Asphalt Emulsion Research Articles

Mechanical Properties of Fly Ash–Asphalt Emulsion Geopolymer Stabilized Crushed Rock for Sustainable Pavement Base

AbstractResearch on the usage of industrial by-products to improve mechanical properties of low-quality materials in infrastructure applications is of global interest. Two industrial by-products, n...

Validation of Adhesive and Temperature Property Characteristics of Microsurfacing by Performance-Based Mixture Design Approach.

Performance-based mixture design of microsurfacing offers a promising solution to the best application of asphalt emulsions. The presented study investigated a novel approach to evaluate the spalling resistance and high and low-temperature resistance of microsurfacing. The laboratory tests, including mixture bond strength (MBS), driving wheel pavement analyzer (DWPA), multi-stress creep recovery (MSCR), load wheel rutting (LWR), and single edge notch beam (SENB) were conducted to characterize the performance-related properties; the response surface method (RSM) was used to obtain the optimal proportions of the mixture. According to the experimental results, the performance-based mixture design method improves the comprehensive performance of microsurfacing, such as adhesion at high and low temperatures. The results of RSM show that temperature is the most important factor that affects the adhesion of mixture. There is a strong correlation between adhesive and temperature performance detected by different test methods. Due to different chemical mechanisms caused by cement and emulsified asphalt, the high-temperature performance index of the microsurfacing mixture is lower than that of HMA. Furthermore, the low-temperature resistance is analyzed and suggested indicator is proposed.

Enhancing the Stability of Asphalt Emulsion Using Environmentally Friendly Cationically Modified Hydroxyethyl Cellulose (CMHEC) at Different Concentrations and pH Values

Abstract The cationically modified hydroxyethyl cellulose (CMHEC) was synthesized successfully and applied for preparing the cationic asphalt emulsion. The apparent viscosity and phase separation of the emulsion were studied at different CMHEC concentrations and pH values. The results indicated that the apparent viscosity of the emulsion was increased with increasing CMHEC concentration, and the phase separation was significantly reduced correspondingly. In addition, the effect of pH value on the emulsion quality was involved. The apparent viscosity of the emulsion showed the tendency to decrease firstly and then increase to the minimum value at pH 2. All results indicated that CMHEC has excellent potential in the manufacture of asphalt emulsion and the research of the pH effect on the formulation of asphalt emulsion has essential significance.

Research on the Performance of Regenerant Modified Cold Recycled Mixture with Asphalt Emulsions

In order to study the mechanical properties and effect of a regenerant on a cold recycled mixture with asphalt emulsions (CRMEs), the moisture susceptibility, high-temperature performance, low-temperature performance, dynamic mechanical properties and durability of CRMEs were analyzed and evaluated by immersion splitting strength tests, freeze-thaw splitting strength tests, rutting tests, semi-circle bending tests, uniaxial compression dynamic modulus tests and indirect tensile tests. Scanning electron microscopy (SEM) was used to analyze the micromorphology of CRMEs modified with regenerant. Finally, a comprehensive evaluation system of five different CRMEs was established based on the efficacy coefficient method to quantitatively analyze the comprehensive performance of the CRMEs. The test results showed that the regenerant can significantly improve the water immersion splitting strength, freeze-thaw splitting strength fracture energy density, and fatigue resistance of CRMEs. However, the addition of regenerant affected the high-temperature performance of the cold recycled mixture. The dynamic modulus of the CRMEs first increased and then decreased with regenerant content increasing. When the regenerant content was 8%, the dynamic modulus of the CRMEs was the highest. Adding styrene-butadiene rubber (SBR) latex can improve the high-temperature performance of CRMEs, but the moisture susceptibility, low temperature performance and fatigue resistance of the cold recycled mixture were not significantly improved, and the dynamic modulus of the mixture was reduced. Based on the efficacy coefficient method, the optimal content of regenerant is 8%. Regenerant are potential modifiers for cold recycled mixture that they can significantly improve the dynamic mechanical properties and durability.

