White cement has currently received increasing attention due to potential for use in sustainable concrete structures. Based on the U.S. Green Building Council certification practice, the LEED Green Building Rating System for New Construction and Major Renovation (LEED-NC) considers that the reflective quality of white surfaces may help to improve lighting efficiency and reduce temperature fluctuations, resulting in lower heating and cooling with reduction of related energy costs. In addition to the environmental impact, white concrete represents a valuable tool for the aesthetic acceptability of a structure, and can also offer important practical benefits in terms of safety (i.e., light reflection in the dark). In this thesis white concrete was combined with off-white rice husk ash and with a glass fibers reinforced polymer to obtain an innovative composite system able to: a) reduce the energy used for the production of the primary materials, b) decrease the temperature fluctuation in the building resulting in less energy needed for heating and cooling, and c) increase the life of the structure and thereby reduce energy usage for material disposal. It is evident that in applications where aesthetics is the driver, a great deal of attention needs to be devoted to the concrete mixture, but also to durability properties. To further improve the durability of white concrete, novel methodologies were introduced to study the corrosion mechanism of steel embedded in concrete and its effect on the color degradation of white surface. This study demonstrates the validity of the sustainable system made by white cement, OWRHA, and GFRP, and of the methodology introduce to evaluate corrosion and color degradation of reinforced concrete.

Les façades des nouveaux bâtiments et des bâtiments existants sont altérées par la pénétration de l'eau. Afin de protéger les bâtiments et surfaces exposées aux intempéries, des traitements contenant des agents hydrophobes doivent être appliqués. Les traitements utilisés à l’heure actuelle sont des traitements de surface qui se dégradent au cours du temps. L'agent hydrophobe, présent en surface, est soumis à des conditions très rudes telles que des rayonnements ultraviolets, de grandes variations de température, de l'abrasion ..., qui réduisent l’efficacité et la durabilité des traitements. La plupart des traitements aujourd'hui disponibles, fournisse une barrière efficace au passage de l’eau à court terme, mais doivent donc être réappliqués régulièrement. Le projet de recherche, présenté ici, traite de la mise en place d'un traitement de masse de matériaux cimentaires utilisés dans la protection de structures (joints, crépi ...). Ce traitement devrait offrir une protection à long terme, mais ne devrait pas modifier de manière significative les propriétés mécaniques des matériaux. Les avantages d'un traitement de masse sont évidents. Seule une petite partie de l'agent hydrophobe est exposée et dégradée par les conditions climatiques et l'abrasion de surface ne porte pas atteinte à l'intégrité du traitement. Une étude fondamentale a été menée afin d'étudier l'influence de l'incorporation d´agents à base de silicium sur les processus d'hydratation des ciments Portland et de comprendre leur mode d'action. Deux agents (alpha,omega dihydroxypolydimethylsiloxane et n-octyltriethoxysilane) et deux ciments Portland (ordinaire et blanc CEM I 42,5N) ont été choisis et étudiés. Trois modes d´introduction (liquides purs, émulsions et granules) ont été mis en œuvre et comparés. Le but est de déterminer les meilleures conditions pour obtenir un traitement efficace et durable tout en préservant les propriétés mécaniques. Les résultats d'absorption d'eau par capillarité et de perméabilité à la vapeur d’eau sont prometteurs et les essais mécaniques sur mortiers n’ont pas montré de diminutions significatives des résistances mécaniques. La microstructure et la progression de l'hydratation des matrices cimentaires adjuvantées et de référence, ont été caractérisées par calorimétrie à conduction, par calorimétrie différentielle à balayage couplée à la thermogravimétrie, par spectroscopie infra-rouge, par diffraction des rayons X, par porosimétrie au mercure, et par microscopie électronique à balayage. La durabilité des matériaux adjuvantés a été étudiée afin de montrer la pertinence des traitements ainsi que l'évaluation de la progression de l'hydratation. Les performances hydrofuges ainsi que l’évolution de la microstructure, à l’issue des différents vieillissements artificiels et naturels, ont été déterminées. Les mortiers mis en œuvre ont été soumis à des vieillissements artificiels simulant des conditions proches de celles rencontrées en pratique (tels que des cycles rayonnements UV, pluie, sel, gel/dégel…). Une amélioration de la durabilité des mortiers adjuvantés a été observée. Les résultats sont très encourageants et confirment l'intérêt d’un tel traitement dans la masse. /Protection of cement-based materials means above all, moisture protection because water is primarily responsible for inducing damaging physical and chemical processes in building materials. In most cases, water repellents are applied either directly during the construction or insulation process; or as a post-treatment of the exposed surfaces in order to protect the buildings from further decay. A new way is to develop a bulk treatment for cement-based materials which should provide a long term protection without modifying the mechanical properties of the cementitious materials. The advantages of a bulk treatment are obvious i.e. only a small part of the hydrophobic agent is exposed and degraded by the UV. In addition, surface abrasion does not affect the integrity of the treatment. A fundamental study was initiated to investigate the influence of the incorporation of two active silicon-based agents (already used as post-building treatments) on the hydration processes of Portland cements and to understand the involved mechanisms of interaction. Two agents (alpha,omega dihydroxypolydimethylsiloxane and n-octyltriethoxysilane) and two Portland cements (Ordinary and White Portland Cement CEM I 42,5N) were chosen and studied. Three incorporation modes (pure liquids, water emulsions and granules) were investigated. The effects of the three modes were compared. The aim was to determine the best conditions for an efficient and sustainable treatment preserving the mechanical properties of the materials. The results of capillary water penetration and water vapor permeability are promising and are not accompanied by a significant decrease of the mechanical performances The microstructure and progression of hydration of admixtured cement pastes were characterized by conduction calorimetry, differential scanning calorimetry, thermo-gravimetry, infra-red spectroscopy, X-ray diffraction, mercury intrusion porosimetry, and scanning electron microscopy. In addition, the durability of water-repellent additives and of the admixtured cement was studied in order to show the relevance of the treatments as well as the assessment of the progression of hydration and the type of products that were developed. Mortar specimens were submitted to artificial ageing cycles such as freeze-thaw cycles, ultraviolet cycles and rain-sun cycles. The general trend is an improvement of the durability of admixtured mortars. The results are very encouraging and confirm the interest of the bulk mortar treatment.

