HW3 CCE321 Fall2023 Asphalt
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Oregon State University, Corvallis *
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Course
321
Subject
Industrial Engineering
Date
Feb 20, 2024
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6
Uploaded by meyemaxw
Maxwell Meyer 1 HW- Asphalt Mix Design (100 points) 1.
Explain the production process of asphalt binder in your own words. (10 points) Asphalt binder, also known as bitumen, is a crucial component in the production of asphalt concrete. The production process of asphalt binder involves several key steps, including extraction, refining, and modification. The first step in the production process of asphalt binder is the extraction of crude oil from natural reserves. It is extracted through drilling operations in oil fields and then transported to refineries for further processing. Once the crude oil is extracted, it undergoes a refining process at oil refineries. During refining, crude oil is heated in a distillation tower to separate it into various components based on their boiling points. This process results in the production of different petroleum products, including gasoline, diesel, jet fuel, and asphalt binder. After the refining process, the production of asphalt binder involves specifically processing the heavy fractions of crude oil. In some cases, asphalt binder may undergo modification and blending to enhance its performance characteristics. Then Various tests are conducted to assess the viscosity, penetration, ductility, and other physical properties of the binder to ensure its suitability for use in asphalt pavement construction. Once the asphalt binder has been produced and tested, it is packaged into containers or transported in bulk form to distribution centers or directly to construction sites. 2.
Explain the steps involved in the mix design of asphalt concrete based on the Superpave method. Also, show the flow chart of the mix design. (10 points)
The first step in the Superpave mix design process is to select the appropriate aggregates for the asphalt mixture. This involves evaluating the properties of available aggregates, including their gradation, shape, and texture. The Superpave method emphasizes the use of aggregates that can withstand high traffic loads and environmental conditions. The next step is to select the appropriate asphalt binder for the mixture. The Superpave method considers factors such as traffic levels, climate, and aging characteristics when choosing the binder. The selection is based on performance grading (PG) system, which categorizes binders based on their high and low-
temperature performance. Once the aggregates and binder are selected, a comprehensive mix design analysis is conducted. This involves determining the volumetric properties of the mixture, including air voids, voids in mineral aggregate (VMA), voids filled with asphalt (VFA), and others. These properties are crucial for ensuring adequate durability and resistance to rutting and cracking. After the mix design analysis, performance testing is conducted to evaluate various aspects of the asphalt mixture’s behavior under different conditions. This may include tests for rutting resistance, moisture susceptibility, fatigue resistance, and thermal cracking resistance. Based on the results of performance testing, adjustments are made to optimize the mix design. This may involve modifying aggregate gradations, adjusting asphalt binder content, or incorporating additives to improve specific performance characteristics.
Maxwell Meyer 2 3.
Table 1 below shows the sieve size and corresponding weight retained for 3 different stockpiles. Calculate the percent passing for all the 3 aggregate stockpiles. (20 points) Table 1. Weight retained of different stockpiles Sieve size (mm) Stockpile 1 Stockpile 2 Stockpile 3 Avg. Wt. Retained (gm) Avg. Wt. Retained (gm) Avg. Wt. Retained (gm) 19 0 0 0 13.2 17 0 0 9.5 409 0 0 4.75 573 370 0 2.36 0 126 41 1.18 0 1 46 0.6 0 0 39 0.3 0 0 52 0.15 0 0 45 0.075 0 0 42 pan 0 0 35 Sieve size (mm) Stockpile 1 Avg. Wt. Retained (gm) Precent passing (%) 19 0 100 13.2 17 1.70 9.5 409 40.94 4.75 573 57.36 2.36 0 0 1.18 0 0 0.6 0 0 0.3 0 0 0.15 0 0 0.075 0 0 pan 0 0 Total weight (gm) 999 NA
Maxwell Meyer 3 Sieve size (mm) Stockpile 2 Avg. Wt. Retained (gm) Precent passing (%) 19 0 100 13.2 0 100 9.5 0 100 4.75 370 74.45 2.36 126 25.35 1.18 1 0.20 0.6 0 0 0.3 0 0 0.15 0 0 0.075 0 0 pan 0 0 Total weight (gm) 497 NA Sieve size (mm) Stockpile 3 Avg. Wt. Retained (gm) Precent passing(%) 19 0 100 13.2 0 100 9.5 0 100 4.75 0 100 2.36 41 13.23 1.18 46 14.84 0.6 39 12.58 0.3 52 16.77 0.15 45 14.52 0.075 42 13.55 pan 35 11.29 Total weight (gm) 310 NA
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Maxwell Meyer 4 4.