A Review on Cement Asphalt Emulsion Mortar Composites, Structural Development, and Performance

The use of cement emulsified asphalt mortar (CA mortar) in the track structure of high-speed speed railways has been gaining considerations by many researchers due to its coupled merits of the strength of cement as well as the flexibility of asphalt material. The asphalt to cement ratio (A/C) and the compatibility among constituent materials are crucial to the properties of CA mortar. To improve the performance properties and application of CA mortar, it is imperative to have a broad understanding of the composition mechanisms and compatibility between constituent materials. This paper summarizes interesting research outcomes related to the composition and properties of CA mortar. The consumption of water by cement promotes the breakdown of emulsified asphalt, likewise, the adsorption of asphalt droplets on the surface of cement grains retards the hydration process of cement. An appropriate A/C is required for the cement hydration rate to match the speed of demulsification of asphalt emulsion. Depending on the type and properties for which the CA mortar is designed to possess, the A/C ranges from 0.2 to 0.6 for type 1 (CAM I), and 0.6 to 1.2 for type 2 (CAM II). This paper also discusses measures taken to improve performance properties, compatibility, the interaction between constituent materials of CA mortar, and the use of additives as a partial replacement of cement in CA mortar production. The current review also suggests areas of interest for future research studies. This paper is useful to those who aim to understand or study the composition mechanisms and performance properties of CA mortar.

The influence of emulsified asphalt on mechanical properties of self-compacting concrete

Polymer emulsion is commonly used to prepare the high-performance concrete, including the self-compacting cement concrete (SCC), but the cost obviously increased. One of the alternative emulsions is the inexpensive emulsified asphalt (EA), which has been applied in SCC in recent years. However, the effects of EA on the improved mechanical properties of self-compacting concrete are still unclear. In order to study the mechanical properties of SCC with emulsified asphalt (EASCC), five groups of SCC concrete specimens with different emulsified asphalt content were prepared, and four kinds of tests were performed to evaluate the compressive strength, compressive elastic modulus, flexural strength and fatigue performance. The results revealed that the compressive strength and the elastic modulus of EASCC decrease with the increased poly-cement ratio (PC ratio). On the contrary, the flexural strength and fatigue life of EASCC increased with the incorporation of EA, indicating that the emulsified asphalt can effectively improve the flexural strength and crack resistance of concrete pavement and prolong the pavement service life. And the better toughness performance was achieved when the PC ratio reaches ten percent. To sum up, the EASCC with ten percent content has better performance and more suitable to apply in the pavement under the.

Effect of curing and compaction on volumetric and mechanical properties of cold-recycled mixture with asphalt emulsion under different cement contents

Cold-recycled mixture with asphalt emulsion (CMAE) has been widely used in pavement rehabilitation due to its environmental and economic advantages. Curing condition and compaction method can both affect the volumetric and mechanical properties of CMAE. The main objective of this paper is to propose a relative reasonable fabrication method of CMAE in consideration of curing and compaction history in the laboratory. The two fast curing conditions (single curing: 2 days curing at 60 °C and mixed curing: 3 days curing at 20 °C followed by 2 days curing 60 °C) and three impact compaction methods (single compaction-50 blows, single compaction-75 blows and double compaction) using Marshall compactor were used to evaluate the volumetric and mechanical properties of CMAE with different cement contents. The result analysis indicates that the single curing condition is beneficial to decreasing the voids content and increasing the indirect tensile strength (ITS), failure strain and critical strain energy density (CSED) of CMAE with low cement content. However, the mixed curing can decrease the voids content and greatly improve the ITS and CSED of CMAE with high cement content. This is because the single curing is better for the film formation of asphalt emulsion but more harmful to the cement hydration than the mixed curing. It is recommended to adopt single curing under relatively low cement content and mixed curing under relatively high cement content in the laboratory. Meanwhile, increasing the number of compaction blows and employing double compaction can greatly reduce the voids content and improve the ITS and CSED with different cement contents, which is beneficial to the mechanical properties of CMAE. Since the double compaction can better simulate the field construction, it is recommended to employ the double compaction to fabricate specimens in the laboratory.

