Exp 567 Marshall Mix Design Method

Jordan University of Science and Technology Faculty of Engineering

Civil Engineering Department Highway Laboratory

CE444 – 234440

Student name: Huthyfh AbdAlmajeed Alkhtatbeh

Student ID: 20120023203

Student number (S.N) & Group number G.N : ( 24 ) / ( 4 )

Section : 1 – ( sun , tue ) – ( 2 – 4 ) ( Highway LAB )

Experiment num & name : experiment # 5 – Marshall Mix Design

Experiment description :

Submission Day & Date : _ 2 / 8 / 2015

Presented to: Prof. Taisir Khedaywi

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Experiment # 5: Marshall Mix Design -------------------------------------------------------------------------------------------------------------------------------

Introduction

The Marshall Method for hot-mix asphalt concrete mix design is a rational approach to selecting and proportioning two materials, asphalt cement and mineral aggregates to obtain the specified properties in the finished asphalt concrete surfacing structure. The method is intended for laboratory design of asphalt hot-mix paving mixtures.

Mix Design: A matter of selecting and proportioning materials to obtain the desired properties in the finished construction product. Stability: The ability to withstand traffic loads without distortion or deflection, especially at higher temperatures. Workability: The ability to be placed and compacted with reasonable effort and without segregation of the coarse aggregate. Too much asphalt cement makes the mix tender. Too little asphalt cement makes it hard to compact.Skid Resistance: Proper traction in wet and dry conditions. To get good skid resistance, use smaller aggregate so there are lots of contact points, use hard aggregate that doesn’t polish and make sure you have enough air voids to prevent bleeding. Some states now use an open-graded friction course (OGFC) that allows water to drain to the sides of the pavement, eliminating hydroplaning. But OGFC is not very durable because of the open pores. Durability The ability to resist aggregate breakdown due to wetting and drying, freezing and thawing, or excessive inter-particle forces. Stripping: Separation of the asphalt cement coating from the aggregate due to water getting between the asphalt and the aggregate. Bleeding: The migration of asphalt cement to the surface of the pavement under wheel loads, especially at higher temperatures. Fatigue Cracking: Cracking resulting from repeated flexure of the asphalt concrete due to traffic loads. Thermal Cracking: Cracking that results from an inability to acclimate to a sudden drop in temperature. To minimize thermal cracking, use the proper asphalt cement grade.

Abstract In asphalt mixtures there is some needed properties that depends on the asphalt content and this experiment is constructed to find the optimum asphalt content to get the best needed properties such as stability and air voids . Marshall Test method starts to disappear in many countries and these countries starts to use super pave method. The Marshal Method starts with preparation of aggregate according to the properties requirement of the project specifications such as density, grading, voids analysis and Specific Gravity of aggregate used. The Specific Gravity of the Asphalt Cement is also according to the requirements. Then the aggregate and the asphalt will be mixed and compacted.

The mix design must have sufficient asphalt to ensure a durable pavement, sufficient stability under traffic loads , sufficient air voids to prevent excessive environmental damage and to allow for a slight addition of compaction by traffic , sufficient workability . The final output of the mix design must give you a unique asphalt content that will give us a balance among all desired properties such as durability , impermeability , strength , stability , stiffness , flexibility , fatigue , resistance and workability . The design we will be considering in our lab is the Marshall mix design.

