No description available.

The use of recycled concrete material (RCM) as pavement base material is a promising but unproven technique for road rehabilitation and construction. A telephone survey conducted to investigate the state of the practice concerning RCM usage in Utah County revealed that RCM is infrequently used in this application due primarily to a lack of practical knowledge about the engineering properties of the material. Therefore, this research was aimed at evaluating the physical properties, strength parameters, and durability characteristics of both demolition and haul-back sources of RCM available in Utah County for use as pavement base material. The study included extensive laboratory and field testing. Laboratory tests included California bearing ratio (CBR), unconfined compressive strength (UCS), stiffness, freeze-thaw cycling, moisture susceptibility, abrasion, salinity, and alkalinity evaluations. Non-destructive testing was utilized in the field to monitor seasonal variation in stiffness of an RCM pavement base layer over a 1-year period. The testing included a dynamic cone penetrometer, ground-penetrating radar, a heavy Clegg impact soil tester, a soil stiffness gauge, and a portable falling-weight deflectometer. The laboratory testing indicated that the demolition material exhibited lower strength and stiffness than the haul-back material and reduced UCS loss after freeze-thaw cycling. However, the demolition material received a moisture susceptibility rating of good in the tube suction test, while the haul-back material was rated as marginal. Both materials exhibited self-cementing effects that led to approximately 180 percent increases in UCS over a 7-day curing period. Seven-day UCS values were 1260 kPa and 1820 kPa for the demolition and haul-back materials, respectively, and corresponding CBR values were 22 and 55. The field monitoring demonstrated that the RCM base layer was susceptible to stiffness changes due primarily to changes in moisture. In its saturated state during spring testing, the site experienced CBR and stiffness losses of up to 60 percent compared to summer-time values. RCM compares well with typical pavement base materials in many respects. Given the laboratory and field data developed in this research, engineers should be able to estimate the strength and durability parameters of RCM needed for pavement design.

The objective of this research was to investigate emulsion-treated base (ETB) frost susceptibility in terms of both freeze-thaw cycling and frost heave. The research performed in this study involved laboratory testing of ETB materials sampled from both the Redwood Road and 7800 South reconstruction projects in northern Utah. The effects of freeze-thaw cycling were evaluated by comparing the stiffness and strength of tested specimens to the same properties of control specimens not subjected to freeze-thaw cycling. Frost heave testing enabled evaluation of the effects of emulsion content and degree of curing on the volumetric stability of ETB materials during sustained freezing. Since permeability affects the frost susceptibility of a material, samples were also prepared to specifically evaluate the effect of curing condition on the permeability of the two base materials when treated with emulsion. The results of freeze-thaw testing showed that both the Redwood Road and 7800 South specimens experienced decreases in modulus as a result of freeze-thaw damage. The results also showed that the Redwood Road specimens experienced substantial decreases in strength as a result of freeze-thaw damage. The specimens from 7800 South did not exhibit such strength loss; since those specimens initially had much lower modulus and unconfined compressive strength values than the Redwood Road specimens, they were less susceptible to stiffness and strength loss during the freeze-thaw test. Results for the frost heave tests showed that the untreated base materials were not susceptible to frost heave and that the addition of emulsion, with or without curing, did not change the frost heave behavior in a practically important way. While susceptibility to frost heave is not expected to be a problem with these base materials, the laboratory results revealed a significant increase in the permeability of the ETB specimens after curing, which could facilitate greater freeze-thaw damage. In consideration of these research results, engineers should ensure proper material sampling and laboratory testing to assess the efficacy of emulsion treatment for a given project. ETB to be constructed in cold regions should be subjected to freeze-thaw testing during the design phase, and designers should be aware that curing of the ETB may dramatically increase permeability and therefore increase frost susceptibility.

No description available.