Rutting Resistance of Stabilized Mixes Using Asphalt Emulsion and Asphaltenes

Rutting Resistance of Stabilized Mixes Using Asphalt Emulsion and Asphaltenes

Performance Evaluation of Stabilized Base Course using Asphalt Emulsion and Asphaltenes Derived from Alberta Oil Sands

Stabilization of the pavement base course using asphalt emulsion is one of the strategies that improves the layer’s strength and, consequently, enhances the pavement performance. In this study, to improve the performance of the asphalt-emulsion-stabilized base course, asphaltenes derived from Alberta oil sands bitumen are added to the mix. Asphaltenes are a byproduct of the deasphalting process of oil sand bitumen and have no significant value in the asphalt industry. The modified mixes are prepared by adding different amounts of asphaltenes in powder form to the mix at ambient temperatures. Marshall stability and indirect tensile strength of the mixtures are evaluated using different contents of asphalt emulsion and asphaltenes. The low-temperature performance properties of the selected mixtures are investigated using an indirect tensile test and for the high-temperature properties a wheel-tracking test is conducted. The results of this study indicate that the addition of asphaltenes to the emulsion-stabilized mix significantly improves rutting resistance, with a slight increase in moisture sensitivity. However, the indirect tensile test results also reveal that modified mixes are slightly more prone to low-temperature cracking than are unmodified ones.

The microstructure evolution of cement paste modified by cationic asphalt emulsion

Cationic asphalt emulsion (CAE) is a type of organic latex that could be used to modify cement hydration products in order to improve the performance of cement paste. In this study, different methodologies were used to investigate the influence of CAE on the process of cement hydration. The results showed that with an increase in the mass ratio of asphalt to cement, the setting time of the cement paste was prolonged while the compressive strength and water absorption of the cement mortar showed obvious reductions. Other techniques were also used to investigate the cement hydration process and the microstructure evolution caused by the addition of CAE, including conductivity measurements, 29Si nuclear magnetic resonance, low-field nuclear magnetic resonance, measurements of chemically bound water and field emission scanning electron microscopy. It was found that the formation of cement hydration products was delayed with an increase in CAE and the microstructure was affected by the CAE in that the pores were separated by asphalt film and the total porosity decreased.

Effect of Nanosilica on Moisture Susceptibility of Asphalt Emulsion Mixture

Moisture susceptibility is a major concern about asphalt emulsion mixtures due to low mixing temperature and compaction. Therefore, herein, nanosilica was used because of its high specific surface, good dispersing ability, and strong adsorption, to improve the moisture susceptibility of asphalt emulsion mixture. The bitumen emulsion was modified with different percentages of nanosilica (0.2, 0.4, 0.7, and 0.9% of the bitumen weight). Then, the indirect tensile strength (ITS) test and compressive strength test were performed to evaluate the moisture susceptibility of the samples. The results demonstrated that the modification of the bitumen emulsion with nanosilica increased the ITS and compressive strength of the samples by improving the bitumen cohesion and increasing the adhesion of the bitumen and aggregates. This resulted in the indirect tensile strength ratio (TSR) and compressive strength ratio (CSR) parameters of 88% and 89%, which had increased by 22.5% and 27%, respectively. Also, the addition of nanosilica significantly increased the secant stiffness modulus and reduced the failure strain of asphalt emulsion mixtures against lateral deformation. The results of the statistical analysis indicated the significant effect of nanosilica addition on reducing the moisture susceptibility and improving the mechanical performance of asphalt emulsion mixtures at the 95% confidence level.