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The Marshall mix design method consists of 6 basic steps :1) Aggregate selection 2) Asphalt binder selection 3) Sample preparation (including compaction )4) Stability determination using the Hveem Stabilometer 5) Density and voids calculations 6) Optimum asphalt binder content selection .In the case of aggregate selection , we often select the aggregates from more than one source to obtain the final aggregate gradation used in a mix design . Trial blends of these different gradations are usually calculated until an acceptable final mix design gradation is achieved , the typical considerations for a trial blend include ; 1) all gradation specifications must be met 2) the gradation should not be to close to the FHWA 0.45 power max density curve , if it is then the VMA is likely to be too low , the gradation should deviate from the FHWA'S 0.45 power max. density curve . Now as for the binder selection , the binder evaluation can be based on local experience , pervious performance or a set procedure . The sample preparation , is a key stage in the Marshall mix design , like other mix designs methods , the use of several trial aggregate –asphalt binder blends ( typically 4 blends with 3 samples each for a total of 12 specimens ), each with a different asphalt binder content . After evaluating each blend an optimum asphalt binder content can be selected, in order for this concept to work , the trial blends must contain a range of asphalt contents both above and below the optimum asphalt content .The samples of the asphalt binder content are typically prepared at 0.5 % increments . In the next step we will be talking about the compaction with the Marshall hammer , each sample is heated to the anticipated compaction temperature and compacted with a Marshall hammer , a device that applies pressure to a sample through a tamper foot , some of those hammers are automatic and some are hand operated , the number of blows are typically 35,50,75 on each size depending upon the anticipated traffic loading .Now we must test our sample for the stability and flow test , this test provides the performance prediction measure for the Marshall mix design method . The stability portion of the test measures the maximum load supported by the test specimen at a loading rate of 50.8mm/ minute . Basically the load is increased until it reaches a maximum then when the load just begins to decrease , the loading is stopped and the maximum load is recorded . During the loading an attached dial gauge measures the specimen plastic flow as a result of the loading . The flow value is recorded in 0.25mm (0.01 inch) increments at the same time the maximum load is recorded .The next step is the density and voids analysis , in all mix design methods use density and voids to determine the basic HMA physical characteristics. Two different measures of densities are taken : Gmb and Gmm , these densities are then used to calculate the volumetric parameters of the HMA . Measured void expressions are usually : 1) Air voids ( VTM ).2) Voids in the mineral aggregate (VMA ).3) Voids filled with asphalt (VFA).

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Now the selection of optimum asphalt binder content , this is selected based on the combined results of Marshall stability and flow , density analysis and void analysis . Finally we must plot the 6 charts 1) Unit weight vs AC% 2) Stability vs AC%3) Flow vs AC%4) Air voids vs AC%5) VMA VS AC%6) VFA VS AC% Now determine the asphalt binder content that corresponds 4% air voids . the asphalt content at maximum unit weight , the asphalt content at maximum stability , average of these 3 values are taken . Now using the optimum AC% go into each curve and compare the values with the specifications.As stated before the amount of asphalt to be added to the aggregate to form the blend is either found using the equation or by experience. In today’s experiment we must develop an economical blend of aggregates and asphalt that meet design requirements, this prepared sample then undergoes all of the steps of the Marshell mix design stated in the above paragraph.The dimensions of the Marshall specimens are 2.5 in ( height ) by 4 in ( diameter )

Objectives

The objective to be achieved using the Marshall Method for hot-mix asphalt concrete mix design is to determine an economical blend and gradation of aggregates (within the limits of project specifications) and asphalt that yields a mix having; 1. Sufficient asphalt cement to ensure a durable asphalt concrete surface course. 2. Sufficient mix stability to satisfy the demands of traffic without distortion or displacement. 3. Sufficient voids in the total compacted mix to allow for a slight amount of additional compaction under traffic loading without flushing, bleeding and loss of stability, yet low enough to keep out harmful air and moisture. 4. Sufficient workability to permit efficient placement of the mix without segregation. 5. Characteristics which allow normal construction operating variations without falling outside of the specified requirements.

Apparatus and materials

1 -The right grade of asphalt cement ( Relates to fatigue cracking, thermal cracking, stability)

2 -The right type of aggregate ( Relates to stability, durability, stripping, skid resistance )

3 )Flasks 4 -Pycnometer

5 -Marshall specimen molds ; dimensions 2.5 in ( height ) by 4 in ( diameter )

6 -Towel 7 -For compaction test ( Marshall Hammer )

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8 -For stability : Hveem Stabilometer and Flow test : Flow meter 9 -Water bath

10 -oven , Balance , Gloves and Thermometer

Test specimens

For preparation of aggregate and asphalt for Marshall Specimens 1 -aggregate with different sizes meet the Marshall criteria and chosen to achieve well graded gradation

also aggregate must have a good properties such as specific gravity, shape, hardness and so on.2 -Asphalt cement that meet the suitable gradation (PG) for project.

(12 Marshall Specimens( )2.5 inches in height and 4 inches in diameter )

Procedure

1 )Select aggregate grading to be used

2 )Determine the proportion of each aggregate size required to produce the design grading 3 )Determine the specific gravity of the aggregate combination and asphalt content.

