<p dir="ltr">Cold mix asphalt (CMA) is an eco-friendly paving material produced at ambient temperatures, offering energy savings by requiring less energy to decrease asphalt binder viscosity. This technology eliminates the need for heating during the mixing and compaction processes, further magnifying its economic benefits when used as a cold-in-place recycling technique. Unlike hot mix asphalts that gain strength through cooling, CMA achieves its final strength through a curing process involving the evaporation of volatiles and the hardening of the emulsified asphalt binder over time. However, its reliance on a curing process for strength development raises concerns about its short-term performance.</p><p dir="ltr">A typical CMA mixture consists of four main components: air voids, mineral aggregate, water, and asphalt droplets suspended in water. The presence of water can significantly influence the overall performance of the mixture under both traffic and environmental loads. Most existing studies on CMA have predominantly focused on the behavior of the mixtures after they have fully cured. However, in real-world scenarios, pavements are often subjected to various stresses during the curing process, which takes up to several months. As a result, premature distress can compromise the early performance of the pavement. Asphalt undergoes significant chemical and physical changes throughout this phase that can influence its final characteristics and in-situ performance. Overlooking this crucial stage can lead to a poor understanding of the material's capabilities and limitations. Despite the importance of this phase, the micromechanical and rheological behaviors of CMA during curing remain largely uncharted territories. Therefore, this dissertation aims to investigate the micromechanical performance of CMA during the curing phase.</p><p dir="ltr">This research study was performed in two study scales: Mastic and Mixture. The first scale focused on the rheological performance of emulsified-cold asphalt mastic (ECAM), considering varying curing levels, different filler-binder ratios, and filler surface treatments. Comprehensive rheological tests, including frequency sweep, temperature sweep, and strain sweep tests, were conducted on fully and partially cured mastic samples, i.e., 20%, 40%, 60%, and 80%, across a wide range of test temperatures. To analyze the physio-chemical adhesion properties between filler and emulsified asphalt, an analytical tool named the “asphalt-filler interaction” theory was formulated to determine the adhesion bond between filler and binder in the presence of moisture. Microscopic images were also captured to analyze the micro-structure and moisture interaction in the CMA’s matrix. Moreover, the presence of moisture in the CMA brings up another complexity during curing time: The water-to-ice phase transition. Normal Force (Nf) was used as a novel measurement parameter to determine water-ice phase transition effects on the rheological study of emulsified mastic. In the mixture scale, mechanical tests were performed on specimens fabricated with two gradations at fully and uncured CMA samples. The mixture experimental tests included the dynamic modulus test, Illinois flexibility index test, Hamburg wheel loaded test, and disc-shaped compact tension test.</p><p dir="ltr">This dissertation presents a thorough analysis and detailed findings that illuminate the complex relationships and behaviors of CMA, particularly at the mastic scale. A significant observation is the direct influence of the filler-to-binder ratio on the curing time; increasing this ratio prolongs the curing process while using a filler with less surface area accelerates it. Notably, 25% of the filler-to-binder ratio enhances the rheological properties of ECAM, particularly at lower loading frequencies. This study further pinpoints the 60% curing level as a crucial threshold in the CMA curing process. Below this, moisture's effect on rheological performance overshadows that of the primary asphalt material, leading to brittle characteristics in freezing conditions and viscous behavior at intermediate temperatures. In the curing stage, the trapped and blocked waters that emerge during the coalescence phase of the emulsified asphalt breaking contribute to the extended curing time of ECAM.