Roads are subjected to mechanical loads from the traffic as well as deteriorating mechanisms originating from the surrounding environment and climate. The damage arising is particularly severe during the winter season, when for example raveling, pot holes and cracks can emerge on the surfaces of asphaltic roads. These winter related damages are difficult to characterize and predict, partly due to the complexity of the asphalt material and partly since they cannot be linked to one single phenomenon but several, such as the (long term) existence of moisture, frost damage and frost heave, low temperature cracking and the embrittlement of the mastic at low temperatures. Further adding to the complexity is the combination of these phenomena which may accelerate the emergence and evolution of the damage mechanisms. This licentiate research project is mainly focusing on the emergence and development of frost damage in the asphalt layer but will include the effect of other damage mechanisms in its continuation. The goal of the project is to develop a multiscale model able to predict the damage development in an asphalt pavement during a desired period of time, to enhance maintenance predictions as well as pavement design choices. This licentiate thesis is the first part of this project and aims to lay the foundation of the multiscale model. To achieve this, a micromechanical model of frost damage in asphalt mixtures has been developed. This model couples the moisture and mechanical damage happening on the short and long term, caused by the infiltration of moisture and the expansion of water turning into ice during temperature drops. Both possible adhesive damage in the mastic-aggregate interface and cohesive damage in the mastic is included. In addition to the developed micromechanical model, this thesis presents the overall concept for the formulation of the multiscale model as well as discusses about its motivations and advantages. / Vägar utsätts både för mekaniska laster från trafiken som kör på vägen samt för nedbrytande mekanismer härstammande från den omgivande miljön och klimatet. Skadorna som uppstår är särskilt stora under vintern, då till exempel stensläpp, potthål och sprickor kan uppstå på ytan av asfalterade vägar. Dessa vinterrelaterade skador är svåra att karakterisera och förutsäga, delvis på grund av det komplexa beteendet hos asfalt och delvis eftersom de inte härstammar från enbart ett fenomen utan flera, såsom existensen av fukt i asfalten (på lång sikt), frostskador, tjällyft, sprickbildning på grund av låg temperatur samt försprödningen av asfalt som sker vid låga temperaturer. Vidare påverkar dessa skademekanismer varandra vilket kan accelerera skadebildningen och utvecklingen, vilket ytterligare ökar komplexiteten. Detta licentiatforskningsprojekt fokuserar till största delen på uppkomsten och utvecklingen av frostskador men kommer även inkludera effekten av andra skademekanismer i dess fortsättning. Målet med detta forskningsprojekt är att utveckla en multiskalemodell som kan förutspå skadeutvecklingen i en asfaltsväg under en önskad tidsperiod, för att förbättra både underhållsprognoser samt designval. Denna licentiatuppsats är den första delen i detta projekt och syftar till att lägga grunden till multiskalemodellen. För att uppnå detta har en mikromekanisk modell av frostskador i asfalt utvecklats. Denna modell kopplar ihop fuktskadan och den mekaniska skadan som sker både på kort och lång sikt, orsakad av infiltrationen av fukt och expansionen av vatten som omvandlas till is vid sjunkande temperatur. Modellen inkluderar de möjliga skadorna som uppstår i både mastics och gränsskiktet mellan mastics och stenmaterialet. Utöver den utvecklade mikromekaniska modellen presenterar denna uppsats det övergripande konceptet för formuleringen av multiskalemodellen samt diskuterar dess motivering och fördelar. / <p>QC20190515</p>