Developing a particle size specification for asphalt emulsion

There are many parameters that influence the properties of asphalt emulsion including emulsifier type, emulsifier dosage, soap solution pH, and milling time. These parameters influence viscosity, residue, storage stability, and particle size of the asphalt emulsion. Current specifications are over 80 years old, therefore, a movement toward more innovative specifications is desirable. This research examined cationic slow set (CSS) and cationic medium set (CMS) asphalt emulsion. Preliminary results for particle size recommends a d10 of 2.4 μm and d50 of 4.4 μm for CSS, and a d10 of 3.2 μm and d50 of 6.9 μm for CMS asphalt emulsion.

Texture Depth and Cost Analysis of Slurry Seal Cationic Rapid Setting Cold Asphalt Mixture

Slurry seal is a mixture of asphalt emulsion, fine aggregate, mineral filler, water, and other added ingredients are mixed evenly without heating and is spread over the surface of the pavement with a maximum thickness of 10 mm. This study was conducted to determine the relationship of the depth texture and skid resistance resulting from the modification of the aggregate and filler slurry seal based texture depth test of sand patches. Slurry seal is made using basalt stone aggregate filler Ordinary Protland Cement (OPC), limestone filler aggregate OPC and aggregate rock with filler standard OPC composition: High Calcium Fly Ash 50%: 50%. Increasing the texture depth will add road surface roughness. Slurry seal with basalt stone aggregate having the largest texture depth is 1.837 mm so as to provide the greatest improvement of skid resistance. Texture depth slurry seal with limestone aggregate is 1,767 mm that mean increasing skid resistance. Slurry seal standard aggregate has a depth of 1,673 mm texture which represents an increase skid resistance smallest slurry seal between basalt stone aggregate and limestone. Slurry seal with cheapest price is limestone slurry seal aggregate Rp. 44,817.00 / m2 compared basalt aggregate Rp. 45,085.00 / m2 and a standard stone mixture of cement and fly ash filler Rp. 44,914.00 / m2.

Caracterização de emulsões asfálticas brasileiras a partir do protocolo Emulsion Performance Grade (EPG)

A especificação Emulsion Performance Grade – EPG indica que os processos de degradação dos tratamentos para preservação de superfícies aplicados a frio com emulsão asfáltica guardam uma relação direta com parâmetros reológicos do ligante residual da emulsão. Apesar do reconhecimento da importância da contribuição da emulsão asfáltica em suas aplicações, no Brasil sua seleção ainda é realizada de maneira empírica, sem avaliação de propriedades relacionadas diretamente ao desempenho da mistura em campo. O presente trabalho visa avaliar o potencial de utilização da especificação por grau de desempenho, para misturas de microrrevestimento asfáltico a frio, mediante a aplicação do protocolo denominado EPG. Foram caracterizadas as propriedades reológicas do resíduo asfáltico de três emulsões brasileiras e o desempenho em serviço de cada uma delas foi previsto com uma estrutura metodológica semelhante às especificações Superpave®. As emulsões frescas foram ainda avaliadas quanto à viscosidade e à estabilidade, que se relacionam com as condições de construtibilidade. A aplicação dos procedimentos e valores admissíveis do EPG levou à definição de graus de desempenho em temperaturas altas e baixas, coerentes com o comportamento esperado segundo as características e o propósito das emulsões avaliadas. No que diz respeito à viscosidade e a estabilidade, apesar de não se tratarem de parâmetros classificatórios, todas as emulsões apresentaram comportamento adequado e resultados aceitáveis do recente protocolo.

Effects of asphalt emulsion on the durability of self-compacting concrete

Asphalt emulsion (AE) is the alternative raw material for self-compacting concrete (SCC), some researchers have reported on the composition design, workability, and strength properties recently. But few attempts have be made on the durability. For a better understanding on the effects of AE on SCC durability and its microscopic mechanism, the SCC specimens were prepared with various AE contents, and the self-compacting workability was confirmed via slump flow test. Then, three kinds of durability tests were performed to evaluate the chloride-penetration resistance, frost resistance and sulfate-corrosion resistance, and the scan electronic microscope (SEM) test and X-ray diffraction (XRD) test were performed to discuss the microscopic mechanism. The results show that the chloride-penetration resistance, frost resistance and sulfate-corrosion resistance of SCC were enhanced by adding AE. Observed from SEM test, the interfacial transition zone (ITZ) of SCC is mainly filled with the C-S-H gel and AE, and the SCC microstructure tends to be compact, resulting that the concrete durability was improved by using appropriate AE. However, the excessive AE may lead to more pores in SCC because of the retardation effect on cement hydration. The AE with the content of 10% given the most desirable effect for durability.

