Alkali-silica reaction (ASR) is a detrimental reaction in concrete that may lead to severe expansion and cracking in structures. The Bibb Graves Bridge is a reinforced concrete bridge that was constructed in 1931, and is located in Wetumpka, Alabama, U.S.A. Both arches of Span 5 have severe cracking and surface deposits caused by ASR. In order to mitigate ASR, a silane-based surface sealer was applied to Spans 4 and 5 of this bridge. The goal of this mitigation procedure was to decrease the internal relative humidity of the ASR-affected concrete to less than 80 percent so that continued ASR-related expansions do not occur. After the execution of the mitigation procedure, the internal relative humidity, concrete expansion, and new crack development in the bridge were monitored for 35 months to evaluate the effectiveness of the mitigation procedure. Analysis of these data revealed few signs of decreasing relative humidity or decreased expansion rates in the ASR-affected concrete. It is concluded that the silane sealer was ineffective and alternative mitigation options should be considered.

The effects of magnesium, copper, and zinc substitutions on spinel ferrites have been investigated by the sol-gel technique. Ferrite compositions of Mg0,25xCu0,25xZn(1−0,5x)Fe2O4 (where x = 0.6, 0.7, 0.8 & 0.9) were prepared at a sintering temperature of 1100 ∘C with a presintering at 500 ∘C. X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-precision impedance analysis are used to characterize structural and dielectric properties, as well as the surface topography and morphology of the samples. A single phase, cubic spinel structure, with decreased lattice constant was observed. SEM micrographs revealed a homogeneous microstructure with uniform size distributions. Both the dielectric constant and dielectric loss tangent decrease, as the incident frequency increases up to a certain saturation point. The direct current (dc) resistivity profile shows that the resistivity increases with the temperature up to the Curie point, then it goes to a constant value. The quality factor (Q-factor) increases with the incident frequency. Hence, the high Q-factor will make ferrites highly useful in applications, especially in multilayer chip inductors.