TRB 85TH ANNUAL MEETING WORKSHOP PRACTICAL APPROACHES TO DESIGN OF HOTMIX ASPHALT ANALYSIS OF OKLAHOMA MIX DESIGNS FOR THE NCAT TEST TRACK USING THE BAILEY METHOD DANNY GIERHART, P.E. ODOT BITUMINOUS ENGINEER

PRESENTATION TOPICS BAILEY METHOD OVERVIEW CASE STUDY – ODOT’s NCAT TEST TRACK MIX DESIGNS Three-point outline of presentation. ODOT OPINION OF THE METHOD AT THIS POINT

ACHIEVING VOLUMETRICS AND THE BAILEY METHOD ACHIEVING VOLUMETRICS AND HMA COMPACTABILITY

TRANSPORTATION RESEARCH CIRCULAR Number E-C044 Bailey Method for Gradation Selection in Hot-Mix Asphalt Mixture Design Vavrick, Huber, Pine, Carpenter, Bailey October 2002 This TR Circular provides full documentation of the Bailey Method.

How Can the Bailey Method Help? In Developing New Blends: Field Compactibility Segregation Susceptibility In Evaluating Existing Blends: What’s worked and what hasn’t? More clearly define ranges referenced in the method How can the Bailey Method help? We can use it to: Develop NEW blends, while considering field compactibility and segregation susceptibility for the aggregates we have to use. Evaluate Existing blends and better understand why they worked well or why they didn’t. Estimate VMA/Void changes between: Design trials QC samples Whenever we need to adjust the blend in the lab or in the field In Estimating VMA/Void changes between: Design trials QC samples Potentially Saves Time and Reduces Risk!

The method focuses on how aggregate particles fit together Originally developed in the 1980’s by Robert D. Bailey, a civil engineer now retired from Illinois DOT The method focuses on how aggregate particles fit together The method was originally developed by Robert Bailey, and it focuses on how aggregate particles fit together.

Aggregate Packing What Influences the Results? GRADATION - continuously-graded, gap-graded, etc. SHAPE - flat & elongated, cubical, round SURFACE TEXTURE - smooth, rough What influences aggregate packing? The gradation of the combined blend has a great affect on the resulting void content. Cubical particles tend to pack more densely than flat and elongated particles, while Angular particles provide more inter-particle void space than do rounded particles. Smooth particles pack more easily than those with rough surface texture (micro-texture). Aggregates of varying strengths pack differently because one may degrade more than another from the type and amount of compactive effort applied. The importance of each of these factors depends on several things, such as the mix characteristics required for the traffic conditions (loading) in which the mix will be used, the vertical location within the pavement structure where the mix is being placed, and the type of mix being designed. Each of these factors directly influence aggregate packing or VMA. STRENGTH - resistance to breaking, abrasion, etc. TYPE & AMOUNT OF COMPACTIVE EFFORT - static pressure, impact, or shearing

REQUIRED LABORATORY TESTING Developing and analyzing combined aggregate blends using the Bailey Method requires certain test data. Design labs are already performing Bulk Specific Gravity testing on Fine and Coarse Aggregate. However, we also need information about how the aggregate particles pack together. This information is provided by Loose and Rodded Unit Weight tests on the Fine and Coarse Aggregate.

Illustration of the Four Principles – Predominantly Coarse Aggregate Mix 100 2 90 80 70 1 60 % Passing 50 Remember the focus is aggregate packing. Before we discuss the pieces of the puzzle, I want to give you an overall picture of the method. This is a maximum density chart or 0.45 power curve, where the X-axis represents the sieve size raised to the 0.45 power, and the Y-axis represents the gradation in % passing. I’ve used letters to label the sieves because these concepts apply, regardless of mix size. The dashed line is an example of a combined blend gradation for a coarse-graded mix. There are FOUR main principles to the Bailey Method. Principle #1 consists of determining what is coarse and fine, along with the volume of each. From this, we can determine which particles create voids and which ones fill them, along with determining which fraction (coarse or fine) is in control of the overall aggregate structure. The other three principles are used to evaluate distinct portions of the combined blend gradation. Principle #2 looks at the coarse fraction and how the various particle sizes are distributed, which relates to the packing of the coarse fraction and in turn how this influences the packing of the fine fraction. Principle #3 looks at the coarse part of the fine fraction, which relates to the packing of the overall fine fraction in the combined blend. Principle #4 looks at the fine part of the fine fraction, which relates to the packing of this portion of the combined blend. Each of these four principles plays a specific role in aggregate packing, or Voids in the Mineral Aggregate (VMA). We will also discuss how to relate these principles to compactibility and segregation susceptibility in the field, and how to use them for estimating the expected change in VMA or Voids from one design trial to the next, or from one QC sample to the next. 40 30 20 4 3 10 Fine Coarse Sieve Size (mm) Raised to 0.45 Power

PRINCIPLE # 1 – CATEGORIZE MIX AS PREDOMINANTLY “COARSE” OR “FINE” Coarse particles create voids Fine particles fill voids Designation of coarse and fine particles is based on the Nominal Maximum Particle Size (NMPS).