4 )Prepare the trial specimens with varying asphalt contents 5 )Determine the specific gravity of each compacted specimen

6 )Perform stability tests on the specimens 7 )Calculate the % of voids , and % voids filled with Bitumen in each specimen

8 )Select the optimum binder content from the data obtained 9 )Evaluate the design with design requirements

**A range of asphalt contents is used so that complete test data curves are obtained ( at least 5 trail mixtures )

**At least 3 replicates are the minimum number required for each asphalt content Preparation of Aggregate:

1 )Aggregate Are dried to constant weight at 105 C to 110 C and sieved using sieve analysis into the required fractions.

2 )After drying, the aggregates are weighted while the container is placed at the top of the balance. (For each group 3 samples of aggregate blend were prepared according to the aggregate distribution given in

the lab).

Preparation of the Marshall Specimen :1 )Get The Marshall specimen Mold ( 2.5" height*4" diameter ).

2 )The asphalt was placed in the oven @ 150 C . for not more then 1 hour 3 )The mold is placed in the oven.

4 )The specimens of aggregate were placed in the oven for 24 hrs @ 150 C5 )Place the aggregate sample into the pan

6 )Place the aggregate on the heater , a hole was made at the center of the aggregate 7 )The asphalt is place at the hole made , according to the weight specified for each group.

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8 )The asphalt mixed with the aggregate using a large spoon until the mixture becomes homogenously mixed.

9 )Put a filter paper at the bottom of the mold ( in order to remove excess asphalt , to make sure the required weight is achieved

10 ) Now place the mixtures into the mold after applying some oil on the interior surface of the mold , add a filter paper on the bottom of the mold . Place the mixture inside the mold while mixing and compacting in order to ensure no segregation occurs

11 )Place the mold under the Marshall hammer , now apply the no. of blows depending on the traffic. 35 Blows for light Traffic

50 Blows for medium traffic 75 blows for heavy traffic

12 )The compaction using the Marshall hammer is to be raised 18" then dropping it down by its own weight on the specimen.

13 )The mold is reversed upside down and then compaction is repeated.14 )The specimen is taken out and subjected to air flow in order to cool

15 )Using chalk write your group # on the specimens 16 )The specimen is then placed the stability-flow machine, turn the machine on, a curve is drawn by

the machine. (Temperature of specimen = 60 C) Determination of the Gmb:

1 )Weight the specimen dry in air using a balance ,g A2 )Place the specimen in the basket submerged in the water for 3-5 minutes , record the weight using

the balance C3 )Now take out the sample and dry it using a towel , now weight the specimen using the balance B

Gmb =A/B-CDetermination Of Gmm

1 )After leaving the sample in the oven 2 )Weight 500g mass of the dry sample in air

3 )Now weight of the pycnometer filled with water , using the balance A4 )Now weight the mass of pycnometer filled with water and 500g sample.

Find Gmm= 500/500+A-B

Test results

This procedure was originally developed by a bituminous engineer with the Mississippi State Highway Department, Bruce Marshall. The U. S. Army Corps. of Engineers improved and added to the procedure as well as developing mix design criteria. The method documented in ASTM D 1559 and AASHTO T245 is applicable only to mixes with maximum particle sizes of 25 mm (1”) or less. The method can be used for both laboratory design and field control. An asphalt mix design

consists of two basic issues :a) based on the gradations of the constituent aggregates to be used in the mix, determine the proportions of each aggregate that will produce a blended gradation that meets the required grading specification (we will use the grading spec. given in the sieve analysis lab, which is for HL3 from the OPSS Spec.).

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b) Determine the optimum asphalt cement content that will satisfy the Asphalt Institute’s mix design criteria (we will consider the bulk specific, the Marshall Stability and the percent air voids in the compacted paving mixture in determining the optimum asphalt content). In addition to the gradation of the constituent aggregates, it is also necessary to know the bulk ASTM specific gravities of the coarse and fine aggregates, the apparent specific gravity of the mineral filler and the specific gravity of the asphalt cement in order to be able to determine the percent air voids, voids in the mineral aggregate (VMA), voids filled with asphalt (VFA) and the effective asphalt content. This lab is organized into five segments (1 – 5 ) in the lab:

1 )sieving and blending of stock aggregates into twenty-two 1200 gram 2 batches using the proportions determined to produce the required grading ,

2 )Manufacturing 18 compacted test specimens (3 trials at 6 different asphalt contents) and two loose specimens ,

3 )Measuring and calculating the bulk specific gravity of each compacted specimen and the maximum specific gravity of the loose specimens ,

4 )Measuring the Marshall Stability and Flow of each preheated, compacted specimen and 5 )Performing all the necessary calculations, plotting the required graphs, determining the

optimum asphalt content and evaluating the mix properties according to the Asphalt Institute’s criteria.

