scholarly journals Strength Mechanism and Influence Factors for Cold Recycled Asphalt Mixture

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Tao Ma ◽  
Hao Wang ◽  
Yongli Zhao ◽  
Xiaoming Huang ◽  
Yuhui Pi
Keyword(s):  
Tensile Strength ◽  
Asphalt Mixture ◽  
Influence Factors ◽  
High Viscosity ◽  
Asphalt Mixtures ◽  
Key Factors ◽  
Recycled Asphalt ◽  
Factors Affecting ◽  
Surface Areas ◽  
Emulsified Asphalt

This study focused on the key factors affecting the tensile strength of cold recycled asphalt mixture with cement and emulsified asphalt. The specific surface areas and strength of RAP were analyzed. The interaction between the emulsified asphalt and cement was observed. Comprehensive laboratory testing was conducted to evaluate the influences of RAP, emulsified asphalt, and cement on the tensile strength of cold recycled asphalt mixture. It is found that although RAP is used as aggregates, its inner structure and strength are much different from real aggregates. The strength of RAP has decisive effect on the strength of cold recycled asphalt mixture. New aggregates and fine gradation design can help improve the bonding between RAP and binder. For emulsified asphalt, slow setting of asphalt can give sufficient time for cement to hydrate which is helpful for strength formation in the cold recycled asphalt mixture. The high viscosity of asphalt can improve the early strength of cold recycled asphalt mixture that is important for traffic opening in the field. Cement is an efficient additive to improve the strength of cold recycled asphalt mixtures by promoting demulsification of emulsified asphalt and producing cement hydrates. However, the cement content is limited by RAP.

scholarly journals Effects of Cement and Emulsified Asphalt on Properties of Mastics and 100% Cold Recycled Asphalt Mixtures

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 754 ◽  
Author(s):  
Yanan Li ◽  
Yuchao Lyv ◽  
Liang Fan ◽  
Yuzhen Zhang
Keyword(s):  
Tensile Strength ◽  
Rheological Properties ◽  
Subsurface Layer ◽  
Temperature Stability ◽  
Asphalt Mixtures ◽  
Mineral Filler ◽  
High Temperature Stability ◽  
Recycled Asphalt ◽  
Technical Specifications ◽  
Emulsified Asphalt

Cold recycled asphalt mixtures (CRAM) are a cost-effective and environmentally-friendly way to reuse reclaimed asphalt pavement (RAP). This paper evaluates the rheological properties and microstructure of mineral filler-asphalt mastic, mineral filler-residue mastic, and cement-residue mastic. Then, based on the premise of using 100% RAP with a gradation that was determined experimentally, the effects of emulsified asphalt and cement on the porosity, indirect tensile strength, tensile strength ratio, dynamic stability, and mechanical properties of CRAM were evaluated. It was found that the rheological properties and cohesive coefficient of the cement-residue mastic varied differently to those of the first two types of mastic and the results show that the addition of cement can greatly improve the interfacial bonding between binders and fillers in the mastic, thereby improving the water damage resistance and high-temperature stability of CRAM. The relationships between cement content and the dynamic modulus and phase angle of CRAM are different to that for emulsified asphalt obviously. In addition, under certain conditions, the properties of CRAM can meet the requirements of relevant technical specifications for its application to subsurface layer of pavement. Hence, the use of 100% RAP in CRAM may be feasible.

scholarly journals Laboratory Evaluation of the Use of Florida Washed Shell in Open-Graded Asphalt Mixtures

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7060
Author(s):  
Mohammad Alharthai ◽  
Qing Lu ◽  
Ahmed Elnihum ◽  
Asad Elmagarhe
Keyword(s):  
Tensile Strength ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Indirect Tensile Strength ◽  
Laboratory Evaluation ◽  
Void Content ◽  
Coarse Aggregates ◽  
Significant Difference ◽  
Indirect Tensile ◽  
Marshall Stability

