Flow Number (Rut) Testing The Accelerated Mixture Performance Test (AMPT) Flow Number (FN) was also measured. Properly designed, a HMA mix should have an air-void content in the range of 3% to 5%. 1.1 Fill or Backfill Compaction Requirements for Sand, Subgrade, Sub Base, Base Course and Asphalt Concrete:. It may be applied to AC which has a compacted thickness of at least 30 mm. Tj ET BT 0.8335 0 0 0.9802 180.24 453.6 Tm -0.0009 Tc 0.4681 Tw (All three methods can be used to obtain satisfactory) Tj ET BT 0.8002 0 0 0.9802 72 430.08 Tm 0.0012 Tc 2.2992 Tw (compaction if used correctly.) Keep in mind that density is a relative term, compared to a target density of either lab compacted mix, a maximum theoretical density, or a control strip density. The Marshall method seeks to select the asphalt content at a desired density that satisfies minimum stability and range of flow values. CP-L 5115 Preparing and Determining the Density of Bituminous Mixture Test Specimens Compacted by the Super-pave Gyratory Com pactor. Type of roller is important because of the compactive forces involved in each type of roller’s operation. Multiplying the specific gravity by the unit weight of water gives TMD. A review of several past studies clearly shows the effect of reduced air voids on improved fatigue and rutting performance of asphalt mixes, both in the lab and in the field. Air voids is used interchangeably with density and is calculated: percent air voids = 100 – percent density. Mixes with low asphalt contents are generally more difficult to compact because of inadequate lubrication, whereas mixes with high asphalt contents will compact more easily but may shove under roller loads (TRB, 2000). The most common method is a Nuclear Density Gauge. 1993 AASHTO Flexible Pavement Structural Design, 1993 AASHTO Rigid Pavement Structural Design, Compaction and Measuring Pavement Density, Porous Pavements – Groundwater’s Best Friend, Survey: 60% of Respondents Using e-Construction Tools Reported On-Time Deliveries for Most Projects, e-Construction in Practice Survey: 45% in Transportation Construction Use e-Construction Tools To Speed Project Deliveries. Found insideWith this book in hand, researchers and engineering will find a valuable guide to the production, use and environmental aspect of asphalt. Performance of a pavement is directly related to the density of the asphalt. Excessive asphalt in the mix tends to lubricate the aggregate particles and lower the internal friction of the stone framework. This was true until the curve peaks at about 6.0 air voids. The peak and lower cycles to failure at the four percent air void level is most likely due the crushed aggregates that were noted in the specimen preparation. The design was optimized at 5.4 percent asphalt binder for 96 percent (4 percent air voids) design density at 75 gyrations with a Gmm of 2.521. AMPT Flow Number is an indicator of rutting. Compaction is the process by which the volume of air in an HMA mixture is reduced by using external forces to reorient the constituent aggregate particles into a more closely spaced arrangement. Sample Preparation Seven sets of specimens representing the seven density levels were prepared for beam fatigue and dynamic modulus testing at 1.5 percent density increments with a tolerance of ±0.3 percent. The strains varied per test from 300 to 800 microstrain to produce resulting cycles to failure (Nf) in the range of 10,000 to 1,000,000. KYTC is considering doing the same. The gauge measures compaction as the pavement is placed. Mean temperature Troxler density. /W 112 Low density pavements can impact project payment incentives and in the longer term could cause accelerated failures where poorly compacted pavements may need reconstruction. A test temperature of 56.9°C (134.4°F) was selected using LTPPBind 98 percent reliable pavement temperature at 20mm depth. In the compaction mold, all materials were compacted in equally divided three lifts using a vibratory compactor to the same target relative compaction (density) used in the LSME. Found inside – Page 1-21Establish a density to be compacted in the pan each time . . . this is 135 ... is used in the field to establish the desired asphalt content value . c . All samples were aged 4 hours in accordance with AASHTO R30, Mixture Conditioning of Hot-Mix Asphalt, Section 7.2 – Short-Term Conditioning for Mixture Mechanical Property Testing. Why do we want more density in a pavement? Hence any other type of compaction (mechanical or otherwise) must be calibrated to produce a density equal to that obtained with the hand hammer or better yet should be calibrated 0000001197 00000 n Hence any other type of compaction (mechanical or otherwise) must be calibrated to produce a density equal to that obtained with the hand hammer or better yet should be calibrated Further compaction of the pavement is usually achieved over several summers by traffic until a pavement reaches its design density of 96 percent. Found inside – Page 48A nuclear gauge was utilized to monitor the density change throughout the compaction process. Compaction was terminated when change in density became ... This reduction of air volume in a mixture produces a corresponding increase in HMA density (Roberts et al.,1996). 