Aggregate gradation used

Table 1 ( aggregate gradation used in the experiment )

sieve sizeinches

sieve sizemm

% passing % passing ( mid point )

% retained % retained in between

weight in between

cumulative weight retained

1" 25 100 100 0 03/4" 19 (90-100) 95 5 5 60 601/2" 12 (71-90) 80.5 19 14.5 174 2343/8" 9.5 (56-80) 68 32 12.5 150 384#4 4.75 (35-56) 45.5 54.5 22.5 270 654#8 2.36 (23-38) 30.5 69.5 15 180 834

#16 1.18 (13-27) 20 80 10.5 126 960#50 0.6 (5-17) 11 89 9 108 1068

#100 0.3 (4-14) 9 91 2 24 1092#200 0.15 (2-8) 5 95 4 48 1140Pan 0.075 0-0 0 100 5 60 1200

Check ….. ……. ……. 100% 1200 grams

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Marshal criteria

Table 2 (Marshall Criteria of aggregate gradation used in mix design method)

Marshall criteriasieve size “ in “ sieve size “ mm “ Minimum Maximum

1" 25 100 1003/4" 19 90 1001/2" 12 71 903/8" 9.5 56 80#4 4.75 35 56#8 2.36 23 38

#16 1.18#50 0.6 5 17

#100 0.3 4 14#200 0.15 2 8Pan 0.075 0 0

10.0 1.0 1 01 00101-

01

03

05

07

09

011

noitadarg etagerggamumixammuminim

(mm) ezis eveis

% re

nif t

necr

ep

Figure 1 ( percent finer V.s sieve size for minimum and maximum Marshall criteria and aggregate gradation used )

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The specific gravity that were calculated used specific gravity formula

Table 3 (specific gravities of materials used in Marshall Mix method: bulk specific gravity of aggregate, effective specific gravity of aggregate and specific gravity of asphalt cement)

Input materials propertiesGsb 2.52Gse 2.593Gb 1.017

Table 4 (first results, properties of materials proportions)

Groups

asphalt % by total

weight of mixture

Pb

weight of asphalt /1200 grams of

aggregate

aggregate % by total weight of mixture

PS

absorbed asphalt % by total wt.

of aggregate Pba

effective asphalt content % by

total wt of mixture Pbe

I 4.5 56.54450262 95.5 1.136163297 3.414964052II 5 63.15789474 95 1.136163297 3.920644868III 5.5 69.84126984 94.5 1.136163297 4.426325685IV 6 76.59574468 94 1.136163297 4.932006501

Table 5 ( Gmb and Gmb-ave of specimens used in the experiment )

Groups specimensA ( weight of dry specimen in air ) g

B ( weight SSD specimen in air ) g

C ( weight of specimen submerged in water ) g Gmb Gmb (ave)

I1 1201.6 1223.4 669.6 2.169736367

2.1737260952 1216.6 1239.4 680.4 2.1763864043 1175.4 1193.4 653 2.175055514

II1 1198 1212.9 668.2 2.199375803

2.2182759862 1182.3 1195.1 667.6 2.2413270143 1181.9 1194.3 660.5 2.214125141

III1 1186 1200.2 659.3 2.192641893

2.2021494212 1237.3 1253.1 691.3 2.202385193 1196.6 1207.6 666.5 2.211421179

IV1 1172.3 1187.4 654 2.197787777

2.2120821252 1214.8 1223.5 680.5 2.2372007373 1190 1204.5 663.9 2.201257862

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Experiment # 5: Marshall Mix Design ------------------------------------------------------------------------------------------------------------------------------

Table 6 ( Gmm calculation and unit weight of specimens used in the experiment )

GroupsA.C % by

total weight of mixture

weight of loose aggregate

coated with asphalt ( g )

A (weight of pycnometer full

of water) ( g )

B ( weight of pycnometer + loose

aggregate coated with asphalt + water) ( g )

Gmm

Unit Weight of mixture KN/m^3

= ( Gmb-ave*9.807)I 4.5 500 1827.8 2121.8 2.427184466 21.31773182II 5 500 1827.8 2119.3 2.398081535 21.75463259III 5.5 500 1827.8 2117.8 2.380952381 21.59647937IV 6 500 1827.8 2115 2.34962406 21.83325057

Table 5 ( volumetric analysis of Marshall specimens )

GroupsA.C % by

total weight of mixture

Gmb (ave) Gmm Air voids in compacted mixture

% of total volume.