No description available.

The major issue concerns how the different lignosulfonate types changes the rheological properties of the cement based material (concrete, mortar and cement paste) as a function of temperature and time. In such terms, it is demonstrated that the high molecular weight lignosulfonates performs far better than the low molecular weight ones. The former type also performs considerable better compared to a naphthalene based polymer. The above investigation is done with help from the second part of this thesis, which identifies some of the parameters p1, p2,... affecting the shear viscosity η = η ( p1, p2,...) of the cement based material. This is done by investigating the thixotropic behavior of cement paste mixed with either lignosulfonates or naphthalene. The thixotropic behavior is directly related to coagulation, dispersion and re-coagulation of the cement particles. In making the analysis, a modification is applied to the Hattori-Izumi theory, which is a theory about the bookkeeping of the number of reversible coagulated connections between the cement particles. The modification consist, among other things, of include a fading memory to the analysis. That is, the cement paste is allowed to remember its recent past. By a combination of experimental results and numerical simulations, it is demonstrated that such memory term is very important. An experimental error is present during a viscometric measurement on concrete (a coaxial cylinders viscometer is used). The error is generated by particle migration. Investigating and compensating for this error constitutes the third part of this thesis. Realizing the nature of this error, some corrections are applied. However, with these corrections, one is only extracting the viscometric values of a "fat'' concrete that surrounds the inner cylinder of the viscometer after the particle migration is basically complete, and not of the concrete in the original homogenous state.