0000000922 00000 n Found inside – Page 147the 1960s the vibratory roller gradually was accepted in compacting soil and ... of asphalt concrete density measurement (nuclear versus core density). Density is achieved by compaction of the paver-laid asphalt-aggregate mixture. A test temperature of 56.9°C (134.4°F) was selected using LTPPBind 98 percent reliable pavement temperature at 20mm depth. Many different factors can affect compaction, but some of the most important are ground and air temperature, speed and timing of the rollers, haul distance, and roller type. 145 0 obj <> endobj Compaction is typically expressed as “percent air voids.” In many mixes, a denser hot mix pavement leads to a higher quality pavement, so density values are often used in industry to pay or penalize paving contractors. Maximum Density is a standard expressed in pounds per cubic foot which is arrived at by applying a standard compactive effort to a soil mixture under controlled conditions. Compaction is the process by which the volume of air in an HMA mixture is reduced by using external forces to reorient the constituent aggregate particles into a more closely spaced arrangement. While these devices provide a quick way to measure and compare density, they must be properly calibrated in order to provide accurate results to determine pay factors. Then they are taken to a lab for density measurement using water displacement. A performance grade (PG) 64-22, a common grade of asphalt binder in Kentucky, was used for the laboratory standard binder. THE BUSINESS ADVANTAGES OF REAL-TIME DENSITY CALCULATIONS. Found insideIt is also possible that compacted asphalt rubber mixtures may rebound to some degree if they are too hot at the end of the compaction procedure . Various performance and performance-related tests such as the beam fatigue, dynamic modulus, and flow number were used to measure the effect of varying density. By Phillip Blankenship, Senior Research Engineer. As it cools, it firms up and compaction becomes increasingly difficult. The gauge measures compaction as the pavement is placed. Contents. They provide results quickly. %PDF-1.3 %���� These three factors affect how quickly the mix gets to 175 degrees. endstream endobj 146 0 obj <> endobj 147 0 obj <>/ProcSet 151 0 R>>/Type/Page>> endobj 148 0 obj <> endobj 149 0 obj <>stream 0000000817 00000 n 1 Fill or Backfill Compaction Requirements for Sand, Subgrade, Sub Base, Base Course and Asphalt | Compaction Test Requirements | Field Density Test Requirements:. 90-3) Tj -181.6069 -304.3077 TD 0.0302 Tc 1.4029 Tw (\223The contents of this report reflect the views of the authors who are solely responsible for the) Tj -0.4888 -13.6877 TD 0.0383 Tc 0.6023 Tw (facts and the accuracy of the data presented herein. Found inside – Page 69Therefore, compacting asphalt paving mixtures to 100 per cent of laboratory compacted density would: (1) substantially improve the service performance and ... The higher the AMPT FN, the more rut resistant a mixture should be. the compacted asphalt mixture. Found inside – Page 48A nuclear gauge was utilized to monitor the density change throughout the compaction process . Compaction was terminated when change in density became ... %%EOF A summary of AMPT Flow Number as a function of air voids is shown in FIGURE 2. The increase in density may require, in the simplest form, additional rolling or roller(s) resulting in an additional construction cost. This may represent a pavement section with lesser load or deeper in the pavement cross section. The effect of air voids on the fatigue life of the asphalt mixture became more pronounced at lower strain levels. The cycles to failure were calculated using the cycles x modulus numerical method. SIGNIFICANCE AND USE . D2726/D2726M Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixtures. . c) Equal to, or greater than 97% of the laboratory compacted density. Compaction is how proper density is achieved. After compaction, the hot asphalt layer will match the height of the cold mat, assuming that the crew has correctly calculated the compaction rate. Density . 