Con la finalidad de lograr la estabilización de pavimentos, surgen nuevas tecnologías de agentes estabilizadores como el asfalto espumado y la emulsión asfáltica. En el Proyecto del corredor vial Dv-Humajalso-Desagüadero y Tacna-Capazo-Mazocruz, se tenía como solución técnica aplicar en el Tramo 7 Tarata-Capazo el asfalto espumado. Sin embargo, la condición termodinámica es fundamental para el asfalto espumado y esto se evidencia en el Tramo 7, donde a temperaturas de 5°C en descenso, las partículas de asfalto no se dispersan sobre el mástic, éstas caen sobre otras partículas de asfalto, provocando una aglomeración de asfalto en forma de chicles e imposibilitando la compactación de la capa del pavimento. Frente a esta problemática, se plantea estabilizar el material granular con emulsión asfáltica, donde las partículas de asfalto están dispersas en una solución acuosa a 25°C y no se requiere calentar al asfalto a elevadas temperaturas. El objetivo de la tesis es lograr la estabilización del pavimento utilizando emulsión asfáltica. Para el diseño de la mezcla asfáltica en frío, se utiliza la metodología Illinois y una emulsión catiónica de rotura lenta como ligante. Prosigue, el diseño del pavimento con la metodología AASHTO 93, para determinar los espesores de las capas del pavimento que satisfarán las cargas de tráfico para la vida útil del proyecto. Finalmente, se logra validar la estabilización del pavimento en campo con los controles de compactación y deflectometría, quedando demostrado la versatilidad de la emulsión como mezcla asfáltica en frío frente a las condiciones termodinámicas críticas del Proyecto. / In order to achieve the stabilization of pavements, emerge new technologies of stabilizing agents such as foamed bitumen and asphalt emulsion. In the Roadway Project Dv-Humajalso-Desagüadero and Tacna-Capazo-Mazocruz, the technical solution was to apply foamed bitumen in road Section 7 Tarata-Capazo. Thermodynamic condition is fundamental where foamed bitumen is evidenced in Section 7, the temperature is lower than 5 °C, so the asphalt don’t disperse on the Mastic, causing an agglomeration of asphalt in the form of chewing gum and making impossible the compaction of the pavement layer. In this problem, It’s proposed to stabilize the granular material with asphalt emulsion, so the asphalt particles are dispersed in a solution to 25°C. The technique is a mixture of cold asphalt and is feasible for the critical thermodynamic conditions of the Section 7 Tarata-Capazo. The objective is to achieve the stabilization of the pavement using asphalt emulsion. The design of the cold asphalt mix applies the Illinois Methodology to determine the optimum quantity of residual asphalt. So that, the design of the pavement is done with the methodology of AASHTO 93, which allows to determine the thicknesses of the pavement layers that will satisfy the serviceability and traffic for the useful life of the project. Finally, It´s possible to validate the stabilization of the pavement in the field with the compaction and deflectometry controls, demonstrating the versatility of the emulsion as a cold asphalt mixture against the critical thermodynamic conditions of the Project. / Tesis

<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>

A aplicação de pintura de ligação entre camadas asfálticas é prática comum em obras de pavimentos novos ou restaurações, sendo importante para garantir a aderência entre as camadas. Esse tratamento da interface geralmente é feito com emulsão asfáltica, que faz com que a estrutura do pavimento trabalhe como um sistema monolítico, evitando problemas de trincamento precoce por fadiga, ou escorregamentos. Esse trabalho tem como objetivo estudar a variabilidade de comportamento dos revestimentos asfálticos quanto à aderência na interface, tendo em vista a taxa aplicada de pintura de ligação, o tipo de emulsão (convencional ou modificada por polímero), a superfície de contato entre as camadas e a presença, ou não, de um sistema anti-reflexão de trincas (geotêxtil e grelha de fibra de vidro). A aderência foi medida