What is the Superpave System?
The Superpave system ties asphalt binder and aggregate selection into the mix design process, and considers traffic and climate as well. The compaction devices from the Hveem and Marshall procedures have been replaced by a gyratory compactor and the compaction effort in mix design is tied to expected traffic.
How to design a Superpave mix?
The Superpave mix design consists of seven stages: (i) aggregate selection, (ii) asphalt binder selection, (iii) sample preparation, including compaction, (iv) performance tests, (v) density and voids calculations, (vi) optimum asphalt binder content selection, and (vii) moisture susceptibility evaluation.
What is a Superpave PG designation?
Superpave asphalt binder performance grade (PG) designations are related to the average seven-day and minimum anticipated pavement design temperatures, and the designations directly state these temperatures.
What is the difference between Marshall and Superpave?
Compared to the Marshall design method, Superpave integrates material selection and mix design and uses an entirely different type of compaction. Instead of the impact of weighted hammer blows, the Superpave gyratory compactor (SGC) uses a hydraulically powered kneading system with an action much closer to the actual field densification of the mix.
What is Superpave made of?
The Superpave system consists of three interrelated elements: asphalt binder specification; volumetric mix design and analysis system; and mix analysis tests and a performance prediction system that includes computer software, weather database, and environmental and performance models.
What is the Superpave method?
The Superpave system ties asphalt binder and aggregate selection into the mix design process, and considers traffic and climate as well. The compaction devices from the Hveem and Marshall procedures have been replaced by a gyratory compactor and the compaction effort in mix design is tied to expected traffic.
What is the difference between Marshall mix and Superpave?
Marshall mix design primarily address the determination of asphalt binder content, while Superpave addresses all element of mix design. The Marshall design/construction method requires in most cases compaction 95% or greater of the maximum lab value.
What are the sequence of steps for Superpave mix design?
The Superpave mix design consists of seven stages: (i) aggregate selection, (ii) asphalt binder selection, (iii) sample preparation, including compaction, (iv) performance tests, (v) density and voids calculations, (vi) optimum asphalt binder content selection, and (vii) moisture susceptibility evaluation.
What is Superpave binder?
Superpave Performance-Graded Binder Selection. The Superpave Performance-Graded Binder Specification (AASHTO MP-1) is based on providing a binder that is resistant to rutting, fatigue cracking, and low-temperature crack- ing at specific pavement temperatures.
What does the term Superpave stand for in Superpave asphalt binders?
Superior Performing Asphalt PavementsThe term "Superpave" is an acronym for Superior Performing Asphalt Pavements, which evolved from partnerships created among the Federal Highway Administration (FHWA), American Association of State Highway, and Transportation Officials (AASHTO), TRB, and others in the SHRP community.
When was Superpave created?
Building on National Research Superpave was one of seven core technology areas originally identified for implementation under the Strategic Highway Research Program (SHRP), a 5-year research effort established by Congress in 1987.
What does a Superpave Gyratory Compactor do?
The Superpave mix design procedure features the Superpave gyratory compactor (SGC) for compacting specimens of hot mix asphalt.
What is Marshall mix design?
The Marshall Mix Design method was originally developed by Bruce Marshall of the Mississippi Highway Department in 1939. The main idea of the Marshall Mix Design method involves the selection of the asphalt binder content with a suitable density which satisfies minimum stability and range of flow values.
What is tack coat in road construction?
Tack coat (also known as bond coat) is a light application of asphalt emulsion between hot mix asphalt layers designed to create a strong adhesive bond without slippage. Heavier applications may be used under porous layers or around patches where it also functions as a seal coat.
What is an asphalt binder?
The asphalt binder functions as an inexpensive (typically, $0.05/pound), waterproof, thermoplastic adhesive. In other words, it acts as the glue that holds the road together. In its most common form, asphalt binder is simply the residue from petroleum refining.
What is Superpave 12.5 FC2?
Superpave 12.5 FC2 Surface course mix for use on Traffic Category D and E roads that provides superior rutting resistance and skid resistance through aggregate selection. Superpave 12.5 FC2 is similar to the traditional DFC mix according to OPSS 1150.
Why is superpave important?
Saving our clients’ money is always at the top of our list. Superpave helps ensure the pavement will last longer and perform better; Basically, we are saving our clients money!
When was superpave introduced?
Collaborate within the industry to guarantee the new qualifications were being used. In 1992 , Superpave was introduced.
How does superpave affect highways?
Implementing Superpave on our highways has increased the longevity of our roads. Commuters are not the only ones positively effected by Superpave. For instance, almost all highways in the United States use asphalt pavements. Moreover, the yearly expense for asphalt pavement is over 10 billion. Furthermore, let’s not forget about the environmental impact. The more sustainable our roads, the more we save. Superpave has done that!
Does BSK invest in superpave?
BSK has made significant capital investments to support our clients as you incorporate Superpave in your capital improvement budgets.
