scholarly journals Strength and Micro-Mechanism Analysis of Cement-Emulsified Asphalt Cold Recycled Mixture

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 128 ◽  
Author(s):  
Yuhui Pi ◽  
Yan Li ◽  
Yingxing Pi ◽  
Zhe Huang ◽  
Zhe Li
Keyword(s):  
Raw Materials ◽  
Asphalt Binder ◽  
Microscopic Analysis ◽  
Hydration Product ◽  
Mechanism Analysis ◽  
Recycled Asphalt ◽  
Aggregate Gradation ◽  
Asphalt Cement ◽  
Emulsified Asphalt ◽  
Cementing Material

The strength of EACRM (emulsified asphalt cold recycled mixture) is closely related to the properties and proportion of raw materials. In this paper, the strength formation mechanism of EACRM was first studied through microscopic analysis, and the influence regular of aggregate gradation, emulsified asphalt, water consumption, cement consumption, and other factors on its strength was analyzed through a series of laboratory tests. The analysis results show that the asphalt binder plays the role of cementing material in cement emulsified asphalt mortar. The combination of cement and emulsified asphalt is a physical combination. The hydration product not only increases the viscosity of asphalt cement, but also makes the surface of asphalt cement become uneven, which increases the adhesion area with the aggregate. Therefore, the microstructure of the interface between mortar and aggregate is improved. The bonding force of the interface and the mechanical properties of concrete are improved. Due to the influence of recycled asphalt pavement (RAP) materials, the excessive amount of emulsified asphalt and cement are not conducive to improve the strength of cold recycled mixture. Through experiments, the optimal amount of emulsified asphalt and cement is determined as 2.9% and 1.5%, respectively, for the RAP materials. At the same time, improving the performance of emulsified asphalt and adding quicklime and organic activator are also helpful to improve the strength of a cold recycled mixture.

Experimental Study on Pavement Performance of Emulsified Asphalt Cement Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 888-892 ◽  
Author(s):  
Hao Chu ◽  
Jun Zhang ◽  
Yan Hua Lu
Keyword(s):  
Opposite Effect ◽  
Raw Material ◽  
Pavement Performance ◽  
Critical Factors ◽  
Cement Concrete ◽  
Aggregate Gradation ◽  
Cement Ratio ◽  
Asphalt Cement ◽  
Emulsified Asphalt ◽  
Mixing Sequence

Based on the research and indoor experiments, this paper investigates the mixing and curing techniques, pavement performance, and influencing factors of emulsified asphalt cement concrete. The results indicate that mixing sequence of raw material and curing condition have great impact on the strength of the mixture. Adding cement to mixture can improve the pavement performance of mixture greatly. However, increasing the content of emulsified asphalt has opposite effect. Proper content of emulsified asphalt will ensure the bonding strength and waterproof property of the mixture. The critical factors that influence the pavement performance of emulsified asphalt cement concrete are asphalt cement ratio, water cement ratio, content of emulsified asphalt and cement, sand percentage, and aggregate gradation.

scholarly journals Laboratory Performance Evaluation of Hot-Mix Asphalt Mixtures with Different Design Parameters

2020 ◽  
Vol 10 (9) ◽  
pp. 3038
Author(s):  
Yining Zhang ◽  
Lijun Sun ◽  
Huailei Cheng
Keyword(s):  
Low Temperature ◽  
Dynamic Modulus ◽  
Hot Mix Asphalt ◽  
Raw Materials ◽  
Asphalt Binder ◽  
Variable Parameter ◽  
Bending Test ◽  
Design Parameters ◽  
Unconfined Compression Test ◽  
Aggregate Gradation