por meio do ensaio de cisalhamento direto Leutner, em amostras produzidas em laboratório e extraídas de pista. Foram produzidas placas com dupla camada de revestimento asfáltico, sendo a camada superior um CBUQ (Concreto Betuminoso Usinado a Quente) e a inferior, ora SAMI (Stress Absorbing Membrane Interlayer), ora CBUQ, variando a taxa de aplicação de pintura de ligação na interface (0,0; 0,25; 0,5 e 0,75 L/m2) e o tipo de emulsão aplicada (RR-1C, RR- 1C-E e RR-2C-E), além de testar duas diferentes dimensões para as amostras cilíndricas ensaiadas (100 e 150 mm de diâmetro). Os ensaios de cisalhamento direto foram feitos com carregamento monotônico, à taxa de deslocamento de 50mm/min e à temperatura de 20ºC. Realizou-se o mesmo ensaio também com velocidade de 1 mm/min para avaliar a influência desse parâmetro nos resultados de aderência para as três emulsões testadas. As amostras de pista, com 100 mm de diâmetro, foram retiradas de um trecho experimental na Rodovia Ayrton Senna (SP- 070), do km 38,000 ao 39,500. Os resultados do teste de aderência em laboratório demonstraram influência do tipo de emulsão, da presença de geotêxtil/grelha na interface, do diâmetro da amostra, da textura superficial entre camadas e da velocidade de ensaio nos valores de tensão cisalhante máxima e na taxa ótima de aplicação de emulsão. Os valores de taxa ótima de pintura de ligação foram maiores quando na presença de geotêxtil na interface e para superfícies de contato com maior macrotextura. Quanto à aderência, as amostras com grelha não apresentaram diferença significativa comparadas ao uso de interface somente com pintura de ligação, enquanto as amostras com geotêxtil na interface resultaram em valores bem 8 inferiores de tensão cisalhante máxima. Para ensaios com diferentes tipos de pintura de ligação, as amostras com emulsão modificada nem sempre apresentaram melhores resultados em relação às amostras com emulsão convencional. / Asphalt tack coat is commonly applied at the interface between asphalt layers during new pavement construction or overlay to ensure proper bond between the layers. This treatment at the interface, usually done with asphalt emulsion, allows the pavement structures to function as a monolithic system, avoiding problems like premature fatigue cracking, or slippage. This study aims to evaluate: (i) the influence of the tack coat type (neat or polymer modified asphalt emulsion), (ii) the application rate, (iii) the surface type, and (iv) the presence, or not, of an anti-reflective cracking interlayer (geotextile and fiber glass grid), in the adhesion properties between asphalt concrete layers. The adhesion between layers was tested through the Leutner shear test in laboratory and field samples. A double-layer system was produced with HMA as the top layer and SAMI (Stress Absorbing Membrane Interlayer), or HMA, as the bottom layer, varying the tack coat type (RR-1C, RR-1C-E e RR-2C-E), the application rate at the interface (0,0; 0,25; 0,50 and 0,75 L/m²) and the samples diameter (100 and 150 mm diameter). It was used the standard shear displacement rate of 50 mm/min, and the test temperature was set at 20°C. The same procedure was run with a displacement rate of 1 mm/min to evaluate its influence on the adhesion of three asphalt emulsions used as the tack coat. An experimental test section was constructed on Rodovia Ayrton Senna (SP-070), from km 38,000 to 39,500, and core samples (100 mm diameter) were extracted. The results of maximum shear stress demonstrate the influence of the tack coat type, the surface type, the sample diameter, the test displacement rate and the presence of a geotextile/grid on the adhesion at the interface between the asphalt layers,. Samples with grid at the interface presented similar results when compared with the samples with only tack coat at the interface. Samples with geotextile, however, presented significant lower values of maximum shear stress. The Leutner results showed that not always the modified asphalt emulsions present higher shear strength when compared to the neat asphalt emulsions.

