The focus of this study was to determine the feasibility of using kaolin, a very small particle clay, as partial replacement of fine aggregates in Portland cement concrete (PCC). Kaolin clay is a locally available (Macon, GA, USA) and inexpensive clay mineral. The product, KaMin 90©, used has an average particle size of 1.5 microns and has a low embodied energy. The slump, air void content and compressive strength were examined on samples of PCC with different % of Kaolin. This research indicated the maximum kaolin substitution of fine aggregate for workability. An optimal dosage range for PCC cylinder compressive strength was also defined and found to be 33% greater than the control group. It was also noted that Kaolin engenders a soft and cohesive concrete mix that prevents segregation. A brief cost analyses was performed and determined the economic feasibility of Kaolin PCC.
Water splitting is one of the most promising technology to solve the current energy and environmental issues. The high overpotential and sluggish kinetics of the oxygen evolution reaction (OER) seriously hinders the energy conversion efficiency of the full water splitting. Therefore, it is of great significance to develop high-active and stable OER catalytic materials for improving the energy transfer efficiency and durability. In this work, we prepared the Ni(OH)2/stainless steel wire mesh (SSWM) self-supporting electrode by a simple one-step method. This in-situ growth method can accurate controllability for improving activity of the catalysts, efficaciously inhibit the self-aggregation of Ni(OH)2, and the obtained two-dimensional array of oriented nanosheets can quickly promote the acquisition of electrolytes and gas release. The integrated Ni(OH)2/SSWM electrodes possess prominent conductivity, abundant porous structure and high specific surface area. As OER catalysts, this obtained electrodes exhibit the relatively low overpotential of 223 mV and low Tafel slope of 25.2 mV dec -1 at 10 mA cm -2 . Moreover, the integrated Ni(OH)2/SSWM electrodes possess stable long-term performance (60 hours). Therefore, this research provides a novel strategy for large-scale production of highly active integrated OER electrodes.
The objective of this research was to investigate the influence of WMA additives on the properties of WMA binders through a series of laboratory testing such as viscosity, penetration, ductility, and softening points on the binders. The experimental design included the use of three WMA additives of Sasobit, Rediset, and Evotherm at a recommended content of 2, 2 and 0.6% respectively, two base binder sources, and one modified binder sources. The properties of WMA binders were compared to those of original asphalts without the additives as controls. Results from this study showed that: (1) Three WMA additives of Sasobit, Evotherm and Rediset increased the dynamic viscosity (60°C) of asphalt binders; (2) The additives of Evotherm and Rediset reduced the kinematic viscosity (130°C) of tested WMA asphalt binders. Adding 2 % Sasobit did not affect the kinematic viscosity; (3) Adding 2 % Sasobit reduced the penetration of WMA asphalt binder obviously. The most reduced rate of penetration is 22.7 % for SK base asphalt binder; (4) The WMA additives increased the softening point of WMA asphalt binders, except for the case with 0.6 % Evotherm. The effect of adding 2% Sasobit on the softening point of asphalt binders is the most significant, while the effect of adding 0.6 % Evotherm is the least; (5) adding 0.6 % Evotherm increased the ductility of warm asphalt binders by 28.6 %, while adding 2 % Sasobit reduced the ductility of warm asphalt binders obviously.
The objective of this study was to evaluate the effect of nano-sized hydrated lime on the moisture susceptibility of the hot mix asphalt (HMA) mixtures in terms of three methodologies to introduce into the mixtures. The experimental design for this study included the utilizations of one binder source (PG 64-22), three aggregate sources and three different methods introducing the lime. A total of 12 types of HMA mixtures and 72 specimens were fabricated and tested in this study. The performed properties include indirect tensile strength (ITS), tensile strength ratio (TSR), flow, and toughness. The results indicated that the nano-sized lime exhibits better moisture resistance. Introducing process of the nano-sized lime will produce difference in moisture susceptibility.
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