<p>Aging public infrastructure in North America continues to challenge engineers and scientists to develop repair and rehabilitation strategies that are practical, durable and cost effective. Of specific interest is the state of concrete and concrete repair in buildings and civil engineering infrastructures that are in deteriorating condition. In particular, cracks pose a threat to the durability and ultimately the structural integrity of concrete. Cracks in concrete may form for several reasons, e.g. plastic shrinkage, thermal contraction, mechanical loading or as a result of overloading. Once formed, cracks present a combination of problems to the service life and performance of the structure. Therefore cracks must be repaired for the following reasons: to prevent the ingress of deleterious agents such as water, other liquids, vapour, gas, chemicals and biological agents; to either restore or increase the structural load-bearing capacity of the cracked concrete member; to restore the aesthetic condition of the structure.</p> <p>The effectiveness of two different repair methods, crack injections and cementitious overlays, were examined. Two repair materials, a low viscosity epoxy and polyurethane were injected into the cracks, and a thin polymer-modified cementious overlay was applied on the cracked surface. Two types of cement were used, an ordinary Portland cement and a blended cement with 8% silica fume. The specimen properties were evaluated using non-destructive testing, prior to being subjected to a series of freeze-thaw conditioning regimes. From the experimental program, it was determined that the epoxy injection repair was more effective in restoring the air tightness than the thin overlay. The polyurethane material was unsuccessful. Following the freeze-thaw regimes, an overall improvement of conditions for all three repairs was observed, with the cementitious overlay seeing the greatest improvement in air tightness. These results indicate that the on-going cement hydration mechanism had a greater effect on the performance in comparison to the deleterious effects of the environmental loads.</p> / Master of Applied Science (MASc)

For repairing concrete transportation infrastructure, such as pavements and bridges, much importance is placed on early-age strength gain as this has a major impact on scheduling and opening to traffic. However, the long-term performance and durability of such repair materials are often not satisfactory, thus resulting in future repairs. This research project focuses on the evaluation of the durability of various rapid-setting cementitious materials. The binders studied in this project include calcium aluminate cement (CAC), calcium sulfoaluminate cement (CSA), Type III portland cement, alkali-activated fly ash (AAFA) , and various prepackaged concrete materials. In addition, selected CAC and CSA mixtures were further modified with the use of a styrene-butadiene latex. The durability aspects studied include freezing-and-thawing damage and the implications of air entrainment in these systems, alkali-silica reaction, sulfate attack, and permeability of the concrete matrix and potential corrosion. / text

Thermal resistance per unit thickness for Vacuum Insulation Panel (VIP) is 5 to 10 times higher than conventional insulation materials. This makes VIP an attractive option for retrofitting exterior building envelopes. Insulation can be added in an exterior wall either on the interior side, exterior side or in the available stud cavity. VIP has high vapor diffusion resistance factor and could lead to moisture management risk in the wall layers because of the steep temperature gradient in the wall generated due to very high thermal resistance of VIP. VIP is a relatively new insulation material for building envelope construction, thus the hygrothermal or moisture management performance of VIP-insulated exterior building envelopes need to be critically analyzed before its application. This study aims to evaluate the moisture management risk associated with wood-frame stucco-cladded exterior walls retrofitted with VIP using a 2-D hygrothermal simulation tool WUFI-2D. Eight North American locations were considered, based on Moisture Index (MI) which varied between 0.13 and 1.17, and two different indoor hygrothermal loading conditions as prescribed by the ASHRAE 160P and EN 13788, respectively. The outputs from hygrothermal simulations (water content, relative humidity and temperature) were critically analysed and expressed further using freeze-thaw cycles and RHT indices. The results show that the appropriately designed VIP retrofitted walls can have superior moisture management performance as compared to conventional stucco-cladded wall. / Graduate

