing involved measurements of stiffness, permeability, and compressive strength at a single site in Orem, Utah. The factor of water saturation and the interaction between the factors of curing condition and clogging condition played significant roles in testing throughout the entire course of freeze-thaw testing. Regarding the factor of water saturation, specimens that were completely submerged in water during freeze-thaw testing were damaged at a notably faster rate than those specimens that were tested in a moist but unsaturated condition for both curing conditions. Regarding the interaction between the factors of curing condition and clogging condition, the effect of clogging on the number of freeze-thaw cycles to failure depended upon the curing condition. A comparison of in situ modulus values, core modulus values, and core compressive strengths associated with clogged locations and unclogged locations in the field indicated no significant differences in structural properties in the clogged and unclogged locations. Although the results of this research suggest that pervious concrete similar to that evaluated in this study can be successfully used in cold regions under essentially ideal conditions, further laboratory and field research should be performed to more carefully examine the effect of moisture content on the freeze-thaw durability of moist but unsaturated specimens. Also, given that clogging can reduce the freeze-thaw durability of pervious concrete, the efficacy of maintenance procedures available for cleaning partially clogged pervious concrete slabs should be investigated. Long-term monitoring of and supplementary experimentation on the pervious concrete slab tested in this research should be considered for these purposes. More conclusive data about the performance of pervious concrete in cold regions will be derived from such field tests.

Membrane durability is one of the limiting factors for proton exchange membrane fuel cell (PEMFC) commercialisation by limiting the lifetime of the membrane via electrochemical / mechanical / thermal degradation. Lower internal humidity in the membrane at high temperature ( > 100 °C) and low relative humidity (25-50 %RH) operating conditions leads to increased resistance, lowering of performance and higher degradation rate. One of the promising candidates is composite proton exchange membranes (CPEMs) which have heteropoly acid (HPA) e.g. Phosphotungstic acid (PTA) doped throughout the Nafion® matrix. HPA is primarily responsible for carrying intrinsic water which reduces the external water dependence. The role of relative humidity during membrane casting was studied using surface analysis tools such as Xray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), and Scanning electron microscopy (SEM) / Energy dispersive spectrometer (EDS). Membrane casting at lower relative humidity (30% approx.) results in finer size, and better PTA incorporation in the composite membrane. The effect of increase in PTA concentration in the Nafion matrix was studied with regards to conductivity, performance and durability. In-plane conductivity measurements were performed at 80 oC and 120 oC. During theses measurements, relative humidity was varied from 20% to 100% RH. Membrane conductivity invariably increases on increasing the relative humidity or operating temperature of the cell. Membrane conductivity increases with increasing PTA content from 3% to 25% PTA but never reaches the conductivity of membrane with 0% PTA. Possible explanation might be the role of cesium in PTA stabilisation process. Cesium forms a complex compound with PTA inside host matrix, rendering the PTA incapable of holding water. In plane conductivity measurements only measure surface conductivity, hence another reason might be the existence of a PTA skin on the membrane surface which is not truly representative of the whole membrane. XRD revealed that the structure of the composite membrane changes significantly on addition of PTA. Membrane with 3% PTA has structure similar to Nafion® and does not exhibit the characteristic 25o and 35o 2Ө peaks while membrane with 15% PTA and 25% PTA have strong characteristic PTA peaks. Also the membrane structure with 25% PTA matches well with that of PTA.6H2O. By applying the Scherer formula, PTA particle size was calculated from Full width half maximum (FWHM) studies at 17o 2Ө peak of the membranes. Particles coalesce on increasing the PTA concentration in the membrane leading to larger particles but still all particles were in nanometer range. Also the FWHM of membranes decreased at 17o 2Ө peak on increasing the PTA concentration, leading to higher crystallinity in the membrane. Structure analysis by FTIR indicated increase in PTA signature intensity dips, as the PTA concentration in membrane increases from 0-25%. Also by FTIR studies, it was found that some PTA is lost during the processing step as shown by comparison of as cast and protonated spectra. Possible reasoning might be that some amount of PTA does not gets cesium stabilized which gets leached away during processing. TGA studies were performed which showed no signs of early thermal degradation (temperature > 300 °C); hence the assumption that all membranes are thermally robust for intended fuel cell applications. The membranes with different amounts of PTA were then catalyst coated and tested for 100-hour at open circuit voltage (OCV), 30% RH and 90 oC. By increasing the PTA in the host Nafion® matrix, the percent change in fuel crossover decreases, percent change in ECA increases, cathode fluoride emission rate decreases, and percent change in OCV decreases after the 100 hour test. Possible reasons for decreasing percentage of fuel crossover might be the increased internal humidity of the membrane due to increasing PTA incorporation. It is reported that during higher relative humidity operation, there is decrease in fuel crossover rate. Increasing ECA percentage loss might be due to the fact that HPA in the membrane can get adsorbed on the catalyst sites, rendering the sites inactive for redox reaction. Decrease in cathode fluorine emission rate (FER) might be due to the fact that there is more water available internally in the membrane as compared to Nafion®. It is reported that at higher relative humidity, FER decreases. ECA and crossover both contribute to the OCV losses. Higher component of OCV is crossover loss, which results in mixed potentials. Hence decreasing percentage of crossover might be the reason behind the decreasing OCV loss. Initial performance of fuel cell increases with increasing PTA concentration, but after the 100 hour test, higher PTA membrane exhibited highest performance loss. Increasing initial fuel cell performance can be due to the lowering of resistance due to PTA addition. Increasing ECA losses might be responsible for the increasing performance losses on adding more PTA to host membrane.

