Faris Matalkah

Characterization of alkali-activated nonwood biomass ash-based geopolymer concrete

AbstractThe combustion ash of a common nonwood biomass (wheat straw) was evaluated for value-added use in production of geopolymer concrete where alkali aluminosilicate hydrates are the primary bin...

Robust, Carbon Nanotube/Polymer Nanolayered Composites with Enhanced Ductility and Strength

Robust, Carbon Nanotube/Polymer Nanolayered Composites with Enhanced Ductility and Strength A new class of robust, nanolayered, self-assembled composite was developed by sequential deposition of electrostatically dispersed negatively charged carbon nanotubes (CNT) (charges were introduced via polymer wrapping) and oppositely charged polyelectrolytes on a polyurethane scaffold and subsequent heating. Heat treatment allowed for the formation of amide bonds between carboxylic acid functionalities on CNT walls and amine groups of the polyelectrolyte resulting strong covalent bonded network (crosslinked) of self-assembled, nanolayered composite. This robust nanolayered composite demonstrated high tensile strength and enhanced ductility compared to that of original polyurethane scaffold. The self-assembled nanolayered composites, after complementary cross-linking steps, were found to provide a unique balance of strength and ductility, which surpassed those of conventional (micro-scale) composites.

High-recycled-content hydraulic cements of alternative chemistry for concrete production

ABSTRACT Sustainable hydraulic cements based on alkali aluminosilicate chemistry were developed with market-limited wastes acting as the primary aluminosilicate precursors. Two sets of formulations were developed with waste brick or impounded coal ash used at relatively large volume as aluminosilicate precursors. Supplementary materials were used to produce raw materials of viable chemistry. Blends of raw materials were transformed into hydraulic cements by input of mechanical energy without resorting to elevated temperatures. The resultant hydraulic cements exhibited viable strength development characteristics. FTIR, SEM, EDS and NMR analyses were conducted in order to gain insight into the structure of the hydraulic cements and their hydration products. The results pointed at the prevalence of calcium aluminosilicate hydrates among the products of hydration which thoroughly bound the non-hydrated cores of cement particles.

Effects of the Duration of Landfill Disposal on the Physicochemical, Mineralogical and Toxicity Characteristics of Coal Ash

ABSTRACT The quantities of coal ash disposed of in landfills over the past decades add up to billions of tons. Weathering in landfill would impact the mineralogical, chemical, physical and toxicity characteristics of coal ash. In order to investigate these effects, ashes were obtained from different depths of landfills representing different durations of disposal. These ashes were subjected to a range of physical, chemical, and toxicity tests. Aging in landfill was noted to produce significant changes in various ash properties. The trends in these changes with increasing disposal duration were identified. These trends were explained based on the weathering and leaching effects experienced by the coal ash in landfills. In addition, hydraulic activity and reactivity of the landfill coal ashes were determined to assess their potential use in alternate cement production.