Superpave grading for high traffic volumetric criteria
The Superpave mix design system is a comprehensive method of designing paving mixes determined by the traffic, climate, and structural section of a particular pavement site. The first project of the Superpave mix design in Malaysia was in 1996. The application was in the technical specifications for runway and taxiway pavement for Kuala Lumpur International Airport (KLIA) project. In the meantime, research work carried out by the Public Works Department (PWD) showed that distresses happened usually on heavily trafficked roads and becomes a major problem as axle loading increased. It is clearly shown that there are inabilities of conventional mix design methods to control the performance of materials. In conjunction with that, the Superpave has been proven in western countries as the best mix design method because it offers performance-based specification for asphalt pavement mixtures. For this reason, this method is selected for the laboratory mix design. After all, the aim of this research is to evaluate the properties of the Superpave mixture design using Malaysian materials. The properties of the mixture design intended to satisfy for heavy duty roadways. As a summary, several trial aggregate gradations were developed and initial trial asphalt content has been calculated for four categories; CLV, CHV, FLV, and FHV. And finally, three design aggregate structures are selected and it's has proven suits for heavy duty roadways volumetric criteria.
Asphalt Pavements: A Practical Guide to Design, Production and Maintenance for Engineers and Architects
Introduction. 1. Binders 2. Aggregates 3. Traffic and Environment 4. Pavement Structural Design 5. Mixture Design 6. Construction 7. Speciality: Asphalt Mixers 8. Pavement Distress 9. Pavement Maintenance 10. Estimating and Specifying Asphalt Pavements 11. Draft Parking Lot Specification Appendix A Appendix B Appendix C Appendix D Appendix E
Failure analysis for poor solderability of Au surface of PCB
Nonwetting is one of the common problems and is always rejected in electronic assemblies. ENIG pads of a PCBA exhibited nonwetting after lead-free reflow soldering. With the aid of stereomicroscope, SEM&EDS and XRF, a series of analysis was performed. And after visual inspection, surface and cross section analysis, thickness measurement and solderability test, it can be inferred that oxidation of plating surface was the main reason for nonwetting, and corrosion in Ni plating caused an adverse impact on solderalibity.