Perform aggregate blending based on the cold feed percentage given in Table 2. (10 points) Table 2. Cold feed percentage of different stockpiles Stockpile Cold feed, % 1 30 2 20 3 50 Using the same aggregate blending the asphalt mixtures were prepared at 3 different binder contents. The theoretical maximum specific gravity and bulk specific gravity of the prepared samples are given in the table 3 below: Sieve size (mm) Stockpile 1 Stockpile 2 Stockpile 3 Precent passing (%) Precent passing (%) Precent passing(%) Job mix (%) 19 100 100 100 100 13.2 1.70 100 100 75.10 9.5 40.94 100 100 82.28 4.75 57.36 74.45 100 82.10 2.36 0 25.35 13.23 11.69 1.18 0 0.20 14.84 7.82 0.6 0 0 12.58 6.29 0.3 0 0 16.77 8.39 0.15 0 0 14.52 7.26 0.075 0 0 13.55 6.78 pan 0 0 11.29 5.65 Cold feed, % 30 20 50 100
Maxwell Meyer 5 Table 3. Binder percentage and specific gravity of the asphalt mix Binder Content, % G
mm G
mb 5.6 2.506 2.333 6.1 2.490 2.390 6.6 2.474 2.420 5.
Calculate the air voids at all the binder content. (10 points) Binder Content, % (Va) Air void (%) 5.6 6.90 6.1 4.02 6.6 2.18 6.
Show roughly the relation between air voids and binder content and report the optimum binder content based on Superpave criteria. (5 + 5 points) 0
1
2
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5
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5.4
5.6
5.8
6
6.2
6.4
6.6
6.8
Air void (%)
Binder Content, %
Optimum binder content
Maxwell Meyer 6 7.
The mix has to be laid and compacted in the field and before that, it has to be verified whether the mix satisfies the volumetric criteria as per ODOT specification or not. Prepare a phase diagram showing all the weight and volume calculation required for a volumetric analysis of the asphalt mix. The total weight of the material is 5100 grams, the specific gravity of binder is 1.019. and the bulk specific gravity of the aggregate is 2.62. Analyze all the associated weight, volumes, dust to binder ratio using the abovementioned data. (20 points) Weight of binder = 5100 grams / 1.019 Volume of binder = 5004.89 grams / 1.019 Weight of binder = 5004.89 g Volume of binder = 4915.63 cm³ = 6.69
in Weight of aggregate = 5100 g - 5004.89 g Volume of aggregate = 95.11 g / 2.62 Weight of aggregate = 95.11 g Volume of aggregate = 36.31 cm³ = 1.31in Total volume = 4915.63 cm³ + 36.31 cm³ Volume air voids = 4915.63 cm³ + 36.31 cm³ - Total volume Total volume = 4951.94 cm³=6.71 in Volume air voids = 0 Dust to binder ratio = 95.11 g / 5004.89 g Dust to binder ratio = 0.019 8.
Compare the volumetric values with the ODOT specification table and comment/summarize (in your own word) the mix design based on the volumetric values. (10 points) From what I got results my values seem to be a bit less than what the ODOT specifications say. The way the volumes and the specific gravity line up they look like what is actually real and required from the ODOT Specifications. My dust binder was low compared to what I have seen from examples and the ODOT.
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