scholarly journals Gradual Meso-Structural Response Behaviour of Characteristics of Asphalt Mixture Main Skeleton Subjected to Load

2019 ◽  
Vol 9 (12) ◽  
pp. 2425 ◽  
Author(s):  
Liwan Shi ◽  
Zhen Yang ◽  
Duanyi Wang ◽  
Xiao Qin ◽  
Xin Xiao ◽  
...  
Keyword(s):  
Particle Size ◽  
Asphalt Mixture ◽  
Structural Response ◽  
Load Resistance ◽  
Development Trend ◽  
Design Criteria ◽  
Coarse Aggregates ◽  
Response Behaviour ◽  
Contact Points ◽  
C Value

In order to provide a reference for the gradation design of dense skeleton asphalt mixtures (DSAM), this study conducts a thorough analysis of the gradual meso-structural response behaviour of characteristics of the asphalt mixture main skeleton subjected to load using the digital image processing (DIP) technique. Moreover, gradation optimisation measures and the design criteria of mesoscopic evaluation indices for the main skeleton are proposed. The results indicate that aggregates with particle sizes of 2.36–4.75 mm can effectively increase the number of contact points; however, the stability of the main skeleton remains insufficient. Furthermore, coarse aggregates with a particle size larger than 4.75 mm provide the most significant contribution to the formation of a steady main skeleton; this is the critical particle size for the formation of a steadier main skeleton. Gradation is the major determinant of mesoscopic evaluation indices, including average coordination number ( n ¯ c ) and the ratio of the quantity of coarse aggregates without contact points to the total quantity of coarse aggregates (C value) for the asphalt mixture of the main skeleton. On the other hand, the performance of asphalt has an insignificant influence on mesoscopic evaluation indices; it mainly affects the development trend of macroscopic rutting. In the design process of DSAM, it is necessary to optimise gradation with the aim of increasing n ¯ c and reducing the C value so as to enhance the load resistance capacity of the primary skeleton. When preparing asphalt mixture specimens using the wheel rolling method, the design criteria for the aforementioned indices are n ¯ c ≥ 1.5 and C ≤ 15%, which can be used as bases for the design of DSAM with a nominal maximum particle size of 13.2 mm to ensure that the coarse aggregates are interlocked and form a steady main skeleton.

Comparison Analysis of the Aggregate Contact Characteristics between Skeleton-Dense and Suspended-Dense Structure Asphalt Mixture

2013 ◽  
Vol 470 ◽  
pp. 889-892 ◽  
Author(s):  
Li Wan Shi ◽  
Duan Yi Wang ◽  
Julius Masley ◽  
Shu Wen Zhang
Keyword(s):  
Asphalt Mixture ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Homogeneous Distribution ◽  
Test Results ◽  
Dense Structure ◽  
Rutting Resistance ◽  
Two Dimension ◽  
Coarse Aggregates ◽  
Contact Points

The contact between aggregates is an important feature of asphalt mixture skeleton. By comparing skeleton-dense and suspended-dense structure asphalt mixture test results, this paper studied the distribution characteristics of coarse aggregate contacts by using two-dimension digital image processing technique. The results indicate that skeleton-dense asphalt mixture has more homogeneous distribution of contact points, and a relatively stable skeleton structure than suspended-dense mixture. In two-dimension image, homogeneous distribution of contact points and little unrestrained coarse aggregates are two evident characteristics of asphalt mixture with good rutting resistance. The rutting resistance of asphalt mixture has no correlation with contact points, but is related to the spatial distribution of the contact points.

scholarly journals Evaluation of the Effects of Filler Fineness on the Properties of an Epoxy Asphalt Mixture

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2003
Author(s):  
Wei Xu ◽  
Jintao Wei ◽  
Zhengxiong Chen ◽  
Feng Wang ◽  
Jian Zhao
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
Asphalt Mixture ◽  
Average Particle ◽  
Fine Dust ◽  
Bonding Structure ◽  
Epoxy Asphalt ◽  
Mineral Powder ◽  
Marshall Stability ◽  
Mixture Sample

The type and fineness of a filler significantly affect the performance of an asphalt mixture. There is a lack of specific research on the effects of filler fineness and dust from aggregates on the properties of epoxy asphalt (EA) mixtures. The effects of aggregate dust and mineral powder on the properties of an EA mixture were evaluated. These filler were tested to determine their fineness, specific surface area and mineral composition. The effects of these fillers on the EA mastic sample and mixture were evaluated. The morphology of the EA mastic samples was analyzed using scanning electron microscopy (SEM). The effects of the fillers on the Marshall stability, tensile strength and fatigue performance of the EA mixture were evaluated. The dust from the aggregates exhibited an even particle size distribution, and its average particle size was approximately 20% of that of the mineral powder. The SEM microanalysis showed that the EA mastic sample containing relatively fine dust formed a tight and dense interfacial bonding structure with the aggregate. The EA mixture sample containing filler composed of dust from aggregate had a significantly higher strength and longer fatigue life than that of the EA sample containing filler composed of mineral powder.

