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Microwave irradiation can be used to heat conductive materials and metallocene precursors to initiate ultrafast CNT growth. It takes only 15-30 seconds to grow CNTs at room temperature in air, without the need for any inert gas protection and additional feed stock gases.

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Recycled Concrete Aggregates (RCAs) have inferior qualities compared with natural aggregates, mainly attributed to the porous nature of the attached cement mortar. To improve the quality of the RCAs, an environmentally friendly and cost-effective method is proposed to treat RCAs in this study. In this method, RCAs are first soaked in acetic acid solution, in which the acetic acid reacts with cement hydration products attached to the surface of the RCAs. This reaction weakens the attached mortar, making it possible to remove it from the RCAs by mechanical rubbing later. The treated RCAs have lower water absorption and less cement mortar attached. Once used as aggregates in new concrete, these RCAs can enhance the compressive strength of the concrete at 28 days up to 25%. It is safe and clean to apply this new method since no dangerous chemical is used and no detrimental chemicals are introduced into the treated RCAs. More importantly, zero hazardous waste solution is

A combined analytical and experimental study is conducted to develop efficient and effective damage detection techniques for beam-type structures. Unlike many other vibration-based damage detection methods, in which the mode shapes are often chosen to retrieve damage information, the uniform load surface (ULS) is employed in this study due to its less sensitivity to ambient noise. In combination with the ULS, two new damage detection algorithms, i.e., the generalized fractal dimension (GFD) and simplified gapped-smoothing (SGS) methods, are proposed. The GFD method is developed by modifying the conventional definition of fractal dimension. By using a moving window, the GFD of ULS can be obtained for each sampling point, and due to the irregularity of ULS introduced by the damage, a peak exists on the GFD curve indicating the location of the damage. Not only does such a peak at the GFD curve locate the damage, but also it reveals the relative size of the damage. The SGS method is also proposed to take advantage of the simple deformation shape of ULS. Both methods are then applied to the ULS of cracked and delaminated beams obtained analytically, from which the damage location and size are determined successfully. Based on the experimentally measured curvature mode shapes, both the GFD and SGS methods are further applied to detect three different types of damage in carbon/epoxy composite beams. The successful detection of damage in the composite beams demonstrates that the new techniques developed in this study can be used efficiently and effectively in damage identification and health monitoring of beam-type structures.