Aggregate gradation and asphalt type are traditional variables that affects mix design of Hot-Mix Asphalt (HMA). Recently, the number of design gyrations (Ndes) has been increasingly accepted as another variable parameter during the design process. Due to the growing shortage of high-quality raw materials, it is necessary to make full use of the combined roles between these design parameters, instead of solely relying on their individual effect, to improve the HMA properties. Therefore, this study comprehensively explored the effect of aggregate gradation, Ndes, and asphalt type on the performance of HMAs. Seven different combinations of aggregate gradation, Ndes, and asphalt type were evaluated. The volumetric indicators, uniaxial penetration shear test (UPST), unconfined compression test (UCT), low-temperature bending test (LBT), four-point bending test (FPBT), and dynamic modulus test (DMT) were used to assess the performance of HMAs designed by various parameter combinations. It was found that the contribution of adopting harder asphalt binder was able to make up for the high-temperature resistance loss caused by lower Ndes or coarser gradation. The dynamic modulus exhibited the similar phenomenon. By contrast, the harder asphalt binder led to the worse tenacity of HMAs at low temperature; however, the tenacity can be restored through using lower Ndes or coarser gradation by increasing asphalt content. In addition, the fatigue life of HMAs went up significantly by about 36 ~ 41%, when both Ndes and asphalt penetration grade decreased to one lower level.

Microscopic Evaluation of Salvia stepposa Des.- Schost above - ground part widespread in Kazakhstan

2021 ◽  
pp. 4773-4776
Author(s):  
Levaya Ya. K. ◽  
Ishmuratova M. Yu. ◽  
Atazhanova G. A. ◽  
Zilfikarov I. N. ◽  
Loseva I. V.
Keyword(s):  
Raw Materials ◽  
Microscopic Analysis ◽  
Raw Material ◽  
Medical Systems ◽  
Anatomical Structures ◽  
Anatomical Features ◽  
Mesophyll Structure ◽  
Microscopic Evaluation ◽  
Diagnostic Signs ◽  
Ground Part

Microscopic analysis of medicinal plants and raw materials is one of the stages of quality control which makes it possible to determine the authenticity of an object. This article presents the results of microscopic analysis of leaves, corolla, leafstalks and stalk of Salvia stepposa (steppe sage). This species is a relative to Salvia officinalis officinal used in traditional medical systems as an anti-inflammatory agent. The purpose of this study is to determine the features of the anatomical structures of the above-ground part of steppe sage and to reveal diagnostic signs at the microscopic level. Preliminary pharmacognostic investigation of vegetative raw material is done and diagnostic signs are identified. The detail microscopy revealed the presence of 3 types of trichomes on leaves’ epidermis: 1) simple unicellular; 2) simple multicellular; 3) glandular; their localization and shape are determined. Type of mesophyll, structure of trichomes; form and location of epidermal cells, the presence of rare simple trichomes along the edge are discovered. As a result of the research the anatomical features of the raw material were established, which make it possible to identify the above-ground part of Salvia stepposa and can be used for the development of regulatory documentation.

Review From Multiple Perspectives for the State of the Practice on the Use of Recycled Asphalt Materials and Recycling Agents in Asphalt Concrete Surface Mixtures

2021 ◽  
pp. 036119812110611
Author(s):  
Jhony Habbouche ◽  
Ilker Boz ◽  
Benjamin Shane Underwood ◽  
Cassie Castorena ◽  
Saqib Gulzar ◽  
...  
Keyword(s):  
Quality Control ◽  
Asphalt Concrete ◽  
Asphalt Binder ◽  
Concrete Surface ◽  
Lessons Learned ◽  
Multiple Perspectives ◽  
Recycled Asphalt ◽  
Recycled Materials ◽  
Continuous Quality ◽  
Virginia Department