Voids in Mineral

AggregateVMA

voids filled with asphalt( %of

VMA) VFA

VTMI 4.5 2.173726095 2.427184466 10.44248488 17.62268171 40.74406467II 5 2.218275986 2.398081535 7.497891385 16.3745164 54.20999802III 5.5 2.202149421 2.380952381 7.509724322 17.41939672 56.88872327IV 6 2.212082125 2.34962406 5.853784763 17.4858255 66.52268568

Table 6 ( stability and flow analysis of Marshall specimens )

Group AC% stability ( KN ) stability ave ( KN ) Flow ( mm ) Flow ave ( mm )

I1

4.5100

126.333333324

282 132 283 147 32

II1

5120

137.666666736

41.333333332 131 403 162 48

III1

5.5109

12634

382 137 443 132 36

IV1

6139

12536

38.666666672 113 403 123 40

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Discussion

First of all we are going to discuss the gradation used in this experiment, when plotted the curve fits exactly between the maximum and minimum Marshall Criteria therefore we can classify our gradation as well graded, which means all particle sizes are available also from the (percent finer – sieve size ) graph we can see that the selected gradation is fallen within Marshall criteria.

As for the compaction test that is achieved on the Marshall specimen, the compaction effort should correspond to that attained in the field after years of traffic, the standard compaction effort should yield an air void of 4%, this value was selected as an avg between two limits 3-5%, at low air void content, load is transmitted by bitumen not by aggregates, and at high air content , air and water will be allowed to circulate in the mixture . The main aim of the process of compaction is to optimize the packing of the aggregate, uniformly distribute the bitumen and air voids , minimize residual air voids . This ensures that a good bond will exist between bitumen and aggregates, high friction between aggregate particles is achieved , and a consistent and

stable mixture system is formed . Good compaction also provides increased resistance to deformation, higher durability under traffic for the wearing course , reduced risk to water

penetration, From the following obtained plotted curves we can notice the following trends :

-the stability value increases with increasing asphalt content up to a maximum and then the stability decreases, from the figure we find that the max-stability occur at AC%= 5.1%.

Figure 2 ( OAC% determination due to stability )

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-the flow value must consistently increases with increasing asphalt content but we fined that the flow value after AC%=5.5% is decreases may be due to error determination of asphalt content or problem in the mixing proportions.

4 5.4 5 5.5 6 5.63.1

53.1

4.1

54.1

5.1

55.1

6.1

56.1

7.1

57.1

8.1

wolF egareva s.V CA%

-the curve of unit weight of total mix follows the trend similar to the stability curve , except that the maximum unit weight normally (but not always ) occurs at a slightly higher asphalt content than the maximum stability as we fined in our experiment AC% at max-unit weight = 5.9%.

Figure 3 ( OAC% determination due to unit weight )

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-the percent of air voids steadily decreases with increasing the asphalt content , ultimately approaching a minimum void content also from the figure we fined that the asphalt content %

at 4% air voids equals to 6.6%.

Figure 4 ( OAC% determination due total air voids in mixture )

-the VMA generally decreases to a minimum value then increases with increasing the asphalt content.

4 5.4 5 5.5 6 5.65.51

61

5.61

71

5.71

81

%AMV s.V %CA

Figure 4 (voids in mineral aggregate curve)

Ways to Increase VMA 1 .Reduce the dust content

2 .Open the aggregate gradation 3 .Gap-grade the aggregate blend

4 .Increase manufactured sand 5 .Reduce flat-and-elongated particles

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-the VFA curve , the curve steadily decreases with increasing asphalt content , We can see that the VFA curve is concave upward , the VFA cannot be increased above the maximum without

increasing or otherwise changing the compaction effort.

4 5.4 5 5.5 6 5.60

2

4

6

8

01

21

AFV s.V %CA

Figure 6 (voids filled with asphalt)

.