Primary Control Sieve ≈ 0.22 x NMPS Diameter = NMPS Average Void Size = 0.22 x NMPS Primary Control Sieve ≈ 0.22 x NMPS

Primary Control Sieve This chart shows the NMPS, calculated PCS and the closest standard sieve typically used here in the United States. Therefore, for a 19mm NMPS mix, everything retained above the 4.75mm sieve is considered part of the coarse fraction, which creates voids. Everything passing the 4.75mm is considered part of the fine fraction, which fits into the voids created by the coarse fraction. This chart is not only important for understanding what it coarse and fine in the combined blend, it also serves as a guideline for determining which category, Coarse Aggregate (CA) or Fine Aggregate (FA), that each individual aggregate falls into. If the majority of it’s gradation is retained ABOVE the PCS of the combined blend, then it will be treated as a CA. If the majority of it’s gradation PASSES the PCS of the combined blend, then it will be treated as a FA. Occasionally, you will find a situation where a virgin aggregate is not predominantly a CA or FA. In these instances, it is generally necessary to perform the unit weight tests (which we will discuss in more detail later) on the coarse (plus PCS) and fine (minus PCS) fractions of the combined blend, to more accurately determine the volume of CA solids and voids. PCS determines the break between Coarse and Fine in the combined blend and if a given aggregate is a CA or FA

Chosen Unit Weight - CA(s) < LUW LUW RUW This is a picture of all three mix types in relation to the CA VOLUME. To establish the desired CA VOLUME in the combined blend, we need to “pick” what we refer to as the CA Chosen Unit Weight (CUW). For Fine-graded and Coarse-graded mixes, the CA CUW references a percentage of the CA Loose Unit Weight. For SMA, the CA CUW references a percentage of the CA Rodded Unit Weight. Therefore, the CA CUW represents the VOLUME of the COARSE fraction in the combined blend. So an increase or decrease in the CA CUW results in an increase or decrease in the VOLUME of the COARSE fraction in the combined blend. As the CA CUW INCREASES, the combined blend gets COARSER. As the CA CUW DECREASES, the combined blend gets FINER. Fine-Graded Coarse-Graded SMA < 90% 95-105% 110-125%

Coarse-Graded Mix Some particle-to-particle contact of CA Coarse and Fine fractions carry load Reduced FA strength acceptable With this example of a coarse-graded mix, we can see the CA’s are touching to some degree, so the volume of CA is equal to or greater than the CA LUW condition. The coarse fraction is playing the primary role in the load carrying capacity of the aggregate structure. However, the fine fraction is also playing a role by supporting the coarse fraction. For this mix type, the coarse fraction properties become more important, while the fine fraction properties, although still important, play less of a role as compared to a fine-graded mix. This may allow more options in regards to blending FA’s.

Fine-Graded Mix Little to No particle-to-particle contact of CA Fine fraction carries most of the load Increased amount of FA support needed This is an example of a fine-graded mix, which has a volume of CA less than the CA LUW condition. As you can see, the coarse fraction is spread apart and floating in the fine fraction. The main point to realize with this mix type is that the load is primarily carried by the fine fraction. Therefore, the support from the fine fraction is very important, which is basically a function of gradation, shape, texture and strength.

Combined Blend Gradation – Predominantly Fine Aggregate Mix 100 PCS 90 New NMPS PCS 1 80 70 60 2 % Passing New PCS = 0.22 x PCS 50 We’re also going to discuss fine-graded mixes, which the dashed line in this example represents. With the Bailey Method, we treat fine-graded blends differently than coarse-graded or SMA blends. We still break the combined blend gradation into coarse and fine fractions, as we do with a coarse-graded or SMA blend; however, with a fine-graded blend, the fine fraction is actually in control of the overall aggregate structure. Because of this, we treat the overall fine fraction as a “blend” in itself. To do this, we break that “blend” into coarse and fine fractions. And look at the 2nd, 3rd and 4th principles on the new coarse fraction, the coarse portion of the new fine fraction, and the fine portion of the new fine fraction. The main difference between these three mix types: coarse-graded, SMA and fine-graded is the volume of the coarse fraction. We’re going to discuss this issue for these mix types in much greater detail later. 40 3 30 4 20 10 Fine Coarse Sieve Size (mm) Raised to 0.45 Power

