SHRP US Highway Strategic Research Program

SHRP (Strategic Highway Research Program), Chinese translation for US Highway Strategic Research Program

In 1987, the US Congress ’s “Ground Transportation and Urban Relocation Assistance Act (STURAA)” was formally adopted and launched the US Highway Strategic Research Program (SHRP), which is a five-year product-oriented focus on asphalt, pavement performance, concrete Research plan with 4 areas of structure and road transport. The goal of the project is to prepare better road technology for the 21st century, making roads safer and more durable. Because the investment in scientific research on highways has fallen into a trough in the late 1980s, a strong scientific research plan is needed to promote major technological breakthroughs.

The SHRP program ended in 1993, and the two fields of asphalt and pavement performance have achieved fruitful results. As the main research results of asphalt, the asphalt performance specifications and mixture design of Superpave technology have been adopted by AASHTO, and have become the routine of American asphalt pavement. practice. After 20 years of long-term observation, the long-term pavement performance database has been shared by highway workers all over the world.

The design method of SHRP asphalt mixture is divided into â… -level design (mixture volume design), â…¡-level design (medium-level pavement performance mixture design), â…¢-level design (advanced pavement performance mixture design).

SHRP performance test and equipment [2]

4.1 Asphalt performance test

(1) Resistance to rutting, that is, road surface permanent deformation and fatigue cracking performance

Instrument: American Malvern CVO asphalt dynamic shear rheometer (DSR)

Uses: To evaluate the viscosity (non-recoverable) and elastic (recoverable) properties of aged and unaged asphalt in the temperature range of 5 to 85 ℃ by measuring the dynamic shear modulus G * and phase angle s of asphalt, and to predict the resistance to rutting and Fatigue cracking ability.

Test standard: AASHTO T315

The dynamic shear modulus G * and phase angle S are used in the software design to:

①Classification or verification of original asphalt: G * /sinδ1.0 k Pa, which requires high temperature performance of asphalt;

②Sample after aging with rotating film oven: G * /sinδ≥2.2 kPa, which requires high temperature performance of asphalt;

③Sample after aging with rotating film oven and pressure aging test: G * / sinδ≤5 000 kPa to control fatigue characteristics.

(2) Avoid low temperature cracking performance of pavement in low temperature areas

â‘  Non-modified asphalt

Instruments: TE-BBR Asphalt Bending Beam Rheometer (BBR) from Cannon, USA

Uses: Accurately measure the bending creep stiffness and creep rate curve of asphalt at the lowest pavement temperature. It is used to evaluate the low-temperature cracking performance of asphalt. It mainly reflects the ability to resist temperature shrinkage cracking and avoid low-temperature cracking of pavement. It is suitable for non-modified asphalt.

Test standard: AASHTO T313

â‘¡polymer modified asphalt

Instrument: Asphalt Direct Tensile Tester (DTT)

Uses: Under low temperature conditions, measure the stress and strain of asphalt binders at failure, used to evaluate the low temperature fracture properties of asphalt binders, to avoid low temperature cracks on the road surface, suitable for polymer modified asphalt.

p Test standard: AASHTO T314

(3) High temperature viscosity of asphalt

Instrument: RVDV-II + Pro Asphalt Rotational Viscometer (RV) of Brookfield Corporation, USA

Uses: Determine the high-temperature viscosity of asphalt by measuring the torque required for the spindle-shaped shaft immersed in the asphalt sample to rotate at a certain speed. It is used to evaluate the high-temperature and ease of asphalt. It is used to control the mixing and compression of asphalt mixture. .

Test standard: AASHTO T316

(4) Long-term aging performance of asphalt

Instrument: PR9300 asphalt pressure aging container (RTFO) of American Prentex

Uses: To simulate the long-term aging process of asphalt under the influence of climate and traffic load, and provide aging asphalt samples for performance testing. The temperature range is 150 ° C with an accuracy of 0.3 ° C.

Test standard: AASHTO PP-1; ASTM D6521

(5) Asphalt aging performance

Instrument: CS325B Asphalt Rotating Film Oven (PAV) of American James.cox Company

Uses: To simulate the aging of asphalt during the production of hot mix asphalt, and to provide asphalt samples for performance testing or further aging.

Test standard: AASHTO T-240; ASTM D2872

4.2 Accelerated performance test of asphalt mixture

(1) Simulated road compaction

Instrument: American Troxlert 5850 SuperPave Rotary Compactor

Australian IPC PReSBOX asphalt mixture shear compaction instrument

Uses: Accurately simulate on-site compaction and provide compaction curves for asphalt mixture design and quality control.

(2) Asphalt mixture dynamic fatigue test system

â‘  Mixture rutting and fatigue performance-trabecular fatigue test;

②Cracking performance of the mixture at low temperature—mainly adopts asphalt performance test control; in addition, indirect tensile test and creep test are also used for control.

Instruments: Australian IPC BFA pneumatic independent four-point bending trabecular fatigue tester (BFA)

Australia IPC BFA hydraulic independent four-point bending trabecular fatigue tester (BFA) way: under laboratory conditions, simulate the actual traffic conditions to carry out fatigue performance tests on asphalt mixtures, can complete a series of tests: indirect tensile stiffness Volume test, indirect tensile fatigue test, that is, cylinder split test, static creep test, dynamic creep test, and trabecular fatigue test, that is, three-point load bending test. In addition, soil dynamic triaxial test and asphalt triaxial test can also be completed.

(3) Low temperature cracking performance of the mixture in particularly cold areas

Instrument: Australian IPC company TSRST confined specimen temperature stress tester (TSRST)

Uses: To determine the temperature stress curve during the cooling process, to determine the low temperature fracture temperature and fracture strength of the asphalt mixture, as well as the slope and turning point temperature of the temperature stress curve.