Cold In-Place Recycling Asphalt Mixtures: Laboratory Performance and Preliminary M-E Design Analysis.

Cold in-place recycling (CIR) asphalt mixtures are an attractive eco-friendly method for rehabilitating asphalt pavement. However, the on-site CIR asphalt mixture generally has a high air void because of the moisture content during construction, and the moisture susceptibility is vital for estimating the road service life. Therefore, the main purpose of this research is to characterize the effect of moisture on the high-temperature and low-temperature performance of a CIR asphalt mixture to predict CIR pavement distress based on a mechanistic–empirical (M-E) pavement design. Moisture conditioning was simulated by the moisture-induced stress tester (MIST). The moisture susceptibility performance of the CIR asphalt mixture (pre-mist and post-mist) was estimated by a dynamic modulus test and a disk-shaped compact tension (DCT) test. In addition, the standard solvent extraction test was used to obtain the reclaimed asphalt pavement (RAP) and CIR asphalt. Asphalt binder performance, including higher temperature and medium temperature performance, was evaluated by dynamic shear rheometer (DSR) equipment and low-temperature properties were estimated by the asphalt binder cracking device (ABCD). Then the predicted pavement distresses were estimated based on the pavement M-E design method. The experimental results revealed that (1) DCT and dynamic modulus tests are sensitive to moisture conditioning. The dynamic modulus decreased by 13% to 43% at various temperatures and frequencies, and the low-temperature cracking energy decreased by 20%. (2) RAP asphalt incorporated with asphalt emulsion decreased the high-temperature rutting resistance but improved the low-temperature anti-cracking and the fatigue life. The M-E design results showed that the RAP incorporated with asphalt emulsion reduced the international roughness index (IRI) and AC bottom-up fatigue predictions, while increasing the total rutting and AC rutting predictions. The moisture damage in the CIR pavement layer also did not significantly affect the predicted distress with low traffic volume. In summary, the implementation of CIR technology in the project improved low-temperature cracking and fatigue performance in the asphalt pavement. Meanwhile, the moisture damage of the CIR asphalt mixture accelerated high-temperature rutting and low-temperature cracking, but it may be acceptable when used for low-volume roads.

The Optimum Pre-mixing Water Content in Asphalt Emulsion Mixture with Cement

The pre-mixing of water is recommended to be added into asphalt emulsion mixture (AEM). However, there is no widely applied method to determine the optimum pre-mixing water (OPW) value during the mixture design. In this study, the OPW values of AEM with cement are determined based on the visual observation of loose mixture, maximum density, and indirect tensile strength (ITS) of compacted mixtures. The effect of different OPW contents on the air voids, ITS, and moisture susceptibility of the mixture is investigated. Furthermore, the cement-asphalt mastic and the mixture with different OPW contents are analyzed by X-ray diffraction analyzer and environmental scanning electron microscope. The results indicate that the different methods lead to more diverse OPW values than the change of cement content or emulsion content does. The visual observation method obviously underestimates or overestimates OPW values compared with other two methods. The higher OPW content from the visual observation is beneficial to reduce the negative effect of asphalt film on hydration reaction, which improves the hydration reaction of cement. However, this OPW value leads to many small pores in the interface zone of the aggregate-mastic, which brings a negative effect on the ITS and moisture resistance of the mixtures. It is suggested that the maximum ITS method should be used to determine the OPW value.