Saskatchewan Ministry of Highways and Infrastructure (MHI) is responsible for maintaining approximately 26,100 km of two lane equivalent highways network. Most highways in Saskatchewan are constructed primarily of granular materials. Granular materials serve various purposes in a pavement structure. In particular, granular materials distribute stress within the road structure and reduce the stress applied to the subgrade. Granular materials also mitigate pumping of subgrade fines into surfacing materials, as well as provide drainage for the pavement structure.<p>As a result of the rapid deterioration of roadways and the increasing highway traffic, a significant portion of the Saskatchewan highway system is in need of rehabilitation in the next couple of decades. However, increasing costs associated with road construction as well as budget constraints render many conventional rehabilitation solutions untenable in many applications. In addition, the depletion of quality aggregate also exists in many areas of Saskatchewan. Given that much of Saskatchewan granular pavement system will be in need of strengthening in the next few decades, there is a need to apply new cost-effective and aggregate-preserving pavement rehabilitation technologies such as cold in-place recycling and base strengthening.<p>The goal of this research is to improve the engineering design and performance of recycled and stabilized granular base systems under Saskatchewan field state conditions. The specific objectives of this research are to characterize the conventional laboratory behaviour, moisture sensitivity, and mechanistic behaviour of various granular base strengthening systems in the laboratory, to characterize the structural responses of various granular base strengthening systems in the field, and to evaluate the pavement thickness design and responses of various granular base pavement structures.<p>This research is based on a cold in-place recycling and base stabilization project undertaken by Saskatchewan MHI in fall 2006. Control Section (C.S.) 15-11 between km 5.0 and km 8.0 was selected as a typical thin granular pavement under primary weight loadings that required strengthening. Unstabilized granular base, cement stabilized granular base, and cement with asphalt emulsion stabilized granular base were constructed and evaluated in this research. Materials employed on C.S. 15-11 were sampled and prepared for the various laboratory tests performed in this research. Conventional tests performed included sieve analysis, Atterberg limits, sand equivalent, standard proctor compaction, and California bearing ratio strength and swell test. Advanced mechanistic and moisture sensitivity testing included indirect tensile strength, moisture capillary rise and surface conductivity, unconfined compressive strength, and rapid triaxial frequency sweep testing.<p>The cement and cement with emulsion asphalt stabilization of the granular base were found to improve the conventional, mechanical and moisture susceptibility properties of in situ C.S. 15-11 granular base materials. The cement stabilization applied on C.S. 15-11 provided a high degree of improvement relative to the cement with emulsion stabilization. The cement stabilization was found to be relatively easy to apply in construction, whereas the cement with emulsion stabilization was more difficult, particularly due to the problems associated with cold temperatures during late season construction.<p>The rapid triaxial tester (RaTT) was found to be a practical and useful apparatus to characterize the mechanistic constitutive behaviours of granular materials. The C.S. 15- 11 in situ unstabilized base was found to have the poorest mechanistic behaviour among all three granular bases on C.S. 15-11, as expected. Cement stabilization improved the mechanistic behaviour of the in situ material significantly by providing the highest mean dynamic modulus, lowest mean Poissons ratio, lowest mean radial microstrain, and the lowest mean phase angle. The cement with emulsion asphalt stabilization also provided a considerable improvement on mechanistic behaviour of C.S. 15-11 granular base materials. However, the degree of improvement was less than the cement stabilization system.<p>Non-destructive falling weight deflection measurements taken across the field test sections showed that the stabilization systems yielded a significant improvement of primary structural response profiles across the C.S. 15-11 test sections after stabilization. The cement stabilization system was found to yield the most significant structural improvements among all the test sections constructed on the C.S. 15-11. The deflection measurements taken in 2007 after hot mix asphalt paving further identified that the unstabilized system is more sensitive to the freeze-thaw effects relative to cement stabilization and cement with emulsion stabilization systems.<p> This research also showed that the Saskatchewan MHI structural design system is not applicable to the design of stabilized granular base systems. Evaluation of the thickness design for C.S. 15-11 showed the unstabilized and the cement with asphalt emulsion stabilized test section met the criterion of fatigue cracking, but failed to meet the criterion of structural rutting in MHI design system. However, the cement stabilized section met both fatigue cracking and rutting criteria. The structural evaluation revealed that mechanistic pavement response analysis and validation are necessary in the thickness design of stabilized granular systems such as C.S. 15-11, where traditional MHI design system is not applicable. This research employed finite element modeling and linear elastic pavement modeling software to determine the maximum shear stresses within granular base under typical Saskatchewan stress state conditions. The maximum shear stress values were found to locate on top of granular base courses under the applied circular loading edges ranging from 177 kPa to 254 kPa. These maximum shear stresses within the C.S. 15-11 test section granular base courses under field stress states were compared to maximum shear stresses occurring within samples measured by rapid triaxial testing performed in this research. The comparison showed that the ranges of shear stresses applied in the laboratory RaTT testing were close to shear stresses of granular bases in the field computed from modeling. Therefore, this research showed a good correlation of lab RaTT testing and field results for granular pavements.<p>In summary, this research met the objectives of mechanistically evaluating various granular base stabilization systems in Saskatchewan by means of various laboratory testing, non-destructive field testing, as well as mechanistic modeling and analysis. This research provided valuable data and showed considerable potential for improving design, construction, and QA/QC of conventional and stabilized granular base systems in Saskatchewan.