The objective of this paper is to provide information from multiple perspectives on the current state of the practice with regard to using recycled materials and recycling agents (RAs) in asphalt concrete mixtures. This information was collected through a survey of U.S. transportation agencies and RA suppliers combined with a search of RA-related specifications and pilot projects previously constructed. Moreover, a case study describing the Virginia Department of Transportation’s experience with RAs provides a tangible example of how at least one agency is approaching the potential implementation of these technologies. This practice review was achieved by documenting the experience, lessons learned, and best practices of multiple asphalt experienced contractors and asphalt binder suppliers in the Virginia area. This paper follows a similar survey conducted in 2014 as part of NCHRP 09-58 and provides a second look at the use of RAs across North America. Not all state departments of transportation have experience with using RAs. Factors preventing the use of RAs included specification limitations, lack of expertise in processing recycled materials, supporting data, and negative prior experiences. Developing a performance-based testing framework is mandatory for the successful use of RAs. In general, good and frequent communication with the RA supplier is critical and necessary during the planning stages, the production of mixtures, and the continuous quality control by the supplier to resolve issues when they arise. Finally, a strong quality control and quality assurance-testing program should be implemented to ensure that materials meet the properties needed to produce a good-performing mixture.

scholarly journals Preparation of Portland Cement with Gold Ore Tailings

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Qiang Wang ◽  
Geng Yao ◽  
Xiangnan Zhu ◽  
Junxiang Wang ◽  
Peng Wu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Portland Cement ◽  
Raw Materials ◽  
Setting Time ◽  
Hydration Product ◽  
Difficult Problem ◽  
Initial Setting Time ◽  
Gold Ore ◽  
Curing Age

The disposal of gold ore tailings (GTs) has been a very difficult problem for a long time. Thus, this study explored a new approach to the management of GTs by preparing Portland cement. Physical properties, reaction mechanisms, and hydration product types of cement prepared with GTs (C-GTs) and ordinary Portland cement (C-SS) were compared. X-ray diffraction (XRD), thermogravimetric (TG), and scanning electron microscope energy-dispersive spectroscopy (SEM-EDS) analysis techniques were used to study the mineralogical phases of the clinker and raw materials, hydration product types, and microtopography. The consistency, setting time, flexural strength and compressive strength values of the cement samples (C-GTs and C-SS), and burnability of the raw materials were also studied. The burnability analysis indicated that GTs provided a higher reactivity. The XRD results showed that the clinker phases of the C-GTs were C3S, C2S, C3A, and C4AF. The XRD, TG, and SEM-EDS results showed that the hydration products were flaky calcium hydroxide, rod-shaped ettringite, and granular C-S-H gels. Its compressive strength and flexural strength were, respectively, 30.4 MPa and 6.1 MPa at the curing age of 3 days and 59.1 MPa and 9.8 MPa at the curing age of 28 days, which were slightly higher than those of the C-SS. Furthermore, the results showed that the consistency, initial setting time, and final setting time for the two kinds of cement were similar, which further suggested that GTs could be used to prepare Portland cement.

scholarly journals Investigation of Cement-Emulsified Asphalt in Plastic Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Xiaohu Yan ◽  
Zaiqin Wang ◽  
Meijuan Rao ◽  
Mingxia Li
Keyword(s):  
Compressive Strength ◽  
Ct Scanning ◽  
Mean Value ◽  
X Ray Diffraction ◽  
Asphalt Cement ◽  
Time Scanning ◽  
Plastic Concrete ◽  
Gradual Development ◽  
Compressive Strength Of Concrete ◽  
Emulsified Asphalt

The mechanical, mesodamage, and the microproperties of cement-emulsified asphalt concrete have been investigated by computed tomography (CT), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TG) in this work. Emulsified asphalt delayed the hydration of cement, making the early compressive strength of concrete develop slowly. However, the concrete compressive strength increased rapidly with the demulsification of emulsified asphalt. The damage stages of condense, expansion of volume, rapid crack propagation, and damage by real-time scanning have been observed. The CT mean value of the place near the lower end face suffered a larger decline but a smaller decline to the upper part of the sample. The evolution of concrete suffering damage to failure is a gradual development process, and no sharp expansion of brittle failure. The unhydrated cement, incorporation asphalt, fibrous C–S–H gel, CH, needle-shaped ettringite, and other hydration products were interwoven to constitute emulsified asphalt-cement paste, forming a spatial structure.

