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
Effect of Spray Dryer Absorber ( SDA ) Ash on the Performance of Warm Mix Asphalt ( WMA )
The field use of Coal Combustion Products (CCPs) in asphalt pavements (ASHphalt) has been limited. Few researchers have reported on the benefits of CCPs in asphalt and even fewer have reported on the benefits of Spray Dryer Absorber (SDA) materials in asphalt. The SDA materials are byproducts of flue gas desulfurization (FGD) air emission control processes that generally do not meet the ASTM C618 specifications for coal fly ash. This research investigates the effect of SDA material that was collected with subbituminous coal fly ash on asphalt properties with respect to laboratory measured performance indicators at the mixture level using the PG58-28 and PG52-34 unmodified Warm Mix Asphalt (WMA) binders. In this study, the SDA ash was introduced to an asphalt mixture at 10% binder replacement (by volume) and then compared to control mixtures. A 12.5 mm maximum aggregates blend was used to evaluate the characteristics of mixture. With respect to performance, all mixtures were tested for workability, aging resistance, indirecttension capacity, moisture damage resistance, fatigue resistance, and low-temperature thermal cracking resistance. 2017 World of Coal Ash (WOCA) Conference in Lexington, KY May 9-11, 2017 http://www.flyash.info/
ASR Potentials of Glass Aggregates in Water-Glass Activated Fly Ash and Portland Cement Mortars
The purpose of the present study was to use two solid wastes—fly ash and mixed color waste glass—as constituents in concrete materials. The fly ash with water glass as activation chemical was used as a binder in the concrete, and the waste glass particles were used as aggregate to replace nature aggregate. The present study focused on the potential of alkali-silica reaction (ASR) of glass aggregates used in portland cement mortar and in water-glass activated fly ash (WAFA) mortar. The ASR potential was examined using the accelerated testing method, ASTM C-1260. The results showed that with 10% substitution of natural aggregate by glass particles, the ASR expansion of portland cement mortar depends on the size of glass aggregate. The ASR expansion of WAFA mortar does not depend on the sizes of glass aggregate but on the content of glass aggregate. The ASR expansion of WAFA mortar was below the critical ASR expansion up to 100% of replacement by glass aggregate. The color of glass does not affect the ASR potential of WAFA mortar.