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INTRODUCTION. The Marshall method of asphalt mix design is widely practiced in construction materials laboratories to select and proportion aggregate and asphalt materials for pavement construction. This holistic approach to asphalt pavement mix design involves the selection of mineral aggregate and binder materials, preparation of trial samples, load testing for strength and flow of materials, and lab tests of material properties. The focus is on the determination of an optimum asphalt content that will provide maximum strength to the mix with minimum deformation from axle loads. Marshall stability and flow test values, density, and air voids in the mix and the mineral aggregate are all used for evaluation of trial mixtures of lab-mixed, lab-compacted (LMLC) asphalt mixtures. Marshall stability and flow tests can also monitor the production of the asphalt mixture using plant mix, laboratory-compacted (PMLC) samples..

OBJECTIVE OF MARSHALL TEST. To determine the optimum bitumen content in the mix wearing course and binder course in designing the pavement structural of Flexible pavement. To find the optimum binder content in a mix where the aggregate grading and type of bituminous binder is predetermined. The result from Marshall Mix Design are often used to set up asphalt mix formulation and specifications. To determine of the specific gravity for asphalt and aggregates.

Abstract image of curvy lines. PROCEDURES. 1) Measure out 1200 gm of aggregates, blended in the desired proportions as will be shown in the lab. Heat the aggregates in the oven to the mixing temperature which is about 177 to 190c. 2) In order to obtain the optimum moisture content for a particular blend of gradation of aggregates, a series of test specimen is prepared for a range of different asphalt content so that test data curve show a well-defined optimum value. Tests should be scheduled on the basis of 0.5% increments of asphalt content, with at least two asphalt contents above optimum and two below optimum. In order to do so, weight the required quantity of asphalt as part per hundred parts of aggregates and heat it to a temperature from 121 to 138c and add it to the heated aggregates. 3) Mix the materials in a heated pan with heated mixing tools. 4) Return the mixture to the oven and reheat it to the compacting temperature which is at least 107.

Abstract image of curvy lines. PROCEDURES. 5) Place the mixture in a heated Marshall mold with a collar and base. Spade the mixture around the sides of the mold. Place filter papers under the sample and on top of the sample. 6) Place the mold in the Marshall compaction pedestal..

Abstract image of curvy lines. PROCEDURES. 8) After compaction, invert the mold. With the collar on the bottom, remove the base and extract the sample by pushing it out with the extractor. 9) Allow the sample to stand for a few hours to cool. 10) Obtain the sample mass in air and submerge. 11) Place the briquettes in a water bath 60c for 30-40 minutes. 12) Place one briquette in the loading yoke , add the top part of the yoke , place the flow meter over one of the posts , and adjust it to read zero. 13) Apply a load at a rate of 50 mm (2 inch) per minute until the max. load reading is obtained. 14) Record the max. load reading . at the same instant , obtain the flow as recorded on the flow meter ( note: a stopwatch can be used to measure the time from start of leading to max. load. Using a rate of loading of 50 mm (2 inch)/ minute , the flow in millimeters are units of 0.01 inch can be calculated..

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ASSPARATUS. Specimen Mold Assembly : briquettes 4 in. (101.6 mm ) in diameter by 3 in. (76.2 mm) in height, base plates and extension collars..

.. .. Flowmeter.. Oven or hot plate.. Mixing apparatus..

Data and analysis. Bitumen Content % Bulk specific gravity G mb =W a /(W a -W w ) Bulk density γ =G mb  9.81 kN /m 3 Sample 1 Sample 2 Sample 3 average 3.50% 2.399023 2.403903 2.410036 2.404321 23.58639 4.00% 2.411065 2.412093 2.424922 2.416027 23.70122 4.50% 2.430066 2.420919 2.410037 2.420341 23.74354 5.00% 2.422979 2.423565 2.418075 2.421539 23.7553 5.50% 2.410951 2.414979 2.408989 2.41164 23.65818.

1. Maximum unit weight =4.85% [Fig. 1] 2. Maximum stability =4.40 % [Fig.2] 3. Percent air voids in compacted mixture using mean of limits [that is, (3+5)/2=4] =5.20%% [Fig. 5].

Table 18.7 Suggested Test Limits (a) Maximum and Minimum Values Marshall Method Mix Criteria Compaction (No. of blows each end of Specimen ) Stability N (lb) Flow. 0.25 mm (0.1 in.) Air Voids ( % ) Light Traffic ESAI- < 104 (see Chapter 19) 35 3336 (750) 8 to 18 Medium Traffic 104 < ESAL < 106 (see Chapter 19) 50 5338 (12(X)) 8 to 16 Heavy Traffic ESAI- > 106 (see Chapter 19) 75 (10) 8 to 14 (b) Mineral Percent Voids in Mineral Aggregates Standard Sieve Designation No. 16 No. 4 No. 8 1/2 in. 3/4 in. I in. 11/2 in. 2 in. 21/2 in. 23.5 21 18 16 15 14 13 12 11.5 11.

CONCLUSION. After a lengthy procedure and calculations, we arrived at the best Asphalt content for the hot mix . Following the tests, we discovered that the Asphaltic content (4.81 percent) meets all of the standards for heavy traffic, which gives us a strong indicator of the strength characteristics of our mix, as well as its longevity and, as a result, its future uses. If any of the checks fail to meet the requirements, we will need to make changes to our mix design, although this is not necessary. Due to the loss of soil masses and the weighing, there were some inaccuracies. However, due of good teamwork, these errors didn't have a significant impact on our performance..