PRINCIPLE # 2 – ANALYSIS OF THE COARSE FRACTION OF THE BLEND The coarse fraction is the portion retained above the Primary Control Sieve (PCS) Smaller particles in the coarse fraction are still too large to fit into the voids created by the larger particles

PRINCIPLE # 2 is evaluated using the Coarse Aggregate Ratio “Half” sieve = “half” of NMPS CA Ratio = Where: % Half sieve = % passing the Half sieve % PCS = % passing the PCS Adjusting CA Ratio Alter volume blend of CA’s Change CA source/gradation NMPS % Half sieve - % PCS 100% - % Half sieve “pluggers” “Half” Sieve “interceptors” PCS

“interceptor” particles increase voids because they are large enough to prevent “plugger” particles both from packing together and from packing the fine fraction

CA Ratio Effects FINE IN CONTROL COARSE IN CONTROL Portion evaluated as new coarse fraction is smaller – less sensitive to changes Portion evaluated as coarse fraction is larger – more sensitive to changes Low New CA Ratio – Lower VMA & air voids Low CA Ratio – Lower VMA & air voids Coarse particles “floating” in fine particles – New CA Ratio does not relate to segregation, Old still does Low CA Ratio – too many “pluggers”, mix prone to segregation As the CA ratio increases, VMA increases, because interceptors decrease packing of the pluggers, which in turn decreases packing of the fine fraction. If the CA ratio is too low, there is an excess of pluggers and even if the mix meets VMA or Voids, it will generally be susceptible to segregation. As the CA ratio approaches the high end of the suggested range (see next slide), the coarse fraction becomes “balanced” and neither sized material (interceptors or pluggers) “controls” the overall coarse fraction, which makes it difficult to lock up, especially in the field where the mix generally isn’t confined as it is in the lab compaction mold. High CA ratios generally occur with “S” shaped combined blend gradations that have gained notoriety in Superpave because they can be difficult to compact in the field. We generally don’t recommend blends with CA ratios above the high end of the corresponding range because of this, but they do exist. As the CA ratio exceeds the range, the interceptors start to control the coarse fraction. In addition to difficulties with field compaction, other issues with having a CA ratio above the high end of the corresponding range are: - Eventually the void size in the coarse fraction (plus PCS) will decrease to the point where the PCS actually changes to the next smaller sieve. First, this causes a shift in the volume of coarse and fine. Second, if the PCS is different, all three ratios that are used to evaluate the combined blend need to reference different sieves. - Segregation susceptibility will likely begin to increase again at some point, probably in inverse proportion to the corresponding range. High New CA Ratio – too many “interceptors,” mix can be difficult to compact High CA Ratio – too many “interceptors,” mix can be difficult to compact

CA Ratio Guidelines NMPS CA Ratio NMPS New CA Ratio COARSE IN CONTROL 25.0mm 19.0mm 12.5mm 9.5mm 4.75mm CA Ratio 0.70 - 0.85 0.60 – 0.75 0.50 – 0.65 0.40 – 0.55 0.30 – 0.45 FINE IN CONTROL As the CA ratio increases, VMA increases, because interceptors decrease packing of the pluggers, which in turn decreases packing of the fine fraction. If the CA ratio is too low, there is an excess of pluggers and even if the mix meets VMA or Voids, it will generally be susceptible to segregation. As the CA ratio approaches the high end of the suggested range (see next slide), the coarse fraction becomes “balanced” and neither sized material (interceptors or pluggers) “controls” the overall coarse fraction, which makes it difficult to lock up, especially in the field where the mix generally isn’t confined as it is in the lab compaction mold. High CA ratios generally occur with “S” shaped combined blend gradations that have gained notoriety in Superpave because they can be difficult to compact in the field. We generally don’t recommend blends with CA ratios above the high end of the corresponding range because of this, but they do exist. As the CA ratio exceeds the range, the interceptors start to control the coarse fraction. In addition to difficulties with field compaction, other issues with having a CA ratio above the high end of the corresponding range are: - Eventually the void size in the coarse fraction (plus PCS) will decrease to the point where the PCS actually changes to the next smaller sieve. First, this causes a shift in the volume of coarse and fine. Second, if the PCS is different, all three ratios that are used to evaluate the combined blend need to reference different sieves. - Segregation susceptibility will likely begin to increase again at some point, probably in inverse proportion to the corresponding range. NMPS All Sizes New CA Ratio 0.60 - 1.00

