This technical memorandum summarizes the analyses performed and the design recommended for the overlay thickness for a portion of Interstate 710 in Southern California. This design is a part of the “Long Life Pavement” system under consideration for this heavily trafficked freeway which serves the Port of Long Beach, California. The analyses consist of a series of finite element simulations performed on idealized representations of an asphalt concrete overlay on an existing plain, jointed, portland cement concrete (PCC) pavement in which the 8 inch thick existing slabs will be broken and seated prior to placement of the overlay. All of the finite element analyses were performed by Dr. Jeffrey Simons of Applied Research Associates (ARA) located in Sunnyvale, California.1 This report is complementary to the Technical Memorandum dated June 1999 which details the mix design and analysis and thickness design for the full-depth asphalt concrete section which will be placed in excavated sections under and adjacent to the bridge structures used as overcrossings for the freeway.

The purpose of this technical memorandum is to provide a summary of work that has contributed to the development of the simple shear test as a tool to evaluate the performance of asphalt concrete (AC) mixes. It is based primarily on investigations at the Pavement Research Center, University of California, Berkeley, related to the definition of the stiffness and permanent deformation characteristics of AC mixes. While the discussion is concentrated on the SHRP-developed simple shear test, some information is presented on the uniaxial and triaxial modes of loading as well. This discussion includes the following: 1. the mechanics of permanent deformation in AC; 2. factors to be considered in test selection including: representative volume element; non-linear response; test specimen preparation; and static versus dynamic loading. 3. use of the simple shear tests for mix evaluation including mix design This memorandum has been prepared to provide information related to activities at the national level directed to the development of a performance test to be included as part of the Superpave mix design and analysis procedure.

This report is one of a series detailing the results of the CAL/APT program, a research effort being performed jointly by the University of California, Berkeley Pavement Research Center and the California Department of Transportation (Caltrans). It contains an evaluation of the performance of asphalt treated permeable base (ATPB) in asphalt concrete pavements based on observation, laboratory testing of ATPB, and computer simulation of representative pavement structures. The evaluation includes: 1) a summary of Caltrans experience with ATPB and drainage systems relative to their development and implementation, together with observations of field performance with respect to maintainability and stripping of asphalt treated materials; 2) a summary of the characteristics and performance of ATPB materials and drainage systems used by two other highway agencies; 3) results of laboratory investigation of the stiffness and permanent deformation characteristics of ATPB mixes, including the effects of soaking and loading while saturated on these parameters; and 4) the results of analyses of representative pavement structures to quantify the expected effects of as-compacted and soaked ATPB on pavement performance.

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.