This study investigates the substitution of conventional aggregate with a Florida washed shell in open-graded asphalt mixtures and evaluates the optimal substitution percentage in aggregate gradations of various nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm). Laboratory experiments were performed on open-graded asphalt mixture specimens with the coarse aggregate of sizes between 2.36 and 12.5 mm being replaced by the Florida washed shell at various percentages (0, 15, 30, 45, and 100%). Specimen properties relevant to the performance of open-graded asphalt mixtures in the field were tested, evaluated, and compared. Specifically, a Marshall stability test, Cantabro test, indirect tensile strength test, air void content test, and permeability test were conducted to evaluate the strength, resistance to raveling, cracking resistance, void content, and permeability of open-graded asphalt mixtures. The results show that there is no significant difference in the Marshall stability and indirect tensile strength when the coarse aggregates are replaced with Florida washed shell. This study also found that the optimum percentages of Florida washed shell in open-graded asphalt mixture were 15, 30, and 45% for 12.5, 9.5, and 4.75 mm NMAS gradations, respectively.

scholarly journals Research on key influence factors of creativity development of applied undergraduates based on PCA

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Xiangmin Ren ◽  
Jingwei Yu
Keyword(s):  
Principal Component Analysis ◽  
Influence Factors ◽  
Principal Component ◽  
Heilongjiang Province ◽  
Key Factors ◽  
Factors Affecting ◽  
The Core ◽  
Creativity Development ◽  
Teachers And Students ◽  
Core Characteristics

Abstract Creativity is one of the core characteristics of talent; for this reason, the creativity development of applied undergraduates should be one of the basic components of their education. This article gives an overview of the meaning of the creativity of applied undergraduates and makes a literature knowledge-mining and expert investigation on the factors affecting the creativity development. We obtained more than 100 influencing factors, filtered out the duplicative factors, and formed the remaining factors into a questionnaire. A survey was conducted among 1460 teachers and students of some applied undergraduates in Heilongjiang Province. By using principal component analysis (PCA) to analyse the questionnaire, the key factors that affect the creativity development of applied undergraduates are obtained, and the key factors are systematically analysed. According to the results of the analysis, the specific ways and methods of the creativity development of applied undergraduates are put forward.

EVALUATION OF THE HIRSCH MODEL FOR DYNAMIC MODULUS ESTIMATION OF ASPHALT MIXTURES

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Hassan Malekzehtab ◽  
Hamid Nikraz
Keyword(s):  
Western Australia ◽  
Dynamic Modulus ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Recycled Asphalt ◽  
Asphalt Mixture Performance Tester ◽  
Comparison Of The Results ◽  
Asphalt Concrete Pavement ◽  
Cylindrical Samples ◽  
Do So

The dynamic modulus of the asphalt mixtures is an important factor in designing or analyzing an asphalt concrete pavement, but it is expensive and time consuming to measure. Therefore, it is important to develop a model to predict this value. In this regard, the Hirsch model is a popular model, however, it is developed based on a range of U.S. asphalt mixtures and standards. Therefore, it is not certain that it can be used for asphalt mixtures based on materials and codes other than U.S. This article investigated whether this model performs satisfactorily with two typical asphalt mixtures in Western Australia (WA) containing 0, 10, 20, and 30% of recycled asphalt pavement. To do so, cylindrical samples were made with materials and locally established standards in Western Australia and then tested in Asphalt Mixture Performance Tester (AMPT) machine to acquire their dynamic modulus and phase angle values in different loading frequencies (0.01 to 10 Hz) and temperatures (4 to 40°C). Meanwhile, the results are estimated by the Hirsch model using some properties of the mixture and binder. The properties of the binder in different test conditions are obtained using a dynamic shear rheometer. The comparison of the results showed that the dynamic modulus underestimation or overestimation error can reach to 50 and 280% respectively. Generally, this model did not perform well in this study.