La modélisation numérique du comportement des matériaux cimentaires sous l’action des sollicitations complexes constitue un point de vue alternatif pour identifier et évaluer les mécanismes internes qui ne peuvent être étudiés directement à travers les essais expérimentaux. A cet effet, le développement des outils de modélisation permettant la prise en compte des interactions entre la microstructure hétérogène de la pâte de ciment et le comportement macroscopique des matériaux cimentaires est fortement apprécié. Une telle approche numérique donne une meilleure description des processus physiques et évite la calibration répétitive des paramètres lorsque la microstructure change.Ce travail de thèse a pour objet de mettre au point une approche de modélisation de l’endommagement des matériaux cimentaires compte tenu des mécanismes physiques qui se produisent à l’échelle microscopique. Dans l’approche proposée, les principes de la construction d’une microstructure virtuelle de la pâte de ciment sont présentés et les paramètres micromécaniques des phases cimentaires sont identifiés. La capacité prédictive de l’approche est testée en comparant les résultats numériques aux résultats des essais expérimentaux réalisés dans ce travail et aux résultats tirés de la littérature. L’application de cette approche est ensuite illustrée à travers des simulations de la pâte de ciment sous fluage et cycles de gel-dégel. Cette approche ouvre la voie à une multitude d’applications, comme l’étude de l’effet du retrait, du fluage, des cycles de gel-dégel, de la fissuration thermique, de l’auto-cicatrisation et de la carbonatation sur les propriétés thermomécaniques des matériaux cimentaires. / Numerical modelling of the constitutivebehaviour of cementitious materials exposed to aggressive environment offers an alternative point of view for the identification and assessment of internal mechanisms which cannot be explicitly explored using standard experimental techniques. In this regard, the development of advanced modelling tools that take into account the interactions between the heterogeneous microstructure of cement paste and the macroscopic behaviour cementitious materials is highly valued. Such modelling approaches give a much better description of the physical processes and avoid recurrent parameter calibration when dealing with a different microstructure.The work presented in this PhD thesis proposes a numerical modelling approach of damage in cement based materials taking heed of the physical mechanics that can only be characterized at the microscopic level. In the proposed approach, the principles of constructing a virtual microstructure of cement paste are laid out and the micromechanical parameters of cement phases are identified. The predictive capacity of the micromechanical approach is put to the test by a comparison of numerical results with experimental data determined in the present study and found in the literature. Finally, the power of the approach is illustrated through simulations of creep and freeze-thaw behaviour at the microscopic scale of cement paste.This approach paves the way for a multitude of applications, such as the study of the effect of shrinkage, creep, freeze-thaw cycles, thermal cracking, self-healing and carbonation on the thermomechanical properties of cement-based materials.

The introduction of the use of Tire Pressure Control Systems (TPCS) to improve the productivity of the Canadian trucking industry is gaining momentum. The imposition of seasonal load restrictions (SLR) on the thaw-weakened secondary roads interrupts the transportation of raw materials to processing facilities For the forestry industry in particular, this has very significant impacts on productivity and costs. FPInnovations-Feric Division (Feric) has investigated the potential for TPCS-equipped trucks to travel with full, legal loading during the SLR period without accelerating road wear and tear. The TPCS monitors and adjusts the inflation pressure of the trucks’ tires while driving and allows the operator to optimize the inflations for changes in loading, travel speed, or road quality encountered in the trip. This thesis describes an investigation to determine whether TPCS can be used to mitigate traffic generated damage to secondary roads and also reduce the need to implement load restrictions. The project involves a partnership with the Ontario Ministry of Transportation Ontario (MTO), Forest Engineering Research Institute of Canada (FERIC), Ontario Ministry of Natural Resources (MNR) and the Centre for Pavement and Transportation Technology (CPATT) located at the University of Waterloo. The thesis will describe the methodology, design, and instrumentation of the two test sites which are located in Dryden, Ontario and Chapleau, Ontario. In addition, repeated Portable Falling Weight Deflectometer (PFWD) testing is being carried out at these sites and the initial results of this examination and associated impacts of the environment and traffic on the road will be presented. This study also involves looking into the reliability of using the portable FWD, offering a lower cost alternative instead of the trailer mounted FWD to monitor pavement strength for the identification the SLR period. The use of innovative sensors and data collection techniques are proving to be very informative and are advancing pavement engineering knowledge. Moreover, the thesis is aimed at exploring the possibilities of achieving the current objectives of the government DOTs such as TPCS potential for addressing the timber industry in crisis, reduced road maintenance budgets, and global warming increasing road damage.