</p><p dir="ltr">Additionally, freezing temperatures yield a water-to-ice phase change in uncured ECAM, resulting in a brittle behavior. Interestingly, a direct correlation emerges between curing percentage and freezing point; higher curing percentages relate to lower freezing points. Another significant discovery is the appearance of micropores in fully-cured ECAM, likely due to water evaporation and emulsifier presence, which potentially compromises its performance compared to ECAM fabricated with residual asphalt binder. Furthermore, adjusting the pH, especially by treating limestone filler with hydrochloric acid (HCl), showed noticeable improvements in CMA’s rheological behavior. At the mixture scale, the CMA mixture contained a higher filler-binder ratio in the mixture scale, presenting a better viscoelastic performance and higher cracking resistance at intermediate and freezing temperatures. Moreover, a minimum amount of water, 2.5% by total mass, added to the CMA mixture is essential to ensure adequate mixability, workability, and compactibility. Viscoelastic analysis showed that the curing process changes the transition point from elastic to viscous behavior of CMA mixtures. This shift towards lower frequencies results in a CMA mixture with poor resistance to higher temperature performance.</p>

Dans un contexte politique où les enjeux énergétiques et environnementaux sont de plus en plus importants, il faut favoriser les techniques économes en énergie et plus respectueuse de l'environnement. Parmi ces pratiques, l'utilisation d’enrobés à l’émulsion de bitume s'est révélée être prometteuse. La fabrication et la conception d’une chaussée comprenant une couche d’enrobé à l’émulsion sont très empiriques et reposent sur des compétences locales qui tendent à en limiter le développement. La première étape pour concevoir une chaussée consiste à connaître le comportement mécanique réversible engendrées par de lourd trafic de chaque matériau qui la compose. Lors d'une deuxième étape, ces valeurs doivent être comparées aux critères de durabilité mécanique des matériaux. Dans le cas de l'enrobé à l’émulsion, aucune loi de comportement mécanique n'a été établie pour tenir compte à la fois de son états frais et durcis. Ce travail de thèse vise donc à pallier à ce manque et à améliorer les connaissances acquises sur ce matériau. Pour cela, un modèle évolutif pour l’enrobé à l’émulsion intégrant l'évolution du matériau de son état frais à l'état durci a été développé. De plus, un nouvel essai de caractérisation a été développé et mis en place pour permettre de suivre l’évolution des performances mécaniques réversibles du matériau. Les résultats obtenus à partir des différentes campagnes d’essais ont permis de caler le modèle et de montrer la pertinence du modèle. / Given a political context in which energy and environmental stakes have become increasingly dominant, road engineering practices have favoured saving energy and protecting the environment. Among these practices, the use of cold mixes treated with bitumen emulsion has proven to be a suitable technique. Cold mix design however, as well as the design of pavements including cold mix asphalt layers, is highly empirical and based on local skills. From prior experience, the transposition of established local rules from one site to another and their application to medium or heavy traffic pavements are not simple steps and tend to limit the development of this environmentally-friendly pavement technique. The first step in designing a pavement consists of knowing the stress-strain relationship of its constitutive materials in order to determine the stresses and strains generated by heavy lorry traffic. During a second step, these values must be compared with the mechanical durability of materials by reliance on damage tests comprising large numbers of load cycles. In the case of CMA, no mechanical behaviour law has been established to take into account both the fresh and cured states. This work aims to improve the knowledge acquired on this material. For this, an evolutiv model for the cold mix asphalt with bitumen emulsion incorporating the evolution of the material from its fresh state to its cured state has been developed. In addition, a new characterization test was developed and put in place to monitor the evolution of the reversible mechanical performance of the material. The results obtained from the test campaigns helped to calibrate the model and show the relevance of the model.

Made available in DSpace on 2014-12-17T15:01:55Z (GMT). No. of bitstreams: 1 CristianKML_TESE.pdf: 2781872 bytes, checksum: b802df1c9b2c68b6ef21241e1bb5281e (MD5) Previous issue date: 2012-08-03 / The main objective of this research was the development and characterization of conventional and modified cationic asphalt emulsions. The asphalt emulsions were developed by using the Petroleum Asphalt Cement (CAP 50-70) from Fazenda Bel?m (Petrobras -Aracati-Ce). The first step in this research was the development of the oil phase (asphalt + solvent) and the aqueous phase (water + emulsifying agent + acid + additives), separately. During the experiments for the obtaining of the conventional asphalt emulsion, the concentration of each constituent was evaluated. For the obtaining of the oil phase, kerosene was used as solvent at 15 and 20 wt.