Study of Water Stability of AC and SMA Asphalt Mixture Based on Water Content

2012 ◽  
Vol 457-458 ◽  
pp. 435-438
Author(s):  
Xue Dong Guo ◽  
Cao Jian ◽  
Xiang Yang Fang
Keyword(s):  
Tensile Strength ◽  
Water Content ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Splitting Tensile Strength ◽  
Water Stability ◽  
Paper Study ◽  
Saturated Condition ◽  
Maximum Water ◽  
Maximum Water Content

In this paper，study water content and water stability of AC and SMA asphalt mixtures, and reach the following conclusions. In the normal saturated condition, the maximum water content of AC and SMA asphalt mixture is 0.28% and 0.32%.And in the vacuum saturated condition, the maximum water content of AC and SMA asphalt mixture is 0.8% and 0.78%.The water of AC and SMA asphalt mixture separately take 8 days and 9 days to drain completely in the normal saturated condition. But in the vacuum saturated condition, the time is more than two months. In different water content conditions, the splitting tensile strength of AC asphalt mixture is 0%> 100%> 25%> 75%> 50%.But the splitting tensile strength of SMA asphalt mixture is 0%> 100%> 25%> 50%> 75%.

Research on Performance of Emulsion Asphalt Cold Reclaimed Mixture with Various RAP Contents

2011 ◽  
Vol 255-260 ◽  
pp. 3432-3436
Author(s):  
Xian Yuan Tang ◽  
Jie Xiao
Keyword(s):  
Tensile Strength ◽  
Low Temperature ◽  
Compression Test ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Indirect Tensile Strength ◽  
Beam Test ◽  
Reclaimed Asphalt ◽  
Indirect Tensile ◽  
The Impact

This paper systematically elaborates the impact upon performance of emulsion asphalt cold reclaimed asphalt mixture by different RAP contents, through a series of testing on six cold reclaimed asphalt mixtures with various RAP contents, such as single axle compression test, 15°C indirect tensile strength (ITS) test, 40°C rutting test and -10°C low-temperature bending beam test. Testing results indicate that 15°C ITS decreases from around 0.75 MPa to 0.58 MPa with the RAP content of mixture increasing from 0% to 100%. 40°C dynamic stabilities reduce considerably from around 19,000 time/mm of 0% RAP mixture to 3,600 time/mm of 100% RAP mixture. -10°C failure strains only change from 1500με to 2000με.

Experimental Study on Mechanical Properties of Recycled Asphalt Mixture with Different Proportion of Rubber Powder

2013 ◽  
Vol 368-370 ◽  
pp. 933-938 ◽  
Author(s):  
Qi Ying Niu ◽  
Jun Yong Zhao ◽  
Ru Kai Li
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Tensile Strength ◽  
Bending Strength ◽  
Asphalt Mixture ◽  
Crumb Rubber ◽  
Rubber Content ◽  
Recycled Asphalt ◽  
Rubber Powder ◽  
Different Content

Through a series of mechanical properties experiment of recycled asphalt mixture composed of waste asphalt mixture 20% and different content of rubber powder, the paper analyzes and compares the elasticity, tensile strength and bending strength of asphalt mixture and recycled asphalt mixture, concluding that recycled asphalt mixture that mixed with crumb rubber content of 20% can completely replace the new asphalt mixture in the application. It has great significance for the future to recycling waste asphalt mixture in the highway.

Microstructural analysis of asphalt mixtures using digital image processing techniques

2014 ◽  
Vol 41 (1) ◽  
pp. 74-86 ◽  
Author(s):  
Ki Hoon Moon ◽  
Augusto Cannone Falchetto ◽  
Jin Hoon Jeong
Keyword(s):  
Image Processing ◽  
Digital Image Processing ◽  
Digital Image ◽  
Microstructural Analysis ◽  
Asphalt Mixture ◽  
Material Model ◽  
Asphalt Mixtures ◽  
Recycled Asphalt ◽  
Air Voids ◽  
Processing Techniques

In this paper, the internal microstructure of asphalt mixture is analyzed through digital image processing (DIP) of two-dimensional asphalt mixture images. A set of 12 mixtures prepared with two binders, two air voids percentages, and different recycled asphalt pavement (RAP) contents is used. First, small asphalt mixture beams of the same size of bending beam rheometer specimens are prepared for the images acquisition. Then, based on mixture volumetric properties, a three-phase material model is obtained. Finally, 2- and 3-point correlation functions of the material phases are numerically evaluated. No significant differences were observed in the microstructure and spatial distributions of aggregates, asphalt mastic, and air voids for asphalt mixtures containing up to 40% of RAP. However, an increase in auto correlation length (ACL) was found for RAP mixtures in comparison with the conventional mixtures.