Table 7 (optimum asphalt content analysis of Marshall Specimens and overall mixture properties)

Curves AC% value

optimum Asphalt content ( OAC )

mixture properties

values at optimum

Asphalt content

comments ( if met Marshall criteria or not )

air voids 6.6

5.866666667

air voids 6% out of Marshall range

stability 5.1 stability 1250 less than Marshall criteria

unit weight

5.9 unit weight 21.78 *

Flow 39 within Marshall range

NMAS=19 mm VMA 17.5 out of Marshall range

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Conclusion

*from the results shown in figures and tables we can conclude that all tested Marshall specimens was failed and all of them were not met the Marshall criteria also the observed optimum asphalt content

present was very high and will causes a problems in the mixture when used like bleeding. *the VFA was found to be decreasing with the increasing in AC% so that this result will not be

acceptable may be due to errors in determination of specific gravities of materials used or obtaining experiment data.

*Mix design is a matter of selecting and proportioning materials to obtain the desired properties in the finished construction product.

*Gmm is the ration of the wt. in air of a unit volume of an uncompacted bituminous paving mixture to wt. of an equal volume of water.

*Gmb is the ratio of the wt. in air of a unit volume of compacted specimen of HMA to wt. of an equal volume of water.

*We must have sufficient asphalt to ensure a durable pavement.

* We must have sufficient stability under traffic loads.

*Sufficient air voids 4%, a value between 3-5%, the upper limit to prevent excessive environmental damage and the lower limit to allow for a slight of additional compaction due to traffic.

*The final output of the mix design must has desirable properties like , durability , impermeability , strength, stability ,etc.

* Impact compaction is used in the Marshall mix design method with 50 standard drops for medium traffic .

*The dimension of the Marshall specimens are 2.5” height by 4” diameter.

*According to the standard we must have at least 5 trial mixtures, with at least 3 replicates for each asphalt content.

*In term of aggregate selection, we have different types of gradation, well ,poor and dense.

*Well gradation must be used to achieve a good mix design specimen.

*The best gradation is one that produces a mixture with high density.*Stability can be defined as the maximum load resistance in N or lb.

*Flow is defined as deformation that occurs in the specimen at load action.

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Calculations

Sample of calculation for aggregate , Sieve #8:

Passing weight specification limits = 23 – 38 %Passing middle point (average) = (upper limit + lower limit) / 2

= (23 + 38) / 2 = 30.5 %Retained percent = 100 – passing middle point = 100 – 30.5 = 69.5 %Percent in between = retained #16 – retained #8 = 80- 69.5 = 10.5 %Weight in between = percent in between * total weight of aggregate

= 10.5 % * 1200 = 126 gCumulative weight = previous weight + weight in between

= 834 + 126 = 960 gSample calculation of asphalt , group # 4:

Assume weight of asphalt = xThen x / (1200 + x) = 6% x = 77 grams

Sample calculation for ( Marshall specimen #1) , group #4 :

Gmb= A / ( B – C ) = 1214.8 / ( 1223.5 - 680.5 ) = 2.237 .We take the average for the three samples and it was = 2.212 .Stability & flow values from the millimeter paper.Stability = 1130 NFlow = 40 * ( 0.25 mm ) = 10 mm G mm = 500 / ( 500 + A – B ) = 500 / ( 500 + 1827.8 – 2115 ) = 2.35G se = ( 1 - pb ) / ( 1 / G mm - pb / Gb ) = ( 1 - 6 / 1200 ) / ( 1 / 2.35 - ( 6 / 1200 ) / 1.017) = 2.593G sb = ( * + * + * ) / 1200 = .A.V % = 100 * ( 1 - Gmb/ G mm) = 100 * ( 1 - 2.212 / 2.35 ) = %.V.M.A % = 100 - W agg. * Gmb / ( W mix * G sb .) 100 = 100 - 1200* 2.212 / ( 1214.8 * 2.52 ) * 100 = 17.5 %.Absorbed asphalt = ( G se - G sb ) * Gb / ( G se* G sb) = 1.136% of aggregate

Asphalt content (AC%) according to stability = 5.1 % Asphalt content (AC%) according to unit weight = 5.9 % Asphalt content (AC%) according to air voids = 6.6 %

** The average value of AC% = 5.9 % by weight of the mix.

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References

*AASHTO (American association of state highway and transportation). *Asphalt Institute Standards.

*pavement analysis and design book - by ( Huang ) 4th EDITION *pavement material and design laboratory notes for civil engineering application by Eng. Maha Shunnag

pavement materials and design notes by Dr. Khalid Ghuzlan .

Wikipedia polished researches*

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Documents

Exp 567 Marshall Mix Design Method