AASHTO M320 PDF

AASHTO Designation: M Release: Group 3 (August ). American Association of State Highway and Transportation Officials North Capitol Street. Find the most up-to-date version of AASHTO M at Engineering AASHTO M Standard Specification for Performance-Graded Asphalt Binder. standard by American Association of State and Highway Transportation.

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Work done under the NCHRP research project used the time sweep test to apply sufficient cycles to induce damage, but the amount of time required to perform the test was a problem. Upon completion of SHRP research ina set of performance-related specifications were developed for asphalt binders as well as mixtures. Fundamental relationships are then obtained between the binder and the hot-mix asphalt and provide an input to pavement performance models.

Performance based purchase specifications enable engineers to specify high quality asphalt binders to build safe and long-lasting roads. A classification assigns the performance grade and gives precise determinations of failure points critical temperatures. The DT test method is not limited to specification use. The mass change shall be less than 1. The grades of asphalt binder shall conform to the requirements given in Table 1 or Table 2.

Asphalt Binder Specification Tests

Compare the failure stress from T to the calculated induced thermal stress as per PP In this practice, only single event thermal cracking is considered.

Many DOTs have noticed a lower to almost negligible incidence of thermal cracking since the implementation and use of the new test methods.

One of the new procedures being considered to characterize fatigue cracking performance of asphalt binders is the Linear Amplitude Sweep LAS test. Table 2 incorporates PP42 for determining the critical low cracking temperature using a combination of T and T test procedures. To prevent aasbto cracking, the S value was limited to a maximum of MPa.

The DT test method as initially proposed at the end of SHRP was found to be inadequate as a standard test method due to persistent m32 with various aspects of the test system.

Cutback Asphalts are commonly used in cold mixes or as prime applications.

From laboratory tests performed on asphalt binder mixtures, m-value has been shown to be related to thermal fracture as well as thermal fatigue cracking. Although Superpave was a significant improvement over earlier approaches, one of the concerns was that it was based primarily on unmodified asphalts.

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In the Koch survey referred to above, it was found that 40 of the 51 transportation agencies have determined that the quality of asphalt binders has improved as a result of using the new test methods specified in the AASHTO M and MP1a specifications.

It is designed to be performance related rather than empirical and to be blind to the type of modifier used. For heavy traffic the Jnr is reduced to 2. So, more recent efforts have been geared to m230 accelerated fatigue procedures. In the United States, the new standards are used in federal, state, city aashfo local government laboratories involved in construction and maintenance of asphalt pavements.

Sang-Soo Kim, simulates thermal cracking and allows the determination of a cracking temperature. The two types are Rapid-Curing and Medium-Curing. This property provides an indication of the delayed elastic response of the binder. These were collectively called the Superpave pavement design system.

Asphalt Binder Specification Tests – Asphalt InstituteAsphalt Institute

Testing at additional temperatures for T m3320 be necessary if MPa is not bracketed at the initial two test temperatures. In road building terminology, this composite of asphalt binder and mineral aggregates is called hot-mix asphalt or, simply, asphalt mixture. The azshto would also be changed to move away from increasing the high temperature designation. This combination of tests provides a more in-depth low temperature property analysis.

Modifiers may be any organic material of suitable manufacture that is used in virgin or recycled condition and that is dissolved, dispersed or reacted in asphalt binder to enhance its performance. If the creep stiffness is below MPa, the direct tension test is not required. Low-temperature cracking, while found in most of the states, is more ubiquitous in the northern latitudes, such as the colder climates of North America and Canada.

They fall into four categories: This shrinkage causes thermal stresses and when these stresses exceed aashfo tensile strength of the mixture, a low temperature crack forms. This system was used extensively prior to the development of Superpave. Two test methods and a calculation practice were developed for use in the Superpave specification to address low-temperature cracking performance of pavements: Low temperature rheological and failure characteristics of asphalt binders may be obtained using D DT test method at other test conditions such as different strain rates, stress control tests and low temperature fatigue.

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A new high-temperature binder specification would require the Jnr value, determined at a shear stress of 3. A majority of the roads pavements in the United States and around the world are constructed using a composite mixture of asphalt binder and aggregates blended to meet preset design requirements.

The asphalt binder is tested at temperatures the pavement is not likely to actually experience. Depending on the type, several combinations of tests can be required to verify adherence to specification. The mean failure strength value determined at a standard strain rate of 3 percent per minute is used along with BBR data to determine critical cracking temperature aashgo described next.

An important phenomenon called physical hardening of asphalt binders during prolonged exposure to low temperatures was discovered during the refinement efforts.

Refining Superpave asphalt binder characterization | Asphalt magazine

The impact of these standards on the quality and safety of the highway pavements is also reported. The rate at which the binder stiffness changes with time at low temperatures is regulated through the m-value.

The new standards may be used by anyone interested in characterizing the low temperature behavior of asphalt binders. Both neat unmodified and modified binders were tested in the development of the MSCR test. The above BBR and DT test methods have been previously used aastho one form mm320 another to characterize various materials including asphalt binder. Same combination of tests as the PG verification with MP1a analysis with the addition of additional test temperatures.

Does not address low temperature properties. The MSCR test starts at the lowest stress level and increases to the higher level at the end of 10 cycles, with no time delay between cycles. The DTT pulls an asphalt specimen in tension at a very slow rate to simulate shrinkage as a pavement cools.