PRINCIPLE # 3 – ANALYSIS OF THE FINE FRACTION OF THE BLEND (COARSE PORTION) The fine fraction is the portion passing the Primary Control Sieve (PCS) The coarser fine particles also create voids which finer particles fill

PRINCIPLE #3 is evaluated using the FAc ratio Secondary Control Sieve (SCS) View fine fraction as a “blend” New coarse and fine break SCS = 0.22 x PCS PCS generally serves as the maximum and NMPS of overall fine fraction FAc Ratio = PCS Fine Fraction SCS Now lets look at the Fine fraction of a coarse-graded mix, the material passing the PCS. Unlike the Coarse fraction, the Fine fraction contains particles that create voids and particles that fit into those voids. Our second of the three combined blend ratios begins with defining the Secondary Control Sieve (SCS), so we can view the Fine fraction as a blend of coarse and fine. We utilize the same principle in determining this break between coarse and fine, as used in the PCS equation (PCS = 0.22 x NMPS). If you calculate the combined blend passing the PCS as 100%, you’ll find that the PCS generally serves as the maximum and NMPS sieves for the combined Fine fraction but BE SURE TO VERIFY THIS FIRST by looking at the “blend” passing the PCS as 100% aggregate. Another way of verifying this is to divide the % passing the first sieve smaller than the PCS, by the % passing the PCS and taking that result x 100. We are still defining the NMPS of this “blend” as the first sieve larger than the first sieve to retain more than 10%. The SCS equation is 0.22 x PCS. % SCS % PCS

FAc Ratio Effects FINE IN CONTROL COARSE IN CONTROL 0.05 increase in New FAc Ratio up to 0.50 results in an approximate 1% decrease in VMA and Air Voids 0.05 increase in FAc Ratio up to 0.55 results in an approximate 1% decrease in VMA and Air Voids Once New FAc Ratio increases beyond 0.50 VMA begins to increase Once FAc Ratio increases beyond 0.55 VMA begins to increase As the CA ratio increases, VMA increases, because interceptors decrease packing of the pluggers, which in turn decreases packing of the fine fraction. If the CA ratio is too low, there is an excess of pluggers and even if the mix meets VMA or Voids, it will generally be susceptible to segregation. As the CA ratio approaches the high end of the suggested range (see next slide), the coarse fraction becomes “balanced” and neither sized material (interceptors or pluggers) “controls” the overall coarse fraction, which makes it difficult to lock up, especially in the field where the mix generally isn’t confined as it is in the lab compaction mold. High CA ratios generally occur with “S” shaped combined blend gradations that have gained notoriety in Superpave because they can be difficult to compact in the field. We generally don’t recommend blends with CA ratios above the high end of the corresponding range because of this, but they do exist. As the CA ratio exceeds the range, the interceptors start to control the coarse fraction. In addition to difficulties with field compaction, other issues with having a CA ratio above the high end of the corresponding range are: - Eventually the void size in the coarse fraction (plus PCS) will decrease to the point where the PCS actually changes to the next smaller sieve. First, this causes a shift in the volume of coarse and fine. Second, if the PCS is different, all three ratios that are used to evaluate the combined blend need to reference different sieves. - Segregation susceptibility will likely begin to increase again at some point, probably in inverse proportion to the corresponding range. As New FAc Ratio increases toward 0.50, compactability of fine fraction increases As FAc Ratio increases toward 0.50, compactability of fine fraction increases

PRINCIPLE # 4 – ANALYSIS OF THE FINE FRACTION OF THE BLEND (FINE PORTION) Now looking at the finer portion of the fine fraction passing the Secondary Control Sieve (SCS) Again, the larger fine particles of this portion also create voids which the finest particles fill

PRINCIPLE #4 is evaluated using the FAf ratio Tertiary Control Sieve (TCS) View fine part of fine fraction as a “blend” New coarse and fine break TCS = 0.22 x SCS SCS generally serves as the maximum and NMPS of fine part of fine fraction FAf Ratio = PCS Fine Fraction TCS SCS Now lets look at the Fine fraction of a coarse-graded mix, the material passing the PCS. Unlike the Coarse fraction, the Fine fraction contains particles that create voids and particles that fit into those voids. Our second of the three combined blend ratios begins with defining the Secondary Control Sieve (SCS), so we can view the Fine fraction as a blend of coarse and fine. We utilize the same principle in determining this break between coarse and fine, as used in the PCS equation (PCS = 0.22 x NMPS). If you calculate the combined blend passing the PCS as 100%, you’ll find that the PCS generally serves as the maximum and NMPS sieves for the combined Fine fraction but BE SURE TO VERIFY THIS FIRST by looking at the “blend” passing the PCS as 100% aggregate. Another way of verifying this is to divide the % passing the first sieve smaller than the PCS, by the % passing the PCS and taking that result x 100. We are still defining the NMPS of this “blend” as the first sieve larger than the first sieve to retain more than 10%. The SCS equation is 0.22 x PCS. % TCS % SCS