scholarly journals Study on the Parameter Optimization and Strength Mechanism of Coal Gangue Emulsified Asphalt Mixture

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
ZhanLiang Liu ◽  
Chen Zhang ◽  
Xin Qu
Keyword(s):  
Power Plants ◽  
Coupling Effect ◽  
Asphalt Mixture ◽  
Microscopic Analysis ◽  
Coal Gangue ◽  
Orthogonal Experimental Design ◽  
Water Stability ◽  
Use Of Resources ◽  
Emulsified Asphalt

Emulsified asphalt mixture has the characteristics of convenient construction and durable performance, but its poor early strength and demulsification seriously restrict the popularization and application of this material. At present, the coal gangue produced by coal-fired power plants is generally discarded, resulting in serious environmental pollution. The combination of coal gangue and emulsified asphalt can explore an efficient utilization way for more and more coal gangue and also solve the curing problem of asphalt. In order to give full play to the advantages of existing materials and make rational use of resources, this paper studies the factors affecting the performance of coal gangue emulsified asphalt mixture based on orthogonal experimental design and optimizes its material composition parameters by considering the coupling effect of two factors. The water stability of coal gangue emulsified asphalt mixture is evaluated by the immersion Marshall test. Finally, the strength formation mechanism of coal gangue emulsified asphalt mixture is analyzed from the microscopic point of view. The results determined 7.5% as the optimum amount of emulsified asphalt in coal gangue emulsified asphalt mixture and recommended the best parameter combination of 7.5% emulsified asphalt, 6% coal gangue, and 5% water consumption. With the increase of coal gangue content, the water loss resistance of emulsified asphalt mixture increases gradually, and the water stability of emulsified asphalt mixture can be improved by adding coal gangue. According to the microscopic analysis, the strength of the mixture is formed by the joint action of emulsified asphalt and coal gangue, in which the hydration products of coal gangue and asphalt play the role of cementation and strength together. The ordinary emulsified asphalt mortar mainly contains CaCO3, which mainly plays the role of physical filling.

scholarly journals Development, Performance, and Microscopic Analysis of New Anchorage Agent with Heat Resistance, High Strength, and Full Length

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Xiaohu Liu ◽  
Zhishu Yao ◽  
Weipei Xue ◽  
Xiang Li
Keyword(s):  
Compressive Strength ◽  
Coupling Agent ◽  
Silane Coupling Agent ◽  
Raw Materials ◽  
Microscopic Analysis ◽  
High Strength ◽  
Full Length ◽  
Technical Problems ◽  
Silane Coupling ◽  
Different Temperatures

To solve the difficult problems of failure of pretensioned bolt supports under high ground pressure and temperature, a new kind of anchorage agent with excellent performance is developed. First, the selection and compounding of raw materials were conducted. The new anchorage agent was obtained by modifying the PET resin by mixing with a phenolic epoxy vinyl ester resin (FX-470 resin) and adding a KH-570 silane coupling agent. Then, the viscosity, thermal stability, compressive strength under different temperatures, and anchorage capacity of the new anchorage agent were tested. Moreover, the best proportion ratio of anchorage agent by mixing resin : coarse stone powder : fine stone powder : accelerator : curing agent : KH-570 = 100 : 275 : 275 : 1 : 32.5 : 1 is obtained. The test results showed that, with the addition of a KH-570 silane coupling agent, the viscosity decreased significantly, thereby solving the difficult technical problems of pretensioned bolt supports in full-length anchorage support. Compared with the conventional anchorage agent, the compressive strength of the new anchorage agent increased by 20.4, 82.5, 118.2, and 237.5% at 10, 50, 80, and 110°C, respectively, and the anchorage capacity increased by 4.7, 8.7, 40.2, and 62.9% at 30, 50, 80, and 110°C, respectively. Finally, the enhancement in compressive strength and heat-resistant mechanism are revealed through microanalysis.

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