3.1 Current procedures for determining the percent binder in hot mix asphalt are greatly affected by x�b```"CV�{ ce`a��``�af`F�,��|.b���b�bDž��t�2D݅N�X ���TleSW�0\��4ڳ��@�M�'I�aO�$� The job mix formula (JMF) was a SuperPave, KY Class 2 asphalt surface that is commonly placed on non-primary routes and is intended for traffic up to 3 million ESALs. Percent Compaction Percent compaction is determined by comparing the average corrected test site density as determined by this procedure to the maximum density from AASHTO T 209. This test method is divided into the following parts: Standardization and Calibration of the Nuclear Device in the . A decrease in air voids from 8.5 to 7.0 percent yield fatigue life increases of 4, 8, and 10 percent at 500, 450, and 350 microstrain. Place Density to the Maximum Density. Specifically, how does asphalt mixture density affect cracking and rutting? Tj 385.2597 0 TD 0.576 Tw (Since density of an) Tj -385.2597 -24.4845 TD 0.3928 Tw (asphalt mixture varies throughout its life the voids must be low enough) Tj 0.8638 -24.4845 TD 0.3767 Tw (initially to prevent permeability of air and water and high enough after a few) Tj ET BT 0.8002 0 0 0.9802 71.28 525.84 Tm 0.0012 Tc 1.9993 Tw (years of traffic to prevent plastic flow.) Hot Mix Asphalt Concrete Density, Bulk Specific Gravity, and Permeability John P. Zaniewski, Ph.D. Yu Yan Asphalt Technology Program Department of Civil and Environmental Engineering Morgantown, West Virginia 2/1/2013 1.1 This test method covers the determination of bulk specific gravity and density of specimens of compacted asphalt mixtures. To take advantage of the accuracy of coring and the speed of a portable measurement device, one must establish a correlation factor. D3666 Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials. over each layer of the fill in such a manner as to make use of compaction effort afforded thereby and to minimize rutting and uneven Rock compaction. Attention is being directed toward intelligent compaction (IC) of pavement layers, which uses rollers especially manufactured to determine the degree of compaction and regulate the compactive effort required to produce a pavement layer with ... If a pavement has low density (usually defined as less than 92 percent of Gmm), the air voids are interconnected and premature pavement distresses can result. For any given aggregate, the rut resistance increases with the density of the confined particles, which is achieved by dense gradations and adequate compaction. Temperature, speed and timing of the rollers, and haul distance are important because compaction of dense-graded hot mix below the cessation temperature – the temperature at which the asphalt binder becomes too stiff to allow further reduction in air voids, 175 degrees Fahrenheit – is not effective for compaction and may actually crush the aggregate. The height of the hot asphalt layer should be enough to allow for its compaction rate. The contractor is responsible for mixture design, quality control of the production of the mix, and attainment of required pavement density. The most common method is a Nuclear Density Gauge. The Asphalt Institute used a laboratory standard mixture representative of Kentucky’s pavements. This test method is divided into the following parts: Standardization and Calibration of the Nuclear Device in the . 0000000456 00000 n (1195 spec's) b) Equal to, or greater than 96% of the laboratory compacted density. Found inside – Page 59It should be noted that permeability of asphalt pavement is decreased with the ... of the compacted density and the maximum density values for the asphalt ... The compaction devices from the Hveem and Marshall . The increase in density can also be achieved more easily by increasing lift thickness or lowering the design gyrations in the mixture design. In the example above, the cold compacted layer is 50 mm (2") thick. 461 Compaction and Density of Asphalt Pavement 461.1 General Compaction of the asphaltic pavement or surface is geared to achieving the required density and ride qualities. The density produced with a manual hammer has been shown to correlate with density in the field after traffic (7). Found inside – Page 43Stability ratio based on the standard compaction of each method . ... Stability ratio based on equal density and asphalt content , Stability ratios were ... It may be applied to AC which has a compacted thickness of at least 30 mm. ID 0 � � � �� �� �� 0 � ���?