A aplicação de pintura de ligação entre camadas asfálticas é prática comum em obras de pavimentos novos ou restaurações, sendo importante para garantir a aderência entre as camadas. Esse tratamento da interface geralmente é feito com emulsão asfáltica, que faz com que a estrutura do pavimento trabalhe como um sistema monolítico, evitando problemas de trincamento precoce por fadiga, ou escorregamentos. Esse trabalho tem como objetivo estudar a variabilidade de comportamento dos revestimentos asfálticos quanto à aderência na interface, tendo em vista a taxa aplicada de pintura de ligação, o tipo de emulsão (convencional ou modificada por polímero), a superfície de contato entre as camadas e a presença, ou não, de um sistema anti-reflexão de trincas (geotêxtil e grelha de fibra de vidro). A aderência foi medida por meio do ensaio de cisalhamento direto Leutner, em amostras produzidas em laboratório e extraídas de pista. Foram produzidas placas com dupla camada de revestimento asfáltico, sendo a camada superior um CBUQ (Concreto Betuminoso Usinado a Quente) e a inferior, ora SAMI (Stress Absorbing Membrane Interlayer), ora CBUQ, variando a taxa de aplicação de pintura de ligação na interface (0,0; 0,25; 0,5 e 0,75 L/m2) e o tipo de emulsão aplicada (RR-1C, RR- 1C-E e RR-2C-E), além de testar duas diferentes dimensões para as amostras cilíndricas ensaiadas (100 e 150 mm de diâmetro). Os ensaios de cisalhamento direto foram feitos com carregamento monotônico, à taxa de deslocamento de 50mm/min e à temperatura de 20ºC. Realizou-se o mesmo ensaio também com velocidade de 1 mm/min para avaliar a influência desse parâmetro nos resultados de aderência para as três emulsões testadas. As amostras de pista, com 100 mm de diâmetro, foram retiradas de um trecho experimental na Rodovia Ayrton Senna (SP- 070), do km 38,000 ao 39,500. Os resultados do teste de aderência em laboratório demonstraram influência do tipo de emulsão, da presença de geotêxtil/grelha na interface, do diâmetro da amostra, da textura superficial entre camadas e da velocidade de ensaio nos valores de tensão cisalhante máxima e na taxa ótima de aplicação de emulsão. Os valores de taxa ótima de pintura de ligação foram maiores quando na presença de geotêxtil na interface e para superfícies de contato com maior macrotextura. Quanto à aderência, as amostras com grelha não apresentaram diferença significativa comparadas ao uso de interface somente com pintura de ligação, enquanto as amostras com geotêxtil na interface resultaram em valores bem 8 inferiores de tensão cisalhante máxima. Para ensaios com diferentes tipos de pintura de ligação, as amostras com emulsão modificada nem sempre apresentaram melhores resultados em relação às amostras com emulsão convencional. / Asphalt tack coat is commonly applied at the interface between asphalt layers during new pavement construction or overlay to ensure proper bond between the layers. This treatment at the interface, usually done with asphalt emulsion, allows the pavement structures to function as a monolithic system, avoiding problems like premature fatigue cracking, or slippage. This study aims to evaluate: (i) the influence of the tack coat type (neat or polymer modified asphalt emulsion), (ii) the application rate, (iii) the surface type, and (iv) the presence, or not, of an anti-reflective cracking interlayer (geotextile and fiber glass grid), in the adhesion properties between asphalt concrete layers. The adhesion between layers was tested through the Leutner shear test in laboratory and field samples. A double-layer system was produced with HMA as the top layer and SAMI (Stress Absorbing Membrane Interlayer), or HMA, as the bottom layer, varying the tack coat type (RR-1C, RR-1C-E e RR-2C-E), the application rate at the interface (0,0; 0,25; 0,50 and 0,75 L/m²) and the samples diameter (100 and 150 mm diameter). It was used the standard shear displacement rate of 50 mm/min, and the test temperature was set at 20°C. The same procedure was run with a displacement rate of 1 mm/min to evaluate its influence on the adhesion of three asphalt emulsions used as the tack coat. An experimental test section was constructed on Rodovia Ayrton Senna (SP-070), from km 38,000 to 39,500, and core samples (100 mm diameter) were extracted. The results of maximum shear stress demonstrate the influence of the tack coat type, the surface type, the sample diameter, the test displacement rate and the presence of a geotextile/grid on the adhesion at the interface between the asphalt layers,. Samples with grid at the interface presented similar results when compared with the samples with only tack coat at the interface. Samples with geotextile, however, presented significant lower values of maximum shear stress. The Leutner results showed that not always the modified asphalt emulsions present higher shear strength when compared to the neat asphalt emulsions.