Effects of maximum particle size of coarse aggregates and steel fiber contents on the mechanical properties and impact resistance of recycled aggregate concrete

2021 ◽  
pp. 136943322110179
Author(s):  
DongTao Xia ◽  
ShaoJun Xie ◽  
Min Fu ◽  
Feng Zhu
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Steel Fiber ◽  
Impact Resistance ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Maximum Particle Size ◽  
Maximum Particle

Fiber reinforced recycled aggregate concrete has become a new type of green concrete material. The maximum particle size of coarse aggregates and steel fiber contents affect the mechanical properties and impact resistance of recycled aggregate concrete. However, such studies are rare in literature. The present paper shortens the gap through experimental study. A total of 144 specimens of 12 kinds of concrete mixtures were tested, which adopted different steel fiber volume admixtures (0%, 0.8%, 1.0%, 1.2%) and recycled coarse aggregates in different maximum particle sizes (9.5, 19, 31.5 mm) replacing 30% natural coarse aggregate. The compressive strength, splitting tensile strength, and impact resistance of the 12 concrete mixtures were tested. The results showed that the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete increased first and then decreased with the increase of the maximum particle size. The recycled aggregate concrete with the maximum particle size of 19 mm had the highest mechanical properties and impact resistance. Besides, with the increase of steel fiber content, the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete showed an increasing trend. Considering a large amount of experimental data and the coupling effect of steel fiber contents and the maximum particle size of coarse aggregates, the Weibull distribution function was introduced to analyze the impact test results and predict the number of resistance to impact under different failure probabilities. The results showed that the number of blows of the recycled aggregate concrete followed a two-parameter Weibull distribution, and the estimated value of the number of resistance to impact for failure increased with the increase of the failure probability.

scholarly journals Chemical and Physical Properties of Limestone Powder as a Potential Microfiller of Polymer Composites

2017 ◽  
Vol 63 (2) ◽  
pp. 67-78 ◽  
Author(s):  
M. Kępniak ◽  
P. Woyciechowski ◽  
W. Franus
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Physical Properties ◽  
Polymer Composites ◽  
Asphalt Mixture ◽  
Limestone Powder ◽  
Coarse Aggregates ◽  
Mineral Powder ◽  
Materials Used ◽  
Scanning Electron

Abstract The preliminary stage of asphalt mixture production involves the drying and dedusting of coarse aggregates. The most common types of coarse aggregates used are limestone and basalt. In the process of drying and dedusting the dryer filter accumulates large quantities of waste in the form of mineral powder. This paper introduces an investigation into limestone powder waste as a potential microfiller of polymer composites. Physical characteristics such as the granulation the of powder collected from the filter - in terms of the season of its collection and the type of input materials used - were analysed. A scanning electron microscope (SEM) was used for the investigation described within this paper. The obtained results were compared against those of other materials which can be used as polymer composites microfillers.

Wellbore Strengthening Design Criteria and Enhanced Fracture Gradient for Widening Stable Mud Weight Window and Enabling Safe and Efficient Drilling in Depleted Reservoirs

2021 ◽  
Author(s):  
Chee Phuat Tan ◽  
Wan Nur Safawati Wan Mohd Zainudin ◽  
M Solehuddin Razak ◽  
Siti Shahara Zakaria ◽  
Thanavathy Patma Nesan ◽  
...  
Keyword(s):  
Particle Size ◽  
Ct Scan ◽  
Design Criteria ◽  
Drilling Mud ◽  
Fracture Width ◽  
Wellbore Strengthening ◽  
Fracture Gradient ◽  
Mud Loss ◽  
Gradient Enhancement ◽  
Compound Particle

Abstract Drilling in permeable formations, especially depleted reservoirs, can particularly benefit from simultaneous wellbore shielding and strengthening functionalities of drilling mud compounds. The ability to generate simultaneous wellbore shielding and strengthening in reservoirs has potential to widen stable mud weight windows to drill such reservoirs without the need to switch from wellbore strengthening compound to wellbore shielding compound, and vice-versa. Wellbore shielding and strengthening experiments were conducted on three outcrop sandstones with three mud compounds. The wellbore shielding stage was conducted by increasing the confining and borehole pressures in 4-5 steps until both reached target pressures. CT scan images demonstrate consistency of the filtration rates with observed CT scanned mud cakes which are dependent on the sandstone pore size and mud compound particle size distributions. In wellbore strengthening stage, the borehole pressure was increased until fracture was initiated, which was detected via borehole pressure trend and CT scan imaging. The fractures generated were observed to be plugged by mud filter solids which are visible in the CT scan images. The extent of observed fracture solid plugging varies with rock elastic properties, fracture width and mud compound particle size distribution. Based on the laboratory test data, fracture gradient enhancement concept was developed for the mud compounds. In addition, the data obtained and observations from the tests were used to develop optimal empirical design criteria and guidelines to achieve dual wellbore strengthening and shielding performance of the mud compounds. The design criteria were validated on a well which was treated with one of the mud compounds based on its mud loss events during drilling and running casing.