What is superpave mix?
Superpave mix ( su perior per forming pave ment mix) is not specifically HMA and refers to a complete paving system. The mix is designed to accommodate the traffic loading expected as well as the historical climatic conditions of the location for the pavement. The components for the HMA mixture are carefully selected, each having to meet specific requirements. The binder grade is established by looking at both the historical high and low temperatures of the pavement at the site. In addition, the aggregate must meet specific consensus properties including coarse and fine aggregate angularity, flat and elongated particles, and clay content. Because of the design criteria, Superpave mixes must have a strong aggregate structure which, in general, results in a coarser aggregate blend and lower asphalt contents than standard mixes (Witczak et al., 2002 ). The Superpave mixes are designed to match the expected traffic loads and the high and low expected temperatures of the pavements.
What is superpave level 1?
Superpave Level 1 is an improved materials selection and volumetric mix design procedure ; Level 2 uses the same volumetric mix design procedure as Level 1 as a starting point, in conjunction with a battery of tests to predict the mix performance; and Level 3 involves a more comprehensive array of tests to achieve a more reliable level of performance prediction.
What is OBC asphalt?
From the graphs, OBC was determined as the asphalt content at which 4% air voids were obtained and have satisfied all the Superpave design requirements stated in Table 20.2. The mixing and compaction temperatures are 165 and 155°C, respectively, which was determined from bitumen rotational viscosity test. The test samples were produced based on OBC of the respective recycled PET fiber content shown in Table 20.3. Samples for resilient modulus and static creep tests were prepared at 4% air voids using their respective optimum bitumen contents.
Why is asphalt fatigue important?
Fatigue of mixtures is believed to be due to the formation of microcracks in the binder or mortar of the mixture. This is supported by the fact that rest periods during fatigue testing appear to improve the fatigue life of mixtures, which is believed to be due to the healing of the microcracks. Therefore, it is unsurprising that testing of the binder alone is found to be unreliable (Boussad and Dony, 1996; Paez et al., 1999 ).
What temperature is asphalt mixed at?
With the optimum asphalt-aggregate ratio, asphalt mixture was mixed at 160°C , and under the compaction effort of 55 gyrations, six cylindrical mix samples at 100 mm in diameter were compacted at 130°C by the SGC. In accordance with the aforementioned formula of computing the index of homogeneity, the index of mixture homogeneity compacted at 130°C was calculated, and the calculated results are given in Table 13.19.
What temperature is good for asphalt?
A temperature of 10 °C was found to be representative of the intermediate service temperatures associated with conditions that are conducive to cracking of asphalt mixtures in the field (Roque et al., 2004).
What is superpave mix?
Superpave mix design specifies aggregate gradation control points, through which aggregate gradations must pass. These control points are very general and are a starting point for a job mix formula.
What is superpave aggregate?
Second, it places “consensus requirements” on coarse and fine aggregate angularity, flat and elongated particles, and clay content. Other aggregate criteria, which the Asphalt Institute (2001 [2]) calls “source properties” (because they are considered to be source specific) such as L.A. abrasion, soundness and water absorption are used in Superpave but since they were not modified by Superpave they are not discussed here.
What is superpave gyratory compactor?
The Superpave gyratory compactor establishes three different gyration numbers: Ninitial. The number of gyrations used as a measure of mixture compactability during construction. Mixes that compact too quickly (air voids at N initial are too low) may be tender during construction and unstable when subjected to traffic.
What is the Superpave Mix Design Method?
The Superpave mix design method was designed to replace the Hveem and Marshall methods. The volumetric analysis common to the Hveem and Marshall methods provides the basis for the Superpave mix design method. The Superpave system ties asphalt binder and aggregate selection into the mix design process, and considers traffic and climate as well. The compaction devices from the Hveem and Marshall procedures have been replaced by a gyratory compactor and the compaction effort in mix design is tied to expected traffic.
What is the optimum asphalt binder content?
The optimum asphalt binder content is selected as that asphalt binder content that results in 4 percent air voids at N design . This asphalt content then must meet several other requirements:
How many aggregate stockpiles are there in a superpave mix?
It is quite common to find a Superpave mix design that uses 3 or 4 different aggregate stockpiles (Figure 1).
How many steps are there in Superpave Mix?
The Superpave mix design method consists of 7 basic steps:
What is superpave standard?
Superpave Standard Specifications are written, tested, and proven true by each state’s Department of Transportation to best suit the needs of the road and the surrounding environmental concerns brought by each varying region.
What is superpave pavement?
Superpave is a pavement that can be customized by adjusting the design mix of constituent materials from aggregate proportions to liquid asphalt content and types of Performance Grade binder to withstand the volume and weight of traffic to allow a better quality and extended service life of pavement. When it is determined Superpave is the best choice, specifications should be chosen, understood, and repeated as shown. Superpave Standard Specifications are written, tested, and proven true by each state’s Department of Transportation to best suit the needs of the road and the surrounding environmental concerns brought by each varying region. Using standard state DOT specifications are very important as these mixes have gone through rigorous testing, as well as proven by the test of time to support the pavement needs. DOT specifications can be found online through each governmental entities website.