The objectives of this research were to evaluate the sensitivity of indirect tensile strength (ITS) test results to stabilizer type, stabilizer concentration, and curing time for multiple clayey soils with varying plasticity indices (PIs), identify cases in which an ITS of 30 psi can be obtained, and create a general linear model that predicts ITS. The scope of work included laboratory testing of three clayey soils sampled from Monticello, Utah; Bloomington, Indiana; and San Antonio, Texas. Each soil was tested using two stabilizers, cement or lime, at three concentrations, and two replicate samples were prepared for each combination. ITS testing was performed on two specimens of each combination at curing times of both 7 days and 28 days, for a total of 72 tests. The procedures outlined in this study include soil characterization, determination of moisture-density relationships, Eades and Grim testing, soil preparation, soil compaction, ITS testing, and statistical analysis. Regarding stabilizer type, treatment with cement consistently yielded higher ITS values than treatment with lime. Regarding stabilization concentration, ITS consistently increased with increasing concentrations of cement for all three soils; however, the effect of lime concentration depended on the PI of the soil, where increasing ITS values were only apparent with higher PI values. Regarding curing time, the ITS values corresponding to 28 days were generally higher than those corresponding to 7 days. Differences in ITS among the soils were largely attributable to differences in PI, which can influence pozzolanic reactivity. A cement or lime concentration that was equal to or 2% above the lime concentration indicated by the Eades and Grim test was typically required for a minimum 28-day ITS value of 30 psi to be attained. For the model developed to predict ITS, the significant predictor variables included PI, stabilizer type, actual stabilizer concentration, and curing time, as well as the two-way interactions between PI and stabilizer type, PI and actual stabilizer concentration, PI and curing time, and stabilizer type and actual stabilizer concentration. Overall, the model has an R2 value of 0.943 and an adjusted R2 value of 0.936. The model is best suited for soils having a fines content greater than 50%, a PI greater than 20, and a soluble sulfate concentration less than 3000 ppm.

Yes / The paper reports an investigation on the mechanical durability of textured thermoplastic surfaces together with their respective wetting properties. A range of laser-induced topographies with different aspect ratios from micro to nanoscale were fabricated on tool steel inserts using an ultrashort pulsed near infrared laser. Then, through micro-injection moulding the topographies were replicated onto polypropylene surfaces and their durability was studied systematically. In particular, the evolution of topographies on textured thermoplastic surfaces together with their wetting properties were investigated after undergoing a controlled mechanical abrasion, i.e. reciprocating dry and wet cleaning cycles. The obtained empirical data was used both to study the effects of cleaning cycles and also to identify cleaning procedures with a minimal impact on textured thermoplastic surfaces and their respective wetting properties. In addition, the use of 3D areal parameters that are standardised and could be obtained readily with any state-of-the-art surface characterisation system are discussed for monitoring the surfaces' functional response. / European Commission H2020 ITN programme “European ESRs Network on Short Pulsed Laser Micro/Nanostructuring of Surfaces for Improved Functional Applications” (Laser4Fun) under the Marie Skłodowska-Curie grant agreement No. 675063 (www.laser4fun.eu) and the UKIERI DST programme “Surface functionalisation for food, packaging, and healthcare applications”. In addition, the work was supported by three other H2020 programmes, i.e. the projects on “Modular laser based additive manufacturing platform for large scale industrial applications” (MAESTRO), “High-Impact Injection Moulding Platform for mass-production of 3D and/or large micro-structured surfaces with Antimicrobial, Self-cleaning, Anti-scratch, Anti-squeak and Aesthetic functionalities” (HIMALAIA) and “Process Fingerprint for Zero-defect Net-shape Micromanufacturing” (MICROMAN).