scholarly journals Review on Applications of Lignin in Pavement Engineering: A Recent Survey

2022 ◽  
Vol 8 ◽  
Author(s):  
Hui Yao ◽  
Yiran Wang ◽  
Junfu Liu ◽  
Mei Xu ◽  
Pengrui Ma ◽  
...  
Keyword(s):  
Low Cost ◽  
Asphalt Mixture ◽  
Complex Mixture ◽  
Development Trend ◽  
Environmental Benefits ◽  
Extraction Technology ◽  
Environmental Friendliness ◽  
Modified Asphalt ◽  
Soil Stabilizer ◽  
Pavement Engineering

Lignin is the second-largest plant polymer on Earth after cellulose. About 98% of lignin produced in the papermaking and pulping industry is used for combustion heating or power generation. Less than 2% of lignin is used in more valuable fields, mainly in the formulation of dispersants, adhesives, and surfactants. Asphalt is one of the most important materials in pavement engineering. It is a dark brown complex mixture composed of hydrocarbons with different molecular weights and their non-metallic derivatives. Because the chemical structure of lignin is similar to that of asphalt, it is a carbon-based hydrocarbon material. More researchers studied the application of lignin in pavement engineering. In this paper, the structure, application, and extraction technology of lignin were summarized. This is a review article describing the different applications of lignin in pavement engineering and exploring the prospects of the application. There are three main types of pavement materials that can be used for lignin in pavement engineering, which are asphalt, asphalt mixture, and roadbed soil. In asphalt, lignin can be used as a modifier, extender, emulsifier, antioxidant, and coupling agent. In asphalt mixtures, lignin can be used as an additive. In road base soils, lignin can be used as a soil stabilizer. Furthermore, the article analyzed the application effects of lignin from the life cycle assessment. The conclusions suggest that lignin-modified asphalt exhibits more viscosity and hardness, and its high-temperature resistance and rutting resistance can be significantly improved compared with conventional asphalt. In addition, some lignin-modified asphalt binders exhibit reduced low-temperature crack resistance and fatigue resistance, which can be adjusted and selected according to the climate change in different regions. The performance of lignin as an asphalt mixture additive and asphalt extender has been proved to be feasible. Lignin can also produce good mechanical properties as well as environmental benefits as a soil stabilizer. In summary, lignin plays an important role in asphalt pavement and roadbed soil, and it is likely to be a development trend in the future due to its environmental friendliness and low cost. More research is needed to generalize the application of lignin in pavement engineering.

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 The use of Crushed Waste Glass as a Partial Replacement of Fine Aggregates in Asphalt Concrete Mixtures (Glassphalt)

2021 ◽  
pp. 1-10
Author(s):  
Gbadamosi Aderemi Tobi ◽  
Ogunsuyi Raphael Abidemi ◽  
Ojo Meshach Felix
Keyword(s):  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Waste Glass ◽  
Partial Replacement ◽  
Glass Waste ◽  
Coarse Aggregates ◽  
Rapid Economic Growth ◽  
Marshall Test ◽  
Bitumen Content ◽  
Asphalt Mix

With the rapid economic growth and continuously increased consumption, a large amount of glass waste materials is generated; this study investigated the effect of crushed waste glass as filler and also as an aggregate in the asphalt binder course. It compares the glassphalt mix with the specification range at different percentages to meet specifications limit according to Nigeria roads and bridges reverse book of 1997 Waste glass are cleaned and crushed from the glass bottles and added to the asphalt as a filler and as a replacement for coarse aggregates, the marshal method is used to determine the optimum bitumen content and evaluate the properties of the asphalt mix. However, 24 samples were prepared in total, 12 samples each for the asphalt mix used to determine the optimum bitumen content and the other 12 samples for the glassphalt mix used to find out the effect of adding the different percentages of crushed waste glass to the asphalt mixture. The Marshall test carried out on the asphalt mixtures showed that the optimum bitumen content of bitumen was found out to be 6.2% of the asphalt mix by weight. Also, Marshall Test carried out on the glassphalt mix showed the optimum percentage of glass used in the binder course of the weights of aggregates in the asphalt mix. The result of this experiment is been checked to be consistent with the Nigeria road and bridges reverse book of 1997, i.e. Marshall Stability, flow, bulk density, and air voids.

An approach to investigate coarse aggregates movement of asphalt mixture based on wheel tracking test

2021 ◽  
Vol 309 ◽  
pp. 125161
Author(s):  
Wenchang Liu ◽  
Hongwei Lin ◽  
Hongyu Guo ◽  
Hongchao Zhang ◽  
Shuguang Zhang ◽  
...  
Keyword(s):  
Asphalt Mixture ◽  
Coarse Aggregates ◽  
Wheel Tracking Test ◽  
Wheel Tracking
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