What additives can be added to asphalt?
There are also other additives that can be added to modify the asphalt such as polymer to give the asphalt a greater elasticity for reducing pavement distress in high traffic, heavy load bearing roads. An Anti-Strip agent can also be added to the liquid binder to create better bond between the aggregates and liquid.
Can you use anti strip on superpave?
Anti-Strip can be partial when limited stone sources are available in a particular region. You can even alter Superpave to include Warm Mix additive which extends the paving season, and reduces emissions at the point of production.
Can you take your specification factors to customize your best pavement yet?
Once the use, and/or volume and ESALs are determined for your bituminous asphalt courses, you can take your specification factors to customize your best pavement yet. Superpave can be broken down as listed below;
What is superpave grading?
Superpave performance grading (PG) is based on the idea that an HMA asphalt binder’s properties should be related to the conditions under which it is used. For asphalt binders, this involves expected climatic conditions as well as aging considerations. Therefore, the PG system uses a common battery of tests (as the older penetration and viscosity grading systems do) but specifies that a particular asphalt binder must pass these tests at specific temperatures that are dependant upon the specific climatic conditions in the area of use. Therefore, a binder used in the Sonoran Desert of California/Arizona/Mexico would have different properties than one used in the Alaskan tundra. This concept is not new – selection of penetration or viscosity graded asphalt binders follows the same logic – but the relationships between asphalt binder properties and conditions of use are more complete and more precise with the Superpave PG system. Information on how to select a PG asphalt binder for a specific condition is contained in Superpave mix design method. Table 1 shows how the Superpave PG system addresses specific penetration, AC and AR grading system general limitations.
What is reliability in asphalt?
Reliability is defined as the percent probability in a single year that the actual temperature (seven-day high or one-day low) will not exceed the corresponding design temperatures. The animation in Figure 3 describes the basic process for selecting the pavement temperature extremes for a PG asphalt binder. Note that pavement temperatures are more extreme than air temperatures.
Is modified asphalt binder a grading system?
Grading is more precise and there is less overlap between grades. Modified asphalt binders are not suited for these grading systems. Tests and specifications are intended for asphalt “binders” to include both modified and unmodified asphalt cements.
What is modified asphalt?
The term “modified” in this context refers to any bituminous concrete that has been altered from its normal/original/neat state. Almost always it is the liquid asphalt binder that is modified or altered from its original state. During a typical refining process, the asphalt binder created or generated is most commonly PG 64S -22 – with PG referring to performance grade, S referring to standard, 64 referring to the upper temperature performance limit in degrees Celsius, and -22 (“negative 22”) referring to the lower temperature performance limit (o C). The upper limit is the average 7-day maximum design temperature and the lower limit is the 1-day minimum design temperature. Much like multi-grade motor oils, asphalt binders are manufactured and formulated to perform over various temperature ranges.
What is HMA S0.25?
HMA S0.25 – Ideal for leveling of deteriorated and raveled surfaces, milled surfaces, or repaired concrete surfaces prior to overlay. Also good for very short-term or temporary thin lift maintenance overlays of any roadway with posted speeds of 40 mph or less. Not to be used as a surface course on wet weather/skid sensitive roadways. Also good for a first lift overlay of many bridge membrane systems. Surface course of choice for walkways, bikeways, and sport courts.
What is a fine graded superpave mix?from fdotewp1.dot.state.fl.us
Fine graded mixes are defined as having a gradation that passes above the restricted zone when plotted on an FHWA 0.45 Power Gradation Chart.
Who is responsible for the design of asphalt mixes which incorporate Rap as a component material?from fdotewp1.dot.state.fl.us
1. The Contractor assumes responsibility for the design of asphalt mixes which incorporate RAP as a component material.
What is the minimum asphalt content for rap?from fdotewp1.dot.state.fl.us
6. Provide RAP having a minimum average asphalt content of 4.0% by weight of total mix. The Engineer may sample the stockpile to verify that this requirement is met.
What is 334-4.1?from fdot.gov
334-4.1 General: Compose the asphalt mixture using a combination of aggregate (coarse, fine or mixtures thereof), mineral filler, if required, and asphalt binder material. Size, grade and combine the aggregate fractions to meet the grading and physical properties of the approved mix design. Aggregates from various sources may be combined.
What is the minimum amount of anti-stripping agent needed for asphalt?from fdotewp1.dot.state.fl.us
3. Use an asphalt binder that contains a minimum of 0.5% anti-stripping agent from the Department’s Qualified Products List. The addition of the specified amount of anti-stripping agent must be certified by the supplier.