FAf Ratio Effects FINE IN CONTROL COARSE IN CONTROL As New FAf Ratio increases toward 0.50, VMA begins to decrease As FAf Ratio increases toward 0.55, VMA begins to decrease Once New FAf Ratio increases beyond 0.50 VMA begins to increase Once FAf Ratio increases beyond 0.55 VMA begins to increase As the CA ratio increases, VMA increases, because interceptors decrease packing of the pluggers, which in turn decreases packing of the fine fraction. If the CA ratio is too low, there is an excess of pluggers and even if the mix meets VMA or Voids, it will generally be susceptible to segregation. As the CA ratio approaches the high end of the suggested range (see next slide), the coarse fraction becomes “balanced” and neither sized material (interceptors or pluggers) “controls” the overall coarse fraction, which makes it difficult to lock up, especially in the field where the mix generally isn’t confined as it is in the lab compaction mold. High CA ratios generally occur with “S” shaped combined blend gradations that have gained notoriety in Superpave because they can be difficult to compact in the field. We generally don’t recommend blends with CA ratios above the high end of the corresponding range because of this, but they do exist. As the CA ratio exceeds the range, the interceptors start to control the coarse fraction. In addition to difficulties with field compaction, other issues with having a CA ratio above the high end of the corresponding range are: - Eventually the void size in the coarse fraction (plus PCS) will decrease to the point where the PCS actually changes to the next smaller sieve. First, this causes a shift in the volume of coarse and fine. Second, if the PCS is different, all three ratios that are used to evaluate the combined blend need to reference different sieves. - Segregation susceptibility will likely begin to increase again at some point, probably in inverse proportion to the corresponding range.

FAc & FAf Ratio Guidelines COARSE IN CONTROL NMPS All Sizes FAc & FAf Ratio 0.35 – 0.50 FINE IN CONTROL As the CA ratio increases, VMA increases, because interceptors decrease packing of the pluggers, which in turn decreases packing of the fine fraction. If the CA ratio is too low, there is an excess of pluggers and even if the mix meets VMA or Voids, it will generally be susceptible to segregation. As the CA ratio approaches the high end of the suggested range (see next slide), the coarse fraction becomes “balanced” and neither sized material (interceptors or pluggers) “controls” the overall coarse fraction, which makes it difficult to lock up, especially in the field where the mix generally isn’t confined as it is in the lab compaction mold. High CA ratios generally occur with “S” shaped combined blend gradations that have gained notoriety in Superpave because they can be difficult to compact in the field. We generally don’t recommend blends with CA ratios above the high end of the corresponding range because of this, but they do exist. As the CA ratio exceeds the range, the interceptors start to control the coarse fraction. In addition to difficulties with field compaction, other issues with having a CA ratio above the high end of the corresponding range are: - Eventually the void size in the coarse fraction (plus PCS) will decrease to the point where the PCS actually changes to the next smaller sieve. First, this causes a shift in the volume of coarse and fine. Second, if the PCS is different, all three ratios that are used to evaluate the combined blend need to reference different sieves. - Segregation susceptibility will likely begin to increase again at some point, probably in inverse proportion to the corresponding range. NMPS All Sizes New FAc & FAf Ratio 0.35 – 0.50

Combined Blend Evaluation Coarse-Graded Mixes CA CUW increase = VMA increase 4% change in PCS  1% change in VMA or Voids CA Ratio increase = VMA increase 0.20 change  1% change in VMA or Voids FAc Ratio increase = VMA decrease 0.05 change  1% change in VMA or Voids FAf Ratio increase = VMA decrease Has the most influence on VMA or Voids This is a summary of the four main principles of the Bailey Method and their effects on VMA or Voids in a coarse-graded mix, along with general rules of thumb as to how much change it takes to create ~1% change in VMA or Voids. Increasing the CA CUW, increases the volume of coarse in the combined blend, which increases the degree of CA interlock and decreases compaction of the fine fraction. Changing the CA ratio generally requires changing the volume blend of CA’s, assuming more than one is being used. Otherwise, for a single CA, it requires a change in gradation of the CA and/or a change in source. Altering the FAc ratio normally involves a change in particle shape, strength and texture, as well as a change in gradation, because the adjustment typically consists of changing the FA volume blend, such as manufactured versus natural sand. We have found this ratio to have the most influence (of the four main principles) on altering VMA or Voids in a coarse-graded mix. A change in the FAf ratio is predominantly a change in the volume of filler material, rather than a change in particle shape. Also remember that VMA or Voids are effected by the characteristics of each individual aggregate, such as shape, strength and texture, which is not directly accounted for in the combined blend evaluation ratios. The main point you can depend on with these principles is the direction of change (I.e. increasing or decreasing VMA or Voids).