Yes / The paper reports an investigation on the mechanical durability of textured thermoplastic surfaces together with their respective wetting properties. A range of laser-induced topographies with different aspect ratios from micro to nanoscale were fabricated on tool steel inserts using an ultrashort pulsed near infrared laser. Then, through micro-injection moulding the topographies were replicated onto polypropylene surfaces and their durability was studied systematically. In particular, the evolution of topographies on textured thermoplastic surfaces together with their wetting properties were investigated after undergoing a controlled mechanical abrasion, i.e. reciprocating dry and wet cleaning cycles. The obtained empirical data was used both to study the effects of cleaning cycles and also to identify cleaning procedures with a minimal impact on textured thermoplastic surfaces and their respective wetting properties. In addition, the use of 3D areal parameters that are standardised and could be obtained readily with any state-of-the-art surface characterisation system are discussed for monitoring the surfaces' functional response.

Yes / This paper evaluates the influence of mineral admixtures partially replacing cement, sea sand replacing quartz, sea water replacing fresh water on ultra-high performance concrete (UHPC). The fluidity and mechanical properties were studied. Besides, the impermeability, chloride resistance and freeze-thaw resistance were investigated. Failure modes, scanning electron microscope (SEM) analysis, mass loss, relative dynamic modulus of elasticity and mechanical properties of UHPCs after freeze-thaw cycles were conducted. The results showed the fluidity of UHPC paste gradually increases with the improvement of water-binder ratio. It is recommended that the water-binder ratio of UHPC be set at 0.19. The fluidity also increases with the improvement of the content of slag, fly ash and water reducer, but decreases with the improvement of silica fume content. The flexural and compressive strengths of UHPC enhance with the improvement of the content of silica fume, but reduce with the improvement of the content of fly ash and slag. The UHPCs made of quartz sand, river sand and sea sand, all, achieve a high strength. UHPCs prepared at standard curing conditions, with or without steel fibers, mixed by artificial seawater and made of sea sand, exhibited excellent impermeability and chloride resistance. The frost resistant grade of all UHPC specimens prepared by standard curing are greater than F500 exhibiting excellent freeze-thaw resistance and sustainability.

Traditional mortise and tenon timber frames have been used in modern construction for a substantial period of time with acceptable performance against weather phenomena and other hazards. However, performance criteria for this style of timber framing are not well defined in current codes and standards. To determine performance criteria for free-standing timber frames with knee-braces, three tasks were undertaken: (1) Two timber frame specimens were tested under cyclic loads to determine hysteretic behavior, damage states, and to explore rehabilitation of a damaged member using self-tapping screws. Three damage states for were identified: peg shear, tenon tearout, and post or beam splitting. Self-tapping screws were able to restore the strength of the 2-peg timber frame with the damaged beam, but not the stiffness of the frame. (2) Four timber frame mortise and tenon connection specimens were subjected to damp conditions for six months and then tested under monotonic tensile load to determine the effect of joint details. The results indicated that connection types tested had similar strength and stiffness. (3) Twelve free-standing timber frames with knee braces located at various sites across the United States were tested in the field under impulse loading to determine the fundamental period of vibration and to estimate damping. A relationship between the fundamental period and the mean roof height was fit to the test data using a power-law equation, and three sets of parameters were determined: a lower-bound equation for seismic loads, an upper-bound equation for wind loads, and mean equation for human-induced vibration performance criteria.

Fiber-reinforced polymer (FRP) composite materials have effectively been used in numerous reinforced concrete civil infrastructure strengthening projects. Although a significant body of knowledge has been established for epoxy matrix carbon FRPs and epoxy adhesives, there is still a need to investigate other matrices and adhesive types. One such matrix/adhesive type yet to be heavily researched for infrastructure application is polyurethane. This thesis investigates use of polyurethane matrix carbon fiber composites for strengthening reinforced concrete civil infrastructure. Investigations on mirco- and macro-mechanical composite performance, strengthened member flexural performance, and bond durability under environmental conditioning will be presented. Results indicate that polyurethane carbon composites could potentially be a viable option for strengthening concrete structures.

This research provides the evaluation of the technical measurements of pavement marking materials from a two-year data collection on 2002 National Transportation Product Evaluation Program (NTPEP)?s Mississippi Test Deck from June, 2002 to June 2004. The materials studied in this research were divided into permanent and temporary material groups on two different pavement surfaces ---- asphalt and concrete. The retro reflectivity and durability of permanent marking materials among different surfaces, colors and groups were studied. Also the characteristics for temporary tapes, which include internal tape strength, adhesion, tackiness and dicernablity were compared and regressed. This correlation analysis is to see whether these ratings are correlated to each other. The results of this study can be used for estimating service lives of pavement marking materials. They also can be used by states to select appropriate pavement marking materials for different needs.

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