Application of Fly Ash in ASHphalt Concrete : from Challenges to Opportunities
Fly ash has been effectively used for many years in producing high performance concrete, with limited use in asphalt pavements. This is possibly because the performance benefits that fly ash provides to asphalt mixtures are under-investigated. The reported research investigated the interaction of fly ash with different types of asphalt binders and documented important improvements found in the critical properties of asphalt. Microstructural investigation demonstrated in previous work, that crack-arresting behavior was successfully induced by evenly distributed fly ash particles within the bitumen matrix. Investigation of the rheological performance of blends of asphalt binders with different types of ash using dynamic shear rheometer confirmed the feasibility of using fly ash to improve the performance of asphalt
A COOPERATIVE STUDY OF FILLERS IN ASPHALTIC CONCRETE
THIS WAS A COOPERATIVE INVESTIGATION BY A NUMBER OF STATE HIGHWAY LABORATORIES, THE PUBLIC ROADS BITUMINOUS LABORATORY AND THE CRUSHED STONE ASSOCIATION. THE PURPOSE OF THE STUDY WAS /1/ TO CORRELATE THE TEST RESULTS OF THE IMMERSION- COMPRESSION TEST FROM A NUMBER OF LABORATORIES, /2/ TO DETERMINE THE WATER-RESISTANT PROPERTIES OF BITUMINOUS CONCRETE MIXTURES COMPOSED OF VARIOUS TYPES OF COARSE AND FINE AGGREGATES, AND /3/ TO DETERMINE THE RELATIVE VALUE OF A NUMBER OF STONE DUSTS AND FLY-ASH MATERIALS AS FILLERS FOR BITUMINOUS CONCRETE. THIS STUDY PROVIDES CONCLUSIVE PROOF OF THE HIGH VALUE OF FLY-ASH AS A FILLER FOR BITUMINOUS CONCRETE PARTICULARILY WHEN EVALUATED ON THE BASIS OF THE STRENGTH AND WATER RESISTANT PROPERTIES OF THE MIXTURE. IT WAS PROPOSED, THAT, SINCE FLY-ASH FROM VARIOUS PRODUCERS DIFFER WIDELY THE MATERIAL SHOULD BE TESTED PRIOR TO USE. /AUTHOR/
APPLICATION OF THE FINITE ELEMENT METHOD TO ROTARY-WING AEROELASTICITY.
Recent research in rotary-wing aeroelasticity has indicated that all fundamental problems in this area are inherently nonlinear. The non-linearities in this problem are due to the inclusion of finite slopes, due to moderate deflections, in the structural, inertia and aerodynamic operators associated with this aeroelastic problem. In this paper the equations of motion, which are both time and space dependent, for the aeroelastic problem are first formulated in P.D.E. form. Next the equations are linearized about a suitable equilibrium position. The spatial dependence in these equations is discretized using a local Galerkin method of weighted residuals resulting in a finite element formulation of the aeroelastic problem. As an illustration the method is applied to the coupled flap-lag problem of a helicopter rotor blade in hover. Comparison of the solutions with previously published solutions establishes the convergence properties of the method. It is concluded that this formulation is a practical tool for solving rotary-wing aeroelastic stability or response problems.