Estimating VMA or Voids Coarse-Graded Mix Example Trial #1 PCS = 38.2% 100% CA LUW CA ratio = 0.693 FAc ratio = 0.492 FAf ratio = 0.394 AC = 4.6% Air Voids = 3.4% VMA = 12.6% Trial #2 PCS = 37.2% 102.5% CA LUW CA ratio = 0.725 FAc ratio = 0.444 FAf ratio = 0.412 AC = 4.6% Expected VMA? Expected Air Voids? So lets look at each of the four main principles for the two trials. The PCS is 38.2% in trial #1 and 37.2% in trial #2. Note the change in the % CA LUW between the two trials. I’ve also calculated the three ratios for each trial. For the moment, let’s leave the AC content the same, so we don’t need to take that into account as far as it’s impact on the expected Voids. We have the VMA and air void results for trial #1, so if we’ve done everything accurately, we know where we’re at. So, can we estimate the expected VMA and Voids for trial #2?

Estimating VMA or Voids Trial #2 vs. Trial #1 PCS 37.2% - 38.2% = - 1.0% CA ratio 0.725 – 0.693 = + 0.032 FAc ratio 0.444 – 0.492 = - 0.048 FAf ratio 0.412 – 0.394 = + 0.018 Increases VMA or Voids 1.0/4.0 = + 0.25% 0.032/0.2 = + .16% 0.048/0.05 = +.96% Decreases VMA or Voids 0.018/0.05 = - 0.36% Total Estimated Change: Plus ~ 1.0% VMA Remember we are evaluating a 19mm NMPS coarse-graded mix. Make sure you are considering the change from trial #1 to trial #2 for each individual principle in the right “direction”, as to whether that change will increase or decrease VMA or Voids. For the PCS, we are decreasing 1%, so the estimated change is ¼ = 0.25% increase in VMA or Voids. We know this is an increase, since to lower the PCS, we have to raise the CA CUW value. For the CA ratio, we are increasing 0.032, so the estimated change is 0.032/0.2 = 0.16% increase in VMA or Voids. For the FAc ratio, we are decreasing 0.048, so the estimated change is 0.048/0.05 = 0.96% increase in VMA or Voids. For the FAf ratio, we are increasing 0.018, so the estimated change is 0.018/0.05 = 0.36% decrease in VMA or Voids. The total estimated change is 0.25+0.16+0.96-0.36 = plus 1.01%

ODOT’S PERPETUAL PAVEMENT STRUCTURAL SECTIONS AT NCAT TEST TRACK PLAN VIEW SECTION 1 – 150’ SECTION 2 – 150’ 25’ TRANSITION 25’ TRANSITION 50’ TRANSITION

ODOT’S PERPETUAL PAVEMENT STRUCTURAL SECTIONS AT NCAT TEST TRACK PLAN VIEW SECTION 1 – 150’ SECTION 2 – 150’ 25’ TRANSITION 25’ TRANSITION 50’ TRANSITION PROFILE VIEW 2” SMA w/PG 76-28 3” SuperPave 19.0mm w/PG 76-28 3” SuperPave 19.0mm w/PG 64-22 2” RBL w/PG 64-22 3” SuperPave 19.0mm w/PG 64-22 3” RBL w/PG 64-22 *RBL = RICH BOTTOM LAYER

AGGREGATE SUMMARY Martin Marietta Hanson Dolese GMI Sand Aggregate Type River Sand Rhyolite Limestone Limestone Aggregate Shape Very Angular Angular Angular Rounded L.A. Abrasion 16.3 26.3 25.2 n/a Micro Deval 7.4 23.8 14.7 n/a Screenings P200 6.8 1.1 12.9 2.0

RBL MIX DESIGN INFORMATION Hanson Dolese 5/8” Chips Screenings 35% 20% 45% 20 40 60 80 100 Pb 6.0 % Air Voids 2.0 % VMA 14.6