The influence of supplementary materials such as slag, metakaolin and limestone in steam-cured ternary and quaternary cement blends on physical and chemical hydration mechanisms was studied by analyzing the evolution of non-evaporable water content, hydration products and compressive strength. The role of limestone in hydration reactions of cement was also investigated. These properties were studied through the use of differential thermal and thermogravimetric analyses, as well as the loss-on-ignition, X-ray diffraction and compressive strength tests at 1, 3, 7, and 28 days. Research findings revealed that it is possible to replace up to 40% cement with other materials and still achieve compressive strengths similar to mixtures with a 25% cement replacement at 0.34 w/b ratio. Additionally, ternary limestone mixtures exhibited superior mechanical properties to ternary metakaolin mixtures. Lastly, limestone powder was determined to behave as inert filler, accelerating hydration at early ages through heterogeneous nucleation.

The influence of supplementary materials such as slag, metakaolin and limestone in steam-cured ternary and quaternary cement blends on physical and chemical hydration mechanisms was studied by analyzing the evolution of non-evaporable water content, hydration products and compressive strength. The role of limestone in hydration reactions of cement was also investigated. These properties were studied through the use of differential thermal and thermogravimetric analyses, as well as the loss-on-ignition, X-ray diffraction and compressive strength tests at 1, 3, 7, and 28 days. Research findings revealed that it is possible to replace up to 40% cement with other materials and still achieve compressive strengths similar to mixtures with a 25% cement replacement at 0.34 w/b ratio. Additionally, ternary limestone mixtures exhibited superior mechanical properties to ternary metakaolin mixtures. Lastly, limestone powder was determined to behave as inert filler, accelerating hydration at early ages through heterogeneous nucleation.

Down-hole damages such as borehole collapse, circulation loss and rock tensile/compressive cracking in the open-hole system are well understood at drilling and well completion stages. However, less effort has been made to understand the instability of cemented sections in High Pressure High Temperature (HPHT) wells. The existing analysis shows that, in the perforation zones, casing/cement is subject to instability, particularly in the presence of cavities. This dissertation focuses on the instability mechanism of casing/cement in the non-perforated zones. We investigate the transient thermal behavior in the casing-cement-formation system resulting from the movement of wellbore fluid using finite element method. The critical value of down-hole stresses is identified in both wellbore heating and cooling effects. Differently with the heating effect, the strong cooling effect in a cased hole can produce significant tension inside casing/cement. The confining formation has an obvious influence on the stability of casing/cement. The proposed results reveal that the casing/cement system in the non-homogeneous formation behaves differently from that in homogeneous formation. With this in mind, a three-dimensional layered finite element model is developed to illustrate the casing/cement mechanical behavior in the non-homogeneous formation. The radial stress of cement sheath is found to be highly variable and affected by the contrast in Young’s moduli in the different formation layers. The maximum stress is predicted to concentrate in the casing-cement system confined by the sandstone. Casing wear in the cased-hole system causes significant casing strength reduction, possibly resulting in the casing-cement tangential collapse. In this study, an approach for calculating the stress concentration in the worn casing with considering temperature change is developed, based on boundary superposition. The numerical results indicate that the casing-cement system after casing wear will suffer from severe tangential instability due to the elevated compressive hoop stress. Gas migration during the cementing process results from the fluid cement’s inability to balance formation pore pressure. Past experience emphasized the application of chemical additives to reduce or control gas migration during the cementing process. This report presents the thermal and mechanical behaviors in a cased hole caused by created gas channels after gas migration. In conclusion, the size and the number of gas channels are two important factors in determining mechanical instability in a casing-cement system.