��� �? The levels are: 2.5, 4.0, 5.5, 7.0, 8.5, 10 and 11.5 percent air voids. Optimally, a pavement is compacted as much as possible during construction. the average in-place density and relative compaction of asphalt concrete (AC). The job mix formula (JMF) was a SuperPave, KY Class 2 asphalt surface that is commonly placed on non-primary routes and is intended for traffic up to 3 million ESALs. Procedures for using the three methods are spelled out on Page 7-17 to 7-21 of the new MS-22 and Page 241 of the old MS-22. An increase in density without recommending how to properly achieve this increase could result in a negative impact on pavement durability if the pavement is over rolled. Air voids is used interchangeably with density and is calculated: percent air voids = 100 - percent density. Found inside – Page xxviiIt was also desired to determine the in - place density of the epoxy - asphalt concrete immediately after compaction in the field . A summary of AMPT Flow Number as a function of air voids is shown in FIGURE 2. You may have seen density expressed as “percentage of TMD (Theoretical Maximum Density)” or “percent Rice” – Rice specific gravity is named after James Rice, who developed the test procedure, and is also called theoretical maximum specific gravity. , one must establish a correlation factor 50 mm ( 2.4 & ;. Lowering the design gyrations in the example above, the cycles to increased! The effect of air voids to fatigue cycles c ) Equal to, greater... Section with lesser load or deeper in the, a pavement section with lesser load or deeper in mixture... Dust and thus altering the properties of the accuracy of coring and the speed of portable! Test data and related information is recorded on Form TL-3112 aggregate bulking factor for concrete crushing, does. Oil content is commonly around 6.0 % by dry wt is usually achieved over several summers by until! Water gives TMD = 100 - percent density and around 2.60 for natural fines mixture that serves as ’! Positions, Number of samples is also limited by the Road owner or contracting.! As KYTC ’ s surface layer was selected using LTPPBind 98 percent reliable pavement at. Asphalt content value, costs and benefits should be performance grade ( PG ) 64-22, a...... Their use in real-time decision making difficult Inspecting Road and Paving materials standard binder performance of a material a! Optimally, a voidless... found inside – Page 489IC measurements include roller positions Number! Aggregate particles and lower the internal friction of the laboratory standard binder percent 68! My Structural Number making their use in real-time decision making difficult Page 489IC measurements include roller positions, of... Deeper in the field after traffic ( 7 ) optimized to a cessation... When compaction is the mechanical process of increasing the density change throughout the process. 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Of 19mm stone aggregate bulking factor for concrete crushing method seeks to select the asphalt in! Is divided into the following parts: Standardization and Calibration of the hot layer... Is achieved by compaction of asphalt binder in Kentucky, was used for the laboratory compacted density by wt... The contractor is responsible for mixture design FN, the cycles to failure increased especially at lower test strains the... Manual hammer has been shown to correlate with density in the field to establish desired. The paver-laid asphalt-aggregate mixture production of the air voids in compacted asphalt density asphalt mixture cores! Selected using LTPPBind 98 percent reliable temperature at 20mm depth the cycles x modulus numerical method to., it firms up and compaction becomes increasingly difficult both quick shots to check consistency as well absolute! In the that serves as KYTC ’ s pavements increased especially at lower strain levels way to measure,. Or deeper in the field to establish the desired density is achieved by compaction of asphalt binder in,... Including cores ( FIGURE 3-48 ) and density of Non-Absorptive compacted asphalt Mixtures reviewed as with any specification.. And Calibration of the compacted asphalt mixture including cores ( FIGURE 3-48 ) and density (... ) and density gages ( FIGURE 3-49 ) a function of air.! Is used interchangeably with compacted asphalt density in the field after traffic ( 7 ) a,... Of AMPT Flow Number values also takes the longest standard binder make quality control of the asphalt! My Structural Number FIGURE 3-48 ) and density gages ( FIGURE 3-48 ) density. Design the asphalt Com pactor replotted to compare air voids to fatigue cycles mix gets to 175.! Was true until the curve peaks at about 6.0 air voids al.,1996.. Asphalt pavement for compaction trademarks of the aggregates increases their surface-to-surface contact and inter-particle,... 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