RBL MIX – EVALUATED AS A FINE-GRADED MIX For fine-graded mixes, the volume of the fine fraction exceeds the CA LUW voids. This value is less than 90% of CA LUW, and ensures that the fine aggregate is in control. CHOSEN UNIT WT. = 78.9% OLD CA RATIO – 0.875 NEW CA RATIO – 0.556 NEW FAc RATIO – 0.558 NEW FAf RATIO – N/A

RBL MIX – EVALUATED AS A FINE-GRADED MIX For coarse-graded mixes, the preferred range is 0.50 – 0.65. For this fine-graded mix, the high CA Ratio indicates a low susceptibility to segregation. CHOSEN UNIT WT. = 78.9% OLD CA RATIO – 0.875 NEW CA RATIO – 0.556 NEW FAc RATIO – 0.558 NEW FAf RATIO – N/A

RBL MIX – EVALUATED AS A FINE-GRADED MIX The preferred range is 0.60 – 1.00. The New CA Ratio is primarily controlled by the FAs rather than the CAs and its affect on the entire blend is therefore mitigated. CHOSEN UNIT WT. = 78.9% OLD CA RATIO – 0.875 NEW CA RATIO – 0.556 NEW FAc RATIO – 0.558 NEW FAf RATIO – N/A

RBL MIX – EVALUATED AS A FINE-GRADED MIX The preferred range is 0.35 – 0.50. The value of 0.558 indicates a high dust/binder ratio (1.4 for this design) and a high mortar stiffness. Higher values → lower VMA. CHOSEN UNIT WT. = 78.9% OLD CA RATIO – 0.875 NEW CA RATIO – 0.556 NEW FAc RATIO – 0.558 NEW FAf RATIO – N/A

RBL MIX – EVALUATED AS A FINE-GRADED MIX CHOSEN UNIT WT. = 78.9% The tertiary sieve for 12.5mm fine-graded mixes would fall below the 0.075mm, therefore the FAf Ratio cannot be calculated. OLD CA RATIO – 0.875 NEW CA RATIO – 0.556 NEW FAc RATIO – 0.558 NEW FAf RATIO – N/A

AIR VOIDS @ 6.0% BINDER – ACTUAL vs. ESTIMATED 9.0 RBL MIX 8.0 ACTUAL 7.0 EST. % AIR VOIDS 6.0 5.0 4.0 3.0 2.0 1.0 0.0 -1.0 2 3 4 5 6 7 TRIAL #

19.0mm SUPERPAVE MIX DESIGN INFORMATION Hanson Dolese MM GMI 1” Chips Screenings Stone Sand Sand 30% 25% 15% 20% 10% 20 40 60 80 100 Pb 4.3 % Air Voids 4.0 % VMA 13.6

19.0mm MIX – EVALUATED AS FINE-GRADED This value is far less than 90% of CA LUW, and ensures that the fine aggregate is in control. However, such a low value indicates that the mix may be difficult to compact. CHOSEN UNIT WT. = 50.7% OLD CA RATIO – 0.358 NEW CA RATIO – 0.681 NEW FAc RATIO – 0.517 NEW FAf RATIO – 0.332

19.0mm MIX – EVALUATED AS FINE-GRADED Even though this is a fine-graded mix, the low CA Ratio means that in the CA there is a higher % of “pluggers” than “interceptors,” indicating a potential problem with segregation. CHOSEN UNIT WT. = 50.7% OLD CA RATIO – 0.358 NEW CA RATIO – 0.681 NEW FAc RATIO – 0.517 NEW FAf RATIO – 0.332

19.0mm MIX – EVALUATED AS FINE-GRADED The preferred range is 0.60 – 1.00. This mix falls within the preferred range, which means any compaction issues would likely not be attributed to this fraction. CHOSEN UNIT WT. = 50.7% OLD CA RATIO – 0.358 NEW CA RATIO – 0.681 NEW FAc RATIO – 0.517 NEW FAf RATIO – 0.332

19.0mm MIX – EVALUATED AS FINE-GRADED The preferred range is 0.35 – 0.50. The value of 0.517 might indicate a tenderness problem if the mix contained a high % sand. However, this mix contains only 10% natural sand. CHOSEN UNIT WT. = 50.7% OLD CA RATIO – 0.358 NEW CA RATIO – 0.681 NEW FAc RATIO – 0.517 NEW FAf RATIO – 0.332

19.0mm MIX – EVALUATED AS FINE-GRADED The preferred range is 0.35 – 0.50. However, the FA ratios are generally a problem only if both are high or both are low. CHOSEN UNIT WT. = 50.7% OLD CA RATIO – 0.358 NEW CA RATIO – 0.681 NEW FAc RATIO – 0.517 NEW FAf RATIO – 0.332