The production of multi-component cement from clinker and two additives such as trass and blast furnace slag has now spread throughout the world. These additives are generally interground with clinker to produce a composite cement of specified surface area. The grinding stage is of great importance as it accounts for a major portion of the total energy consumed in cement production and also as it affects the quality of composite cements by the particle size distribution of the individual additives produced during grinding. This thesis study was undertaken to characterize the breakage properties of clinker and the additives trass and slag with the intention of delineating their grinding properties in separate and intergrinding modes. Single particle breakage tests were conducted by means of a drop weight tester in order to define an inherent grindability for the clinker and trass samples in terms of the median product size ( ). In addition, a back-calculation procedure was applied to obtain the breakage rate parameters ( ) of perfect mixing ball mill model using industrial data from a cement plant. Kinetic and locked-cycle grinding tests were performed in a standard Bond mill to determine breakage rates and distribution functions for clinker, trass and slag. Bond work indices of these cement components and of their binary and ternary mixtures were determined and compared. Attempts were made to use back-calculated grinding rate parameters to simulate the Bond grindability test. The self-similarity law was proved to be true for clinker and trass that their shapes of the self-similarity curves are unique to the feed material and independent of the grinding energy expended and overall fineness attained. The self-similar behaviour of tested materials will enable process engineers to get useful information about inherent grindability and energy consumption in any stage of the comminution process. The parameters, and indicating the degree of size reduction were defined with different theoretical approaches as a function of energy consumption by using single particle breakage test data of clinker and trass. The breakage distribution functions were found to be non-normalizable. On the other hand, the breakage rate functions were found to be constant with respect to time but variable with respect to changing composition in the Bond ball mill. These variations are critical in computer simulation of any test aiming to minimize the experimental efforts of the standard procedure. As a result of the back calculation of breakage rate parameters for clinker and trass samples in the Bond mill, no common pattern was seen for the variation of the rate parameters. Therefore, computer simulation of the Bond grindability test did not result in an accurate estimation of the Bond work index.

Asphalt and Portland cement concrete constitutes a significant portion of the total infrastructure all over the world. It has been reported that much of this concrete infrastructure is now approaching or has already passed its original design life. Thus it is critical to be able to quantitatively assess the condition of these concrete components. In order to rehabilitate or repair the civil infrastructure, nondestructive evaluation (NDE) techniques have been of great interest for infrastructure management agencies. However concrete components present several specific NDE challenges that must be addressed. . Concrete naturally exhibits large scale heterogeneous microstructure with a great deal of local material property variability, For this reasons, many conventional NDE techniques that work well for steel and other homogeneous materials cannot be applied to concrete; concrete is unable to transmit high frequencies, as the heterogeneity of the concrete causes signals of smaller wavelengths or wavelengths equal to the nominal aggregate size to be scattered and severely attenuated. Nevertheless, progress has been made towards accurate and reliable in-place NDE of concrete structures and materials, for example impact echo, ultrasonic pulse velocity method, and the ultrasonic wave transmission method. However, the detection of smaller sized defects or remote defects that are located away from the testing location still pose problems. In addition, the large size and potential limited access conditions of civil structures raise additional challenges. To overcome the limitations of current NDE techniques for concrete, this research considers two different types of ultrasonic waves (coherent and incoherent wave) to quantitatively characterize and monitor defects in heterogeneous concrete materials. The global objective of this research is to determine the feasibility and applicability of using these ultrasonic waves as a global, rapid, reliable, and non-biased technique for the routine screening of defects or monitoring of concrete structures and materials. Three different problems are considered: 1) characterization of segregation in asphaltic concrete, 2) crack depth determination in pier cap of concrete bridge structure, and 3) monitoring of self-healing process in cement-based concrete.