Short-Term Field Performance and Cost-Effectiveness of Crumb-Rubber Modified Asphalt Emulsion in Chip Seal Applications

Chip sealing is a commonly used pavement maintenance technique that aims to delay pavement deterioration by reducing water infiltration and restoring skid resistance. The objective of this study was to evaluate the short-term field performance and cost-effectiveness of chip seals prepared with different types of asphalt emulsion and application rates. A newly introduced crumb-rubber modified asphalt emulsion was evaluated, one that allows chip seal installation at the same temperature as a standard emulsion. Types of emulsion included a crumb-rubber modified asphalt emulsion (CRS-2TR), a polymer-modified emulsion (CRS-2P), and a conventional unmodified emulsion (CRS-2). Application rates were obtained from the Louisiana Department of Transportation and Development (DOTD), the Texas Department of Transportation (DOT) specifications, and from the chip seal design method recommended in NCHRP Report 680. Seven chip seal sections were constructed and monitored regularly over a 12-month period. In the northbound lane, the chip seal section constructed with CRS-2TR (0.37 gal per square yard [gsy]) was the best performer statistically. In the southbound lane, the chip seal sections constructed with CRS-2TR and CRS-2P (0.31 gsy) performed similarly. Furthermore, the maximum Service Life Extension (SLE) was observed for the CRS-2TR (0.31 gsy) chip seal sections, whereas the chip seal sections constructed with CRS-2 had the lowest SLE. In addition, the most cost-effective chip seal section was achieved by the application of CRS-2TR emulsion at the Louisiana DOTD recommended emulsion application rate.

Cellulose Microfibril and Micronized Rubber Modified Asphalt Binder

Cellulose microfibrils (CMFs) and micronized rubber powder (MRP) can be derived from low or negative-cost agricultural/industrial waste streams and offer environment-friendly and cost-effective pathways to develop engineering products. This study investigated the efficacy of adding these micromodifiers on the performance characteristics of asphalt binders. In this work, samples were produced using a mixture of slow-setting anionic asphalt emulsion with various combinations of MRP (at 0, 2 and 10 wt %) and four types of CMFs (hydrophobic and hydrophilic with crystalline ratios of 86% and 95%) at 0, 2 and 5 wt %. The performance of modified asphalt samples was assessed by penetration depth (PD), softening point (SP), and penetration index (PI). Linear regression analysis showed that adding CMFs and/or MRP reduced PD and increased SP values. The type of CMFs significantly affected the performance, which becomes more distinct with the increased weight content of CMFs. While hydrophilic CMFs caused increases in SP and PI values, no clear trend was seen to determine the effect of CMF crystallinity. It was also discovered that the combined addition of CMF and MRP achieved similar PI values at lower total weight content compared to using MRP alone.

Compaction Characteristics of Cold Recycled Mixtures with Asphalt Emulsion and Their Influencing Factors

The objective of this study is to investigate the compaction characteristics of cold recycled mixtures with asphalt emulsion (CRME) using the Superpave gyratory compactor (SGC) method. Five characteristic parameters were proposed and calculated including the compaction energy index, the compaction energy index, three compaction energy indicators at different compaction stages. The influence of these parameters and material compositions were analyzed for the pavement performance. The difference between SGC and Marshall double-sided compaction/heavy compaction method was compared. The results show that the proposed parameters can better reflect the compaction characteristics of CRME, and the mixture effect with SGC of 50 gyrations was close to that with 75 blows using the Marshall compaction. The asphalt emulsion contents and compaction temperatures had a significant effect on compaction characteristics, but the effect of aggregate gradations was not significant. The appropriate asphalt emulsion and the new aggregate content can increase the capability of the CRME to resist the permanent deformation. The optimum mixing water content of CRME obtained by the SGC method was reduced by 18%, but the density increased by 3.5%, compared with the heavy compaction method. Finally, a new idea to determine the optimum emulsified asphalt content of CRME was provided through analyzing the compaction characteristic parameters.