AIR VOIDS @ 4.3% BINDER – ACTUAL vs. ESTIMATED 19.0mm SUPERPAVE MIX 5.0 % AIR VOIDS 4.0 ACTUAL EST. 3.0 2.0 1.0 2 TRIAL #

SMA MIX DESIGN INFORMATION Hanson Dolese Boral 5/8” Chips Screenings Mineral Filler 67% 13% 10% 20 40 60 80 100 Pb 6.8 % Air Voids 4.0 % VMA 17.9

SMA MIX This value barely falls within the preferred range of 110 - 125% of CA RUW. This indicates that the %CA, although acceptable, is on the low side for a SMA mix. CHOSEN UNIT WT. = 110.0% CA RATIO – 0.398 FAc RATIO – 0.720 FAf RATIO – 0.843

SMA MIX This value falls within the preferred range of 0.25 – 0.40. Be careful interpolating the value for the “half sieve” on a 12.5mm SMA. It would be best to insert a ¼” sieve into the nest. CHOSEN UNIT WT. = 110.0% CA RATIO – 0.398 FAc RATIO – 0.720 FAf RATIO – 0.843

SMA MIX CHOSEN UNIT WT. = 110.0% This value falls within the preferred range of 0.60 – 0.85, indicating a good balance in the relative fractions of the fine aggregate. CA RATIO – 0.398 FAc RATIO – 0.720 FAf RATIO – 0.843

SMA MIX This value falls within the preferred range of 0.65 – 0.90. Typically, the higher the ratio, the greater P200. This mix was designed on the high side to decrease permeability potential. CHOSEN UNIT WT. = 110.0% CA RATIO – 0.398 FAc RATIO – 0.720 FAf RATIO – 0.843

AIR VOIDS @ 7.0% BINDER – ACTUAL vs. ESTIMATED 12.5mm SMA MIX 7.0 % AIR VOIDS 6.0 ACTUAL EST. 5.0 4.0 3.0 2 TRIAL #

EXAMPLE OF ACTUAL ODOT QC/QA PROJECT DATA AIR VOIDS – ACTUAL vs EXAMPLE OF ACTUAL ODOT QC/QA PROJECT DATA AIR VOIDS – ACTUAL vs. ESTIMATED 9.0 19.0mm SuperPave Mix 8.0 7.0 ACTUAL % AIR VOIDS 6.0 EST. 5.0 4.0 3.0 2.0 1.0 0.0 -1.0 2 3 4 SAMPLE #

OUR THOUGHTS SO FAR: The Bailey Method principles make sense when reviewed in the context of previous mix design experience The Method provides a way to quantify changes that we have only made “educated guesses” at before Don’t worry about the various calculations because we have spreadsheets for doing them. I want to emphasize how the Bailey Method helps. We can use it to: Develop NEW blends, while considering field compactibility and segregation susceptibility for the aggregates we have to use. Evaluate Existing blends and better understand why they worked well or why they didn’t. Estimate VMA/Void changes between: Design trials QC samples Whenever we need to adjust the blend in the lab or in the field Based on previous experience, the Method gives a reasonable indication of aggregate combinations which are susceptible to segregation and field compactability problems

OUR THOUGHTS SO FAR: Based on previous experience, the mixes that fall into the “Coarse-Graded” category are often too permeable The voids estimation process looks at gradation only, and is therefore “blind” to changes in aggregate shape and texture Don’t worry about the various calculations because we have spreadsheets for doing them. I want to emphasize how the Bailey Method helps. We can use it to: Develop NEW blends, while considering field compactibility and segregation susceptibility for the aggregates we have to use. Evaluate Existing blends and better understand why they worked well or why they didn’t. Estimate VMA/Void changes between: Design trials QC samples Whenever we need to adjust the blend in the lab or in the field The voids estimation process performs better when working with aggregates of similar properties

OUR THOUGHTS SO FAR: Although the Bailey Method is a good tool, users must not forget the things they already know about the materials they are using The “default” values used in the void estimation process should vary depending on the types of aggregate used Don’t worry about the various calculations because we have spreadsheets for doing them. I want to emphasize how the Bailey Method helps. We can use it to: Develop NEW blends, while considering field compactibility and segregation susceptibility for the aggregates we have to use. Evaluate Existing blends and better understand why they worked well or why they didn’t. Estimate VMA/Void changes between: Design trials QC samples Whenever we need to adjust the blend in the lab or in the field Each user should analyze historical data and interview field personnel to “calibrate” the method to their own materials

SOME TOOLS REQUIRE MORE PRACTICE AND EXPERIENCE THAN OTHERS…

THANK YOU!