scholarly journals Experimental Study on Photocatalytic Effect of Nano TiO2 Epoxy Emulsified Asphalt Mixture

2019 ◽  
Vol 9 (12) ◽  
pp. 2464 ◽  
Author(s):  
Ming Huang ◽  
Xuejun Wen
Keyword(s):  
Degradation Rate ◽  
Asphalt Mixture ◽  
Influence Factors ◽  
Tio2 Particle ◽  
Exhaust Gas ◽  
Vehicle Exhaust ◽  
Nano Tio2 ◽  
Photocatalytic Effect ◽  
Photocatalytic Material ◽  
Emulsified Asphalt

The two major problems that have plagued urban underground roads since their introduction are the harmful emissions caused by hot mix paving and vehicle exhaust accumulation during operation. In order to solve these two problems at the same time, a new asphalt mixture degrading automobile exhaust, which has the advantage of cold mix and cold-application, was presented and studied. A considerable amount of research shows that the use of titanium dioxide (TiO2) for pavements has received considerable attention in recent years to improve air quality near large metropolitan areas. However, the proper method of applying TiO2 to asphalt pavements is still unclear. The new mixture presented in this article contains epoxy emulsified asphalt as the binder; therefore, how to apply TiO2 in the special asphalt mixture proves to be the main focus. By experimental design, four influence factors on the photocatalytic effect, which are the nano-TiO2 particle sizes, dosage, degradation time, and light intensity, have been investigated. The experimental results showed that the 5-nm particle size of TiO2 is better than 10–15 nm for exhaust gas degradation, especially for HC and NO; with an increase in the amount of photocatalytic material, the degradation of CO and CO2 in the exhaust gas did not increase obviously, while the degradation effects of HC and NO were remarkable; in the 4-h time extended degradation test, the experimental data show that the extended time has little effect on the degradation rate of CO2 and CO, and the general trend is that the degradation of exhaust became significant with the extension of time; while setting a 2-h NO degradation rate as an indicator, to make the index more than 50% or 25%, the average illumination of the road surface cannot be less than 60 lx or 40 lx.

scholarly journals Further Investigation on Damage Model of Eco-Friendly Basalt Fiber Modified Asphalt Mixture under Freeze-Thaw Cycles

2018 ◽  
Vol 9 (1) ◽  
pp. 60 ◽  
Author(s):  
Wensheng Wang ◽  
Yongchun Cheng ◽  
Guirong Ma ◽  
Guojin Tan ◽  
Xun Sun ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Asphalt Mixture ◽  
Basalt Fiber ◽  
Asphalt Mixtures ◽  
Splitting Tensile Strength ◽  
Stiffness Modulus ◽  
Freeze Thaw ◽  
Damage Characteristics ◽  
Indirect Tensile

The main distresses of asphalt pavements in seasonally frozen regions are due to the effects of water action, freeze-thaw cycles, and so on. Basalt fiber, as an eco-friendly mineral fiber with high mechanical performance, has been adopted to reinforce asphalt mixture in order to improve its mechanical properties. This study investigated the freeze-thaw damage characteristics of asphalt mixtures reinforced with eco-friendly basalt fiber by volume and mechanical properties—air voids, splitting tensile strength, and indirect tensile stiffness modulus tests. Test results indicated that asphalt mixtures reinforced with eco-friendly basalt fiber had better mechanical properties (i.e., splitting tensile strength and indirect tensile stiffness modulus) before and after freeze-thaw cycles. Furthermore, this study developed logistic damage models of asphalt mixtures in terms of the damage characteristics, and found that adding basalt fiber could significantly reduce the damage degree by about 25%, and slow down the damage grow rate by about 45% compared with control group without basalt fiber. Moreover, multi-variable grey models (GM) (1,N) were established for modelling the damage characteristics of asphalt mixtures under the effect of freeze-thaw cycles. GM (1,3) was proven as an effective prediction model to perform better in prediction accuracy compared to GM (1,2).

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