%. For the development of the aqueous phase, the emulsifying agent was used at 0.3 and 3.0 wt.%, whereas the acid and the additive were set at 0.3 wt.%. The percentage of asphalt in the asphalt emulsion was varied in 50, 55, and 60 wt.% and the heating temperature was set at 120 ?C. The aqueous phase in the asphalt emulsion was varied from 16.4 to 34.1 wt.% and the heating temperature was set at 60 ?C. After the obtaining of the oil and the aqueous phases, they were added at a colloidal mill, remaining under constant stirring and heating during 15 minutes. Each asphalt emulsion was evaluated considering: sieve analysis, Saybolt Furol viscosity, pH determination, settlement and storage stability, residue by evaporation, and penetration of residue. After the characterization of conventional emulsions, it was chosen the one that presented all properties in accordance with Brazilian specifications (DNER-EM 369/97). This emulsion was used for the development of all modified asphalt emulsions. Three polymeric industrial residues were used as modifier agents: one from a clothing button industry (cutouts of clothing buttons) and two from a footwear industry (cutouts of sandals and tennis shoes soles), all industries located at Rio Grande do Norte State (Brazil).The polymeric residues were added into the asphalt emulsion (1 to 6 wt.%) and the same characterization rehearsals were accomplished. After characterization, it were developed the cold-mix asphalts. It was used the Marshall mix design. For cold-mix asphalt using the conventional emulsion, it was used 5, 6 and 7 wt.% asphalt emulsion. The conventional mixtures presented stability values according Brazilian specification (DNER-369/97). For mixtures containing asphalt modified emulsions, it was observed that the best results were obtained with emulsions modified by button residue / Neste trabalho desenvolveu-se e caracterizou-se emuls?es asf?lticas cati?nicas convencionais e modificadas. As emuls?es asf?lticas convencionais foram obtidas utilizandose como mat?ria-prima o Cimento Asf?ltico de Petr?leo (CAP 50-70), oriundo da Fazenda Bel?m (PETROBRAS-Aracati-CE), cedido pela LUBNOR-Lubrificantes e Derivados de Petr?leo do Nordeste (Fortaleza-CE). A pesquisa foi iniciada com o desenvolvimento da fase ?leo (asfalto + solvente) e da fase aquosa (?gua + emulsificante + ?cido + aditivo), separadamente. Para a obten??o da emuls?o asf?ltica convencional, a concentra??o de cada constituinte foi avaliada. Para a fase ?leo, o asfalto foi utilizado nas concentra??es de 50, 55 e 60 %, e o solvente (querosene) nas concentra??es de 15 e 20 %. A temperatura de aquecimento desta fase foi de 120 ?C. Para o desenvolvimento da fase aquosa, o emulsificante foi utilizado nas concentra??es de 0,3 e 3,0 %, enquanto que o ?cido e o aditivo foram utilizados apenas na concentra??o de 0,3 %. A concentra??o de ?gua variou de 16,4 a 34,1 % e a temperatura de aquecimento da fase aquosa foi de 60 ?C. Ap?s o preparo de ambas as fases, estas foram introduzidas no moinho coloidal, onde permaneceram em aquecimento e em sistema de refluxo, durante 15 minutos. Ap?s a obten??o de cada emuls?o asf?ltica, foram feitos os seguintes ensaios de caracteriza??o: peneiramento, viscosidade Saybolt Furol, pH, sedimenta??o, adesividade, res?duo por evapora??o e penetra??o. Ap?s a caracteriza??o das emuls?es asf?lticas convencionais, escolheu-se a emuls?o que apresentou resultados de acordo com a especifica??o (DNER-EM 369/97) para, em seguida, desenvolver as emuls?es asf?lticas modificadas. As emuls?es asf?lticas foram modificadas atrav?s da adi??o de res?duos polim?ricos provenientes da ind?stria de bot?es e de cal?ados (sand?lia e t?nis), localizadas no Rio Grande do Norte. Os res?duos polim?ricos foram adicionados na emuls?o asf?ltica de 1 a 6 %. Ap?s a obten??o das emuls?es asf?lticas modificadas foram feitos os ensaios de caracteriza??o. Conclu?da tais etapas, continuou-se a pesquisa com o desenvolvimento de misturas asf?lticas a frio. O m?todo Marshall foi utilizado como m?todo de dosagem destas misturas. De acordo com os resultados obtidos, conclui-se que foi poss?vel determinar uma composi??o de emuls?o asf?ltica convencional que atendesse a alguns requisitos presentes na especifica??o (DNER-EM 369/97). Quanto ?s misturas asf?lticas a frio, utilizando as emuls?es convencionais, conclui-se que, para os teores de emuls?o utilizados (5, 6 e 7 %), estas apresentaram valores de estabilidade acima do recomendado na especifica??o. Para as misturas asf?lticas a frio, que utilizaram as emuls?es modificadas, os melhores resultados de estabilidade foram obtidos com a emuls?o modificada com res?duo de bot?o